US3516875A - Process for coating ferrous surfaces - Google Patents
Process for coating ferrous surfaces Download PDFInfo
- Publication number
- US3516875A US3516875A US644069A US3516875DA US3516875A US 3516875 A US3516875 A US 3516875A US 644069 A US644069 A US 644069A US 3516875D A US3516875D A US 3516875DA US 3516875 A US3516875 A US 3516875A
- Authority
- US
- United States
- Prior art keywords
- bath
- solution
- lead
- coating
- nitrate
- 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.)
- Expired - Lifetime
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Classifications
-
- 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
- C23C22/05—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 using aqueous solutions
- C23C22/06—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 using aqueous solutions using aqueous acidic solutions with pH less than 6
- C23C22/07—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 using aqueous solutions using aqueous acidic solutions with pH less than 6 containing phosphates
- C23C22/08—Orthophosphates
- C23C22/12—Orthophosphates containing zinc cations
- C23C22/13—Orthophosphates containing zinc cations containing also nitrate or nitrite anions
Definitions
- the presence of the lead in the solution increases the amount of nitrite re generated from the nitrate in the bath, thus maintaining sufficient nitrite ion concentration in the bath to keep the bath sufiiciently free of divalent iron without the necessity for replenishing nitrite in the bath.
- the lead is added in an amount of at least about milligrams per liter, preferably in the form of lead nitrate, lead acetate, lead oxide, or lead carbonate.
- This invention relates to a method for treating metal surfaces and more particularly relates to an improved process for forming a phosphate coating on ferrous metal surfaces.
- the coating solutions have been aqueous solutions of acid zinc phosphate, which solutions have also contained various accelerating agents, such as nitrate ions and nitrite ions, and the like.
- various accelerating agents such as nitrate ions and nitrite ions, and the like.
- ferrous ions i.e., divalent iron.
- this is done by effecting oxidation of substantially all of the dissolved iron in the processing solution to the trivalent state.
- the oxidation rate of the nitrate and/or nitrite accelerators in the bath will be sufiicient to convert substantially all of the dissolved iron into the trivalent state, thus maintaining the bath substantially free of divalent iron.
- nitrite ions will :be regenerated in the processing solution, by the reduction of the nitrate ion, so that the oxidizing characteristics of the bath will be continually maintained. This method of operation is very desirable to achieve, inasmuch as it eliminates the necessity for the additional replenishment of the nitrite ions in the bath as it is operated.
- an object of the present invention to provide an improved method for forming a phosphate coating on ferrous metal surfaces, using a nitrate and/or nitrite accelerated zinc phosphate solution.
- a further object of the present invention is to provide an improved method for operating a nitrate and/or nitrite accelerated zinc phosphatizing solution whereby the necessity for adding nitrite to the processing bath during operation is eliminated.
- the present invention includes a process for treating ferrous metal surfaces to provide therein -a protective and/or paint-base coating which comprises contacting ferrous metal surface to be treated with an aqueous acidic zinc phosphate solution, substantially free of divalent iron, which solution contains nitrite ions and an accelerating amount of lead, and maintaining said solution in contact with the ferrous metal surface for a period suflicient to form the desired coating. It has been found that by the addition of the lead to the above processing solutions, the solutions are maintained substantially free of divalent iron over a wide range of operating temperatures and work throughput, without the necessity of adding additional nitrite ions to replenish the solution.
- the metal coating composition used is an aqueous acidic zinc phosphate solution substantially free of divalent iron, which solutions contains zinc ions, phosphate ions, nitrate ions, nitrite ions, and lead. Desirably, these components are present in the treating solution in the following amounts:
- Lead at least 20 milligrams per liter.
- the lead added to the processing solutions of the present invention is desirably in the form of a water and/or phosphoric acid soluble compound.
- exemplary of such compounds which may be used are lead nitrate, lead acetate, lead oxide, lead carbonate, and the like.
- These lead compounds may be added directly to the phosphatizing solution after it has been formulated although, desirably, the lead compounds are incorporated in the concentrate compositions used in making up and replenishing the phosphatizing solution.
- the amount of the lead compound added, either to the formulated phosphatizing solution or included in the concentrate compositions will be suflicient to provide an accelerating amount of lead in the phosphatizing solution.
- amounts of lead of at least about 20 milligrams per liter of the phosphatizing solution are sufficient to provide the desired acceleration. Amounts of lead in excess of this, i.e., up to the maximum solubility of the lead compound in the phosphatizing solution may also be used.
- the metal treating solution of the present invention may also contain additional adjuvants, including metal ions such as nickel, cobalt, lithium, bismuth, cesium, and magnesium. Accordingly, in a preferred composition, the processing solutions of the present invention may contain the following components in the amount indicated'.
- suitable materials may be used to supply the desired com ponents.
- suitable starting materials are zinc oxide, phosphoric acid, zinc dihydrogen phosphate, zinc nitrate, and the like.
- metallic ions such as nickel ions
- they may conveniently be added in the form of the nitrate, phosphate, or carbonate salt, while the lead is desirably added in the form of a water and/or phosphoric acid soluble compounds as has been indicated above.
- the nitrite ions may conveniently be added to the solution as the alkali metal nitrite, such as sodium nitrite.
- materials used are desirably those which will not introduce extraneous ions into the treating soltuions, or, that at least will not introduce ions into the solution which are detrimental either to the solution itself or to the coating which is produced.
- the processing solution may be formulated, initially, without nitrite and then operated so as to form the nitrite in situ in the solution as the coating bath is used. This may be done by providing a relatively high nitrate to phosphate ratio, e.g., a ratio of at least about 1.25 to 1, in the bath as originally formulated and then coating the ferrous metal surfaces using less than the normal metal loading rate. In this manner, nitrate will be developed in the bath and, thereafter, the bath may be operated at normal loading rates and will continue to operate on the nitrite side, i.e., without the buildup of divalent iron in the bath.
- a relatively high nitrate to phosphate ratio e.g., a ratio of at least about 1.25 to 1
- the bath may be operated at normal loading rates and will continue to operate on the nitrite side, i.e., without the buildup of divalent iron in the bath.
- the processing baths of the present invention may be applied to ferrous metal surfaces, such as iron, steel, or the like by immersing the surface in the coating solution.
- the coating solution is at an elevated temperature above room temperature, i.e., 20 degrees centigrade, with temperatures of at least about 40 degrees centigrade being preferred.
- the processing solution may be operated at higher temperatures, e.g., 60 to 120 degrees centigrade, the advantages obtained by the inclusion of the lead in the coating solutions are found to be most pronounced at the lower operating temperature.
- the phosphate coatings produced by the present method are found to have excellent protective and/or paint base properties.
- the phosphate coating produced may be further treated, such as by the application of aqueous solutions containing hexavalent chromium ions. Where such solutions are used, they typically contain from about 0.01 to about 1 percent by weight of CrO either alone or in admixture with other acids, such as phosphoric acid, or the like.
- aqueous solutions containing hexavalent chromium ions typically contain from about 0.01 to about 1 percent by weight of CrO either alone or in admixture with other acids, such as phosphoric acid, or the like.
- the pointage of this bath was 40, the point being equal to the number of milliliters of 0.1 normal sodium hydroxide solution required to neutralize a 10 milliliter sample of bath solution to the phenolphthalein end point.
- Steel plates which had been degreased in perchloroethylene vapors and pickled in 15 percent hydrochloric acid at room temperature and then thoroughly rinsed in cold Water were immersed in the phosphatizing solution, which was at a temperature of 55 degrees centigrade for 10 minutes.
- the steel plates were phosphatized in the bath at the rate of 0.2 square meter of steel plate surface per liter of solution per hour. After one hour, the solution was found to be clear, dark brown color and gave a strongly positive reaction to the analysis for divalent iron in the bath.
- Example 2 The procedure of Example I was repeated with the exception that about 1.2 milligrams per liter of lead was added to the phosphatizing bath, as lead nitrate. After operating the bath for one hour, as in Example 1, the bath was found to be clear and dark brown in color and gave a strongly positive reaction to the analysis for divalent iron.
- Example 3 The procedure of Example 1 was repeated with the exception that 34 milligrams per liter of lead was added to the phosphatizing bath, as lead nitrate. After operation of the bath for one hour, as in Example 1, the bath was found to be milky white in color and gave a substantially negative reaction to the analysis for divalent iron.
- Example 4 The procedure of Example 1 was repeated with the exception that milligrams per liter of lead was added to the phosphatizing bath, as lead nitrate. After operating the bath for one hour in accordance with the procedure of Example 1, it was found that the bath was milky white in color and gave a substantially negative reaction to the analysis for divalent iron.
- the phosphate coatings produced on the steel panel are found to have excellent protective and/ or paint-base properties.
- the solution became turbid and substantially all of the dissolved iron in the bath was transformed, during the bath operation into the difiiculty soluble trivalent iron phosphate.
- appreciable amounts of divalent iron are contained in the bath as shown by the discoloration of the bath solution to a dark brown color indicating the formation of soluble ferronitroso complexes, While the baths remained clear, indicating the lack of formation of the trivalent iron phosphate sludge in the bath.
- a process for coating ferrous metal surfaces to provide a phosphate coating thereon which comprises contacting the surface to be coated with a coating composition comprising an aqueous acidic zinc phosphate solution, substantially free of divalent iron, which solution contains nitrite ions, and at least 20 milligrams per liter of lead, and maintaining the coating solution in contact with the metal surface for a period sufiicient to form a phosphate coating, whereby the solution is maintained substantially free of divalent iron during the treatment of the ferrous metal surfaces without the further addition of nitrite ions.
- the coating solution contains from about 0.05 to 5.0 percent by weight zinc, from about 2.0 to 10 percent by weight P04, from about 0.001 to 0.08 percent by weight of NQ and from about 0 to 10.0 percent by weight NOE.
- the coating composition also contains nickel ions in an amount within the range of about 0.001 to about 0.005 percent weight of the coating 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)
Description
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE19661521876 DE1521876B1 (en) | 1966-06-11 | 1966-06-11 | Process for dip phosphating of steel |
Publications (1)
Publication Number | Publication Date |
---|---|
US3516875A true US3516875A (en) | 1970-06-23 |
Family
ID=5674914
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US644069A Expired - Lifetime US3516875A (en) | 1966-06-11 | 1967-06-07 | Process for coating ferrous surfaces |
Country Status (1)
Country | Link |
---|---|
US (1) | US3516875A (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3996072A (en) * | 1974-08-23 | 1976-12-07 | Nippon Paint Co., Ltd. | Phosphate coating process and control of the phosphate coating solution |
US4950339A (en) * | 1988-02-03 | 1990-08-21 | Metallgesellschaft Aktiengesellschaft | Process of forming phosphate coatings on metals |
Citations (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1949090A (en) * | 1930-11-17 | 1934-02-27 | Metal Finishing Res Corp | Method and material for coating and cleaning metal |
US2329065A (en) * | 1942-03-06 | 1943-09-07 | Westinghouse Electric & Mfg Co | Corrosion resistant coating for metal surfaces |
US2813812A (en) * | 1952-06-24 | 1957-11-19 | Parker Rust Proof Co | Method for coating iron or zinc with phosphate composition and aqueous solution therefor |
US2863793A (en) * | 1955-04-20 | 1958-12-09 | Montedison Spa | Method of maintaining the efficiency of phosphate coating baths used at room temperature |
DE1060693B (en) * | 1953-03-27 | 1959-07-02 | Metallgesellschaft Ag | Means and method for applying black coatings to metals |
US3166444A (en) * | 1962-04-26 | 1965-01-19 | Lubrizol Corp | Method for cleaning metal articles |
US3261723A (en) * | 1962-11-30 | 1966-07-19 | Lubrizol Corp | Method for reducing combustion chamber deposits in internal combustion engines |
US3338755A (en) * | 1963-09-03 | 1967-08-29 | Hooker Chemical Corp | Production of phosphate coatings on metals |
US3364081A (en) * | 1965-01-15 | 1968-01-16 | Lubrizol Corp | Aqueous phosphating solutions |
-
1967
- 1967-06-07 US US644069A patent/US3516875A/en not_active Expired - Lifetime
Patent Citations (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1949090A (en) * | 1930-11-17 | 1934-02-27 | Metal Finishing Res Corp | Method and material for coating and cleaning metal |
US2329065A (en) * | 1942-03-06 | 1943-09-07 | Westinghouse Electric & Mfg Co | Corrosion resistant coating for metal surfaces |
US2813812A (en) * | 1952-06-24 | 1957-11-19 | Parker Rust Proof Co | Method for coating iron or zinc with phosphate composition and aqueous solution therefor |
DE1060693B (en) * | 1953-03-27 | 1959-07-02 | Metallgesellschaft Ag | Means and method for applying black coatings to metals |
US2863793A (en) * | 1955-04-20 | 1958-12-09 | Montedison Spa | Method of maintaining the efficiency of phosphate coating baths used at room temperature |
US3166444A (en) * | 1962-04-26 | 1965-01-19 | Lubrizol Corp | Method for cleaning metal articles |
US3261723A (en) * | 1962-11-30 | 1966-07-19 | Lubrizol Corp | Method for reducing combustion chamber deposits in internal combustion engines |
US3338755A (en) * | 1963-09-03 | 1967-08-29 | Hooker Chemical Corp | Production of phosphate coatings on metals |
US3364081A (en) * | 1965-01-15 | 1968-01-16 | Lubrizol Corp | Aqueous phosphating solutions |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3996072A (en) * | 1974-08-23 | 1976-12-07 | Nippon Paint Co., Ltd. | Phosphate coating process and control of the phosphate coating solution |
US4950339A (en) * | 1988-02-03 | 1990-08-21 | Metallgesellschaft Aktiengesellschaft | Process of forming phosphate coatings on metals |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: HOOKER CHEMICALS & PLASTICS CORP 32100 STEPHENSON Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:OXY METAL INDUSTRIES CORPORATION;REEL/FRAME:003942/0016 Effective date: 19810317 |
|
AS | Assignment |
Owner name: OXY METAL INDUSTRIES CORPORATION Free format text: CHANGE OF NAME;ASSIGNOR:OXY METAL FINISHING CORPORATION;REEL/FRAME:003967/0084 Effective date: 19741220 |
|
AS | Assignment |
Owner name: OCCIDENTAL CHEMICAL CORPORATION Free format text: CHANGE OF NAME;ASSIGNOR:HOOKER CHEMICAS & PLASTICS CORP.;REEL/FRAME:004126/0054 Effective date: 19820330 |
|
AS | Assignment |
Owner name: PARKER CHEMICAL COMPANY, 32100 STEPHENSON HWY., MA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:OCCIDENTAL CHEMICAL CORPORATION;REEL/FRAME:004194/0047 Effective date: 19830928 |