CA1170514A - Method for forming an anticorrosive coating on a metal substrate - Google Patents
Method for forming an anticorrosive coating on a metal substrateInfo
- Publication number
- CA1170514A CA1170514A CA000377139A CA377139A CA1170514A CA 1170514 A CA1170514 A CA 1170514A CA 000377139 A CA000377139 A CA 000377139A CA 377139 A CA377139 A CA 377139A CA 1170514 A CA1170514 A CA 1170514A
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- Canada
- Prior art keywords
- metal
- coating
- coated surface
- substrate
- coated
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C24/00—Coating starting from inorganic powder
- C23C24/08—Coating starting from inorganic powder by application of heat or pressure and heat
- C23C24/10—Coating starting from inorganic powder by application of heat or pressure and heat with intermediate formation of a liquid phase in the layer
- C23C24/103—Coating with metallic material, i.e. metals or metal alloys, optionally comprising hard particles, e.g. oxides, carbides or nitrides
- C23C24/106—Coating with metal alloys or metal elements only
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F7/00—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression
- B22F7/02—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite layers
- B22F7/04—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite layers with one or more layers not made from powder, e.g. made from solid metal
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
- C23C18/14—Decomposition by irradiation, e.g. photolysis, particle radiation or by mixed irradiation sources
- C23C18/143—Radiation by light, e.g. photolysis or pyrolysis
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
- C23C18/14—Decomposition by irradiation, e.g. photolysis, particle radiation or by mixed irradiation sources
- C23C18/145—Radiation by charged particles, e.g. electron beams or ion irradiation
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C24/00—Coating starting from inorganic powder
- C23C24/08—Coating starting from inorganic powder by application of heat or pressure and heat
Abstract
ABSTRACT OF THE DISCLOSURE
A method for forming an anticorrosive coating on the surface of a metal substrate, which comprises, in one embodiment, (1) coating the surface of the metal substrate with an anticorrosive metal capable of forming an alloy with the substrate metal and/or a hydride of the anticorrosive metal; (2) heating the coated surface, and then; (3) heating the coated surface in a vacuum or in an atmosphere substantially inert to the metal coating and the metal substrate by irradiating the coated surface with electron beams, laser beams or a plasma arc to sinter the coated metal and form an alloy layer in the interface between the metal substrate and the metal coating and, in another embodiment, subsequent to Step (2) and prior Step (3) above, coating the coated surface with a solution of a thermally decomposable platinum-group metal compound and then heating the resulting coated surface at about 40°C to about 600°C.
A method for forming an anticorrosive coating on the surface of a metal substrate, which comprises, in one embodiment, (1) coating the surface of the metal substrate with an anticorrosive metal capable of forming an alloy with the substrate metal and/or a hydride of the anticorrosive metal; (2) heating the coated surface, and then; (3) heating the coated surface in a vacuum or in an atmosphere substantially inert to the metal coating and the metal substrate by irradiating the coated surface with electron beams, laser beams or a plasma arc to sinter the coated metal and form an alloy layer in the interface between the metal substrate and the metal coating and, in another embodiment, subsequent to Step (2) and prior Step (3) above, coating the coated surface with a solution of a thermally decomposable platinum-group metal compound and then heating the resulting coated surface at about 40°C to about 600°C.
Description
~ 17051 4 This invention relates to a method for forming an anticorrosive metal coating on the surface of a metal substrate.
Metallic materials are used as elements, alloys or as composites in various mech~mical devices, chemical devices, etc., depending on their physical and chemical properties.
When they are used as parts which need to be corrosion resistant, only the surface of such parts needs to have sufficient corrosion resist:ance. It has been the practice, therefore, to coat the surface of a metal substrate with a material having superior corrosion resistance.
For example, it is known that titanium exhibits excellent corrosion resistance by forming a passive oxide film on the surface thereof. Thus, titanium has recently gained acceptance as a material for various machines, appliances and instruments such as chemical devices. In particular, in electrolysis app~ratus for sea water, brine, etc., pure titanium has been used widely as a material for an electrolytic cell or a substrate of an insoluble metallic electrode. However, since titanium i~
expensive, development of a method which permits a less expensive metal substrate t:o be covered with a thin titanium layer has long been desired. However, crevice cor-rosion, etc., still tends to occur with pure titanium. The _ I _ ~ 1 17051 4 corrosion resistance of pure titanium is still not suffi-cient when titanium is used as an electrode substrate in electrolysis of strongly acidic electrolytic solutions containing hydrochloric acid, sulfuric acid, etc.
Attempts have, therefore, been made to coat the surface of the titanium with a platinum-group metal, such as palladium, or a platinum-group metal alloy, or with anti-corrosive metals such as tantalum or niobium and alloys thereof.
various methods to form a coating of an anticorrosive metal on the surface of a metal substrate have been proposed. For example, Japanese Patent Publication No.
415/1968 and Japanese Patent Application (OPI) No.
19672/1975 disclose a method for preventing crevice corrosion by bonding a titanium-palladium alloy material to à titanium substrate by welding or the like. Bonding by welding, however, requires a high level of welding skill.
It i5 difficult, therefore, to apply this method to materials with a complex profile, and the strength of adhesion of such a material to the substrate is not entirely satisfactory.
On the other hand, various methods are known for depositing an anticorrosive material on the surface of a metal substrate by electroplating, chemical (electroless) plating, thermal decomposition, spraying, powder calcina-tion, vacul~ decomposition, etc., to coat the surface with such a material, and heat-treating the coated substrat~
(see, for example, Japanese Patent Publication Nos.
12882/1971, 2669/1973 and 24136/1973, and ~apanese Patent Application (OPI) Nos. 25641/1973, 143733/1975, 4736/1378 and 18433/1978).
.
1 17051 ~
According to these methods, the thickness of the coating can be made as thin as is required. However, formation of micropores in the coated layer cannot be avoided, and heat-treatmen1 must be performed in a~vacuum, etc., for a long period o.~ time. Because of these diffi-culties, prior art methods have not been able to provide products having a high degree of corrosion resistance and satisfactory adhesion of the coated layer to the substrate.
A major object of this invention is to overcome or mitigate the above-described difficulties of the prior art, and to provide a method for easily forming a compact anti-corrosive metal coating having adhesion and corrosion resistance on the surface of a metal substrate.
This invention, therefore, provides a method for forming an anticorrosive coating on the surface of a metal substrate, which comprises:
(1) coating the surface of the metal substrate with a powder of an anticorrosive metal capable of forming an alioy with the substrate metal and/or a powder of a hydride of the anti-corrosive metal;
Metallic materials are used as elements, alloys or as composites in various mech~mical devices, chemical devices, etc., depending on their physical and chemical properties.
When they are used as parts which need to be corrosion resistant, only the surface of such parts needs to have sufficient corrosion resist:ance. It has been the practice, therefore, to coat the surface of a metal substrate with a material having superior corrosion resistance.
For example, it is known that titanium exhibits excellent corrosion resistance by forming a passive oxide film on the surface thereof. Thus, titanium has recently gained acceptance as a material for various machines, appliances and instruments such as chemical devices. In particular, in electrolysis app~ratus for sea water, brine, etc., pure titanium has been used widely as a material for an electrolytic cell or a substrate of an insoluble metallic electrode. However, since titanium i~
expensive, development of a method which permits a less expensive metal substrate t:o be covered with a thin titanium layer has long been desired. However, crevice cor-rosion, etc., still tends to occur with pure titanium. The _ I _ ~ 1 17051 4 corrosion resistance of pure titanium is still not suffi-cient when titanium is used as an electrode substrate in electrolysis of strongly acidic electrolytic solutions containing hydrochloric acid, sulfuric acid, etc.
Attempts have, therefore, been made to coat the surface of the titanium with a platinum-group metal, such as palladium, or a platinum-group metal alloy, or with anti-corrosive metals such as tantalum or niobium and alloys thereof.
various methods to form a coating of an anticorrosive metal on the surface of a metal substrate have been proposed. For example, Japanese Patent Publication No.
415/1968 and Japanese Patent Application (OPI) No.
19672/1975 disclose a method for preventing crevice corrosion by bonding a titanium-palladium alloy material to à titanium substrate by welding or the like. Bonding by welding, however, requires a high level of welding skill.
It i5 difficult, therefore, to apply this method to materials with a complex profile, and the strength of adhesion of such a material to the substrate is not entirely satisfactory.
On the other hand, various methods are known for depositing an anticorrosive material on the surface of a metal substrate by electroplating, chemical (electroless) plating, thermal decomposition, spraying, powder calcina-tion, vacul~ decomposition, etc., to coat the surface with such a material, and heat-treating the coated substrat~
(see, for example, Japanese Patent Publication Nos.
12882/1971, 2669/1973 and 24136/1973, and ~apanese Patent Application (OPI) Nos. 25641/1973, 143733/1975, 4736/1378 and 18433/1978).
.
1 17051 ~
According to these methods, the thickness of the coating can be made as thin as is required. However, formation of micropores in the coated layer cannot be avoided, and heat-treatmen1 must be performed in a~vacuum, etc., for a long period o.~ time. Because of these diffi-culties, prior art methods have not been able to provide products having a high degree of corrosion resistance and satisfactory adhesion of the coated layer to the substrate.
A major object of this invention is to overcome or mitigate the above-described difficulties of the prior art, and to provide a method for easily forming a compact anti-corrosive metal coating having adhesion and corrosion resistance on the surface of a metal substrate.
This invention, therefore, provides a method for forming an anticorrosive coating on the surface of a metal substrate, which comprises:
(1) coating the surface of the metal substrate with a powder of an anticorrosive metal capable of forming an alioy with the substrate metal and/or a powder of a hydride of the anti-corrosive metal;
(2) heating the coated surface; and then
(3) heating the coated surface in a vacuum or in an atmosphere substantially inert to the metal coating and the metal substrate by irradiating the coated surace with electron beams, laser beams or a plasma arc to sinter the coated metal and form an alloy layer in the interface between the metal substrate and the metal coating.
Additionally this invention provides a method for forming an anticorrosive coating on the surface of a metal ~ i -" 117~5~ 4 substrate, which comprises:
(l) coating the surface of the metal substrate with a powder of an anticorrosive metal capable of forming an alloy with the substrate metal and/or a powder of a hydride of the anticorrosive metal;
(2) heating the coated surfacei (3) coating the coated surface with a solution of a thermally decomposable platinum-group metal compound;
Additionally this invention provides a method for forming an anticorrosive coating on the surface of a metal ~ i -" 117~5~ 4 substrate, which comprises:
(l) coating the surface of the metal substrate with a powder of an anticorrosive metal capable of forming an alloy with the substrate metal and/or a powder of a hydride of the anticorrosive metal;
(2) heating the coated surfacei (3) coating the coated surface with a solution of a thermally decomposable platinum-group metal compound;
(4) heating the resulting coated surface at about 40 to about 600C; and then
(5) heating the coated surface in a vacuum or in an atmosphere substantially inert to the metal coating and the metal substrate by irradj.ating the coated surface with electron beams, laser beam, or a plasma arc to sinter the coated metal and form an alloy layer in the interace between the metal substrate and the metal coating.
This invention has the particular advantage that a firmly adherent anticorrosive metal coating with sufficient corrosion resistance may De easily formed on the surface of a metal substrate which has insufficient corrosion resist-ance by forming an alloy lalyer in the interface between the metal substrate and the metal coating.
Furthermore, in accordance with this invention, since the coating of an anticorrosive metal is performed by a powder coating method and the sintering and heat treatment are performed using a high-energy source such as electron beams, high melting metals having a melting point of about 2,500C or more, such as tungsten, molybdenum, tantalum and niobium, can be easily emp:Loyed as a coating material and ,.~
-` ~170514 the coating treatment can be completed within a very short period of time.
The method of this invention, therefore, does not require long term high-temperature heat-treatment as in the prior art methods, and adverse oxidative or thermal effects on the substrate or metal coating can be markedly reduced.
Even after assembly of a particular device, a part of the device, as required, can easily be coated using the method of this invention.
A metal coating obtained by the method~of this inven-tion may be compact and have a sufficient corrosion resist-ance Furthermore, since the metal coating is formed by a powder sintering method, the coated surface has a moderate degree of roughness and good adhesion to an electrode active substance which subsequently might be coated thereon.
Accordingly, the coated metal substrate is especially suitable for use as an electrolysis electrode or an elec-trode substrate.
Suitable metal substrates which can be used i~ this invention may be any of those metal materials which are generally used in various apparatus, appliances and instruments, and there is no particular limitation on the nature of the metal substr.ate. Exemplary metal substrates include, for example, st:cuctural materials, electrically conductive materials, valve metals with corrosion resist-ance, such as titanium, tantalum, zirconium, and niobium, alloys composed mainly, e.g., containing more than about 50 % by weight, of these valve metals, for example, alloys such as l'i-Ta, Ti-Ta-Nb, Ti-Ta-Zr, Ti-Pd, etc., and less expensive metal materials with good workability, such as iron, nickel, cobalt, copper, alloys composed mainly, e.g., ~; , ~ 17051 4 ,~
containing more than about 50 % by weight, of these metals, for example, alloys such as steel, stainless steel, Ni-Cu, brass, etc. When the final coated product is to be used as an electrolysis electrode or a substrate therefore, titanium can be suitably used as an anode, and titanium, iron and nickel can be suitably used as a cathode.
Suitable metals which can be coated on the surface of - the substrate metal are any of those metals which have excellent corrosion resistance and can be alloyed with the substrate metal. Exemplary coating metals include tantalum, zirconium, niobium, titanium, molybdenum, tungsten, vanadium, chromium, nickel, silicon, and alloys composed - mainly of these metals, for example, alloys such as Ta-Ti, Nb-Ti, W-Ni, W-Mo, etc.
When the anticorrosive coating metal also has electrode activity, the resulting metal-coated product according to this invention can be directly used as an electrode. ~n example is a cathode for electrolysis of an aqueous solution comprising iron coated with nickel or tungsten. Suitable combinations of the substrate and the coating metal are, for example, a combination of a titanium or zirconium substrate and a tantalum or tungsten coating, and a combination of an iron or nickel substrate and a titanium, tantalum, niobium, zirconium or molybdenum coating or alloy thereof coating.
The coating of the anticorrosive metal on the surface of the metal substrate can be performed by a powder coating method. According to this powder coating method, a powder of the above-described anticorrosive metal as used in powder metallurgy or a hydride of the above-described anticorrosive metal, specific examples of which hydrides are set forth hereinafter, or a mixture thereof is added to a solvent, such as water and an alcohol, e.g., methanol, ethanol, propanol and butanol, together with a binder, such as dextrin, polyvinyl alcohol or carboxymethyl cellulose (CMC), to prepare a mixed solution. The thus-obtained mixed solution is then coated on a metal substrate using known techniques such as brush-coating, spray-coating and immer-sion-coating. Subsequent heat-treatment causes evaporation of the solvent, decomposition of the binder and organic substances, and decomposition of bonded hydrogen of the metal hydride, and coating and sintering of the anti-corrosive metal results. This powder coating method is described in detail in, for example, Japanese Patent Application (OPI) Nos. 25641/1973, 143733/1975 and 118636/1974.
Where the powder of the anticorrosive metal is not easy to use because of oxidation or the like, powders of metal hydrides, ~uch as TiH2, ZrH2, NbHX, TaHx and VHX, which are easily handled as a powder, are preerably used.
This particle size of the coating metal or hydride thereof preferably is about 0.15 mm or less, e.g., about 0.05 ~ to about 0.15 mm, because the smaller the particle size is, the more compact the coating becomes. The thickness of the metal coating suitably ranges from about 0.5 ~ to about 1 mm.
After coating of the anticorrosive metal and/or hydride thereof on the metal substrate, the coated sur~ace is heated by irradiation with electron beams, laser beams or a plasma arc to sinter the coating metal and, at the same time, to form an alloy layer between the metal substrate and the coat-~0 ing metal. It is believed that thé coated surface is raised to a high temperature in a very short period of time by irradiation with the high energy electron beam, laser beams "" 11705~ 4 or plasma arc, resulting in sintering of the metal powder.
At the same time, mutual diffusion and melting of metal atoms occurs in the interface between the metal substrate and the coating metal, resulting in the formation of a compact alloy layer and a firm bonding between the metal substrate and the coating metal.
Irradiation with electron beams, laser beams or a plasma arc can be performed using known techniques such as those heretofore used in welding, etc. Suitable irradiation techniques for electron beams, laser beams and a plasma arc are described in D.R. Dreger, "Pinpoint Hardening by Electron Beams", Machine Desiqn, 89, oct. 26, 1978, "Heat Treating in a Flash", Production, 56, Nov. 1978, and Gary C.
Irons, "Laser Fusing of Flamed Sprayed Coatings", Welding Journal, Dec. 30, 1978, pp 29-32. In the method of this invention, such conventional means may be performed with appropriate choices of irradiation conditions such as the intensity of the radiation and irradiation time, which provide the energy required for alloying at the interface, depending on the type of the metal used. In this way, the coated surface can be easily heated to about 1,000C to about 2,800C. For example, the technique described in Japanese Patent Application (OPI) No. 20988/1977 can be used.
The electron beam acceleration voltage usually ranges from about several killovolts (e.g., about 2 KV) to about 200 KV, and the current value ranges from about several milliamperes, (e.g., about 2mA) to about several amperes (e.g., about 3A).
0 Irradiation with laser beams is preferably carried out at an acceleratlon voltage of from about several hundred watts (e.g., about 100W) to about several killowatts (e.g., about 5KW) in a vacuum of about 10 3 to 10 6 Torr or in an atmosphere of an inert gas, such as argon, helium, etc.
Irradiation with laser beams is preferably carried out at a current value of about 1 A to about 1 KA at an argon gas pressure of from about 1 Kg/cm2 to about 10 Kg/cm2, and in an atmosphere of argon gas. Helium gas or a vacuum of lO 4 Torr or more can also be used.
Irradiation with electron beams should ~e effected in a vacuum e.g., 10 Torr or more or in an inert atmosphere such as of helium, etc.
The terms "vacuum" and "inert atmosphere" as used in this invention denote any atmosphere which does not impede irradiation of electron beams or the like, and does not give rise to any difficulties due to the reaction of gas in the atmosphere with the metal coating during the irradiation treatment. Thus, sometimes, air may be employed and is included within this definition. Preferably, the irradia-tion of electron beams is in a vacuum of a degree of vacuum of about 10-2 to 10-7 Torr.
In one embodiment of the method of this invention, before the coated surface of the metal and/or a hydride thereof formed by the powder coating method is heated by irradiation with electron beams or the like, an additional step is performed which comprises coating a solution of a thermally decomposable platinum-group metal compound on the coated surface and heating this coating to about 40 to 600C. By performing this additional step, the platinum-group metal compound penetrates into the micropores or interstices present in the metal coating formed by the 0 powder coating method, and the platinum-group metal with corrosion resistance, which results from thermal decomposition and reduction of the platinum-group metal compound by heat-treatment through irradiation with electron beams or the like, is embedded in the metal coating. Thus, the metal coating becomes more compact, and the corrosion resistance of the metal coating is further improved.
Examples of suitable thermally decomposable platinum-group metal compounds which can be used include halogen-compounds or organic compounds of platinum, ruthenium, iridium, palladium or rhodium, e.g., RUCl3, RUCl4, H2PtCl6, platinum metal resinates (of Pt, Ir, Ru, etc.) or mixtures thereof. These compounds can be used as a solution in a suitable solvent e.g., in ethanol, propanol, butanol, water, etc. Solutions of such compounds are well known and used in manufacturing insoluble metal electrodes. Suitable specific examples are described in detail in Japanese Patent Publication No. 3954/1973 corresponding to U.S. Patent 3,711,385.
In another embodiment of the method of this invention, after the irradiation with electron beams, laser beams or a plasma arc, if desired, the coated surface can be subjected to a rolling-treatment at a pressure of from about 5 Kg/cm2 to about 200 kg/cm2 by using compression rolls. This rolling-treatment reduces the voids present in the coated metal layer, formed by the powder coating and heat-sintering treatment, thereby increasing the compactne~s and further improving the corrosion resistance and strength of a &esion.
This rolling-treatment is, therefore, particularly useful where a powder having a relatively large particle size is employed in the powder coating. Furthermore, the resulting 0 coated surface becomes smooth, and it is suitable for coating of apparatuses and instruments. Furthermore, by heating using additional irradiation with electron beams or '- 117~51 4 the like after the rolling-trea-tment, the, strength of adhesion and the compactness of the metal coating can be further increased.
The following examples are given to illustrate this invention more specifically. It should be understood that these examples are not in any way intended to be interpreted as limiting the scope of this invention. Unless otherwise indicated herein, all parts, percents, ratios and the like are by weight.
Example 1 The surface of a mild steel plate (SS-41)(200 x 100 x 2 mm) was degreased and washed with hydrochloric acid. A mixed solution of 50 parts by weight of titanium hydride powder having a particle size of 0.044 mm or less, 25 parts by weight of polyvinyl alcohol and 25 parts by weight of water was coated on the above-described cleaned surface in a dry thickness of ahout 120 ~ by spraying and then fully heated in a vacuum of about 10 4 Torr at 500C. The coated s,urface was then irradiated with electron beams under the conditions indicated in Table 1 below.
Table 1 Electron Beam Irradiation Conditions Voltage 100 KV
Current 15 mA
Sample Movement Speed 0.2 m/minute Irradiation Distance 1.2 m Electron Beam Diameter 5 x 20 mm (oval) -"` 1170514 After irradiation with the electron beams, the micro-pores in the titanium coating layer were reduced, an about 20 to 30 ~ thick alloy layer was formed in the interface between the mild steel plate and the titanium coating layer, and the titanium coating layer was firmly bonded to the mild steel plate.
The thus-obtained sample was subjected to corrosion resistance testing under the conditions shown in Table 2 below. For comparison, a mild steel plate (SS-41) which had not been subjected to this titanium coating treatment was tested for corrosion resistance under the same conditions as above.
Table 2 Corrosion Resistance Test Conditions Corrosion Solution 25 % Aqueous Solution of Hydrochloric Acid Temperature 80C
Time 10 minutes The sample prepared in accordance with this invention ~howed a weight loss of 7.5 mg/cm2, whereas the comparative sample without the titanium coating showed a weight loss of 58.0 mg/cm2. Thus, the coating of titanium by powder coating and irradiation with electron beams was found to markedly increase corrosion resistance.
Example 2 The surface of a commercially available pure titanium plate (100 x 50 x 3 mm) was etched with hydrochloric acid, and a mixed solution of 3 parts by weight of titanium hydride powder having a particle size of 2 to 3 ~, 47 parts by weight of tungsten powder having a particle size of 2 to 3 ~, 1 part by weight of dextrin and 49 parts by weight of water was coated on the etched surface of the titanium plate in a dry thickness of about 50 ~ by spraying.
The thus-coated surface was subjected to a heat-treatment in a vacuum oven (10 1 to 10 2 Torr) at 700C for about 1 hour.
Subsequently, the coated surface was irradiated with electron beams in a vacuum of 10 4 Torr under the conditions shown in Table 3 below.
Table 3 Electron Beam Irradiation Conditions Voltage 12KV
Current 0.4 A
Sample Movement 10 mm/sec Speed Irradiation 1.2 m Distance Electron Beam 20 mm Diameter The thus-irradiated surface was subjected to a rolling-treatment at a pressure of 50 Kg/cm2 by using a rolling machine, and it was additionally irradiated with electron beams under the same conditions as indicated in Table 3 above.
The thus-obtained sample according to this invention and a comparative sample, a titanium plate without any coating, were tested for corrosion resistance under the conditions shown in Table 4.
--` 117051 4 Table 4 Corrosion Resistance Test Conditions Corrosive Solution 15 % Aqueous Solution ` of Hydrochloric Acid Temperature 60C
Time 48 hours The rate of corrosion of the comparative sample was O.01 mg/hr/cm2, whereas that of the sample according to this invention was 0.001 mg/hr/cm . Thus, these results demonstrate that the coating in accordance to the method of this invention markedly increased corrosion resistance.
ExamPle 3 A titanium plate (200 x 100 x 1.5 mm) was degreased and washed with hydrochloric acid. A mixed solution of 45 parts by weight of tantalum powder having a particle size of o.a4 mm or less, S parts by weight of titanium hydride having a particle size of 0.44 mm or less, 25 parts by weigh~ of polyvinyl alcohol and 25 parts by weight of water was coated on the àbove-described titanium plate in a dry thickness of about 100 ~ with a brush. The coated surface was fully dried by heating at 500C in a vacuum of about 10 4 Torr and then irradiated with laser beams under the conditions shown in Table 5.
Table 5 Laser Beam Irradiation Conditions Beam Output 500 W
Beam Dimension 10.2 x 0.3 mm Sample Movement 15 mm/second Speed ~o The irradiation with the laser beams was carried out in air. During this irradiation, argon gas was blown onto the 1 17~51 4 ,,.,~
coated surface so that the surface metal was not oxidized or protected against oxidation.
Subse~uently, the plate was subjected to a rolling treatment at a pressure of 10 Kg~cm2 using a roll machine, and the plate was then irradiated with laser beams under the conditions shown in Table 5 above.
Electron microscopic observation revealed that prior to the irradiation with laser beams of the tantalum and a small amount of titanium-coated titanlum plate, the coating layer contained a number of micropores, and the adhesion between the substrate and the coating layer was insufficient.
It was also found that after irradiation with laser beams according to the method of this invention, almost all o the micropores present in the coating layer of the above-obtained coated titanium plate had been eliminated, and thesintering o tantalum and titanium powder, and the formation of an alloy layer in the interface between the titanium ~ub~trate and the sintered coating layer were effected sufficiently.
Next, an electrode coating solution having the composi-tion shown in Table 6 below was coated on the above-obtained tantalum-titanium coated titanium plate as an electrode substrate and heated in air at 450C to form an electrolysis anode coated with a mixed oxide of a noble metal and a valve metal.
Table 6 Electrode Coatinq Solution Iridium Trichloride 2 g Tantalum Tetrachloride 1.5 g 10 % Aqueous Solution 10 ml -, of Hydrochloric Acid ,,.~. . ' :
For comparison, an electrode coating solution having a composition shown in Table 6 above was coated on a titanium plate without a tantalum-titanium coating to form a compara-tive anode.
The thus-obtained electrolysis anode, produced according to the method of this invention and the compara-tive anode were subjected to electrolysis testing under the conditions shown in Table 7 below. A carbon plate was used as a cathode.
lo Table 7 ElectroYlsis Test Conditions Electrolyte Solution 10 % Aqueous Solution of Sulfuric ~cid Current Density 15 A/dm2 Temperature 40 - 50C
With the comparative sample, an increase in electroly-sis voltage was observed after the sample was used in electrolysis for about 12 months, whereas with the anode sample prepared according to the method of this invention, no appreciable increase in electrolysis voltage was observed after electrolysis for about 15 months. Thus, it can be seen that the coated substrate prepared according to this invention has excellent properties as an anode substrate for electrolysis of sulfuric acid.
Exam~le 4 The surface of a mild steel plate (SS-41)(200 x 100 x 2 mm) was degreased and washed with hydrochloric acid. A
mixed solution of 50 parts by weight of niobium hydride powder having a particle size of 0.074 mm or less, 25 parts by weight of polyvinyl alcohol and 25 parts by weight of water was coated on the surface of the mild ~ 17~ 4 steel plate in a dry thickness of about 100 ~ with a brush and fully dried by heating in ~acuum of about 10 4 Torr at 500~C.
The thus-coated surface was irradiated with a plasma arc under the conditions shown in Table 8 below using a plasma torch, and the resulting coated surface was then cold-rolled at a pressure of 5 Kg/cm2.
Table 8 Plasma Arc Irradiation Conditions Argon Gas Pressure 2 Kg/cm Current 70 - 80 A
Irradiation Time 5 - lO seconds The thus-obtained sample and a mild steel plate (SS-41) without a niobium coating were corrosion resistance tested under the conditions shown in Table 2 of Example 1.
The sample prepared by the method of this invention showed a weight loss of 3.2 mg/cm2, whereas the comparative sample showed a weight loss of 58.0 mg/cm2. Thus, it can be seen that the coating of niobium produced in accordance with the method of this invention markedly increased corrosion resistance.
ExamPle 5 A nickel plate (100 x 50 x 2 mm) was degreased and cleaned. A mixed solution of 40 parts by weight of titanium powder having a particle size of 0.15 mm or less, 20 parts by weight of titanium hydride having a particle slze of O.044 mm or less, 20 parts by weight of polyvinyl alcohol and 20 parts by weight of water was coated on the cleaned surface of the plate in a dry thickness of about 100 ~ using a brush.
- 1170~1~
`- The thus-coated surface was fully heated in a vacuum at about 500~C, and a platinum-group metal compound solution having the composition shown in Table 9 below was then coated on the coated-surface by spraying and fully dried at about 50C.
Table 9 Platinum-Grou~ Metal Compound Solution Palladium Chloride 2 g Ethyl Alcohol 5 g Hydrochloric Acid 5 g (20% aq. soln.) Subsequently, the coated surface was irradiated with electron beams in a vacuum of 10 4 Torr under the conditions shown in Table lO below.
Table 10 Electron Beam Irradiation Conditions Voltage 80 KV
Current 12 mA
Sample Movement Speed 50 cm/minute Irradiation Distance l.O m Electron Beam Diameter 2 mm The thus-obtained sample was corrosion resistance tested under the conditions shown in Table 4 of Example 2.
For comparison, a nickel plate without a coating was tested in the same manner.
With the comparative sample, the rate of corrosion was 0.5 mg/hr/cm2, whereas with the sample prepared in accord-ance with this invention, the rate of corrosion was 0.005 mg/hr/cm2. Thus this demonstrates that the sample according to this invention has improved corrosion resistance.
, --` 1 1705~ 4 While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein withcut departing from the spirit and scope thereof.
~J
This invention has the particular advantage that a firmly adherent anticorrosive metal coating with sufficient corrosion resistance may De easily formed on the surface of a metal substrate which has insufficient corrosion resist-ance by forming an alloy lalyer in the interface between the metal substrate and the metal coating.
Furthermore, in accordance with this invention, since the coating of an anticorrosive metal is performed by a powder coating method and the sintering and heat treatment are performed using a high-energy source such as electron beams, high melting metals having a melting point of about 2,500C or more, such as tungsten, molybdenum, tantalum and niobium, can be easily emp:Loyed as a coating material and ,.~
-` ~170514 the coating treatment can be completed within a very short period of time.
The method of this invention, therefore, does not require long term high-temperature heat-treatment as in the prior art methods, and adverse oxidative or thermal effects on the substrate or metal coating can be markedly reduced.
Even after assembly of a particular device, a part of the device, as required, can easily be coated using the method of this invention.
A metal coating obtained by the method~of this inven-tion may be compact and have a sufficient corrosion resist-ance Furthermore, since the metal coating is formed by a powder sintering method, the coated surface has a moderate degree of roughness and good adhesion to an electrode active substance which subsequently might be coated thereon.
Accordingly, the coated metal substrate is especially suitable for use as an electrolysis electrode or an elec-trode substrate.
Suitable metal substrates which can be used i~ this invention may be any of those metal materials which are generally used in various apparatus, appliances and instruments, and there is no particular limitation on the nature of the metal substr.ate. Exemplary metal substrates include, for example, st:cuctural materials, electrically conductive materials, valve metals with corrosion resist-ance, such as titanium, tantalum, zirconium, and niobium, alloys composed mainly, e.g., containing more than about 50 % by weight, of these valve metals, for example, alloys such as l'i-Ta, Ti-Ta-Nb, Ti-Ta-Zr, Ti-Pd, etc., and less expensive metal materials with good workability, such as iron, nickel, cobalt, copper, alloys composed mainly, e.g., ~; , ~ 17051 4 ,~
containing more than about 50 % by weight, of these metals, for example, alloys such as steel, stainless steel, Ni-Cu, brass, etc. When the final coated product is to be used as an electrolysis electrode or a substrate therefore, titanium can be suitably used as an anode, and titanium, iron and nickel can be suitably used as a cathode.
Suitable metals which can be coated on the surface of - the substrate metal are any of those metals which have excellent corrosion resistance and can be alloyed with the substrate metal. Exemplary coating metals include tantalum, zirconium, niobium, titanium, molybdenum, tungsten, vanadium, chromium, nickel, silicon, and alloys composed - mainly of these metals, for example, alloys such as Ta-Ti, Nb-Ti, W-Ni, W-Mo, etc.
When the anticorrosive coating metal also has electrode activity, the resulting metal-coated product according to this invention can be directly used as an electrode. ~n example is a cathode for electrolysis of an aqueous solution comprising iron coated with nickel or tungsten. Suitable combinations of the substrate and the coating metal are, for example, a combination of a titanium or zirconium substrate and a tantalum or tungsten coating, and a combination of an iron or nickel substrate and a titanium, tantalum, niobium, zirconium or molybdenum coating or alloy thereof coating.
The coating of the anticorrosive metal on the surface of the metal substrate can be performed by a powder coating method. According to this powder coating method, a powder of the above-described anticorrosive metal as used in powder metallurgy or a hydride of the above-described anticorrosive metal, specific examples of which hydrides are set forth hereinafter, or a mixture thereof is added to a solvent, such as water and an alcohol, e.g., methanol, ethanol, propanol and butanol, together with a binder, such as dextrin, polyvinyl alcohol or carboxymethyl cellulose (CMC), to prepare a mixed solution. The thus-obtained mixed solution is then coated on a metal substrate using known techniques such as brush-coating, spray-coating and immer-sion-coating. Subsequent heat-treatment causes evaporation of the solvent, decomposition of the binder and organic substances, and decomposition of bonded hydrogen of the metal hydride, and coating and sintering of the anti-corrosive metal results. This powder coating method is described in detail in, for example, Japanese Patent Application (OPI) Nos. 25641/1973, 143733/1975 and 118636/1974.
Where the powder of the anticorrosive metal is not easy to use because of oxidation or the like, powders of metal hydrides, ~uch as TiH2, ZrH2, NbHX, TaHx and VHX, which are easily handled as a powder, are preerably used.
This particle size of the coating metal or hydride thereof preferably is about 0.15 mm or less, e.g., about 0.05 ~ to about 0.15 mm, because the smaller the particle size is, the more compact the coating becomes. The thickness of the metal coating suitably ranges from about 0.5 ~ to about 1 mm.
After coating of the anticorrosive metal and/or hydride thereof on the metal substrate, the coated sur~ace is heated by irradiation with electron beams, laser beams or a plasma arc to sinter the coating metal and, at the same time, to form an alloy layer between the metal substrate and the coat-~0 ing metal. It is believed that thé coated surface is raised to a high temperature in a very short period of time by irradiation with the high energy electron beam, laser beams "" 11705~ 4 or plasma arc, resulting in sintering of the metal powder.
At the same time, mutual diffusion and melting of metal atoms occurs in the interface between the metal substrate and the coating metal, resulting in the formation of a compact alloy layer and a firm bonding between the metal substrate and the coating metal.
Irradiation with electron beams, laser beams or a plasma arc can be performed using known techniques such as those heretofore used in welding, etc. Suitable irradiation techniques for electron beams, laser beams and a plasma arc are described in D.R. Dreger, "Pinpoint Hardening by Electron Beams", Machine Desiqn, 89, oct. 26, 1978, "Heat Treating in a Flash", Production, 56, Nov. 1978, and Gary C.
Irons, "Laser Fusing of Flamed Sprayed Coatings", Welding Journal, Dec. 30, 1978, pp 29-32. In the method of this invention, such conventional means may be performed with appropriate choices of irradiation conditions such as the intensity of the radiation and irradiation time, which provide the energy required for alloying at the interface, depending on the type of the metal used. In this way, the coated surface can be easily heated to about 1,000C to about 2,800C. For example, the technique described in Japanese Patent Application (OPI) No. 20988/1977 can be used.
The electron beam acceleration voltage usually ranges from about several killovolts (e.g., about 2 KV) to about 200 KV, and the current value ranges from about several milliamperes, (e.g., about 2mA) to about several amperes (e.g., about 3A).
0 Irradiation with laser beams is preferably carried out at an acceleratlon voltage of from about several hundred watts (e.g., about 100W) to about several killowatts (e.g., about 5KW) in a vacuum of about 10 3 to 10 6 Torr or in an atmosphere of an inert gas, such as argon, helium, etc.
Irradiation with laser beams is preferably carried out at a current value of about 1 A to about 1 KA at an argon gas pressure of from about 1 Kg/cm2 to about 10 Kg/cm2, and in an atmosphere of argon gas. Helium gas or a vacuum of lO 4 Torr or more can also be used.
Irradiation with electron beams should ~e effected in a vacuum e.g., 10 Torr or more or in an inert atmosphere such as of helium, etc.
The terms "vacuum" and "inert atmosphere" as used in this invention denote any atmosphere which does not impede irradiation of electron beams or the like, and does not give rise to any difficulties due to the reaction of gas in the atmosphere with the metal coating during the irradiation treatment. Thus, sometimes, air may be employed and is included within this definition. Preferably, the irradia-tion of electron beams is in a vacuum of a degree of vacuum of about 10-2 to 10-7 Torr.
In one embodiment of the method of this invention, before the coated surface of the metal and/or a hydride thereof formed by the powder coating method is heated by irradiation with electron beams or the like, an additional step is performed which comprises coating a solution of a thermally decomposable platinum-group metal compound on the coated surface and heating this coating to about 40 to 600C. By performing this additional step, the platinum-group metal compound penetrates into the micropores or interstices present in the metal coating formed by the 0 powder coating method, and the platinum-group metal with corrosion resistance, which results from thermal decomposition and reduction of the platinum-group metal compound by heat-treatment through irradiation with electron beams or the like, is embedded in the metal coating. Thus, the metal coating becomes more compact, and the corrosion resistance of the metal coating is further improved.
Examples of suitable thermally decomposable platinum-group metal compounds which can be used include halogen-compounds or organic compounds of platinum, ruthenium, iridium, palladium or rhodium, e.g., RUCl3, RUCl4, H2PtCl6, platinum metal resinates (of Pt, Ir, Ru, etc.) or mixtures thereof. These compounds can be used as a solution in a suitable solvent e.g., in ethanol, propanol, butanol, water, etc. Solutions of such compounds are well known and used in manufacturing insoluble metal electrodes. Suitable specific examples are described in detail in Japanese Patent Publication No. 3954/1973 corresponding to U.S. Patent 3,711,385.
In another embodiment of the method of this invention, after the irradiation with electron beams, laser beams or a plasma arc, if desired, the coated surface can be subjected to a rolling-treatment at a pressure of from about 5 Kg/cm2 to about 200 kg/cm2 by using compression rolls. This rolling-treatment reduces the voids present in the coated metal layer, formed by the powder coating and heat-sintering treatment, thereby increasing the compactne~s and further improving the corrosion resistance and strength of a &esion.
This rolling-treatment is, therefore, particularly useful where a powder having a relatively large particle size is employed in the powder coating. Furthermore, the resulting 0 coated surface becomes smooth, and it is suitable for coating of apparatuses and instruments. Furthermore, by heating using additional irradiation with electron beams or '- 117~51 4 the like after the rolling-trea-tment, the, strength of adhesion and the compactness of the metal coating can be further increased.
The following examples are given to illustrate this invention more specifically. It should be understood that these examples are not in any way intended to be interpreted as limiting the scope of this invention. Unless otherwise indicated herein, all parts, percents, ratios and the like are by weight.
Example 1 The surface of a mild steel plate (SS-41)(200 x 100 x 2 mm) was degreased and washed with hydrochloric acid. A mixed solution of 50 parts by weight of titanium hydride powder having a particle size of 0.044 mm or less, 25 parts by weight of polyvinyl alcohol and 25 parts by weight of water was coated on the above-described cleaned surface in a dry thickness of ahout 120 ~ by spraying and then fully heated in a vacuum of about 10 4 Torr at 500C. The coated s,urface was then irradiated with electron beams under the conditions indicated in Table 1 below.
Table 1 Electron Beam Irradiation Conditions Voltage 100 KV
Current 15 mA
Sample Movement Speed 0.2 m/minute Irradiation Distance 1.2 m Electron Beam Diameter 5 x 20 mm (oval) -"` 1170514 After irradiation with the electron beams, the micro-pores in the titanium coating layer were reduced, an about 20 to 30 ~ thick alloy layer was formed in the interface between the mild steel plate and the titanium coating layer, and the titanium coating layer was firmly bonded to the mild steel plate.
The thus-obtained sample was subjected to corrosion resistance testing under the conditions shown in Table 2 below. For comparison, a mild steel plate (SS-41) which had not been subjected to this titanium coating treatment was tested for corrosion resistance under the same conditions as above.
Table 2 Corrosion Resistance Test Conditions Corrosion Solution 25 % Aqueous Solution of Hydrochloric Acid Temperature 80C
Time 10 minutes The sample prepared in accordance with this invention ~howed a weight loss of 7.5 mg/cm2, whereas the comparative sample without the titanium coating showed a weight loss of 58.0 mg/cm2. Thus, the coating of titanium by powder coating and irradiation with electron beams was found to markedly increase corrosion resistance.
Example 2 The surface of a commercially available pure titanium plate (100 x 50 x 3 mm) was etched with hydrochloric acid, and a mixed solution of 3 parts by weight of titanium hydride powder having a particle size of 2 to 3 ~, 47 parts by weight of tungsten powder having a particle size of 2 to 3 ~, 1 part by weight of dextrin and 49 parts by weight of water was coated on the etched surface of the titanium plate in a dry thickness of about 50 ~ by spraying.
The thus-coated surface was subjected to a heat-treatment in a vacuum oven (10 1 to 10 2 Torr) at 700C for about 1 hour.
Subsequently, the coated surface was irradiated with electron beams in a vacuum of 10 4 Torr under the conditions shown in Table 3 below.
Table 3 Electron Beam Irradiation Conditions Voltage 12KV
Current 0.4 A
Sample Movement 10 mm/sec Speed Irradiation 1.2 m Distance Electron Beam 20 mm Diameter The thus-irradiated surface was subjected to a rolling-treatment at a pressure of 50 Kg/cm2 by using a rolling machine, and it was additionally irradiated with electron beams under the same conditions as indicated in Table 3 above.
The thus-obtained sample according to this invention and a comparative sample, a titanium plate without any coating, were tested for corrosion resistance under the conditions shown in Table 4.
--` 117051 4 Table 4 Corrosion Resistance Test Conditions Corrosive Solution 15 % Aqueous Solution ` of Hydrochloric Acid Temperature 60C
Time 48 hours The rate of corrosion of the comparative sample was O.01 mg/hr/cm2, whereas that of the sample according to this invention was 0.001 mg/hr/cm . Thus, these results demonstrate that the coating in accordance to the method of this invention markedly increased corrosion resistance.
ExamPle 3 A titanium plate (200 x 100 x 1.5 mm) was degreased and washed with hydrochloric acid. A mixed solution of 45 parts by weight of tantalum powder having a particle size of o.a4 mm or less, S parts by weight of titanium hydride having a particle size of 0.44 mm or less, 25 parts by weigh~ of polyvinyl alcohol and 25 parts by weight of water was coated on the àbove-described titanium plate in a dry thickness of about 100 ~ with a brush. The coated surface was fully dried by heating at 500C in a vacuum of about 10 4 Torr and then irradiated with laser beams under the conditions shown in Table 5.
Table 5 Laser Beam Irradiation Conditions Beam Output 500 W
Beam Dimension 10.2 x 0.3 mm Sample Movement 15 mm/second Speed ~o The irradiation with the laser beams was carried out in air. During this irradiation, argon gas was blown onto the 1 17~51 4 ,,.,~
coated surface so that the surface metal was not oxidized or protected against oxidation.
Subse~uently, the plate was subjected to a rolling treatment at a pressure of 10 Kg~cm2 using a roll machine, and the plate was then irradiated with laser beams under the conditions shown in Table 5 above.
Electron microscopic observation revealed that prior to the irradiation with laser beams of the tantalum and a small amount of titanium-coated titanlum plate, the coating layer contained a number of micropores, and the adhesion between the substrate and the coating layer was insufficient.
It was also found that after irradiation with laser beams according to the method of this invention, almost all o the micropores present in the coating layer of the above-obtained coated titanium plate had been eliminated, and thesintering o tantalum and titanium powder, and the formation of an alloy layer in the interface between the titanium ~ub~trate and the sintered coating layer were effected sufficiently.
Next, an electrode coating solution having the composi-tion shown in Table 6 below was coated on the above-obtained tantalum-titanium coated titanium plate as an electrode substrate and heated in air at 450C to form an electrolysis anode coated with a mixed oxide of a noble metal and a valve metal.
Table 6 Electrode Coatinq Solution Iridium Trichloride 2 g Tantalum Tetrachloride 1.5 g 10 % Aqueous Solution 10 ml -, of Hydrochloric Acid ,,.~. . ' :
For comparison, an electrode coating solution having a composition shown in Table 6 above was coated on a titanium plate without a tantalum-titanium coating to form a compara-tive anode.
The thus-obtained electrolysis anode, produced according to the method of this invention and the compara-tive anode were subjected to electrolysis testing under the conditions shown in Table 7 below. A carbon plate was used as a cathode.
lo Table 7 ElectroYlsis Test Conditions Electrolyte Solution 10 % Aqueous Solution of Sulfuric ~cid Current Density 15 A/dm2 Temperature 40 - 50C
With the comparative sample, an increase in electroly-sis voltage was observed after the sample was used in electrolysis for about 12 months, whereas with the anode sample prepared according to the method of this invention, no appreciable increase in electrolysis voltage was observed after electrolysis for about 15 months. Thus, it can be seen that the coated substrate prepared according to this invention has excellent properties as an anode substrate for electrolysis of sulfuric acid.
Exam~le 4 The surface of a mild steel plate (SS-41)(200 x 100 x 2 mm) was degreased and washed with hydrochloric acid. A
mixed solution of 50 parts by weight of niobium hydride powder having a particle size of 0.074 mm or less, 25 parts by weight of polyvinyl alcohol and 25 parts by weight of water was coated on the surface of the mild ~ 17~ 4 steel plate in a dry thickness of about 100 ~ with a brush and fully dried by heating in ~acuum of about 10 4 Torr at 500~C.
The thus-coated surface was irradiated with a plasma arc under the conditions shown in Table 8 below using a plasma torch, and the resulting coated surface was then cold-rolled at a pressure of 5 Kg/cm2.
Table 8 Plasma Arc Irradiation Conditions Argon Gas Pressure 2 Kg/cm Current 70 - 80 A
Irradiation Time 5 - lO seconds The thus-obtained sample and a mild steel plate (SS-41) without a niobium coating were corrosion resistance tested under the conditions shown in Table 2 of Example 1.
The sample prepared by the method of this invention showed a weight loss of 3.2 mg/cm2, whereas the comparative sample showed a weight loss of 58.0 mg/cm2. Thus, it can be seen that the coating of niobium produced in accordance with the method of this invention markedly increased corrosion resistance.
ExamPle 5 A nickel plate (100 x 50 x 2 mm) was degreased and cleaned. A mixed solution of 40 parts by weight of titanium powder having a particle size of 0.15 mm or less, 20 parts by weight of titanium hydride having a particle slze of O.044 mm or less, 20 parts by weight of polyvinyl alcohol and 20 parts by weight of water was coated on the cleaned surface of the plate in a dry thickness of about 100 ~ using a brush.
- 1170~1~
`- The thus-coated surface was fully heated in a vacuum at about 500~C, and a platinum-group metal compound solution having the composition shown in Table 9 below was then coated on the coated-surface by spraying and fully dried at about 50C.
Table 9 Platinum-Grou~ Metal Compound Solution Palladium Chloride 2 g Ethyl Alcohol 5 g Hydrochloric Acid 5 g (20% aq. soln.) Subsequently, the coated surface was irradiated with electron beams in a vacuum of 10 4 Torr under the conditions shown in Table lO below.
Table 10 Electron Beam Irradiation Conditions Voltage 80 KV
Current 12 mA
Sample Movement Speed 50 cm/minute Irradiation Distance l.O m Electron Beam Diameter 2 mm The thus-obtained sample was corrosion resistance tested under the conditions shown in Table 4 of Example 2.
For comparison, a nickel plate without a coating was tested in the same manner.
With the comparative sample, the rate of corrosion was 0.5 mg/hr/cm2, whereas with the sample prepared in accord-ance with this invention, the rate of corrosion was 0.005 mg/hr/cm2. Thus this demonstrates that the sample according to this invention has improved corrosion resistance.
, --` 1 1705~ 4 While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein withcut departing from the spirit and scope thereof.
~J
Claims (8)
1. A method for forming an anticorrosive coating on the surface of a metal substrate, which comprises:
(1) coating the surface of the metal substrate with a powder of an anticorrosive metal capable of forming an alloy with the substrate metal and/or a hydride of the anticorrosive metal;
(2) heating the coated surface; and then (3) heating the coated surface in a vacuum or in an atmosphere substantially inert to the metal coating and the metal substrate by irradiating the coated surface with electron beams, laser beams or a plasma arc to sinter the coated metal and form an alloy layer in the interface between the metal substrate and the metal coating.
(1) coating the surface of the metal substrate with a powder of an anticorrosive metal capable of forming an alloy with the substrate metal and/or a hydride of the anticorrosive metal;
(2) heating the coated surface; and then (3) heating the coated surface in a vacuum or in an atmosphere substantially inert to the metal coating and the metal substrate by irradiating the coated surface with electron beams, laser beams or a plasma arc to sinter the coated metal and form an alloy layer in the interface between the metal substrate and the metal coating.
2. A method for forming an anticorrosive coating on the surface of a metal substrate, which comprises:
(1) coating the surface of the metal substrate with a powder of an anticorrosive metal capable of forming an alloy with the substrate metal and/or a hydride of the anticorrosive metal;
(2) heating the coated surface;
(3) coating the coated surface with a solution of a thermally decomposable platinum-group metal compound;
(4) heating the resulting coated surface at about 40°C to about 600°C; and then (5) heating the coated surface in a vacuum or in an atmosphere substantially inert to the metal coating and the metal substrate by irradiating the coated surface with electron beams, laser beams or a plasma arc to sinter the coated metal and form an alloy layer in the interface between the metal substrate and the metal coating.
(1) coating the surface of the metal substrate with a powder of an anticorrosive metal capable of forming an alloy with the substrate metal and/or a hydride of the anticorrosive metal;
(2) heating the coated surface;
(3) coating the coated surface with a solution of a thermally decomposable platinum-group metal compound;
(4) heating the resulting coated surface at about 40°C to about 600°C; and then (5) heating the coated surface in a vacuum or in an atmosphere substantially inert to the metal coating and the metal substrate by irradiating the coated surface with electron beams, laser beams or a plasma arc to sinter the coated metal and form an alloy layer in the interface between the metal substrate and the metal coating.
3. The method as in Claim 1 , wherein after irradiation with the electron beams, laser beams or plasma arc, the method includes subjecting the coated surface to a rolling treatment.
4. The method as in Claim 3, wherein after said rolling treatment, the method includes heating the coated surface by irradiating the coated surface with electron beams, laser beams or a plasma arc.
5. The method as in Claim 1 or 2, wherein the metal substrate is titanium, tantalum, zirconium, niobium or an alloy composed mainly of these metals.
6. The method as in Claim 1 or 2, wherein the metal substrate is iron, nickel, cobalt, copper, or an alloy composed mainly of these metals.
7. The method as in Claim 1 or 2, wherein the anti-corrosive metal and/or the hydride of the metal is selected from the group consisting of tantalum, zirconium, niobium, titanium, molybdenum, tungsten, vanadium, chromium, nickel, silicon and hydrides thereof.
8. The method as in Claim 2, wherein the platinum-group metal compound is selected from the group consisting of halogen-compounds of and organic compounds of platinum, iridium, ruthenium, palladium and rhodium, and mixtures thereof.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62880/80 | 1980-05-14 | ||
| JP55062880A JPS5948873B2 (en) | 1980-05-14 | 1980-05-14 | Method for manufacturing electrode substrate or electrode provided with corrosion-resistant coating |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1170514A true CA1170514A (en) | 1984-07-10 |
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ID=13213013
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000377139A Expired CA1170514A (en) | 1980-05-14 | 1981-05-08 | Method for forming an anticorrosive coating on a metal substrate |
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| Country | Link |
|---|---|
| US (1) | US4400408A (en) |
| EP (1) | EP0040092B1 (en) |
| JP (1) | JPS5948873B2 (en) |
| CA (1) | CA1170514A (en) |
| DE (1) | DE3165203D1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111676476A (en) * | 2020-06-02 | 2020-09-18 | 江西瑞曼增材科技有限公司 | Method for preparing copper-chromium-zirconium slideway by laser 3D printing technology |
Families Citing this family (50)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3224810A1 (en) * | 1982-07-02 | 1984-01-05 | Siemens AG, 1000 Berlin und 8000 München | METHOD FOR PRODUCING HARD, WEAR-RESISTANT EDGE LAYERS ON A METAL MATERIAL |
| DE3234671C1 (en) * | 1982-09-18 | 1983-06-01 | Dornier System Gmbh, 7990 Friedrichshafen | Process for coating hydrogen storage material with palladium |
| DE3300449A1 (en) * | 1983-01-08 | 1984-07-12 | Philips Patentverwaltung Gmbh, 2000 Hamburg | METHOD FOR PRODUCING AN ELECTRODE FOR A HIGH PRESSURE GAS DISCHARGE LAMP |
| JPS6070136A (en) * | 1983-09-14 | 1985-04-20 | Honda Motor Co Ltd | Surface treatment of work |
| JPS60230986A (en) * | 1984-04-28 | 1985-11-16 | Mazda Motor Corp | Method for highly alloying metal of metallic surface |
| JPS60235773A (en) * | 1984-05-01 | 1985-11-22 | 株式会社豊田中央研究所 | Ceramic body bonding method |
| CH665349A5 (en) * | 1985-01-08 | 1988-05-13 | Sulzer Ag | METALLIC BONE IMPLANT. |
| JPS6213521A (en) * | 1985-07-09 | 1987-01-22 | Honda Motor Co Ltd | Wear resistant member and its production |
| LU86753A1 (en) * | 1987-01-30 | 1988-08-23 | Centre Rech Metallurgique | PROCESS FOR THE SURFACE TREATMENT OF A ROLLER CYLINDER |
| US4804815A (en) * | 1987-06-01 | 1989-02-14 | Quantum Laser Corporation | Process for welding nickel-based superalloys |
| SE463213B (en) * | 1988-05-06 | 1990-10-22 | Ibm Svenska Ab | DEVICE AND PROCEDURE TO ENSURE A METAL SUBSTRATE WITH A RESISTANT SURFACE |
| US5167791A (en) * | 1991-12-20 | 1992-12-01 | Xerox Corporation | Process for electrolytic deposition of iron |
| GB2285633B (en) * | 1994-01-11 | 1997-07-23 | Anjum Tauqir | Energy beams synthesize metal-carbide composite surfaces on mild steel substrates |
| CN1041490C (en) * | 1994-11-24 | 1999-01-06 | 中国科学院安徽光学精密机械研究所 | High-efficient automatic tobacco sheet production line by rolling method |
| US20040105999A1 (en) * | 1995-06-29 | 2004-06-03 | Stanley Abkowitz | Bi-metallic macro composite |
| US6139656A (en) * | 1995-07-10 | 2000-10-31 | Ford Global Technologies, Inc. | Electrochemical hardness modification of non-allotropic metal surfaces |
| DE29810483U1 (en) * | 1998-06-12 | 1999-10-14 | Micro Science Medical Ag | Surface implantation or surface coating for stents or other implants |
| US7045015B2 (en) | 1998-09-30 | 2006-05-16 | Optomec Design Company | Apparatuses and method for maskless mesoscale material deposition |
| FI20011116A (en) * | 2001-02-21 | 2002-08-22 | Fortum Oyj | coating process |
| DK174876B1 (en) * | 2001-02-26 | 2004-01-12 | Danfoss As | Implant and implant surface modification process |
| EP1402085A1 (en) * | 2001-05-28 | 2004-03-31 | Fortum OYJ | Laser coating of a seal surface used in an oil refinery |
| US6566665B2 (en) * | 2001-08-17 | 2003-05-20 | International Business Machines Corporation | Method and apparatus for linking and/or patterning self-assembled objects |
| KR100493887B1 (en) * | 2002-08-09 | 2005-06-08 | 한국과학기술연구원 | Clad sheets for corrosion resistance and fabricating method thereof |
| US7674671B2 (en) | 2004-12-13 | 2010-03-09 | Optomec Design Company | Aerodynamic jetting of aerosolized fluids for fabrication of passive structures |
| US20070154634A1 (en) * | 2005-12-15 | 2007-07-05 | Optomec Design Company | Method and Apparatus for Low-Temperature Plasma Sintering |
| US20070160759A1 (en) * | 2006-01-10 | 2007-07-12 | General Electric Company | Method for coating surfaces exposed to hydrocarbon fluids |
| US20070207328A1 (en) * | 2006-03-01 | 2007-09-06 | United Technologies Corporation | High density thermal barrier coating |
| US7458358B2 (en) * | 2006-05-10 | 2008-12-02 | Federal Mogul World Wide, Inc. | Thermal oxidation protective surface for steel pistons |
| JP5101838B2 (en) * | 2006-05-16 | 2012-12-19 | ヤンマー株式会社 | Surface hardening method for metal members |
| TWI482662B (en) | 2007-08-30 | 2015-05-01 | Optomec Inc | Mechanically integrated and closely coupled print head and mist source |
| US7883736B2 (en) * | 2007-09-06 | 2011-02-08 | Boston Scientific Scimed, Inc. | Endoprostheses having porous claddings prepared using metal hydrides |
| JP2009081223A (en) * | 2007-09-26 | 2009-04-16 | Tokyo Electron Ltd | Electrostatic chuck member |
| US20100297582A1 (en) * | 2007-09-26 | 2010-11-25 | Straumann Holding Ag | Dental implant system |
| WO2009088934A2 (en) * | 2007-12-31 | 2009-07-16 | University Of Utah Research Foundation | Processes for in-situ coating of metals |
| US20090274850A1 (en) * | 2008-05-01 | 2009-11-05 | United Technologies Corporation | Low cost non-line-of -sight protective coatings |
| DE102011000984A1 (en) * | 2011-03-01 | 2012-09-06 | Rasselstein Gmbh | Process for refining a metallic coating on a steel strip |
| CN102601362A (en) * | 2012-03-20 | 2012-07-25 | 清华大学 | Metal nanoparticle based hot interface material and preparation method of metal nanoparticle based hot interface material |
| CN103060797B (en) * | 2013-01-14 | 2015-01-07 | 北京工业大学 | Preparation method of plasma cladding high-entropy alloy coating layer |
| CN104357834A (en) * | 2014-10-17 | 2015-02-18 | 燕山大学 | Remanufacturing method for continuous casting roller |
| CN104451664B (en) * | 2014-11-27 | 2017-04-05 | 湖北汽车工业学院 | The preparation method of in-situ authigenic WC+TiC composite strengthening iron-based wear-resistant coatings |
| CN104593766B (en) * | 2014-12-15 | 2017-06-30 | 江苏中科大港激光科技有限公司 | A kind of laser preparation method on Coal Chemical Industry ball for ball valve erosion resistance top layer |
| EP3256308B1 (en) | 2015-02-10 | 2022-12-21 | Optomec, Inc. | Fabrication of three-dimensional structures by in-flight curing of aerosols |
| WO2017070922A1 (en) | 2015-10-30 | 2017-05-04 | Hewlett-Packard Development Company, L.P. | Sol‐gel hybrid coating composition, coating process and composite coating layers |
| CN105695989B (en) * | 2016-04-21 | 2018-05-25 | 黄山学院 | Laser cladding layer powder laying apparatus and mould steel laser cladding layer powder |
| CN107385193B (en) * | 2017-07-05 | 2019-03-01 | 温州大学激光与光电智能制造研究院 | A kind of raising combination treatment method of the metal component containing corrosion resistance in solutions of chlorine |
| US10236517B2 (en) * | 2017-08-16 | 2019-03-19 | GM Global Technology Operations LLC | Method for manufacturing and cleaning a stainless steel fuel cell bipolar plate |
| US10632746B2 (en) | 2017-11-13 | 2020-04-28 | Optomec, Inc. | Shuttering of aerosol streams |
| CN109093115B (en) * | 2018-09-05 | 2020-04-28 | 燕山大学 | Method for manufacturing gradient composite material by Cu surface laser additive |
| CN114351179A (en) * | 2021-12-02 | 2022-04-15 | 江苏友诺环保科技有限公司 | Iridium tantalum manganese coating titanium anode plate with intermediate layer and preparation method thereof |
| CN114381723B (en) * | 2022-01-12 | 2022-12-20 | 南京工程学院 | Steel workpiece surface corrosion-resistant layer and preparation method thereof |
Family Cites Families (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2351798A (en) * | 1941-08-14 | 1944-06-20 | Peter P Alexander | Coating metal articles |
| US3102044A (en) * | 1960-09-12 | 1963-08-27 | United Aircraft Corp | Applying protective coating from powdered material utilizing high temperature and low pressure |
| US3293064A (en) * | 1962-07-23 | 1966-12-20 | Ling Temco Vought Inc | Method of making heat resistant article |
| IL42550A (en) * | 1972-10-24 | 1976-08-31 | Gen Electric | Alloy coating method |
| FR2205583B1 (en) * | 1972-11-07 | 1975-09-12 | Commissariat Energie Atomique | |
| DE2300422C3 (en) * | 1973-01-05 | 1981-10-15 | Hoechst Ag, 6000 Frankfurt | Method of making an electrode |
| FR2235206B1 (en) * | 1973-06-26 | 1976-09-17 | Onera (Off Nat Aerospatiale) | |
| US3934059A (en) * | 1974-02-04 | 1976-01-20 | Rca Corporation | Method of vapor deposition |
| US4157923A (en) * | 1976-09-13 | 1979-06-12 | Ford Motor Company | Surface alloying and heat treating processes |
| GB1578889A (en) * | 1977-05-27 | 1980-11-12 | British Steel Corp | Surfacing circular-section metal members |
| US4181590A (en) * | 1977-08-16 | 1980-01-01 | The United States Of America As Represented By The Secretary Of The Air Force | Method of ion plating titanium and titanium alloys with noble metals and their alloys |
| US4138512A (en) * | 1977-10-17 | 1979-02-06 | The United States Of America As Represented By The Secretary Of The Army | Process for chemical vapor deposition of a homogeneous alloy of refractory metals |
| IT1172891B (en) * | 1978-07-04 | 1987-06-18 | Fiat Spa | PROCEDURE FOR COATING A METALLIC SURFACE WITH ANTI-WEAR MATERIAL |
| US4212900A (en) * | 1978-08-14 | 1980-07-15 | Serlin Richard A | Surface alloying method and apparatus using high energy beam |
| JPS589151B2 (en) * | 1980-02-13 | 1983-02-19 | ペルメレック電極株式会社 | Method of forming a corrosion-resistant coating on a metal substrate |
-
1980
- 1980-05-14 JP JP55062880A patent/JPS5948873B2/en not_active Expired
-
1981
- 1981-05-08 CA CA000377139A patent/CA1170514A/en not_active Expired
- 1981-05-12 DE DE8181302097T patent/DE3165203D1/en not_active Expired
- 1981-05-12 EP EP81302097A patent/EP0040092B1/en not_active Expired
- 1981-05-14 US US06/263,542 patent/US4400408A/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111676476A (en) * | 2020-06-02 | 2020-09-18 | 江西瑞曼增材科技有限公司 | Method for preparing copper-chromium-zirconium slideway by laser 3D printing technology |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5948873B2 (en) | 1984-11-29 |
| JPS56158871A (en) | 1981-12-07 |
| US4400408A (en) | 1983-08-23 |
| EP0040092A1 (en) | 1981-11-18 |
| EP0040092B1 (en) | 1984-08-01 |
| DE3165203D1 (en) | 1984-09-06 |
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