US3671332A - Metal treating process - Google Patents
Metal treating process Download PDFInfo
- Publication number
- US3671332A US3671332A US841993A US3671332DA US3671332A US 3671332 A US3671332 A US 3671332A US 841993 A US841993 A US 841993A US 3671332D A US3671332D A US 3671332DA US 3671332 A US3671332 A US 3671332A
- Authority
- US
- United States
- Prior art keywords
- bath
- sulfur
- nitrite
- steel
- iron
- 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
-
- 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
- C23C22/34—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 fluorides or complex fluorides
- C23C22/36—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 fluorides or complex fluorides containing also phosphates
- C23C22/362—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 fluorides or complex fluorides containing also phosphates containing also zinc cations
Definitions
- iron and steel may be treated at room temperature and up to 50 degrees centigrade by immersion in nitrate containing phosphate solutions based upon zinc phosphate, whereby a strongly adhering zinc phosphate layer is produced upon the metal.
- the purpose of the nitrite, which is usually added to the bath in the form of alkali nitrite, is to accelerate the process of film formation and to convert the dissolved iron into its three-valent form to enable its precipitation from the bath in the form of the difiicult to dissolve iron- III-phosphate.
- the ferro-nitroso-complex enrichment in the bath is undesirable on several grounds, and with the increasing iron content in the bath there is an increasing danger that coating films containing iron- II-phosphates will be produced.
- the anti-corrosion properties as well as the adhesion strength of the layer to the base metal will be considerably less effective, furthermore, as great quantities of nitrous gases are bound in the complexes which, for example under agitation of the bath, may be easily liberated and pass into the atmosphere of the workshop, thereby creating industrial health hazards.
- Such agitation of the bath may occur for example when introducing or removing the work pieces from the bath as well as during cleaning.
- ferro-nitroso complexes in nitrite containing phosphatizing solutions based upon zinc phosphate may be essentially reduced during the immersion phosphate coating process of iron and steel in the temperature range from room temperature to 50 degrees centigrade, by adding to the phosphate coating bath apart from nitrite and by way of additional components, one or more soluble, reducing,
- sulfur-oxygen compounds wherein the sulfur is in positive form, having valency from 2 to -5.
- the addition of the reducing sulfur-oxygen compound may be effected by means of gaseous S0 Na SO Na S O NflzSzOs, N21 S O N32S203, (Rongalite) and similar materials.
- the addition of the reducing sulfur-oxygen compound calculated as Net- 50 should be preferably 0.0l-l g./l.
- the nitrite is being added to the phosphatizing solution preferably in the form of alkali nitrite, for example, NaNO This may be added to the bath preferably in quantities ranging from 0.1 to 1 g./l., calculated as NaNO
- alkali nitrite for example, NaNO
- other film-forming cations for example, Mn, Ca
- other oxidizing agents such as for example nitrate may be also present in the bath. Copper and/or nickel additions, as well as the presence of simple and/or complex fluorides will accelerate the process of film formation.
- the basis weight of the phosphate layer may be reduced in a manner known per se, by the addition of condensed phosphates, hydrocarbon acids and similar materials. Wetting agents will promote the penetration of the bath solution into densely packed work pieces, such as for example wire coils.
- the addition proposed according to the present invention is generally fully utilized only when the phosphatizing solution is used in conjunction with dipping or immersion processes.
- the preferred bath temperature is either at room temperature or slightly higher. Under these conditions the formation of ferro-nitroso complexes is being particularly promoted. This may be seen quite clearly from the example of various experiments, wherein steel wires were phosphatized by immersion into a 45 point zinc phosphate bath, containing Cu, N0 F and about 700 mg./l. NaNO At a throughput density of 0.2 m?
- the addition according to the present invention may be used for new baths as well as for baths already in operation.
- the bath is prepared in the customary manner with zinc phosphate concentrate and, if desired, by the necessary further additions, and then, before the start of the throughput of work pieces, the bath is reacted with about 300 to 600 mg./l. NaNO and with about an identical quantity of reducing sulfur-oxygen compound, for example Na SO
- the zinc phosphate nitrite and sulfur-oxygen compound are being continually consumed.
- the replenishment of the zinc phosphate may be effected, for example in the customary manner to the consistency of the points of the bath by means of a replenishment concentrate.
- the nitrite may be added to the bath, for example in such quantities that the reducing effect of a sample taken from the bath remains approximately constant when determined against KMnO -titration solution.
- the bath still remains brown colored for a longer time, i.e., for about 10 to 20 minutes after the removal of the last charged, then again the sulfur-oxygen compound should be added in approximately the same quantity as initially.
- the solution will become either clear again or will discolor only to such small extent that at the latest minutes after the removal of the last charge the solution will become clear.
- the coatings produced according to the method of the present invention are suitable for the known applications of phosphate coatings, such as anti-corrosion, to promote noncutting cold shaping, electrical insulation, reducing friction, and the like.
- EXAMPLE 1 The roll scales were removed from steel wire sections in sulfuric acid, then these wire segments were rinsed in Water and subsequently phosphatized by dipping at 30 degrees centigrade.
- the phosphatizing bath was an aqueous solution having the following basic composition:
- the bath was adjusted with NaOH to a free acid content of about 4.3 points and to a total content of about 40 points. Subsequently, 0.1, 0.2, 0.4, respectively 0.6 g./l. Na SO quantities were added to this basic bath.
- Into the individual baths in every instance 400 cm. steel surfaces were dipped for minutes per 1 liter of phosphatizing solution. Immediately after the removal of the wires, respectively after 10 minutes, the Fe II contents of the baths were determined by colorimetry with ortho-phenaflthroline. Furthermore, a visual assessment was used to establish the time period required for the baths to regain their clear color. The results are summarized in Table I.
- EXAMPLE 2 Steel wire sections were pretreated in the manner described in Example 1, and subsequently phosphatized by dipping for 10 minutes at 30 degrees centigrade.
- a phosphatizing bath was used which corresponded to the basic composition described in Example 1, including the corresponding adjustment of free acids and total acidity.
- a bath of identical composition was used, however, with the addition of 0.6 g./l. Na SO at the start.
- EXAMPLE 3 A phosphatizing solution, having a basic composition according to that described in Example 1 was used. Per every 1 liter of this bath, 800 cm. of steel plate surface was dipped for 20 minutes at 30 degrees centigrade, and this has resulted in dark brown discoloration. Afterwards determined quantities of various reducing sulfur-oxygen compounds were added to the baths. The time required for the discoloration to disappear were determined after 2 hours of standing period of 30 degrees centigrade. The results are summarized in Table III.
- a method for treating ferrous metal surfaces which comprises immersing the surfaces to be treated in an aqueous zinc phosphate phosphatizing bath maintained at a temperature from about room temperature to about 50 C., which bath contains nitrite ions in an amount from about 0.1 to 1.0 gram per liter, calculated as NaNO and at least one soluble reducing sulfur-oxygen compound independent selected from a group consisting of S 13.2803, Na S O Na S O Nazsgoi Na S O and NaHSO CH O, wherein the sulfur-oxygen compounds in the bath are present in an amount from about 0.01 to References Cited UNITED STATES PATENTS 2,121,520 6/1938 Curtin 1486.17 2,591,479 4/1952 Ward 148-6.15 X 2,762,733 9/1956 Borghetti et a1. 148-6.17 2,975,082 3/ 1961' Henricks.
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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)
Abstract
Description
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US84199369A | 1969-07-15 | 1969-07-15 |
Publications (1)
Publication Number | Publication Date |
---|---|
US3671332A true US3671332A (en) | 1972-06-20 |
Family
ID=25286271
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US841993A Expired - Lifetime US3671332A (en) | 1969-07-15 | 1969-07-15 | Metal treating process |
Country Status (1)
Country | Link |
---|---|
US (1) | US3671332A (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3961993A (en) * | 1971-11-18 | 1976-06-08 | The Empire Plating Company | Coated metal article and method of coating |
EP0363200A2 (en) * | 1988-10-06 | 1990-04-11 | Nippon Paint Co., Ltd. | Improvement of zinc phosphate treatment for cold working |
-
1969
- 1969-07-15 US US841993A patent/US3671332A/en not_active Expired - Lifetime
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3961993A (en) * | 1971-11-18 | 1976-06-08 | The Empire Plating Company | Coated metal article and method of coating |
EP0363200A2 (en) * | 1988-10-06 | 1990-04-11 | Nippon Paint Co., Ltd. | Improvement of zinc phosphate treatment for cold working |
EP0363200A3 (en) * | 1988-10-06 | 1990-07-18 | Nippon Paint Co., Ltd. | Improvement of zinc phosphate treatment for cold working |
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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 |