US2887420A - Surface treatments for articles made from heat resisting alloys - Google Patents
Surface treatments for articles made from heat resisting alloys Download PDFInfo
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- US2887420A US2887420A US649604A US64960457A US2887420A US 2887420 A US2887420 A US 2887420A US 649604 A US649604 A US 649604A US 64960457 A US64960457 A US 64960457A US 2887420 A US2887420 A US 2887420A
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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
- C23C10/34—Embedding in a powder mixture, i.e. pack cementation
- C23C10/52—Embedding in a powder mixture, i.e. pack cementation more than one element being diffused in one step
Definitions
- This invention relates to the surface treatment of articles having a finished surface and made. from metals or alloys which are subject to oxidation penetrating between the grain boundaries, and more particularly, articles made from nickel base and cobalt base alloys containing chromium, the treatment being for the purpose of decreasing the adverse effect which oxidation has upon the service life of such articles and of improving the resistance of such articles to thermal shock.
- a surface treatment for an article having a finished surface and made from a metal or alloy which is subject to oxidation penetrating between the grain boundaries comprising heating the article in contactwitha powdered alloy containing not less than 15% by weight of titanium and not less than 6% by weight of aluminum and in an atmosphere which is inert in relation to the metals of which the article and the powdered alloy are composed, the article being heated at a temperature above the normal maximum working temperatureof the article but not so high as to permanently adversely affect.
- the article may. be heated in contact with a powdered alloy known com-;
- ferro-titanium hardener Alternatively, however, a powdered alloy known commercially as nickeltitanium hardener may be used.
- the so-called hardeners referred to above are alloys which are rich in certain improvement metals or substances such as iron, nickel, titanium, aluminum, manganeseand silicon, the hardeners usually also containing certain other elements in the form of minor traces or impurities. Such hardeners are usually used for the purpose of adding the improvement metals or substances to other metals or alloys, the hardeners being mixed therewith. The hardeners are usually supplied in lump form but are brittle and easily crushed Nimonic type.
- the powdered alloy used should have Aggregateness between and 16 mesh per inch and preferably the powdered alloy has a fineness of 100 mesh per inch.
- the preferred way of carrying out a surface treatment according to the invention is to pack the article to be treated, together with the powdered alloy, in a box made from a heat resisting material such as stainless steel or a nickel b'ase alloy of the Nimonic type, the box being provided with an outlet and with a pipe for the supply into'the box of a gas to form an inert atmosphere which is maintained within the box throughout the treatment by passing the gas into the box and allowing it to escape through the outlet.
- An inert atmosphere of argon has been found satisfactory for carrying out the treatment according to the invention but preferably commercially pure hydrogen, from which all, or substantially all, traces of oxygen and moisture have been removed, is used.
- the atmosphere should be inert in the sense that the gas used for the atmosphere is inert in relation to the metals of which the article and the powderedalloy are composed.
- the gas used to form an atmosphere may however, and preferably has, as in the case of hydrogen, a reducing action on oxides of the metal or metals of which the article is composed.
- the gas is passed over palladised asbestos at room temperature, and then through activated alumina, before being fed into the box.
- the palladised asbestos acts as a catalyst for the combination of oxygen and hydrogen toform water and the water so formed, together with any other moisture present in the commercially pure hydrogen, is absorbed by the activated alumina.
- the resulting-hydrogen is thus free, or substantially free, from oxygen and moisture.
- the box While maintaining the flow of hydrogen through the box, the box .is heated to a temperature somewhat below the lowest temperature which would permanently adversely affect the physical. properties of the article being treated, but higher than the maximum temperature of the article at which the article will normally be required to work.
- the box is heated to a temperature equal to or approximating to the temperature to which the alloy of which the article is made would normally be subjected in the solution heat treatment.
- the article being treated is made of a nickel base alloy of the A solution heat treatment for such an alloy involves heating the alloy at a temperature between 1000 C. and 1190 C. and in the present case the box is heated to a temperature within this range.
- the heating is continued for a suflicient time to form on the article a modified layer of suitable thickness.
- a layer from 0.0005 inch to 0.001 inch in thickness is suitable.
- the box is then cooled in air while still maintaining the atmosphere of hydrogen in the box and when cooled the article is removed.
- the modified layer formed on the article by the treatment just described is an original surface layer of the article which has been modified by the treatment and not a surface layer which has subsequently been applied to the article duringthe treatment.
- the article may be taken from the box while still hot and cleaned of powdered alloy before being cooled. It is to be understood, however, that in this case the cooling must be elfected in a way appropriate to the material from which the article is made.
- a removable coating of the powdered alloy may be applied to the surface of the article in any appropriate manner, as for example by mixing the powder with a bonding medium which will give to the coating sufficient coherence to enable it to remain in place during the heating of the article.
- the article is then heated in an inert atmosphere for a predetermined time at a predetermined temperature suificient to form on the article a modified layer of desired thickness.
- the article may require to be aged at a temperature and for a period of time appropriate to the material composing the article.
- a temperature and for a period of time appropriate to the material composing the article.
- tween 690 C. and 710 C. for twelve to sixteen hours and cooling in air.
- the alloy in an un-aged or partially aged condition, and in this case the period of the ageing heat treatment would be appropriately reduced or it would be omitted altogether.
- the surface treatment according to the invention is applicable to articles made of mild steel and other ferrous alloys subject to intergranular oxide penetration, to titanium and molybdenum base alloys, to nickel base alloys of the Nimonic type and to cobalt base heat resisting alloys, a typical example of which comprises by weight, 0.5% carbon, 28.0% chromium, 7.5% tungsten, 12.0% nickel and the remainder cobalt.
- a sample of nickel titanium hardener which also proved satisfactory was composed by Weight, of 43.4% titanium, 3.7% manganese, 3.3% silicon, 9.3% aluminium, 0.36% iron, 0.51% cobalt and the remainder nickel.
- a surface treatment according to the invention may be carried out using other powdered alloys provided that these contain not less than 6% by Weight of aluminiumand not less than 15% by weight of titanium, but it is to be noted that these elements must be alloyed in the powder which is used. That is to say, the powder must be powdered alloy and not a mere admixture of metal powders.
- a number of articles made from Nimonic 90 ' were heated in contact with powdered ferro-titanium hardener having the composition set forth above and in an atmosphere of commercially pure hydrogen from which all, or substantially all, traces of oxygen and moisture had been removed, for one hour at a temperature of 1100 C.
- Nimonic type refers to an alloy that is predominantly nickel and chromium.
- the specific example referred to as Nimonic 90 contains 18% to 21% chromium, 15% to 21% cobalt and small percentages of titanium, aluminum, silicon, iron and manganese, the balance being nickel.
- a surface treatment for an article having a finished surface and made from a metal or alloy which is subject to oxidation penetrating between the grain boundaries comprising heating the article in contact with'a powdered alloy containing not less than 15 by weight of titanium and not less than 6% by weight of 1 aluminium the remainder consisting essentially of a metal pure hydrogen from which all, or substantially all, traces of oxygen and moisture have been removed.
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Powder Metallurgy (AREA)
- Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
Description
SURFACE TREATMENTS FOR ARTICLES MADE FROM HEAT REISTING ALLOYS Geirionydd Llewelyn and Raymond George Ubank, Bristol, England, assignors to Bristol Acre-Engines Limited, Bristol, England, a company of Great Britain No Drawing. Application April 1, 1957 Serial No. 649,604
Claims priority, application Great Britain April 6, 1956 9 Claims. (Cl. 148-'13.1)
This invention relates to the surface treatment of articles having a finished surface and made. from metals or alloys which are subject to oxidation penetrating between the grain boundaries, and more particularly, articles made from nickel base and cobalt base alloys containing chromium, the treatment being for the purpose of decreasing the adverse effect which oxidation has upon the service life of such articles and of improving the resistance of such articles to thermal shock.
It is known that when such an article is used at high temperatures the surface of the articles is subject to a type of oxidation which not only forms a surface layer but also penetrates between the grain boundaries. These grain boundary penetrations are particularly objectionable since .they can form the starting point for the propagation of cracks due to thermalshock, fatigue and creep, and this seriously reduces the service life of the article.
According to the invention there is provided a surface treatment for an article having a finished surface and made from a metal or alloy which is subject to oxidation penetrating between the grain boundaries, said treatment comprising heating the article in contactwitha powdered alloy containing not less than 15% by weight of titanium and not less than 6% by weight of aluminum and in an atmosphere which is inert in relation to the metals of which the article and the powdered alloy are composed, the article being heated at a temperature above the normal maximum working temperatureof the article but not so high as to permanently adversely affect.
According to a feature of the inventionithe article may. be heated in contact with a powdered alloy known com-;
mercially as ferro-titanium hardener. Alternatively, however, a powdered alloy known commercially as nickeltitanium hardener may be used.
Perm-titanium hardener and nickel-titanium hardener both contain a significant content of aluminum, the'presence of which element is, of course, essential for carrying out the treatment according to the invention as defined in the third paragraph of this specification.
As will readily be understood, the so-called hardeners referred to above are alloys which are rich in certain improvement metals or substances such as iron, nickel, titanium, aluminum, manganeseand silicon, the hardeners usually also containing certain other elements in the form of minor traces or impurities. Such hardeners are usually used for the purpose of adding the improvement metals or substances to other metals or alloys, the hardeners being mixed therewith. The hardeners are usually supplied in lump form but are brittle and easily crushed Nimonic type.
to a powder. In carrying out the surface treatment according to the present invention the powdered alloy used should have afineness between and 16 mesh per inch and preferably the powdered alloy has a fineness of 100 mesh per inch. e
The preferred way of carrying out a surface treatment according to the invention is to pack the article to be treated, together with the powdered alloy, in a box made from a heat resisting material such as stainless steel or a nickel b'ase alloy of the Nimonic type, the box being provided with an outlet and with a pipe for the supply into'the box of a gas to form an inert atmosphere which is maintained within the box throughout the treatment by passing the gas into the box and allowing it to escape through the outlet. An inert atmosphere of argon has been found satisfactory for carrying out the treatment according to the invention but preferably commercially pure hydrogen, from which all, or substantially all, traces of oxygen and moisture have been removed, is used.
It is to be understood that the atmosphere should be inert in the sense that the gas used for the atmosphere is inert in relation to the metals of which the article and the powderedalloy are composed. The gas used to form an atmosphere may however, and preferably has, as in the case of hydrogen, a reducing action on oxides of the metal or metals of which the article is composed.
Where commercially pure hydrogen is used the gas is passed over palladised asbestos at room temperature, and then through activated alumina, before being fed into the box. As is well known the palladised asbestos acts as a catalyst for the combination of oxygen and hydrogen toform water and the water so formed, together with any other moisture present in the commercially pure hydrogen, is absorbed by the activated alumina. The resulting-hydrogen is thus free, or substantially free, from oxygen and moisture.
It may here be noted that it is possible to carry out the surface treatment according to the invention by passing commercially pure hydrogen into the box without first removing the oxygen and moisture from the gas, provided that asufficient thickness of the powdered alloy is placed around the articlebeing treated to absorb the deleterious components of the gas before the gas reaches the immediate vicinity of the article. Such a method of working, however, rapidly renders the powdered alloy useless for the treatment .of further articles and consequently the method is uneconomic.
While maintaining the flow of hydrogen through the box, the box .is heated to a temperature somewhat below the lowest temperature which would permanently adversely affect the physical. properties of the article being treated, but higher than the maximum temperature of the article at which the article will normally be required to work. Where the article is made of an alloy which would normally be subjected to a solution heat treatment, the box is heated to a temperature equal to or approximating to the temperature to which the alloy of which the article is made would normally be subjected in the solution heat treatment. In the present case it is assumed that the article being treated is made of a nickel base alloy of the A solution heat treatment for such an alloy involves heating the alloy at a temperature between 1000 C. and 1190 C. and in the present case the box is heated to a temperature within this range.
The heating is continued for a suflicient time to form on the article a modified layer of suitable thickness. For
most purposes a layer from 0.0005 inch to 0.001 inch in thickness is suitable. In order to form a modified layer Within this range of thickness in the present case, it is necessary to heat the box at a temperature between 1000 C. and 1190 C. for a period of time between forty minutes and one hour. The box is then cooled in air while still maintaining the atmosphere of hydrogen in the box and when cooled the article is removed.
It is to be understood'that the modified layer formed on the article by the treatment just described is an original surface layer of the article which has been modified by the treatment and not a surface layer which has subsequently been applied to the article duringthe treatment.
Instead of cooling the box before removing the article, the article may be taken from the box while still hot and cleaned of powdered alloy before being cooled. It is to be understood, however, that in this case the cooling must be elfected in a way appropriate to the material from which the article is made.
Instead of packing the article in a box with the powdered. alloy, a removable coating of the powdered alloy may be applied to the surface of the article in any appropriate manner, as for example by mixing the powder with a bonding medium which will give to the coating sufficient coherence to enable it to remain in place during the heating of the article. The article is then heated in an inert atmosphere for a predetermined time at a predetermined temperature suificient to form on the article a modified layer of desired thickness.
Following a surface treatment according to the invention as so far described, in order to develop desired mechanical properties of the material forming the article, the article may require to be aged at a temperature and for a period of time appropriate to the material composing the article. Thus, for example, for development of full mechanical strength an article made from a nickel base Nimonic alloy would be aged by heating it. at be-.
tween 690 C. and 710 C. for twelve to sixteen hours and cooling in air. For some purposes however it may be desired to have the alloy in an un-aged or partially aged condition, and in this case the period of the ageing heat treatment would be appropriately reduced or it would be omitted altogether.
The surface treatment according to the invention is applicable to articles made of mild steel and other ferrous alloys subject to intergranular oxide penetration, to titanium and molybdenum base alloys, to nickel base alloys of the Nimonic type and to cobalt base heat resisting alloys, a typical example of which comprises by weight, 0.5% carbon, 28.0% chromium, 7.5% tungsten, 12.0% nickel and the remainder cobalt.
Commercial ferro-titanium hardener varies in composition as between different samples but a particular sample which proved satisfactory for surface treating articles according to the present invention, which articles were made from Nimonic 90 heat resisting alloy, was composed, by weight, of 33.6% titanium, 1.4% manganese, 1.2% silicon, 16.9% aluminium and the remainder .irdn.
A sample of nickel titanium hardener which also proved satisfactory was composed by Weight, of 43.4% titanium, 3.7% manganese, 3.3% silicon, 9.3% aluminium, 0.36% iron, 0.51% cobalt and the remainder nickel.
A surface treatment according to the invention may be carried out using other powdered alloys provided that these contain not less than 6% by Weight of aluminiumand not less than 15% by weight of titanium, but it is to be noted that these elements must be alloyed in the powder which is used. That is to say, the powder must be powdered alloy and not a mere admixture of metal powders.
By way of example of the improvement in service life of an article effected by a surface treatment of the article in accordance with the present invention, the following is given:
A number of articles made from Nimonic 90 'were heated in contact with powdered ferro-titanium hardener having the composition set forth above and in an atmosphere of commercially pure hydrogen from which all, or substantially all, traces of oxygen and moisture had been removed, for one hour at a temperature of 1100 C. The
Endurance limit on a basis ofl0 7 cycles (83 10 cycles (833 hrs.) hrs.)
Before treatment. After treatment 6.6 tons/ink".
:l: 1 :1: 14 tons/in. i 16.3 tons/in.
.2 :1: 15.4 tons/in.
These results show that the treated material is maintaining a higher level of fatigue resistance with increasing time and support metallographic tests upon used specimens of the treated article which showed no evidence of intergranular oxide penetration. Oxidation tests, operating by noting increase of weight with time, also showed that the rate of oxidation has been reduced to about one half of that of untreated specimens.
In illustration of the improved resistance to thermal shock of articles treated according to the invention, a specimen article of standardised narrow angle wedge shape made of Nimonic and treated as above described was subjected to a thermal shock test in which a localised portion of the edge of the article was alternately heated in a gas flame and cooled in an air blast, the cycle being of one minute duration. This specimen was found to survive 229 cycles. A similar article, surface treated in accordance with the invention in the manner above described, but using powdered nickel-titanium hardener instead of ferro-titanium hardener, gave a life of 230 cycles following the same thermal shock test. In distinction, however, three specimens made of Nimonic 90 fully aged after machining, but not subjected to a surface treatment in accordance with the invention, survived respectively without cracking only 70, and cycles following the above described thermal shock test.
Nimonic type refers to an alloy that is predominantly nickel and chromium. The specific example referred to as Nimonic 90 contains 18% to 21% chromium, 15% to 21% cobalt and small percentages of titanium, aluminum, silicon, iron and manganese, the balance being nickel.
We claim:
1. A surface treatment for an article having a finished surface and made from a metal or alloy which is subject to oxidation penetrating between the grain boundaries, said treatment comprising heating the article in contact with'a powdered alloy containing not less than 15 by weight of titanium and not less than 6% by weight of 1 aluminium the remainder consisting essentially of a metal pure hydrogen from which all, or substantially all, traces of oxygen and moisture have been removed.
3. A surface'treatment as claimed in claim 1, wherein the article is cooled in said inert atmosphere whilst still in contact with said powdered alloy.
4. A surface treatment as claimed in claim 1, wherein thearticle is heated in contact with powdered ferro-titanium hardener. a
5. A surface treatment as claimed in claim 1, wherein the article is heated in contact with nickel-titanium hardener.
6. A surface treatment as claimed in claim 1, wherein said powdered alloy has a fineness of between 100 and 16 mesh per inch.
7. A surface treatment as claimed in claim 1, wherein the article is heated in contact with said powdered alloy and in said inert atmosphere for a time sufiicient to form on the article a modified layer of a thickness from 0.0005 inch to 0.001 inch.
8. A surface treatment as claimed in claim 1, for an article made of a nickel base alloy containing chromium and cobalt, wherein the article is heated in contact with said powdered alloy and in said inert atmosphere at a temperature substantially between 1000 C. and 1190 C.
9. A surface treatment as claimed in claim 8, wherein the article is aged by reheating the article between 690 C. and 710 C. for a period of time between twelve hours and sixteen hours.
Rossi Mar. 14, 1911 Ramage June 5, 1951
Claims (1)
1. A SURFACE TREATMENT FOR AN ARTICLE HAVING A FINISHED SURFACE AND MADE FROM A METAL OF ALLOY WHICH SUBJECT TO OXIDATION PENETRATING BETWEEN THE GRAIN BOUNDARIES, SAID TREATMENT COMPRISING HEATING THE ARTICLE IN CONTACT WITH A POWDERED ALLOY CONTAINING NOT LESS THAN 15% BY WEIGHT OF TITANIUM AND NOT LESS THAN 6% BY WEIGHT OF ALUMINUM THE REMAINDER CONSISTING ESSENTIALLY OF A METAL SELECTED FROM THE GROUP CONSISTING OF NICKEL AND IRON AND IN AN ATMOSPHERE WHICH IS INERT IN RELATION TO THE METALS OF WHICH THE ARTICLE AND THE POWDERED ALLOY ARE COMPOSED, THE ARTICLE BEING HEATED AT A TEMPERATURE SUBSTANTIALLY BETWEEN 1000*C. AND 1190*C., AND FOR A TIME SUFFICIENT TO FORM A MODIFIED LAYER ON THE SURFACE OF THE ARTICLE, THE ARTICLE BEING THEREAFTER COOLED.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB2887420X | 1956-04-06 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US2887420A true US2887420A (en) | 1959-05-19 |
Family
ID=10917192
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US649604A Expired - Lifetime US2887420A (en) | 1956-04-06 | 1957-04-01 | Surface treatments for articles made from heat resisting alloys |
Country Status (1)
| Country | Link |
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| US (1) | US2887420A (en) |
Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3063816A (en) * | 1959-06-08 | 1962-11-13 | American Can Co | Method of controlling crystal growth |
| US3079276A (en) * | 1960-10-14 | 1963-02-26 | Union Carbide Corp | Vapor diffusion coating process |
| US3090702A (en) * | 1961-01-23 | 1963-05-21 | Chromizing Corp | Protective coating of refractory metals |
| US3155548A (en) * | 1961-10-11 | 1964-11-03 | Ashikari Katsuyo | Penetration hardening treatment for iron and steels |
| US3254969A (en) * | 1961-11-24 | 1966-06-07 | Misco Prec Casting Company | Method of aluminizing chromium alloys and oxidation resistant article produced thereby |
| US3310440A (en) * | 1964-10-21 | 1967-03-21 | United Aircraft Corp | Heat treatment of nickel base alloys |
| US3415672A (en) * | 1964-11-12 | 1968-12-10 | Gen Electric | Method of co-depositing titanium and aluminum on surfaces of nickel, iron and cobalt |
| US3415676A (en) * | 1964-09-14 | 1968-12-10 | Sintobrator Ltd | Aluminum cementation process |
| US3502493A (en) * | 1966-01-24 | 1970-03-24 | Forestek Plating & Mfg Co | Deposition of micron-sized particles into porous surfaces |
| US3787245A (en) * | 1970-10-26 | 1974-01-22 | Inst Haertereitechn | Method for the boration of titanium and titanium alloys |
| US3958046A (en) * | 1969-06-30 | 1976-05-18 | Alloy Surfaces Co., Inc. | Coating for corrosion resistance |
| US4654091A (en) * | 1980-12-10 | 1987-03-31 | United Technologies Corporation | Elimination of quench cracking in superalloy disks |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US986504A (en) * | 1908-04-08 | 1911-03-14 | Titanium Alloy Mfg Co | Process of treating metallic bodies. |
| US2555372A (en) * | 1944-10-02 | 1951-06-05 | Westinghouse Electric Corp | Method of coating refractory readily oxidizable metals |
-
1957
- 1957-04-01 US US649604A patent/US2887420A/en not_active Expired - Lifetime
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US986504A (en) * | 1908-04-08 | 1911-03-14 | Titanium Alloy Mfg Co | Process of treating metallic bodies. |
| US2555372A (en) * | 1944-10-02 | 1951-06-05 | Westinghouse Electric Corp | Method of coating refractory readily oxidizable metals |
Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3063816A (en) * | 1959-06-08 | 1962-11-13 | American Can Co | Method of controlling crystal growth |
| US3079276A (en) * | 1960-10-14 | 1963-02-26 | Union Carbide Corp | Vapor diffusion coating process |
| US3090702A (en) * | 1961-01-23 | 1963-05-21 | Chromizing Corp | Protective coating of refractory metals |
| US3155548A (en) * | 1961-10-11 | 1964-11-03 | Ashikari Katsuyo | Penetration hardening treatment for iron and steels |
| US3254969A (en) * | 1961-11-24 | 1966-06-07 | Misco Prec Casting Company | Method of aluminizing chromium alloys and oxidation resistant article produced thereby |
| US3415676A (en) * | 1964-09-14 | 1968-12-10 | Sintobrator Ltd | Aluminum cementation process |
| US3310440A (en) * | 1964-10-21 | 1967-03-21 | United Aircraft Corp | Heat treatment of nickel base alloys |
| US3415672A (en) * | 1964-11-12 | 1968-12-10 | Gen Electric | Method of co-depositing titanium and aluminum on surfaces of nickel, iron and cobalt |
| US3502493A (en) * | 1966-01-24 | 1970-03-24 | Forestek Plating & Mfg Co | Deposition of micron-sized particles into porous surfaces |
| US3958046A (en) * | 1969-06-30 | 1976-05-18 | Alloy Surfaces Co., Inc. | Coating for corrosion resistance |
| US3787245A (en) * | 1970-10-26 | 1974-01-22 | Inst Haertereitechn | Method for the boration of titanium and titanium alloys |
| US4654091A (en) * | 1980-12-10 | 1987-03-31 | United Technologies Corporation | Elimination of quench cracking in superalloy disks |
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