US3920486A - Method of blackening ferrous metal surfaces - Google Patents
Method of blackening ferrous metal surfaces Download PDFInfo
- Publication number
- US3920486A US3920486A US448168A US44816874A US3920486A US 3920486 A US3920486 A US 3920486A US 448168 A US448168 A US 448168A US 44816874 A US44816874 A US 44816874A US 3920486 A US3920486 A US 3920486A
- Authority
- US
- United States
- Prior art keywords
- solution
- bath
- workpiece
- nitrate
- ammonium
- 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
- C23C22/48—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 not containing phosphates, hexavalent chromium compounds, fluorides or complex fluorides, molybdates, tungstates, vanadates or oxalates
- C23C22/50—Treatment of iron or alloys based thereon
Definitions
- ABSTRACT Disclosed is a method of forming a corrosion resistant and decorative black coating on a ferrous metal surface.
- the method involves contacting the ferrous workpiece with an aqueous slightly acidic solution containing the nitrate ion and a soluble nitrogen containing cation.
- the solution is obtained by dissolving both ammonium nitrate and a neutral nitrate salt in water and maintaining a pH of between 4.0 and 6.8.
- This invention relates to the treatment of ferrous metal surfaces to form a corrosion resistant coating thereon. More particularly, it relates to the formation of such a corrosion resistant coating which is also a decorative black coating.
- the molten salt baths above-referred-to are exemplified by US. Pat. Nos. 2,370,959; 2,394,899; 2,431,986; and 3,540,942, the contents of which are incorporated herein by reference.
- the molten salt process requires extremely high temperatures for its effectiveness. Temperatures range from between 600 and 1500F and higher. A process operating at much more moderate temperatures in the neighborhood of 200F would avoid the expensive heating costs and would also avoide the complications of working with molten salt materials.
- the treating bath may additionally include accelerators to speed up the reaction, surfactants to inhibit film and scum formation, and scavenger compounds which operate to remove undesirable ions from the solution.
- the workpiece is first cleaned in a conventional alkaline cleaning bath optionally pickled and then contacted with the treating bath of our invention for a period of between 30 seconds and 2 hours under slight agitation.
- the pH of the bath will be in the range of between 4.0 and 6.8.
- the nitrate ion may be supplied to the treating bath from any suitable source. While nitrate ion concentrations in excess of 0.01 weight have been found effective to some extent, the preferred concentration range is between 0.15 and 20.5% and the most preferred range is between 0.25 and 15.0%. At higher percentages, the quality of the coating decreases and at lower concentrations the corresponding temperature and treating time requirements become undesirably long.
- the nitrogen containing cation of the present invention may be supplied from any suitable source. Suitable nitrogen cations may be selected from ammonium, pyridinium and derivatives thereof. The major requirements of the compound serving as the cation source are that it be appreciably soluble in the solution and that it not contribute to undesirable side reactions. While the most preferred nitrogen cation is ammonium, substituted ammonium ions have also been found effective to produce the desired coating. Such ions have the general formula:
- pyridinium, an aromatic nitrogen cation, and its derivatives are also effective for producing the desired black oxide coating.
- Such compounds have the formula:
- R through R may be independently selected from hydrogen, alkyl, aryl, substituted alkyl, and substituted aryl.
- R through R may be independently selected from hydrogen, alkyl, aryl, substituted alkyl, and substituted aryl.
- the above formula may also encompass compounds where adjacent R groups are part of a fused benzene ring or substituted benzene ring (such as occur in the compound quinoline).
- aromatic nitrogen compounds containing more than one nitrogen atom per aromatic ring, such as pyrimidine or its derivitives are also included within the invention as equivalent of the above formula. In general, the nitrogen should comprise at least about 1.8 weight of the cation to help avoid solubility problems.
- the appropriate limitations on the derivatives are that they must be soluble in the bath to an appreciable extent and they must not contain any substituent which would interfere by causing undersirable side reactions.
- the preferred component of this type is the unsubstituted pyridinium ion.
- the precise concentration of the cationic nitrogen containing compound in the bath is not critical so long as the pH requirements stated hereafter are met.
- the mole ratio of nitrogen in the cationic nitrogen compound to total nitrate in the solution will be not in excess of :1.
- the ratio is between .001 and 1:1. It should be appreciated, however, that one may conveniently add an excess of the nitrogen compound in order to increase the pH of the solution after the addition of the nitrate compound.
- the pH will nonnally be within the desired range, and there will be no need to do any pH adjusting.
- a mole ratio of less than 1 may be obtained by adding a portion of the nitrate as a neutral salt such as sodium, potassium, magnesium calcium or the like. Good results have been obtained for the widest variety of steel alloys when the ratio is from 0.0l0.5 to l.
- the pH of the slightly acidic treating bath should be adjusted to give a value of between about 4.0 and 6.8.
- the bath should have a pH of between 4.5 and 6.5 and most preferably between about 5.0 and 6.0.
- the use of more acidic baths results in an undesired extent of pickling whereas baths of a higher pH result in no coatings or lengthy coating times and, in the case of very simple nitrogen compounds, may result in the evolution of ammonia or similar nitrogen containing gases if the pH is adjusted to about 7 or above.
- the workpiece should be maintained in contact with the treating solution for a time sufficient to produce the desired black oxide coating.
- Application may be either by flooding or immersion techniques.
- the desired contact time will vary between 30 seconds and 2 hours and preferably between 5 and 30 minutes depending upon the temperature of the solution and concentration of the reactive ingredients.
- the temperature of the treating solution should be between l40F and the boiling point of the solution. Preferably, the temperature will be between land 2l5F and most preferably between l80and 210F. Higher temperatures are undesirable because of changes in the solution due to boiling and the need for additional heat input, whereas lower temperatures tend to result in a poorer quality coating and an increased rate of scum formation.
- the active ingredients are provided in the form of ammonium nitrate
- a 1 weight solution of ammonium nitrate will require a temperature of in the range of 200 210F whereas a 10 weight solution will require a temperature of approximately lF in order to produce the desired coating on ordinary steel after 15 minutes immersion.
- the workpiece be thoroughly cleaned in accordance with conventional metal cleaning proce dures known in the art.
- a phosphate containing alkaline cleaning bath will be suitable. Improper cleaning will result in spotty and streaked coatings which are not acceptable from either a corrosion or an esthetic viewpoint.
- the workpiece may be pickled prior to treatment in accordance with the invention. When the workpiece is treated via immersion in our bath, it is preferred that slight agitation be employed to insure uniformity of the resulting coating.
- nitrite nitrite, chlorate, bromate and peroxide
- concentration is desirably maintained at low levels depending on the particular agent employed, generally less than 1 weight
- a preferred concentration range for the nitrite ion is from 0.0005 to 0.01%. In an active bath through which ferrous metal workpieces are being passed on a regular basis or where the bath has a high nitrate concentration, a nitrite concentration within the above range will normally be present as a result of reduction of the nitrate ion.
- nitrite concentration would decrease essentially to 0.
- additonal nitrite ion should be added during these startup periods so that nitrite ion will continuously be present while workpieces are being processed. While it is not entirely understood, it has been found that a failure to include a small amount of nitrite ion during these startup stages may result in a bath which will neither coat at all or will coat unpredictably from one time to the next. Chlorate may also be used as an advantageous additional component.
- Supplemental components may be added to accomplish various purposes.
- Surfactants may be added to suspend or disperse the insoluble by-products and to inhibit the rate of formation of film and scum on the surface of the bath. Film and scum are, of course, undesirable because components thereof may adhere to the workpiece as it is withdrawn from the bath.
- the surfactants found most preferred are those of the non-ionic variety such as the nonyl phenol compounds because these tend to interfere least with reactive components and mechanisms of the bath. Suitable non-ionic surfactants are well-known in the art and need not be here recited.
- ferric nitrate An additive which has been found particularly useful in our bath is ferric nitrate.
- Ferric nitrate may act as a scavenger in order to regenerate a bath which has become poisoned by the presence of extraneous ions. It has been found that very small quantities of phosphate ions which tend to be carried over from the prior cleaning step will inactivate the bath.
- the addition of ferric nitrate initiates a series of reactions which precipitate the phosphate ion from the bath and, in effect, operates to regenerate the activity of the bath, renewing its activity toward the formation of the black oxide coating.
- Ferrous metal workpieces which may be treated in the bath of our invention are those which consist predominantly of iron.
- Common steel compositions and alloys containing other metals such as chromium, nickel, maganese, vanadium, lead as well as compositions including common amounts of phosphorous, sulfur and carbon may be treated.
- the corrosion resistance and physical appearance of the black oxide coating obtained by our technique equal that obtained by the conventional alkali treating process.
- the conventional processes often employ a subsequent treatment with a rust-preventive oil such as those referred to at page 565 et. seq. of Metals Hand- 6 thetic properties will be imparted to the workpiece by a final treatment with a rust-preventive oil.
- the ferrous metal article is first carefully cleaned and water-washed, then contacted with the treating bath of our invention, water-washed, and then subjected to further anticorrosive treatment by contact with a rust-preventive oil.
- EXAMPLE 1 Three inch by 5 inch cold-rolled steel (SAE 1010) test panels were flat polished on one side and cleaned so as to be free from grease and oil and surface oxides. They were then immersed in a 0.80% ammonium nitrate solution prepared by dissolving 30 grams of commercial grade ammonium nitrate in one gallon of water. The solution also contains 0.028% sodium chlorate obtained by dissolving 2 millileters of a 40% sodium chlorate solution in the gallon of water. The solution was maintained at a temperature of 205F and the contact time was 15 minutes. At the end of this time, a black oxide coating was observed on the metal surface. The workpiece was then rinsed in water and dried by means of a compressed air jet.
- SAE 1010 Three inch by 5 inch cold-rolled steel
- a panel of the same type was coated in a conventional alkaline oxidizing bath containing approximately 80% sodium hydroxide, 15% sodium nitrate and 5% sodium nitrite dissolved in water at a concentration of about 7 pounds per gallon for 15 minutes at 285F. Panels treated by each of the processes were then spotted with a drop of 5% oxalic acid solution. This test is one employed in accordance with military specifications in order to determine the quality of the coating. If the spot turns a deep black after 5 minutes, then the coating is satisfactory, whereas if it turns a light gray, it is unsatisfactory. After 5 minutes had elapsed, both spots were rinsed and the panels were again air dried and the color of the spots compared. Both spots were a deep black indicating both had a satisfactory black oxide coating.
- EXAMPLE 2 Additional panels were treated in the bath of Example 1 and they were subsequently treated with the solvent based rust-preventive oil above-referred-to for several seconds and allowed to drain. Both sets of panels were then subjected to salt spray corrosion testing in gravity at 75F of approximately .95, a flash point of approximately 330F and a melting point of approximately 95F. This active ingredient may be dissolved in a conventional mineral spirits solvent to provide an f;'
- An oil and water emulsion may be prepared by adding Alox 575, a proprietary product of Alox Corporation, having an acid number of betweenv about 9 and 10, a saponification number of between 28 and 30, a specific gravity at F of approx- ,imately 1.02, apour point of about 80F and a flash point of about 425F, about'25 partsby weight, to a balance of a mixture of a high viscosity aromatic oil and a sulfonated hydrocarbon emulsifier which are conventional in the art.
- additional anti-corrosive and es accordance with ASTM B-l 17. After 72 hours in the 5% salt fog, the amount of rust formed on the panels treated in the ammonium nitrate-sodium chlorate bath was equivalent to that formed on the panels coated inv the conventional alkaline oxidizing bath.
- EXAMPLE 3 Numerous baths were prepared containing from between .37 and 23.6 weight ammonium nitrate. All were effective in producing the black oxide coating on the ferrous metal workpieces of Example 3. Baths were prepared both with and without sodium nitrite and with nitrite concentrations varying between 13 and 135 parts per million. All were found effective in producing the lack oxide coating; however, those solutions containing nitrite did so more quickly and with more reliability. Various baths were prepared including various other accelerators and supplemental ingredients in order to determine their effect on the bath activity. The results obtained verified the scope of the invention as earlier described. Temperatures employed varied from 160F to 212F. While the most desirable results were obtained at the higher temperatures, the lower temperatures effected acceptable coatings but a longer contact time was required. The black color of the plug shells was comparable in every way to those treated in a conventional alkaline oxidizing bath.
- EXAMPLE 6 Clean spark plug shells employed in Example 3 were treated in a 1.5 weight NH NO solution containing 9 ppm N0 for 15 minutes at 195F. Following water rinsing, the shells were dipped in a water-emulsified rust preventive oil for 3 minutes at room temperature. The black color of the resultant coating was comparable in every way to those treated in a conventional alkaline bath.
- EXAMPLE 7 Several previously weighed SAE 1010 cold-rolled steel panels were cleaned in a conventional alkaline immersion cleaner and were treated in a 0.75% ammonium nitrate solution for fifteen minutes at 205F to give a black oxide coating. Ater water rinsing, the panels were air-dried and reweighed, and it was found that they had lost an average of 664 mg. per ft The panels were then stripped along with a clean but uncoated panel in an inhibited hydrochloric acid solution and found to have an average coating weight of 283 mg. per ft Thus, a maximum of 30% of the reacting metal finds its way into the black oxide coating.
- EXAMPLE 8 Spark plug shells composed of SAE l 106 and SAE 8 ethylaniline and urea. Total nitrate concentration varied from 87 g/] or 24 g/l.
- a method of forming a corrosion resistant and decorative black coating on a predominately iron surface of a workpiece comprising contacting said surface with an aqueous acidic solution consisting essentially of:
- a soluble nitrogen containing cation selected from the group consisting of a. ammonium derivatives of which have the formula 1 R N H and,
Abstract
Description
Claims (12)
Priority Applications (9)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AR253699A AR204720A1 (en) | 1973-05-10 | 1974-01-01 | METHOD OF FORMING A CORROSION RESISTANT COATING ON A FERROUS WORKPIECE |
US448168A US3920486A (en) | 1973-05-10 | 1974-03-04 | Method of blackening ferrous metal surfaces |
AU67927/74A AU485487B2 (en) | 1974-04-16 | Method of blackening ferrous metal surfaces | |
FR7415254A FR2228862B1 (en) | 1973-05-10 | 1974-05-02 | |
JP5031874A JPS5344889B2 (en) | 1973-05-10 | 1974-05-08 | |
GB2055674A GB1432750A (en) | 1973-05-10 | 1974-05-09 | Method for forming corrosion resistand coatings on metal surfaces |
DE2422569A DE2422569A1 (en) | 1973-05-10 | 1974-05-09 | METHOD FOR GENERATING OVERLAYS ON IRON SURFACES |
CA199,584A CA1026655A (en) | 1973-05-10 | 1974-05-09 | Method of blackening ferrous metal surfaces |
BR3786/74A BR7403786D0 (en) | 1973-05-10 | 1974-05-09 | PROCESS FOR FORMING A BLACK DECORATIVE COATING AND RESISTANT TO CORROSION |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US35914673A | 1973-05-10 | 1973-05-10 | |
US448168A US3920486A (en) | 1973-05-10 | 1974-03-04 | Method of blackening ferrous metal surfaces |
Publications (1)
Publication Number | Publication Date |
---|---|
US3920486A true US3920486A (en) | 1975-11-18 |
Family
ID=27000354
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US448168A Expired - Lifetime US3920486A (en) | 1973-05-10 | 1974-03-04 | Method of blackening ferrous metal surfaces |
Country Status (8)
Country | Link |
---|---|
US (1) | US3920486A (en) |
JP (1) | JPS5344889B2 (en) |
AR (1) | AR204720A1 (en) |
BR (1) | BR7403786D0 (en) |
CA (1) | CA1026655A (en) |
DE (1) | DE2422569A1 (en) |
FR (1) | FR2228862B1 (en) |
GB (1) | GB1432750A (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4881913A (en) * | 1988-06-16 | 1989-11-21 | General Motors Corporation | Extended life spark plug/igniter |
US4968362A (en) * | 1986-10-08 | 1990-11-06 | American Cyanamid Company | Dark metallic product |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS607260Y2 (en) * | 1979-06-27 | 1985-03-11 | マツダ株式会社 | Car steering wheel safety device |
JP5721984B2 (en) * | 2010-09-15 | 2015-05-20 | 株式会社東芝 | Power plant anticorrosion management method |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1997141A (en) * | 1931-05-23 | 1935-04-09 | Guerini Berardo | Improved process for bronzing articles and parts made of iron and alloys of iron and carbon |
US2366796A (en) * | 1941-02-28 | 1945-01-09 | Solvay Process Co | Preventing corrosion of ferrous metals by ammoniacal solutions of ammonium nitrate |
US3011862A (en) * | 1959-12-21 | 1961-12-05 | Sinclair Refining Co | Sodium carbonate as inhibitor against corrosion by ammonia-ammonium nitrate solutions |
US3097117A (en) * | 1961-06-14 | 1963-07-09 | Macdermid Inc | Method of and composition for producing electroless black nickel coatings |
US3677827A (en) * | 1969-09-09 | 1972-07-18 | Oxford Chem | Composition and method for blackening metal articles |
US3682713A (en) * | 1969-06-28 | 1972-08-08 | Collardin Gmbh Gerhard | Process for applying protective coatings on aluminum,zinc and iron |
-
1974
- 1974-01-01 AR AR253699A patent/AR204720A1/en active
- 1974-03-04 US US448168A patent/US3920486A/en not_active Expired - Lifetime
- 1974-05-02 FR FR7415254A patent/FR2228862B1/fr not_active Expired
- 1974-05-08 JP JP5031874A patent/JPS5344889B2/ja not_active Expired
- 1974-05-09 BR BR3786/74A patent/BR7403786D0/en unknown
- 1974-05-09 CA CA199,584A patent/CA1026655A/en not_active Expired
- 1974-05-09 GB GB2055674A patent/GB1432750A/en not_active Expired
- 1974-05-09 DE DE2422569A patent/DE2422569A1/en active Pending
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1997141A (en) * | 1931-05-23 | 1935-04-09 | Guerini Berardo | Improved process for bronzing articles and parts made of iron and alloys of iron and carbon |
US2366796A (en) * | 1941-02-28 | 1945-01-09 | Solvay Process Co | Preventing corrosion of ferrous metals by ammoniacal solutions of ammonium nitrate |
US3011862A (en) * | 1959-12-21 | 1961-12-05 | Sinclair Refining Co | Sodium carbonate as inhibitor against corrosion by ammonia-ammonium nitrate solutions |
US3097117A (en) * | 1961-06-14 | 1963-07-09 | Macdermid Inc | Method of and composition for producing electroless black nickel coatings |
US3682713A (en) * | 1969-06-28 | 1972-08-08 | Collardin Gmbh Gerhard | Process for applying protective coatings on aluminum,zinc and iron |
US3677827A (en) * | 1969-09-09 | 1972-07-18 | Oxford Chem | Composition and method for blackening metal articles |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4968362A (en) * | 1986-10-08 | 1990-11-06 | American Cyanamid Company | Dark metallic product |
US4881913A (en) * | 1988-06-16 | 1989-11-21 | General Motors Corporation | Extended life spark plug/igniter |
Also Published As
Publication number | Publication date |
---|---|
JPS5344889B2 (en) | 1978-12-02 |
AU6792774A (en) | 1975-10-16 |
CA1026655A (en) | 1978-02-21 |
BR7403786D0 (en) | 1974-12-03 |
FR2228862A1 (en) | 1974-12-06 |
GB1432750A (en) | 1976-04-22 |
JPS5030750A (en) | 1975-03-27 |
DE2422569A1 (en) | 1974-11-28 |
AR204720A1 (en) | 1976-02-27 |
FR2228862B1 (en) | 1978-10-20 |
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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 |
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Owner name: OXY METAL INDUSTRIES CORPORATION Free format text: CHANGE OF NAME;ASSIGNOR:OXY METAL FINISHING CORPORATION;REEL/FRAME:003967/0084 Effective date: 19741220 |
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Free format text: PATENTED FILE - (OLD CASE ADDED FOR FILE TRACKING PURPOSES) |
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Owner name: OCCIDENTAL CHEMICAL CORPORATION Free format text: CHANGE OF NAME;ASSIGNOR:HOOKER CHEMICAS & PLASTICS CORP.;REEL/FRAME:004126/0054 Effective date: 19820330 |
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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 |