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Publication numberUS3640815 A
Publication typeGrant
Publication dateFeb 8, 1972
Filing dateSep 8, 1969
Priority dateSep 8, 1969
Also published asCA922988A1, DE2043952A1
Publication numberUS 3640815 A, US 3640815A, US-A-3640815, US3640815 A, US3640815A
InventorsMartini Richard W, Schwartz Charles W
Original AssigneeHowmet Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Method for surface treatment of nickel and cobalt base alloys
US 3640815 A
Abstract
The treatment of high nickel and cobalt base alloy to improve the corrosion resistance of parts formed thereof by first applying a coating of nickel and then subjecting the part to diffusion coating to aluminize the surface.
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Description  (OCR text may contain errors)

United States Patent Schwartz et al.

[ Feb. 8, 1972 [54] METHOD FOR SURFACE TREATMENT OF NICKEL AND COBALT BASE ALLOYS [72] Inventors: Charles W. Schwartz, Whitehall, Mich;

Richard W. Martini, Scotia, NY.

[73] Assignee: Howmet Corporation, New York, NY.

[22] Filed: Sept. 8, 1969 [21] Appl. No.: 856,188

[56] References Cited UNlTED STATES PATENTS 3,345,197 10/1967 Martini et a1 ..117/107.2 P 3,079,276 2/1963 Puyear et a1... ...117/107 2 P 2,957,782 10/1960 Boiler ..204/38 2,917,818 12/1959 Thomson... ...117/114C 2,894,884 7/1959 Gray ..204/38.3 2,611,163 9/1952 Schaefer et a1. ..204/3 8.3 1,637,033 7/1927 Basch .117/107.2 P 1,480,779 1/1924 Pacz ..148/6.35 1,881,064 10/1932 Sayles eta1.... .117/107.2 P 2,970,065 l/1961 Greene et al. ..l17/8 FOREIGN PATENTS OR APPLICATIONS 428,855 5/1935 Great Britain ..1 17/1072 P Primary Examiner-John H. Mack Assistant Examiner-R. L. Andrews AttorneyMcDougall, Hersh, Scott & Ladd [5 7] ABSTRACT The treatment of high nickel and cobalt base alloy to improve the corrosion resistance of parts formed thereof by first applying a coating of nickel and then subjecting the part to difiusion coating to aluminize the surface.

14 Claims, No Drawings METHOD FOR SURFACE TREATMENT OF NICKEL AND COBALT BASE ALLOYS This invention relates to the art of aluminizing metal surfaces by diffusion to provide a surface on the metal which is rendered more resistant to corrosion or oxidation at high temperatures and/or in corrosive atmospheres, such as exist in a combustion engine, turbine, and the like. By diffusion of aluminum into the surface of such metals as high nickel or cobalt alloys and high alloy steels, heat shock erosion, corrosion resistance and other physical and mechanical properties are markedly improved.

To the present, in the aluminizing treatment by diffusion coating, the metal part is heated to a temperature above 1000 C. in a pack formed of a powdered mixture of metallic aluminum and aluminum oxides, without and preferably with a small amount of halide salt such as ammonium chloride or ammonium fluoride, for about 4 to hours in a nonoxidizing atmosphere.

The aluminum diffuses into the surface, usually to a depth within the range of about 10-20 microns, depending somewhat upon the time and temperature of the aluminizing treatment and the amount of aluminum in the pack, with the amount of aluminum in the diffusion layer decreasing from the surface inwardly toward the center in amounts somewhat proportionate to the distance from the surface.

It is an object of this invention to provide an improved aluminized article and method for preparation of same wherein the diffusion coating of aluminum remains concentrated in a narrow layer on the surface of the article without excessive diffusion into the interior of the article; whereby a better bond is achieved between the diffusion coating and metal substrate; and whereby a complex series of compounds are formed in the diffusion layer to provide an improved coating which offers higher temperature corrosion resistance.

In accordance with the practice of this invention, the parts formed of a superalloy, and preferably nickel and cobalt based alloys, are first processed to provide the surface portions to be aluminized with a thin coating of nickel, in a first coating step. The coated parts are then packed in the conventional manner and conventional compositions for aluminizing the surface by diffusion transfer of aluminum. The presence of nickel as a precoat on the metal surface is believed to operate as a barrier coat which concentrates the diffused aluminum in the surface portions of the metal parts to provide an aluminized surface having greatly improved corrosion resistance, especially when measured at high temperature and in the presence of highly corrosive gases.

In the described two-stage process of first nickel plating and then diffusion coating to aluminize the plated surface by a pack cementation process it is desirable to deposit a nickel coating in the first stage having a thickness greater than 0.000] inch and preferably having a thickness within the range of0.000l to 0.001 inch.

The desired thickness of nickel coating can be deposited by conventional electroplating processes, such as described in the article published by the ASM Committee on Nickel Plating, entitled Nickel Plating, published in the Metals Handbook, Volume II, pages 432-443, under general purpose plating baths. Instead, the desired thickness of nickel coating can be deposited on the surface of the parts nonelectrically, as described on pages 443-445 of the Metals Handbook, Volume ll, supra, under theheading Nonelectrolytic Nickel Plating.

The aluminizing pack employed in the pack cementation process for aluminizing the nickel-coated surfaces can be formulated to contain aluminum metal in finely divided form in an amount within the range of 0.1 to 10 percent by weight with the remainder formed of a finely divided filler, preferably alumina. Although it is not essential, use can be made of an energizer, such as ammonium chloride or ammonium fluoride, in an amount within the range of 0.01 to 5 percent by weight of the pack. A hydrogen or inert atmosphere is maintained during diffusion coating while the materials are heated to a temperature within the"range of 1,800 to l,200 F. or a time sufficient to build up a final coating thickness within the range of 0.001 to 0.005 and preferably within the range of 0.00 l 5 to 0.003 inch. The desired coating thickness is obtained with a pack of the type described in about 9 to 10 hours of heating.

The following examples are given by way of illustration, but not by way of limitation, of the practice of this invention:

Alloy Composition:

Example 1 Percent by Weight Ni 70.0 Cr l2.0 W 5.0 Al 5.0 M0 3.5 Ti, Nb, 'la 2.5 Fe, C, Mn, Si Balance Example 2 Percent by Weight C0 60.0 Cr 20.0 W 10.0 Nb 2.0 Ni LO Fe, C, Mn, Si Balance Example 3 Percent by Weight C 0.08 Mn 0.75 Si 0.75 Cr |9.0 Co l9.5 M0 4.0 Ti 2.) Al 2.9 Fe 4.0 Ni Balance Example 4 Percent by Weight C 0. l 2 Mn 0. l5 Si 04 Cr I10 M0 4.5 Ti 06 Al 6.0 Fe L0 Cb 2.25

' Ni Balance First stage of nickel coating:

Example 5 Composition of Electrolytic Bath Nickel sulfate. NiSO GILO 30 to 55 Nickel chloride, NiCl,6H,O 4 to 8(a) Nickel sulfamate,

Ni so,NH, Nickel fluoborate,

K m Total nickel as metal 7.7 to [4.2 Boric acid, H BO 4 to 6 Antipitting additives (b) 3 4 Operatlng Conditions Operating Conditions pH 1.5 m 52 PH H5 Temperature, F. 190 to 210 Cullen dcnslly, Plating rate (approx). a. per sq. ft. to I00 5 mil pct Example 6 Example l0 l0 a Composition of Electrolytic Bath Pack:

5 pounds powdered aluminum metal Nickel sulfate 100 pounds powdered alumina NiSO,6H,0 Nickel chloride, Nicl,6li,o 0 m 4 Example 1 1 Nickel sulfamate, Ni(SO,NI-l,), 3s m 60 Nickel fluobora'e- 7 pounds powdered aluminum metal N'(BF4)= 100 pounds powdered alumina Total nickel as metal 8.2 to 15 01 Pound ammonium cmmidc Boric acid. M430 4 to 6 Antipitting additives (b) Operating C diti In the electrolytic plating systems of Examples 5 to 7, the part is suspended as a cathode in the electrolyte until a coating 2 F g thickness within the range of 0.0001 to 0.001 inch has been empemure. deposited. The part is then removed and rinsed with water to Current density, a. per sq. ft. 25 to 300 remove electrolytic.

EXample 7 In the nonelectrolytic systems of Examples 8 and 9, a thinner nickel coating is deposited on the metal surfaces. In practice, the parts are immersed in the bath with continuous C i i f El l i h movement until a nickel coating having a thickness within the range of 0.0001 to 0.001 inch is deposited and the part is then Nickel sulfate removed and rinsed. l The nickel plated parts are packed with the pack composi- Nlckel chlorlde, NiclzfiHzo 0 lo 2 non of Examples 10 and l 1 m a retort. The parts formed of the Nickel sulfamatc. cobalt alloy of Example 2 are heated in a hydrogen atft i m mosphere for 10 hours at 1950 F. while the parts formed of :12: 30 1 40 the nickel-based alloys of Examples 1, 3 and 4 are heated in a O 31 g g as mm M w 105 40 hydrogen atmosphere for 9 hours at l,950 F. to form parts Boric acid, a so, 2 to 4 having a final coating thickness withln the range of 0.0015 to Antipitting additives (b) inch.

Instead of making use of the nickel or cobalt based alloys of Operatmg Commons Examples 1 to 4, use can be made of parts formed of nickel or P" U m 4 cobalt based superalloys in which corrosion resistance at high Temperature, F 100 m 160 temperature and resistance to deterioration by the sulfides CUIICl'll density, present in corrosive gases is greatly improved. 25 The term powdered or finely divided" form, as applied to the elements in the pack composition, is meant to refer to Example 8 aluminum metal particles of preferably less than 5 microns and is meant to refer to particles of less than 100 microns and preferably within the range of 5-100 microns for the filler or alumina component of each pack. Composmon Nonelectmlyuc Bath 5 5 It will be understood that changes may be made in the c ch10 details of formulation and o eration without de artin from lck l n p p g (Nicl,eH,o so oz. P01 gal. the spirit of the invention, especially as defined in the follow- Boric acid (H3805) 4 oz. per gal. l i

0 c We claim:

pew mg on I Ions 1. A method for surface treatment to improve the corrosion PH 4,5 resistance of products having surface portions formed of a Temperature 160 F. metal selected from the group consisting of nickel base alloys,

cobalt base alloys, and superalloys, comprising the steps of ap- Example 9 plying a first coating of nickel on surfaces of the product, and then alumlnlzlng the nickel coated surfaces by dlffuslon transfer. 2. The method as claimed in claim 1 in which the first coat- Composmo" Nonelectl'olytlc Bath ing of nickel is applied in a coating thickness greater than Nickel chloride 30 00001 inch" Nickel sulfa: 7O 3. The method as claimed ln claim 1 ln Much the first coat- Sodium hypophosphite 3 l0 ing of nickel is applied by a nonelectrolytic system in a coating Sodium acetate thickness within the range of 0.0001 to 0.001 inch. f 4. The method as claimed in claim 1 m which the first coat- Sodlum succlnate d k h. h Lactic acid mg of nlckel ls app lle in a coatlng t lc ness wlt m t e range 75 of0.0001 to 0.001 inch.

Propionic acid 5. The method as claimed in claim 1 in which the nickel coating is applied by electroplating the product.

6. The method as claimed in claim 1 in which the nickel coating is deposited by chemical deposition.

7. The method as claimed in claim 1 in which the aluminizing coating is applied with the materials at elevated temperature.

8. The method as claimed in claim 7 in which the materials are applied at elevated temperature within the range of 1 ,800 to 2,000 F.

9. The method as claimed in claim 1 in which the aluminizing coating is applied in a nonoxidizing temperature.

10. The method as claimed in claim 1 in which the aluminizing coating is applied in an amount to provide an overall coating thickness within the range of 0.001 to 0.005 inch.

11. The method as claimed in claim I in which the aluminizing coating is applied in an amount to provide an overall coating thickness within the range of 0.0015 to 0.003 inch.

12. The method as claimed in claim 1 in which the product is aluminized by packing the nickel coated product in an aluminizing composition containing aluminum metal in finely divided form in an amount within the range of 0.l to l0 percent by weight uniformly distributed in a filler.

13. The method as claimed in claim 12 in which the tiller is alumina.

14. The method as claimed in claim 12 in which the aluminizing composition contains an energizer.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1480779 *Mar 26, 1920Jan 15, 1924Pacz AladarComposition of matter and method of making same
US1637033 *Jun 5, 1925Jul 26, 1927Gen ElectricComposite electric conductor
US1881064 *May 28, 1929Oct 4, 1932Calorizing CompanyCarburizing box
US2611163 *Aug 20, 1947Sep 23, 1952Cleveland Graphite Bronze CoMethod of making bearings
US2894884 *Oct 17, 1950Jul 14, 1959Allen G GrayMethod of applying nickel coatings on uranium
US2917818 *Dec 29, 1954Dec 22, 1959Gen Motors CorpAluminum coated steel having chromium in diffusion layer
US2957782 *Jul 13, 1956Oct 25, 1960Boller Dev CorpProcess for coating ferrous metals
US2970065 *Dec 31, 1956Jan 31, 1961Gen Motors CorpForming an aluminum-containing alloy protective layer on metals
US3079276 *Oct 14, 1960Feb 26, 1963Union Carbide CorpVapor diffusion coating process
US3345197 *Aug 9, 1963Oct 3, 1967Howmet CorpAluminizing process and composition
GB428855A * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3873347 *Apr 2, 1973Mar 25, 1975Gen ElectricCoating system for superalloys
US3874901 *Apr 23, 1973Apr 1, 1975Gen ElectricCoating system for superalloys
US3904789 *Apr 24, 1974Sep 9, 1975Chromalloy American CorpMasking method for use in aluminizing selected portions of metal substrates
US3922396 *Sep 25, 1974Nov 25, 1975Chromalloy American CorpCorrosion resistant coating system for ferrous metal articles having brazed joints
US3978251 *Jun 14, 1974Aug 31, 1976International Harvester CompanyNickel, cobalt, chromium, intermetallics
US3998603 *Mar 27, 1975Dec 21, 1976General Electric CompanyProtective coatings for superalloys
US4031274 *Oct 14, 1975Jun 21, 1977General Electric CompanyAluminum, chromium, nickel, alloys
US4084025 *May 24, 1976Apr 11, 1978General Electric CompanyProcess of applying protective aluminum coatings for non-super-strength nickel-chromium alloys
US4087589 *Nov 19, 1976May 2, 1978General Electric CompanyAlloys, turbines
US4260654 *Sep 7, 1979Apr 7, 1981Alloy Surfaces Company, Inc.Smooth coating
US4407871 *Oct 8, 1981Oct 4, 1983Ex-Cell-O CorporationCorrosion resistant
US4431711 *Oct 8, 1981Feb 14, 1984Ex-Cell-O CorporationVacuum depositing non-conductive indium particles, and protective overcoating with resin
US4714624 *Feb 21, 1986Dec 22, 1987Textron/Avco Corp.High temperature oxidation/corrosion resistant coatings
US5208070 *Apr 12, 1991May 4, 1993Rolls-Royce PlcMethod of aluminum plating an article
US5308399 *Jun 4, 1993May 3, 1994Mtu Motoren- Und Turbinen-Union Muenchen GmbhAluminizing in vessel with different temperature zones; turbine engine blades
US5334416 *Dec 23, 1992Aug 2, 1994Pohang Iron & Steel Co., Ltd.Heat resistant stainless steel coated by diffusion of aluminum and the coating method thereof
US5455071 *Apr 25, 1994Oct 3, 1995Mtu Motoren- Und Turbinen-Union Muenchen GmbhMethod for coating a structural component by gas diffusion
US7468122 *Dec 29, 2005Dec 23, 2008KistComposite layer including metal and inorganic powders and method for manufacturing the same
US8142854 *Mar 28, 2008Mar 27, 2012Ebara CorporationMethod for forming corrosion-resistant film and high-temperature apparatus member
US20100105570 *Oct 9, 2009Apr 29, 2010Alliance For Sustainable Energy, LlcMulti-Chamber Pretreatment Reactor for High Throughput Screening of Biomass
EP1013786A1 *Dec 10, 1999Jun 28, 2000GE Aviation Services Operation (Pte) Ltd.Method for repairing a superalloy turbine component
EP1123987A1 *Feb 7, 2001Aug 16, 2001General Electric CompanyRepairable diffusion aluminide coatings
Classifications
U.S. Classification205/191, 427/252
International ClassificationC23C10/02, C23C10/00
Cooperative ClassificationC23C10/02
European ClassificationC23C10/02
Legal Events
DateCodeEventDescription
Jun 6, 1988AS01Change of name
Owner name: HOWMET CORPORATION
Owner name: HOWMET TURBINE COMPONENTS CORPORATION (CHANGED TO)
Effective date: 19870422
Jun 6, 1988ASAssignment
Owner name: HOWMET CORPORATION
Free format text: CHANGE OF NAME;ASSIGNOR:HOWMET TURBINE COMPONENTS CORPORATION (CHANGED TO);REEL/FRAME:004886/0082
Effective date: 19870422
Jan 14, 1988ASAssignment
Owner name: HOWMET CORPORATION
Free format text: CHANGE OF NAME;ASSIGNOR:HOWMET TURBINE COMPONENTS CORPORATION;REEL/FRAME:004876/0559
Effective date: 19870422
Jul 28, 1983ASAssignment
Owner name: HOWMET TURBINE COMPONENTS CORPORATION 825 THIRD AV
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST. SUBJECT TO AGREEMENT DATED DECEMBER 31, 1975.;ASSIGNOR:HOWMET CORPORATON A CORP. OF DE;REEL/FRAME:004164/0321
Effective date: 19830705