US2555372A - Method of coating refractory readily oxidizable metals - Google Patents
Method of coating refractory readily oxidizable metals Download PDFInfo
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- US2555372A US2555372A US556810A US55681044A US2555372A US 2555372 A US2555372 A US 2555372A US 556810 A US556810 A US 556810A US 55681044 A US55681044 A US 55681044A US 2555372 A US2555372 A US 2555372A
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- chromium
- molybdenum
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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
- C23C10/00—Solid state diffusion of only metal elements or silicon into metallic material surfaces
- C23C10/28—Solid state diffusion of only metal elements or silicon into metallic material surfaces using solids, e.g. powders, pastes
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- Another object of my invention is to protect articles which are constructed of refractory, but readily-oxidizable metal such as molybdenum, tungsten, tantalum, zirconium, thorium, uranium and other similar metals and alloys thereof, by electroplating with chromium and then heattreating in a hydrogen atmosphere at a temperature sufficient to cause the plating to forml a chromium-molybdenum eutectic or such between the chromium and metal on which it is plated, which provides for firm adherence between the chromium and the refractory metal, whereby the latter is protected from oxidation up to 1500 C., and possibly as high as the melting point of the chromium-refractory-metal eutectic, that is, about 1725 C. if the refractory metal is molybdenum.
- refractory metal is molybdenum.
- a further object of my invention is to protect such metals and alloys as above mentioned by chromizing the surfaces thereof, that is, packing moderately high temperatures.
- Molybdenum for example, starts to oxidize at about 400 C. and at about 700 C. the oxide is volatile, so that at any temperature above that mentioned, it not only oxidizes when exposed to an oxidizing atmosphere, but the oxide formed volatilizes away very quickly and at an increasing rate as the temperature is increased.
- Still further objects of my invention are articles of refractory readily-oxidizable metals, the surfaces of which are protected against oxidation by firmly adherent coatings of chromium.
- Fig. 1 is a vertical sectional view of a plating bath which may be used for coating articles with chromium.
- Fig. 2 is a vertical sectional view of a furnace in which articles so plated may be heat-treated, or in which articles may be chromized.
- Fig. 3 is a transverse sectional view of an article of molybdenum coated or plated with chromium.
- molybdenum there are a number of metals such as molybdenum, tungsten, tantalum, zirconium, thorium, uranium, and other similar metals and alloys thereof, and particularly molybdenum, which have very good and useful properties as to strength, hardness, and relatively-high melting points, but which are susceptible to oxidation at atmosphere.
- My method consists in coating the surface of the molybdenum with chromium, either by plating and heat treating, or chromizing by heat treating the article while covered with powdered chromium or a mixture of powdered chromium and chromic oxide, as distinguished from using therewith a lower melting-point alloying metal or metals.
- the heat treating of the plated molybdenum is in hydrogen or other reducing or protective atmosphere, preferably at about 1100 C. for from about 15 minutes to 1/2 hour.
- the chromizing of molybdenum parts ⁇ requires several hours in hydrogen or other reducing or protective atmosphere at about 1100 C.
- molybdenum, so coated or plated with chromium in this manner resisted oxidation and volatili zation even in an oxidizing atmosphere up to about l500 C. It is believed that such resistance extends up to the melting point of the chromium-molybdenum eutectic, that is, up to about 1725 C.
- the thickness of the coating in the instance referred to was about 11/2 mils, but such thickness may be varied depending on the uses to which the article is to be put and the temperature to which it is to be subjected.
- the chromium migrates into the molybdenum at such a rate that it will be absorbed completely in about 25 hours at 1630 C. It is conceivable, therefore, that the effectiveness of chromium as a protector may be impaired if the coated article is held at a temperature as high f as 1630 C. for about 50 hours or more.
- the coated article is held at a temperature as high f as 1630 C. for about 50 hours or more.
- a container Il is shown in Fig. 1 holding an electroplating bath l2 of a chromium compound such as is used conventionally for chromium plating.
- the article to be plated designated I3, is made the cathode and in this instance, is formed of molybdenum.
- the anode lli may be made of chromium or carbon.
- the plated article After electroplating the article I3, or as much thereof as desired, with chromium to the required thickness, the plated article is covered with powdered chromium or a mixture of at least 50% chromium powder and powdered chromic oxide, and transferred to an electric furnace l5 where it is heated in a hydrogen or other reducing or protective atmosphere, as by means of an electrical resistance element IB surrounding a tube Il of alumina, to about 1100o C. for from about to 30 minutes.
- an article I3a of molybdenum may be covered with powdered chromium I8, or a mixture of at least 50% of such powdered chromium and powdered chromic oxide, and placed in a boat i9 of alumina or other inertrefractory material and subjected to heating in a hydrogen or other reducing atmosphere for several hours at about 1100 C.
- This causes chromium to be deposited on the surface of the molybdenum article, the thickness of the coating depending on the length and temperature of treatment.
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Description
June 5, 1951 J H RAMAGE 2,555,372
METHOD OF (OATING REFRACTORY READILY-OXIDIZABLE METALS Filed Oct. 2. 1944 BWQMW ATTORN EY Patented June 5, 1951 UNITED STATES PATENT OFFICE METHOD F COATING REFRACTORY READILY OXIDIZABLE METALS John H. Ramage, Bloomfield, N. J., assigner to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application October 2, 1944, Serial N o. 556,810
3 Claims.
of refractory but readily-oxidizable metals; in
which oxidation thereof is prevented by a coating or plating of chromium.
Another object of my invention is to protect articles which are constructed of refractory, but readily-oxidizable metal such as molybdenum, tungsten, tantalum, zirconium, thorium, uranium and other similar metals and alloys thereof, by electroplating with chromium and then heattreating in a hydrogen atmosphere at a temperature sufficient to cause the plating to forml a chromium-molybdenum eutectic or such between the chromium and metal on which it is plated, which provides for firm adherence between the chromium and the refractory metal, whereby the latter is protected from oxidation up to 1500 C., and possibly as high as the melting point of the chromium-refractory-metal eutectic, that is, about 1725 C. if the refractory metal is molybdenum.
A further object of my invention is to protect such metals and alloys as above mentioned by chromizing the surfaces thereof, that is, packing moderately high temperatures. Molybdenum, for example, starts to oxidize at about 400 C. and at about 700 C. the oxide is volatile, so that at any temperature above that mentioned, it not only oxidizes when exposed to an oxidizing atmosphere, but the oxide formed volatilizes away very quickly and at an increasing rate as the temperature is increased.
I have found a method to prevent this oxidation and volatilization and thus make it possible to utilize the high temperature properties of a metal such as molybdenum, even in an oxidizing them in powdered chromium or a mixture of v powdered chromium and chromic oxide, and heating for several hours in hydrogen at a temperature of about 1100 C.
Still further objects of my invention are articles of refractory readily-oxidizable metals, the surfaces of which are protected against oxidation by firmly adherent coatings of chromium.
Other objects and advantages of the invention will become apparent as the description proceeds.
Referring to the drawing:
Fig. 1 is a vertical sectional view of a plating bath which may be used for coating articles with chromium.
Fig. 2 is a vertical sectional view of a furnace in which articles so plated may be heat-treated, or in which articles may be chromized.
Fig. 3 is a transverse sectional view of an article of molybdenum coated or plated with chromium.
There are a number of metals such as molybdenum, tungsten, tantalum, zirconium, thorium, uranium, and other similar metals and alloys thereof, and particularly molybdenum, which have very good and useful properties as to strength, hardness, and relatively-high melting points, but which are susceptible to oxidation at atmosphere. My method consists in coating the surface of the molybdenum with chromium, either by plating and heat treating, or chromizing by heat treating the article while covered with powdered chromium or a mixture of powdered chromium and chromic oxide, as distinguished from using therewith a lower melting-point alloying metal or metals. The heat treating of the plated molybdenum is in hydrogen or other reducing or protective atmosphere, preferably at about 1100 C. for from about 15 minutes to 1/2 hour. However, the chromizing of molybdenum parts `requires several hours in hydrogen or other reducing or protective atmosphere at about 1100 C. I have found that molybdenum, so coated or plated with chromium in this manner, resisted oxidation and volatili zation even in an oxidizing atmosphere up to about l500 C. It is believed that such resistance extends up to the melting point of the chromium-molybdenum eutectic, that is, up to about 1725 C. The thickness of the coating in the instance referred to was about 11/2 mils, but such thickness may be varied depending on the uses to which the article is to be put and the temperature to which it is to be subjected.
On heating, the chromium migrates into the molybdenum at such a rate that it will be absorbed completely in about 25 hours at 1630 C. It is conceivable, therefore, that the effectiveness of chromium as a protector may be impaired if the coated article is held at a temperature as high f as 1630 C. for about 50 hours or more. However,
I have found that operating as low as 1500" C., the chromium-plated molybdenum would still effectively resist oxidation for several thousand hours and at lower temperatures almost indefinitely. Although the surfaces do tarnish or darken a little, probably due to a superficial coating of some oxide of chromium, such coating adheres very tightly to the metal therebeneath and stops further oxidation.
Referring to the drawing, like parts being designated by like reference characters, a container Il is shown in Fig. 1 holding an electroplating bath l2 of a chromium compound such as is used conventionally for chromium plating. The article to be plated, designated I3, is made the cathode and in this instance, is formed of molybdenum. The anode lli may be made of chromium or carbon.
After electroplating the article I3, or as much thereof as desired, with chromium to the required thickness, the plated article is covered with powdered chromium or a mixture of at least 50% chromium powder and powdered chromic oxide, and transferred to an electric furnace l5 where it is heated in a hydrogen or other reducing or protective atmosphere, as by means of an electrical resistance element IB surrounding a tube Il of alumina, to about 1100o C. for from about to 30 minutes.
As an alternative, an article I3a of molybdenum may be covered with powdered chromium I8, or a mixture of at least 50% of such powdered chromium and powdered chromic oxide, and placed in a boat i9 of alumina or other inertrefractory material and subjected to heating in a hydrogen or other reducing atmosphere for several hours at about 1100 C. This causes chromium to be deposited on the surface of the molybdenum article, the thickness of the coating depending on the length and temperature of treatment.
From the foregoing, it will be seen that I have provided for the protection of molybdenum and other similar materials against oxidation, whereby such may be used in oxidizing atmospheres up to relatively high temperatures. Although specic methods for treating molybdenum only has been disclosed, it will be understood that similar methods may be used for applying protective coatings to molybdenum alloys, tungsten and alloys, and tantalum and alloys with equal facility. It is also believed that such coatings can be applied to other similar metals such as zirconium, thorium, uranium and other easily oxidizable but refractory metals and alloys thereof.
Although preferred embodiments of my invention have been disclosed, it will be understood that modifications may be made within the spirit and scope of the appended claims. The term .4 hydrogen or hydrogen atmosphere in said claims includes such in which hydrogen is a diluted active ingredient and the word "meta includes alloys of metals.
I claim:
1. The method of protecting against oxidation at high temperatures, articles constructed of refractory but readily-oxidizable metals and alloys thereof comprising electroplating them with chromium, covering said plated articles with powdered chromium, and heating in hydrogen at a temperature of about 1100 C., to obtain a firmlyadherent coating of chromium thereon.
2. The method of protecting molybdenum articles against oxidation at high temperatures, comprising electroplating them with chromium, covering said plated articles with powdered chromium, and heating in hydrogen at a temperature of about 1100 C., to obtain a firmly-adherent coating of chromium thereon.
3. The method of protecting against oxidation at high temperatures, articles constructed of metal selected from the group consisting of molybdenum, tungsten, tantalum, zirconium, thorium, uranium, and refractory but readily oxidizable' alloys thereof, comprising electroplating them with chromium, covering said plated articles with powdered chromium, and heating in hydrogen at a temperature of about 1100 C., to obtain a firmly-adherent coating of chromium thereon.
JOHN H. RAMAGE.
REFERENCES CITED The following references are of record in the le of this patent:
UNITED STATES PATENTS Number Name Date 1,365,499 Kelley Jan. 11, 1921 1,590,101 Kyropoulos June 22, 1926 1,899,569 Howe Feb. 28, 1933 2,304,297 Anton Dec. 8, 1942 OTHER REFERENCES Protective Coating for Metals (ACS Monograph 79) 1939, page 185.
Claims (1)
1. THE METHOD OF PROTECTING AGAINST OXIDATION AT HIGH TEMPERATURES, ARTICLES CONSTRUCTED OF REFRACTORY BUT READILY-OXIDIZABLE METALS AND ALLOYS THEREOF COMPRISING ELECTROPLATING THEM WITH CHROMIUM, COVERTING SAID PLATED ARTICLES WITH POWDERED CHROMIUM, AND HEATING IN HYDROGEN AT A TEMPERATURE OF ABOUT 1100* C., TO OBTAIN A FIRMLYADHERENT COATING OF CHROMIUM THEREON.
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US556810A US2555372A (en) | 1944-10-02 | 1944-10-02 | Method of coating refractory readily oxidizable metals |
Applications Claiming Priority (1)
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US556810A US2555372A (en) | 1944-10-02 | 1944-10-02 | Method of coating refractory readily oxidizable metals |
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Cited By (23)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2650903A (en) * | 1947-07-05 | 1953-09-01 | Westinghouse Electric Corp | Protection of molybdenum against oxidation |
US2697130A (en) * | 1950-12-30 | 1954-12-14 | Westinghouse Electric Corp | Protection of metal against oxidation |
US2709154A (en) * | 1948-04-05 | 1955-05-24 | Josephine Maria Hansgirg | Corrosion resisting coatings |
US2772227A (en) * | 1953-06-29 | 1956-11-27 | Westinghouse Electric Corp | Protection of molybdenum and tungsten at high temperatures |
US2819208A (en) * | 1950-06-27 | 1958-01-07 | Onera (Off Nat Aerospatiale) | Chromizing and analogous methods |
US2835630A (en) * | 1952-05-06 | 1958-05-20 | Huddle Roy Alfred Ulfketel | Treatment of metals prior to electro-plating |
US2859158A (en) * | 1957-01-31 | 1958-11-04 | Glenn R Schaer | Method of making a nickel-chromium diffusion alloy |
US2872348A (en) * | 1946-05-06 | 1959-02-03 | Lowell D Eubank | Fused salt method for coating uranium with a metal |
US2887420A (en) * | 1956-04-06 | 1959-05-19 | Bristol Aero Engines Ltd | Surface treatments for articles made from heat resisting alloys |
US2894884A (en) * | 1945-01-09 | 1959-07-14 | Allen G Gray | Method of applying nickel coatings on uranium |
US2894885A (en) * | 1945-01-06 | 1959-07-14 | Allen G Gray | Method of applying copper coatings to uranium |
US2902392A (en) * | 1954-09-18 | 1959-09-01 | Siemens Planiawerke Ag | Work pieces for high temperature operation and method of making them |
US2936250A (en) * | 1953-06-22 | 1960-05-10 | Borolite Corp | Cemented zirconium boride material having a protective chromium containing coating |
US2981672A (en) * | 1952-01-29 | 1961-04-25 | Walter E Kingston | Nuclear reactor fuel element |
US2993678A (en) * | 1955-07-21 | 1961-07-25 | Gen Electric | Coated molybdenum article |
US3034971A (en) * | 1958-09-09 | 1962-05-15 | Gen Electric | Process for producing an electrically insulated conductor |
NL6805383A (en) * | 1967-04-17 | 1968-10-18 | ||
US3627650A (en) * | 1969-07-15 | 1971-12-14 | Atomic Energy Commission | Method for producing a chromium-tungsten coating on tungsten for protection against oxidation at elevated temperatures |
US4342577A (en) * | 1980-10-27 | 1982-08-03 | Owens-Corning Fiberglas Corporation | Method and apparatus for forming glass fibers |
US4348216A (en) * | 1980-10-27 | 1982-09-07 | Owens-Corning Fiberglas Corporation | Method and apparatus for forming glass fibers |
US4402719A (en) * | 1980-10-27 | 1983-09-06 | Owens-Corning Fiberglas Corporation | Method and apparatus for forming glass fibers |
US4402718A (en) * | 1980-10-27 | 1983-09-06 | Owens-Corning Fiberglas Corporation | Method and apparatus for forming glass fibers |
US4404009A (en) * | 1982-12-22 | 1983-09-13 | Owens-Corning Fiberglas Corporation | Method and apparatus for forming glass fibers |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1365499A (en) * | 1919-10-23 | 1921-01-11 | Gen Electric | Surface-alloyed metal |
US1590101A (en) * | 1923-07-26 | 1926-06-22 | Kyropoulos Spiro | Process of coating iron and iron alloys with chromium |
US1899569A (en) * | 1929-05-28 | 1933-02-28 | Gen Electric | Process of coating metals |
US2304297A (en) * | 1939-05-12 | 1942-12-08 | Amperex Electronic Products In | Art of utilizing molybdenum |
-
1944
- 1944-10-02 US US556810A patent/US2555372A/en not_active Expired - Lifetime
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1365499A (en) * | 1919-10-23 | 1921-01-11 | Gen Electric | Surface-alloyed metal |
US1590101A (en) * | 1923-07-26 | 1926-06-22 | Kyropoulos Spiro | Process of coating iron and iron alloys with chromium |
US1899569A (en) * | 1929-05-28 | 1933-02-28 | Gen Electric | Process of coating metals |
US2304297A (en) * | 1939-05-12 | 1942-12-08 | Amperex Electronic Products In | Art of utilizing molybdenum |
Cited By (23)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2894885A (en) * | 1945-01-06 | 1959-07-14 | Allen G Gray | Method of applying copper coatings to uranium |
US2894884A (en) * | 1945-01-09 | 1959-07-14 | Allen G Gray | Method of applying nickel coatings on uranium |
US2872348A (en) * | 1946-05-06 | 1959-02-03 | Lowell D Eubank | Fused salt method for coating uranium with a metal |
US2650903A (en) * | 1947-07-05 | 1953-09-01 | Westinghouse Electric Corp | Protection of molybdenum against oxidation |
US2709154A (en) * | 1948-04-05 | 1955-05-24 | Josephine Maria Hansgirg | Corrosion resisting coatings |
US2819208A (en) * | 1950-06-27 | 1958-01-07 | Onera (Off Nat Aerospatiale) | Chromizing and analogous methods |
US2697130A (en) * | 1950-12-30 | 1954-12-14 | Westinghouse Electric Corp | Protection of metal against oxidation |
US2981672A (en) * | 1952-01-29 | 1961-04-25 | Walter E Kingston | Nuclear reactor fuel element |
US2835630A (en) * | 1952-05-06 | 1958-05-20 | Huddle Roy Alfred Ulfketel | Treatment of metals prior to electro-plating |
US2936250A (en) * | 1953-06-22 | 1960-05-10 | Borolite Corp | Cemented zirconium boride material having a protective chromium containing coating |
US2772227A (en) * | 1953-06-29 | 1956-11-27 | Westinghouse Electric Corp | Protection of molybdenum and tungsten at high temperatures |
US2902392A (en) * | 1954-09-18 | 1959-09-01 | Siemens Planiawerke Ag | Work pieces for high temperature operation and method of making them |
US2993678A (en) * | 1955-07-21 | 1961-07-25 | Gen Electric | Coated molybdenum article |
US2887420A (en) * | 1956-04-06 | 1959-05-19 | Bristol Aero Engines Ltd | Surface treatments for articles made from heat resisting alloys |
US2859158A (en) * | 1957-01-31 | 1958-11-04 | Glenn R Schaer | Method of making a nickel-chromium diffusion alloy |
US3034971A (en) * | 1958-09-09 | 1962-05-15 | Gen Electric | Process for producing an electrically insulated conductor |
NL6805383A (en) * | 1967-04-17 | 1968-10-18 | ||
US3627650A (en) * | 1969-07-15 | 1971-12-14 | Atomic Energy Commission | Method for producing a chromium-tungsten coating on tungsten for protection against oxidation at elevated temperatures |
US4342577A (en) * | 1980-10-27 | 1982-08-03 | Owens-Corning Fiberglas Corporation | Method and apparatus for forming glass fibers |
US4348216A (en) * | 1980-10-27 | 1982-09-07 | Owens-Corning Fiberglas Corporation | Method and apparatus for forming glass fibers |
US4402719A (en) * | 1980-10-27 | 1983-09-06 | Owens-Corning Fiberglas Corporation | Method and apparatus for forming glass fibers |
US4402718A (en) * | 1980-10-27 | 1983-09-06 | Owens-Corning Fiberglas Corporation | Method and apparatus for forming glass fibers |
US4404009A (en) * | 1982-12-22 | 1983-09-13 | Owens-Corning Fiberglas Corporation | Method and apparatus for forming glass fibers |
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