US3849206A - Densification of hard chrome plated surfaces - Google Patents
Densification of hard chrome plated surfaces Download PDFInfo
- Publication number
- US3849206A US3849206A US00320217A US32021773A US3849206A US 3849206 A US3849206 A US 3849206A US 00320217 A US00320217 A US 00320217A US 32021773 A US32021773 A US 32021773A US 3849206 A US3849206 A US 3849206A
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- US
- United States
- Prior art keywords
- chromic acid
- heating
- solution
- chrome plated
- temperature
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- 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.)
- Expired - Lifetime
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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
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C22/73—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals characterised by the process
- C23C22/74—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals characterised by the process for obtaining burned-in conversion coatings
Definitions
- chromium is very resistant to the corrosive action of many chemicals, such as corrosive acids and alkalies, these chemicals penetrate the pores and cracks and corrode the metal substrate. This action results in the flaking or pealing of the chromium plating from the substrate and parts which are subject to very high pressures, such as hydraulic components, may leak after a short service period.
- the object of the present invention is to treat chrome plated surfaces to densify the surface by filling in inherent defects such as micropores and cracks. This densitication will prevent penetration of the chrome plating by chemicals and thereby reduce the tendency of the chrome plating to become detached from the substrate and reduce chemical attack on the substrate.
- the objects of the present invention are accomplished by treating the chrome plated surfaces with a chromic acid solution and then converting the chromic acid to chromic oxide.
- the chromic acid solution for use in the present invention isprepared by dissolving chromium trioxide in water to produce a chromic acid solution having a specific gravity of 1.64-1.66 at 70F. The preferred specific gravity is 1.65.
- the chrome plated metal part to be treated is then immersed into the chromic acid solution or otherwise treated with the solution and the chromic acid wets and penetrates the micropores and cracks of the chrome plated surface.
- the treated metal part is then heated so as to convert the chromic acid to a refractory chromic oxide.
- the conversion of the chromic acid to chromic oxide takes place at a temperature between 700F and 1,200F.
- This heating cycle involves first heating the treated metal part to 230F t F and held at this temperature for a period of time sufficient to insure that all the moisture is removed from the micropores and cracks of the chrome plated surface. The part is then gradually brought to a temperature of 700F i 50F. The rate of heating to this temperature level is determined by the mass and complexity of the metal part and is selected to avoid thermal stresses. Sufficient time is allowed to stabilize the temperature throughout the metal substrate. After the temperature has stabilized at 700F i 50F, the temperature of the surface is rapidly brought to 1200F 5 0F and then the part is removed from the heating equipment. This rapid heating from 700 to 1,200F converts the chromic acid to chromic oxide and the chromic oxide becomes very dense and is more strongly bonded to the base metal.
- the repeated coating with chromic acid and curing to form chromic oxide will tend to more completely fill the pores and cracks of the chrome electroplated surface.
- the part is then cooled to F and again treated with chromic acid solution, heated to 230F, gradually brought to the stabilized temperature of 700F and then rapidly heated to 1,200F. This procedure is repeated until the pores and cracks have been filled.
- the part may then be finished by polishing by conventional means.
- Heating of the metal parts may be accomplished by any conventional means such as in ovens or furnaces, or by means of radiant heat burners or by direct flame.
- parts which have been heated with induction heating have proved to be the most effective in bonding the chromic oxide to the substrate. This fact is apparent on a microscopic examination of sections of parts treated in accordance with the present invention.
- a method of treating metal parts having chrome plating thereon wherein said chrome plating contains pores and cracks comprising the steps of:
- step of heating comprises the step of heating by induction heating.
- said chromic acid solution contains a material selected from the group consisting of carbon black and lamp black, said material being present in an amount equivalent to 0.05 to 0.5 percent by weight of the chromic acid present in the chromic acid solution.
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- Chemical & Material Sciences (AREA)
- General Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Chemical Treatment Of Metals (AREA)
- Electroplating Methods And Accessories (AREA)
Abstract
Porous chrome plated surfaces are densified by treating the surface with a chromic acid solution and heating the part to cure and bring about the conversion of the chromic acid to chromic oxide. The procedure may be repeated as required until the pores and cracks have been filled.
Description
llmte States Patent 1 1 1111 3,849,206
Jacobs Nov. 19, 1974 [54] DENSIFICATION OF HARD CHROME 2,438,013 3/1948 Tanner... 204/35 R x PLATED SURFACES 2,618,578 11/1952 Kreml 148/62 X 2,746,915 5/1956 Giesker et al 204/35 R Inventor: Louis John Ja o s, cago, 111. 2,755,242 7/1956 Keller et al. 1. 204 35 R x 2,773,623 12/1956 Schuster et al. 148/612 X [73] Ass'gnee' cqmgustmn 3,526,486 9 1970 Smith et al 204/35 R x Wm 3,755,091 8/1973 Austin 204 35 R x [22] Filed: Jan. 2, 1973 2 Primary Examiner-Ralph S. Kendall [21] Appl- 320,217 Attorney, Agent, or Firm-Richard H. Berneike [52] US. Cl. 148/6.2, 204/35 R, 204/38 R ABSTRACT [51] Int. Cl. C23f 7/26 Porous chrome plated surfaces are densified by treat- [58] Field of Search 148/62; 204/35 R, 38 S, ing the surface with a chromic acid solution and heat- 204/38 R ing the part to cure and bring about the conversion of the chromic acid to chromic oxide. The procedure [56] References Cited may be repeated as required until the pores and UNITED STATES PATENTS cracks have been filled.
2,327,885 8/1943 Grace et a1 117/71 M X 3 Claims, N0 Drawings DENSIFICATION OF HARD CHROME PLATED SURFACES BACKGROUND OF THE INVENTION There are many commercial applications for hard chrome plated parts such as refractory patterns, dies for forming plastic and ceramic parts, hydraulic actuators, cylinder liners, and ball and check valves as well as many other uses. All of the present commercial chrome electroplated surfaces of metal parts contain micropores and a chicken wire crazing pattern of cracks which are visable with a low power microscope. It is these inherent defects which cause destruction of the chrome plated surface and failure of the part. Although chromium is very resistant to the corrosive action of many chemicals, such as corrosive acids and alkalies, these chemicals penetrate the pores and cracks and corrode the metal substrate. This action results in the flaking or pealing of the chromium plating from the substrate and parts which are subject to very high pressures, such as hydraulic components, may leak after a short service period.
SUMMARY OF THE INVENTION The object of the present invention is to treat chrome plated surfaces to densify the surface by filling in inherent defects such as micropores and cracks. This densitication will prevent penetration of the chrome plating by chemicals and thereby reduce the tendency of the chrome plating to become detached from the substrate and reduce chemical attack on the substrate. The objects of the present invention are accomplished by treating the chrome plated surfaces with a chromic acid solution and then converting the chromic acid to chromic oxide.
DESCRIPTION OF THE PREFERRED EMBODIMENT The chromic acid solution for use in the present invention isprepared by dissolving chromium trioxide in water to produce a chromic acid solution having a specific gravity of 1.64-1.66 at 70F. The preferred specific gravity is 1.65. The chrome plated metal part to be treated is then immersed into the chromic acid solution or otherwise treated with the solution and the chromic acid wets and penetrates the micropores and cracks of the chrome plated surface. The treated metal part is then heated so as to convert the chromic acid to a refractory chromic oxide. The conversion of the chromic acid to chromic oxide takes place at a temperature between 700F and 1,200F. However, a preferred heating cycle should be followed to obtain the most effective densification. This heating cycle involves first heating the treated metal part to 230F t F and held at this temperature for a period of time sufficient to insure that all the moisture is removed from the micropores and cracks of the chrome plated surface. The part is then gradually brought to a temperature of 700F i 50F. The rate of heating to this temperature level is determined by the mass and complexity of the metal part and is selected to avoid thermal stresses. Sufficient time is allowed to stabilize the temperature throughout the metal substrate. After the temperature has stabilized at 700F i 50F, the temperature of the surface is rapidly brought to 1200F 5 0F and then the part is removed from the heating equipment. This rapid heating from 700 to 1,200F converts the chromic acid to chromic oxide and the chromic oxide becomes very dense and is more strongly bonded to the base metal.
The repeated coating with chromic acid and curing to form chromic oxide will tend to more completely fill the pores and cracks of the chrome electroplated surface. After the first coating has been applied and cured, the part is then cooled to F and again treated with chromic acid solution, heated to 230F, gradually brought to the stabilized temperature of 700F and then rapidly heated to 1,200F. This procedure is repeated until the pores and cracks have been filled. The part may then be finished by polishing by conventional means.
Heating of the metal parts may be accomplished by any conventional means such as in ovens or furnaces, or by means of radiant heat burners or by direct flame. However, parts which have been heated with induction heating have proved to be the most effective in bonding the chromic oxide to the substrate. This fact is apparent on a microscopic examination of sections of parts treated in accordance with the present invention.
It has been found to be helpful in the practice of the present invention to add about 0.05 to 0.5 percent by weight of carbon black or lamp black based on the weight of the chromic acid used to make the chromic acid solution. The presence of the carbon reduces the oxygen content of the solution and in some manner in creases the rate of filling of the pores and cracks with chromic oxide.
Although the present invention has been described with reference to specific examples it will be understood that these are merely illustrative and that changes may be made without departing from the invention as claimed.
What is claimed is:
l. A method of treating metal parts having chrome plating thereon wherein said chrome plating contains pores and cracks comprising the steps of:
a. applying a solution to said chrome plated metal parts whereby solution penetrates said pores and cracks, said solution consisting essentially of a chromic acid solution having'a specific gravity of from 1.64 to 1.66; and
b. heating said chrome plated metal parts having said chromic acid applied thereto to a temperature of about 230F- 10F, graduallyheating to a temperature of 700F 50F, permitting said temperature to stabilize at 700F 50F throughout said part and then rapidly heating said part to 1,200F to convert said chromic acid to chromic oxide.
2. A method as recited in claim 1 wherein said step of heating comprises the step of heating by induction heating.
3. A method as recited in claim 1 wherein said chromic acid solution contains a material selected from the group consisting of carbon black and lamp black, said material being present in an amount equivalent to 0.05 to 0.5 percent by weight of the chromic acid present in the chromic acid solution.
Claims (3)
1. A METHOD OF TREATING METAL PARTS HAVING CHROME PLATING THEREON WHEREIN SAID CHROME PLATING CONTAINS PORES AND CRACKS COMPRISING THE STEPS OF: A APPLYING A SOLUTION TO SAID CHROME PLATED METAL PARTS WHEREBY SOLUTION PENETRATES SAID PORES AND CRACKS, SAID SOLUTION CONSISTING ESSENTIALLY OF A CHROMIC ACID SOLUTION HAVING A SPECIFIC GRAVITY OF FROM 1.64 TO 1.66; AND B. HEATING SAID CHROME PLATED METAL PARTS HAVING SAID CHROMIC ACID APPLIED THERETO TO A TEMPERATURE OF ABOUT 230*F +- 10*F, GRADUALLY HEATING TO A TEMPERATURE OF 700*F+50*F, PERMITTING SAID TEMPERATURE TO STABILIZED AT 700*+50*F, THROUGHOUT SAID PART AND THEN RAPIDLY HEATING SAID PART TO 1,200*F TO CONVERT SAID CHROMIC ACID TO CHROMIC OXIDE.
2. A method as recited in claim 1 wherein said step of heating comprises the step of heating by induction heating.
3. A method as recited in claim 1 wherein said chromic acid solution contains a material selected from the group consisting of carbon black and lamp black, said material being present in an amount equivalent to 0.05 to 0.5 percent by weight of the chromic acid present in the chromic acid solution.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US00320217A US3849206A (en) | 1973-01-02 | 1973-01-02 | Densification of hard chrome plated surfaces |
| CA187,004A CA993285A (en) | 1973-01-02 | 1973-11-29 | Densification of hard chrome plated surfaces |
| DE2364329A DE2364329A1 (en) | 1973-01-02 | 1973-12-22 | PROCESS FOR TREATMENT OF CHROMED METAL PARTS |
| JP48144796A JPS4998342A (en) | 1973-01-02 | 1973-12-28 |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US00320217A US3849206A (en) | 1973-01-02 | 1973-01-02 | Densification of hard chrome plated surfaces |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US3849206A true US3849206A (en) | 1974-11-19 |
Family
ID=23245400
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US00320217A Expired - Lifetime US3849206A (en) | 1973-01-02 | 1973-01-02 | Densification of hard chrome plated surfaces |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US3849206A (en) |
| JP (1) | JPS4998342A (en) |
| CA (1) | CA993285A (en) |
| DE (1) | DE2364329A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4576655A (en) * | 1983-06-23 | 1986-03-18 | Ssab Svenskt Stal Ab | Method for producing high strength steel with good ductility |
| US10519322B2 (en) * | 2014-01-03 | 2019-12-31 | The Boeing Company | Composition and method for inhibiting corrosion |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3145236C2 (en) * | 1981-11-13 | 1984-11-22 | M.A.N. Maschinenfabrik Augsburg-Nürnberg AG, 8000 München | Process for the production of deformation-resistant oxidic protective layers |
| JPH05240156A (en) * | 1992-08-21 | 1993-09-17 | Toshiba Corp | Reciprocating type piston pump |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2327885A (en) * | 1939-05-13 | 1943-08-24 | Remington Arms Co Inc | Ammunition manufacture |
| US2438013A (en) * | 1940-07-22 | 1948-03-16 | Patents Corp | Treated steel sheet and process |
| US2618578A (en) * | 1950-10-13 | 1952-11-18 | Armco Steel Corp | Blackening stainless steel |
| US2746915A (en) * | 1951-10-15 | 1956-05-22 | Autoyre Co Inc | Electrolytic metal treatment and article |
| US2755242A (en) * | 1954-04-09 | 1956-07-17 | Aluminum Co Of America | Treatment for chromium plated aluminum |
| US2773623A (en) * | 1954-06-01 | 1956-12-11 | Heintz Mfg Co | Corrosion resistant coated steel members and method of making |
| US3526486A (en) * | 1967-02-21 | 1970-09-01 | Nat Steel Corp | Corrosion resistant ferrous metal articles and method of preparing the same |
| US3755091A (en) * | 1969-06-19 | 1973-08-28 | Nat Steel Corp | Process for reducing discoloration of electrochemically treated chromium plated ferrous metal strip |
-
1973
- 1973-01-02 US US00320217A patent/US3849206A/en not_active Expired - Lifetime
- 1973-11-29 CA CA187,004A patent/CA993285A/en not_active Expired
- 1973-12-22 DE DE2364329A patent/DE2364329A1/en active Pending
- 1973-12-28 JP JP48144796A patent/JPS4998342A/ja active Pending
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2327885A (en) * | 1939-05-13 | 1943-08-24 | Remington Arms Co Inc | Ammunition manufacture |
| US2438013A (en) * | 1940-07-22 | 1948-03-16 | Patents Corp | Treated steel sheet and process |
| US2618578A (en) * | 1950-10-13 | 1952-11-18 | Armco Steel Corp | Blackening stainless steel |
| US2746915A (en) * | 1951-10-15 | 1956-05-22 | Autoyre Co Inc | Electrolytic metal treatment and article |
| US2755242A (en) * | 1954-04-09 | 1956-07-17 | Aluminum Co Of America | Treatment for chromium plated aluminum |
| US2773623A (en) * | 1954-06-01 | 1956-12-11 | Heintz Mfg Co | Corrosion resistant coated steel members and method of making |
| US3526486A (en) * | 1967-02-21 | 1970-09-01 | Nat Steel Corp | Corrosion resistant ferrous metal articles and method of preparing the same |
| US3755091A (en) * | 1969-06-19 | 1973-08-28 | Nat Steel Corp | Process for reducing discoloration of electrochemically treated chromium plated ferrous metal strip |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4576655A (en) * | 1983-06-23 | 1986-03-18 | Ssab Svenskt Stal Ab | Method for producing high strength steel with good ductility |
| US10519322B2 (en) * | 2014-01-03 | 2019-12-31 | The Boeing Company | Composition and method for inhibiting corrosion |
Also Published As
| Publication number | Publication date |
|---|---|
| DE2364329A1 (en) | 1974-07-11 |
| CA993285A (en) | 1976-07-20 |
| JPS4998342A (en) | 1974-09-18 |
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Owner name: VFR, INC., 901 EAST 8TH AVENUE, KING OF PRUSSIA, P Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:COMBUSTION ENGINEERING, INC.;REEL/FRAME:004993/0109 Effective date: 19880927 |
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Owner name: PREMIER REFRACTORIES AND CHEMICALS INC., Free format text: ASSIGNMENT OF ASSIGNORS INTEREST. EFFECTIVE 10-28-88;ASSIGNOR:VFR, INC.,;REEL/FRAME:005020/0764 Effective date: 19890118 |
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Owner name: CONTINENTAL BANK N.A., A NATIONAL BANKING ASSOCIAT Free format text: SECURITY INTEREST;ASSIGNOR:PREMIER REFRACTORIES AND CHEMICALS INC.;REEL/FRAME:005125/0289 Effective date: 19890621 |
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Owner name: PREMIER REFRACTORIES AND CHEMICALS INC., A DE CORP Free format text: RELEASE BY SECURED PARTY OF A SECURITY AGREEMENT RECORDED AT REEL 5125 FRAME 0289;ASSIGNOR:CONTINENTAL BANK N.A.;REEL/FRAME:006098/0524 Effective date: 19911211 |