US2431728A - Treatment of ferrous metals to improve resistance to rusting - Google Patents
Treatment of ferrous metals to improve resistance to rusting Download PDFInfo
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- US2431728A US2431728A US522802A US52280244A US2431728A US 2431728 A US2431728 A US 2431728A US 522802 A US522802 A US 522802A US 52280244 A US52280244 A US 52280244A US 2431728 A US2431728 A US 2431728A
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- bath
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- alkali metal
- rusting
- treatment
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- -1 ferrous metals Chemical class 0.000 title description 13
- 229910052751 metal Inorganic materials 0.000 title description 6
- 239000002184 metal Substances 0.000 title description 6
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 24
- 229910052783 alkali metal Inorganic materials 0.000 description 13
- 238000000034 method Methods 0.000 description 12
- SZVJSHCCFOBDDC-UHFFFAOYSA-N ferrosoferric oxide Chemical compound O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 description 10
- 239000000203 mixture Substances 0.000 description 10
- 239000007800 oxidant agent Substances 0.000 description 10
- 239000000243 solution Substances 0.000 description 10
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 9
- 239000002253 acid Substances 0.000 description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 9
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 8
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 8
- 235000011121 sodium hydroxide Nutrition 0.000 description 8
- 238000000576 coating method Methods 0.000 description 6
- XTEGARKTQYYJKE-UHFFFAOYSA-M Chlorate Chemical compound [O-]Cl(=O)=O XTEGARKTQYYJKE-UHFFFAOYSA-M 0.000 description 5
- 238000009835 boiling Methods 0.000 description 5
- 239000011248 coating agent Substances 0.000 description 5
- 229940056319 ferrosoferric oxide Drugs 0.000 description 5
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 4
- 238000007792 addition Methods 0.000 description 4
- 229910001963 alkali metal nitrate Inorganic materials 0.000 description 4
- 229910052910 alkali metal silicate Inorganic materials 0.000 description 4
- 150000001340 alkali metals Chemical class 0.000 description 4
- 229910052742 iron Inorganic materials 0.000 description 4
- 239000007787 solid Substances 0.000 description 4
- IQUPABOKLQSFBK-UHFFFAOYSA-N 2-nitrophenol Chemical group OC1=CC=CC=C1[N+]([O-])=O IQUPABOKLQSFBK-UHFFFAOYSA-N 0.000 description 3
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 3
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 3
- 229910000831 Steel Inorganic materials 0.000 description 3
- 235000011941 Tilia x europaea Nutrition 0.000 description 3
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 3
- 150000004973 alkali metal peroxides Chemical class 0.000 description 3
- 239000004202 carbamide Substances 0.000 description 3
- 238000007598 dipping method Methods 0.000 description 3
- 239000004571 lime Substances 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 229910052708 sodium Inorganic materials 0.000 description 3
- 239000011734 sodium Substances 0.000 description 3
- 239000010959 steel Substances 0.000 description 3
- 238000003860 storage Methods 0.000 description 3
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- 239000004115 Sodium Silicate Substances 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- 239000012670 alkaline solution Substances 0.000 description 2
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 2
- SOCTUWSJJQCPFX-UHFFFAOYSA-N dichromate(2-) Chemical compound [O-][Cr](=O)(=O)O[Cr]([O-])(=O)=O SOCTUWSJJQCPFX-UHFFFAOYSA-N 0.000 description 2
- 239000004615 ingredient Substances 0.000 description 2
- VCJMYUPGQJHHFU-UHFFFAOYSA-N iron(3+);trinitrate Chemical compound [Fe+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O VCJMYUPGQJHHFU-UHFFFAOYSA-N 0.000 description 2
- 239000004922 lacquer Substances 0.000 description 2
- NUJOXMJBOLGQSY-UHFFFAOYSA-N manganese dioxide Chemical compound O=[Mn]=O NUJOXMJBOLGQSY-UHFFFAOYSA-N 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- VWDWKYIASSYTQR-UHFFFAOYSA-N sodium nitrate Chemical compound [Na+].[O-][N+]([O-])=O VWDWKYIASSYTQR-UHFFFAOYSA-N 0.000 description 2
- LPXPTNMVRIOKMN-UHFFFAOYSA-M sodium nitrite Chemical compound [Na+].[O-]N=O LPXPTNMVRIOKMN-UHFFFAOYSA-M 0.000 description 2
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 2
- 229910052911 sodium silicate Inorganic materials 0.000 description 2
- TUSDEZXZIZRFGC-UHFFFAOYSA-N 1-O-galloyl-3,6-(R)-HHDP-beta-D-glucose Natural products OC1C(O2)COC(=O)C3=CC(O)=C(O)C(O)=C3C3=C(O)C(O)=C(O)C=C3C(=O)OC1C(O)C2OC(=O)C1=CC(O)=C(O)C(O)=C1 TUSDEZXZIZRFGC-UHFFFAOYSA-N 0.000 description 1
- UFBJCMHMOXMLKC-UHFFFAOYSA-N 2,4-dinitrophenol Chemical compound OC1=CC=C([N+]([O-])=O)C=C1[N+]([O-])=O UFBJCMHMOXMLKC-UHFFFAOYSA-N 0.000 description 1
- XFXPMWWXUTWYJX-UHFFFAOYSA-N Cyanide Chemical compound N#[C-] XFXPMWWXUTWYJX-UHFFFAOYSA-N 0.000 description 1
- 239000001263 FEMA 3042 Substances 0.000 description 1
- PVNIIMVLHYAWGP-UHFFFAOYSA-N Niacin Chemical compound OC(=O)C1=CC=CN=C1 PVNIIMVLHYAWGP-UHFFFAOYSA-N 0.000 description 1
- LRBQNJMCXXYXIU-PPKXGCFTSA-N Penta-digallate-beta-D-glucose Natural products OC1=C(O)C(O)=CC(C(=O)OC=2C(=C(O)C=C(C=2)C(=O)OC[C@@H]2[C@H]([C@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)[C@@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)[C@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)O2)OC(=O)C=2C=C(OC(=O)C=3C=C(O)C(O)=C(O)C=3)C(O)=C(O)C=2)O)=C1 LRBQNJMCXXYXIU-PPKXGCFTSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 150000001339 alkali metal compounds Chemical class 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000004040 coloring Methods 0.000 description 1
- 239000012895 dilution Substances 0.000 description 1
- 238000010790 dilution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000006260 foam Substances 0.000 description 1
- 239000013505 freshwater Substances 0.000 description 1
- 229910003439 heavy metal oxide Inorganic materials 0.000 description 1
- 229910003480 inorganic solid Inorganic materials 0.000 description 1
- YWXYYJSYQOXTPL-SLPGGIOYSA-N isosorbide mononitrate Chemical compound [O-][N+](=O)O[C@@H]1CO[C@@H]2[C@@H](O)CO[C@@H]21 YWXYYJSYQOXTPL-SLPGGIOYSA-N 0.000 description 1
- HTUMBQDCCIXGCV-UHFFFAOYSA-N lead oxide Chemical compound [O-2].[Pb+2] HTUMBQDCCIXGCV-UHFFFAOYSA-N 0.000 description 1
- YEXPOXQUZXUXJW-UHFFFAOYSA-N lead(II) oxide Inorganic materials [Pb]=O YEXPOXQUZXUXJW-UHFFFAOYSA-N 0.000 description 1
- LBSANEJBGMCTBH-UHFFFAOYSA-N manganate Chemical compound [O-][Mn]([O-])(=O)=O LBSANEJBGMCTBH-UHFFFAOYSA-N 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 150000002978 peroxides Chemical class 0.000 description 1
- 238000005554 pickling Methods 0.000 description 1
- NNFCIKHAZHQZJG-UHFFFAOYSA-N potassium cyanide Chemical compound [K+].N#[C-] NNFCIKHAZHQZJG-UHFFFAOYSA-N 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 229910000029 sodium carbonate Inorganic materials 0.000 description 1
- 239000004317 sodium nitrate Substances 0.000 description 1
- 235000010344 sodium nitrate Nutrition 0.000 description 1
- 235000010288 sodium nitrite Nutrition 0.000 description 1
- 235000019794 sodium silicate Nutrition 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- LRBQNJMCXXYXIU-NRMVVENXSA-N tannic acid Chemical compound OC1=C(O)C(O)=CC(C(=O)OC=2C(=C(O)C=C(C=2)C(=O)OC[C@@H]2[C@H]([C@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)[C@@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)[C@@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)O2)OC(=O)C=2C=C(OC(=O)C=3C=C(O)C(O)=C(O)C=3)C(O)=C(O)C=2)O)=C1 LRBQNJMCXXYXIU-NRMVVENXSA-N 0.000 description 1
- 229940033123 tannic acid Drugs 0.000 description 1
- 235000015523 tannic acid Nutrition 0.000 description 1
- 229920002258 tannic acid Polymers 0.000 description 1
- 239000002966 varnish Substances 0.000 description 1
- 239000002023 wood Substances 0.000 description 1
- NWONKYPBYAMBJT-UHFFFAOYSA-L zinc sulfate Chemical compound [Zn+2].[O-]S([O-])(=O)=O NWONKYPBYAMBJT-UHFFFAOYSA-L 0.000 description 1
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
- C23C22/60—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 alkaline aqueous solutions with pH greater than 8
- C23C22/62—Treatment of iron or alloys based thereon
Definitions
- This invention relates to improvements in the treatment of ferrous metals.
- One object of the invention is to provide processes for so treating the surfaces of ferrous articles capable of rusting that the development of rust is inhibited.
- a further object of the present invention is to provide a simple process which can be operated at low temperatures and without the use of expensive plant or equipment.
- a further object of the present invention is to ,provide a simplified process of forming a coating of ferroso-ferric-oxide on the surfaces of ferrous articles.
- the process of the present invention comprises subjecting ferrous articles to the action of an alkaline bath containing an oxidising agent and an alkali metal silicate at a temperature above 100 C. but not above 200 C.
- the bath comprises an aqueous alkaline solution of the oxid zing agent containing an alkali metal silicate and of such concentration that it can be heated to a temperature between and 200 C. preferably between and C. without boiling.
- Oxidizing agents comprising alkali metal compounds are particularly suitable and accordingly there may be used an alkali metal nitrate.
- bath is a proportion of alkali metal nitrite.
- Other suitable oxidizing agents are alkali metal (such as sodium) chlorate, permanganate or peroxide.
- An example of a suitable organic oxidizing agent is nitrophenol.
- Other oxidizing agents capable of functioning in alkaline solution may be used such as bichromates.
- a bath suitable for the present invention may consist of caustic soda and sodium silicate with a smaller proportion of sodium intrate and sodium nitrite and a quantity of water rather less than the weight of these inorganic solids,
- the resulting mixture will liquefy at a temperature of 125 to 150 C. and the articles to be treated can be immersed in the bath, for example, in a, wire basket for a time of from 5 to 20 minutes and after removal from the bath can be cooled and washed and then dried in a current of warm air.
- the resulting coating of ferroso-ferric-oxide is deep black and may be polished or matt according to the conditions of the surface which was treated.
- the final blackened surface may be treated with any suitable lacquer or can if de sired simply be wiped withoil.
- the solution gradually becomes inactive owing to absorption of carbon dioxide from the air, the caustic soda being thereby converted into inactive sodium carbonate. This should be prevented by covering the tanks with airtight lids when not in use. Also the baths may be regenerated, as far as caustic soda is concerned, by adding lime; this precipitates in- A useful addition to the 3 soluble calcium carbonate and the caustic soda is thereby regenerated. It has been found preferable to replenish the solution with a mixture of caustic soda, sodium silicate, sodium nitrate, lime and manganese dioxide.
- the rust preventing eifect of the bath may be greatly improved by afterwards dipping the articles for 10 minutes into an acid solution of an oxidizing agent such as a 5% solution of sodium'bichromate.
- the process can be accelerated by heatin the articles before immersing them in the bath preferably by first immersing them in a preheating bath such as a bath of boiling aqueous liquid.
- the preheating is preferably done by immersing the ferrous articles in a bath of liquid heated to a suitable temperature.
- the liquid may, for example, be water, but is preferably a weak acid such as a weakaqueous solution of phosphoric acid.
- the use of such weak acid in thepreheating bath accelerates the action of the oxidizing agent in the subsequent bath.
- a weak acid as the preheating medium the articles are to some extent pickled and the resulting removal of rust facilitates the subsequent processing.
- Baths having the compositions shown in Examples 1 to 4 above can be replenished by the addition of mixtures of the same ingredients in the proportions shown, the replenishing mixtures containing, however, in addition 27 parts by weight of lime and 34 parts by weight of man- 'ganese dioxide for every 139 parts by weight of mixture.
- a preheating bath which may consist of boiling water or boiling weak acid and then left in a bath of the composition shown in any of the above examples at a temperature of to Cuuntil theyhave acquired a jet black color. This generally requires about 20 minutes. They are then dipped in a rinsing bath of boiling If the articles treated are such that small quantities of the treatment solution may be trapped, they may be clipped in a final bath of weak acid (e, g. a 5% solution of acetic acid).
- weak acid e, g. a 5% solution of acetic acid
- the articles treated must .be free from rust, scale and resinous coatings. Heavily greased articles must be degreased before treatment but lightly greased articles may be treated directly. Acid pickling is required only if mill scale is present.
- Steel tanks may be used for the-baths and theirsize will naturally depend uponthe articles treated. Long, shallow tanks are preferable to deep wide tanks.
- water may be lost from "the treatment bath. This should be made good, preferably by transferring liquor from the water rinsing tank to which in turn fresh water may be added.
- the other ingredients of the bath are to some extent used up by the treatment of ferrous articles, this being indicated by an increase in the time required to produce a jet black finish or :difficulty in raising the temperature to 127 C. This can .beremediedby adding a replenishing mixture of the com-position indicated after the foregoing examples.
- the treated articles should have :an even dead black color. ;'If they have ,little-or-no color or if the finish is not durable :it :isan indication that the temperature of the bath I or its concentration have fallen'too low; in the latter case, replenishment is required. If thearticles have a yellowish-green or reddish layer like-rust or if the treatment liquor becomes thick and foams it is an indication that the temperature of the bath is too high oritsconcentration is-too highyin the latter case dilution is required. Poor coloring may also result if the @articles are not leftlong enoughin the bath.
- Thearticles after treatment may be given any desired finish e. g. they may simply be greased or may be coated e.-g. with paint or varnish.
- alkali metal permanganate alkali :metal'bichromate, alkali metal peroxide ;and nitrophen ol, thebalanoe being an amount of water :rather less than the weight of the -,s. 1ids.
- Process for treating ferrous articles capable of rusting to inhibit the formation of rust thereon which comprises preheating said articles, then subjecting them at a temperature between 100 C. and 200 C. to an aqueous alkaline bath containing from 28.5% to 42.5% solid caustic soda, 3.25% to 15% of alkali silicate, 2.33% to 9.5% of an oxidizing agent selected from the group which consists of alkali metal nitrate, alkali metal nitrite, alkali metal chlorate, alkali metal pertil 6 manganate, alkali metal bichromate, alkali metal peroxide and nitrophenol, the balance being an amount of water rather less than the weight of solids.
Description
Patented Dec. 2, 1.947
iJNlTED STATES FFICE TREATMENT OF FERROUS METALS TO IM- PROVE RESISTANCE TO RUSTING Gerson Kurt Bergstein, St. Johns Wood, London, England, assignor, by mesne assignments, to Despo Manufacturing Co. Limited, London, England, a British company No Drawing. Application February 17, 1944, Se-
rial No. 522,802. In Great Britain April 29,
3 Claims. 1
This invention relates to improvements in the treatment of ferrous metals.
One object of the invention is to provide processes for so treating the surfaces of ferrous articles capable of rusting that the development of rust is inhibited.
Processes are known for treating ferrous articles such as iron or steel in order that serious rusting shall not take place during ordinary storage. The object of such processes is not to make the articles resistant to rusting under all conditions of storage and use but simply to provide a surface which is more resistant to rusting than the clean metal and which can, if necessary, be provided with an oil or lacquer coating so that the surface will not become seriously rusted during ordinary storage. In one well known process of this kind articles have to remain in a bath containing phosphoric acid for more than 1 hour and the finish comprises a dull matt surface which is not always desirable. Moreover, in such processes a com- 'plicated and expensive plant is required' A further object of the present invention is to provide a simple process which can be operated at low temperatures and without the use of expensive plant or equipment.
It is known that when an iron surface is treated so as to produce a layer of ferroso-ferric-oxide thereon either by strong oxidation of the surface or by first coating the surface with ferrous oxide and then oxidising this to ferroso-ferricoxide, the resistance to rusting is considerably enhanced. The direct production of ferroso-ferrip-oxide requires the use of a high temperature. Only at about 220 C. does the iron surface begin to oxidise in the air at an appreciable speed but the resulting layer of ferroso-ferric-oxide is formed as a very thin, strongly adhering layer whose colour depends upon the thickness and varies between pale yellow and dark bluish black. It is known, also, that certain combinations of inorgan c salts will bring about this oxidation but temperatures of about 300 C. are necessary requiring skilled operators and these high temperatures are undesirable for many articles.
A further object of the present invention is to ,provide a simplified process of forming a coating of ferroso-ferric-oxide on the surfaces of ferrous articles. f
{ With these and other objects in view the process of the present invention comprises subjecting ferrous articles to the action of an alkaline bath containing an oxidising agent and an alkali metal silicate at a temperature above 100 C. but not above 200 C. Preferably the bath comprises an aqueous alkaline solution of the oxid zing agent containing an alkali metal silicate and of such concentration that it can be heated to a temperature between and 200 C. preferably between and C. without boiling. Oxidizing agents comprising alkali metal compounds are particularly suitable and accordingly there may be used an alkali metal nitrate. bath is a proportion of alkali metal nitrite. Other suitable oxidizing agents are alkali metal (such as sodium) chlorate, permanganate or peroxide. An example of a suitable organic oxidizing agent is nitrophenol. Other oxidizing agents capable of functioning in alkaline solution may be used such as bichromates.
For example, a bath suitable for the present invention may consist of caustic soda and sodium silicate with a smaller proportion of sodium intrate and sodium nitrite and a quantity of water rather less than the weight of these inorganic solids, The resulting mixture will liquefy at a temperature of 125 to 150 C. and the articles to be treated can be immersed in the bath, for example, in a, wire basket for a time of from 5 to 20 minutes and after removal from the bath can be cooled and washed and then dried in a current of warm air.
The resulting coating of ferroso-ferric-oxide is deep black and may be polished or matt according to the conditions of the surface which was treated. The final blackened surface may be treated with any suitable lacquer or can if de sired simply be wiped withoil.
It has been found that the results are improved by adding a small quantity of an lron salt, for example, ferric nitrate, to the bath.
It has further been found that an improvement is effected by adding a heavy metal oxide or cyanide to the bath; the addition of urea to the bath further improves the effect. Alternatively tannic acid may be added, also though less preferably, potassium cyanide and litharge. These additions have the advantage of giving a more uniform coating and also causing the bath to work at a lower temperature, namely about 133 C. for many kinds of steel and iron. I
It has also been found that the solution gradually becomes inactive owing to absorption of carbon dioxide from the air, the caustic soda being thereby converted into inactive sodium carbonate. This should be prevented by covering the tanks with airtight lids when not in use. Also the baths may be regenerated, as far as caustic soda is concerned, by adding lime; this precipitates in- A useful addition to the 3 soluble calcium carbonate and the caustic soda is thereby regenerated. It has been found preferable to replenish the solution with a mixture of caustic soda, sodium silicate, sodium nitrate, lime and manganese dioxide.
Finally it has been found that the rust preventing eifect of the bath may be greatly improved by afterwards dipping the articles for 10 minutes into an acid solution of an oxidizing agent such as a 5% solution of sodium'bichromate.
Articles rust-proofed by the'p'resent process haveatendency to eiiloresce, probably owingto the fact that the caustic soda has not been thoroughly rinsed away. This will also be prevented by the above after treatment. Another way of preventing this is by dipping the treated articles in a dilute solution of acetic or other acid.
The process can be accelerated by heatin the articles before immersing them in the bath preferably by first immersing them in a preheating bath such as a bath of boiling aqueous liquid.
If a bulk of coldmeta-l is immersed in the hot processing solution there is a sudden drop in temperature of the solution. which considerably slows down the reaction and may detrimentally affect it. The preheating 'is preferably done by immersing the ferrous articles in a bath of liquid heated to a suitable temperature. The liquid may, for example, be water, but is preferably a weak acid such as a weakaqueous solution of phosphoric acid. The use of such weak acid in thepreheating bath accelerates the action of the oxidizing agent in the subsequent bath. By using a weak acid as the preheating medium the articles are to some extent pickled and the resulting removal of rust facilitates the subsequent processing.
The following are examples of the compositions of some baths which may beused.
(In place of urea,1tan'nic acid can be used but the percentage should be about one quarter of that of urea, 'theIotherfproportions being correspondingly adjusted!) Water.
In the above examples, all percentages are by weight.
Baths having the compositions shown in Examples 1 to 4 above can be replenished by the addition of mixtures of the same ingredients in the proportions shown, the replenishing mixtures containing, however, in addition 27 parts by weight of lime and 34 parts by weight of man- 'ganese dioxide for every 139 parts by weight of mixture.
In treating ferrous articles they are first dipped in a preheating bath, which may consist of boiling water or boiling weak acid and then left in a bath of the composition shown in any of the above examples at a temperature of to Cuuntil theyhave acquired a jet black color. This generally requires about 20 minutes. They are then dipped in a rinsing bath of boiling If the articles treated are such that small quantities of the treatment solution may be trapped, they may be clipped in a final bath of weak acid (e, g. a 5% solution of acetic acid).
The articles treated must .be free from rust, scale and resinous coatings. Heavily greased articles must be degreased before treatment but lightly greased articles may be treated directly. Acid pickling is required only if mill scale is present.
Steel tanks may be used for the-baths and theirsize will naturally depend uponthe articles treated. Long, shallow tanks are preferable to deep wide tanks.
In use, water may be lost from "the treatment bath. This should be made good, preferably by transferring liquor from the water rinsing tank to which in turn fresh water may be added. Moreover, the other ingredients of the bath are to some extent used up by the treatment of ferrous articles, this being indicated by an increase in the time required to produce a jet black finish or :difficulty in raising the temperature to 127 C. This can .beremediedby adding a replenishing mixture of the com-position indicated after the foregoing examples.
The treated articles should have :an even dead black color. ;'If they have ,little-or-no color or if the finish is not durable :it :isan indication that the temperature of the bath I or its concentration have fallen'too low; in the latter case, replenishment is required. If thearticles have a yellowish-green or reddish layer like-rust or if the treatment liquor becomes thick and foams it is an indication that the temperature of the bath is too high oritsconcentration is-too highyin the latter case dilution is required. Poor coloring may also result if the @articles are not leftlong enoughin the bath.
Thearticles after treatment may be given any desired finish e. g. they may simply be greased or may be coated e.-g. with paint or varnish.
I declaretha-t what I claim is:
1. Processfor treating ferrous-articles capable of rusting to inhibit the development of rust thereon which consists :in forming an oxide film thereon, :integral with the -rnetal by subjecting them ata temperature of between 100 C. and 200 C. toan aqueous alkaline bath containing from 23.5%-to14=2:5% solidcausticsoda, 3.25% to 15% of alkali gsilicate, 2.33% to 9.5% of an oxidizing agent selected from the group-which consists of alkalimetal nitrate, alkali metal nitrite, alkali metal chlorate. :alkali metal permanganate, alkali :metal'bichromate, alkali metal peroxide ;and nitrophen ol, thebalanoe being an amount of water :rather less than the weight of the -,s. 1ids.
2. Process for treating ferrous articles capable of rusting to inhibit the development of rust thereon which consists in forming an oxide film thereof, integral with the metal by subjecting them at a temperature between 100 C. and 200 C. to an aqueous alkaline bath containing from 28.5% to 42.5% solid caustic soda, 3.25% to 15% of alkali silicate, 2.33% to 9.5% of an oxidizing agent selected from the group which consists of alkali metal nitrate, alkali metal nitrite, alkali metal chlorate, alkali metal permanganate, alkali metal bichromate, alkali metal peroxide and nitrophenol, the balance being an amount of water rather less than the weight of the solids, and then dipping the articles into a bath containing a weak acid.
3. Process for treating ferrous articles capable of rusting to inhibit the formation of rust thereon which comprises preheating said articles, then subjecting them at a temperature between 100 C. and 200 C. to an aqueous alkaline bath containing from 28.5% to 42.5% solid caustic soda, 3.25% to 15% of alkali silicate, 2.33% to 9.5% of an oxidizing agent selected from the group which consists of alkali metal nitrate, alkali metal nitrite, alkali metal chlorate, alkali metal pertil 6 manganate, alkali metal bichromate, alkali metal peroxide and nitrophenol, the balance being an amount of water rather less than the weight of solids.
GERSON KURT BERGSTEIN.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS OTHER REFERENCES Chemical Abstracts, volume 29 (1935), page 6868.
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GB2431728X | 1942-04-29 |
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US2431728A true US2431728A (en) | 1947-12-02 |
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US522802A Expired - Lifetime US2431728A (en) | 1942-04-29 | 1944-02-17 | Treatment of ferrous metals to improve resistance to rusting |
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Cited By (7)
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US2579752A (en) * | 1950-03-11 | 1951-12-25 | Newell Isaac Laird | Process for blackening iron and steel and composition of matter therefor |
US2665232A (en) * | 1950-12-18 | 1954-01-05 | United States Steel Corp | Method and solution for treating zinc surfaces to inhibit formation of white rust |
US2680081A (en) * | 1950-09-14 | 1954-06-01 | Rolls Royce | Silicate impregnation of porous castings |
US2800421A (en) * | 1954-05-28 | 1957-07-23 | Parker Rust Proof Co | Composition and method for coating stainless metals |
US2850417A (en) * | 1955-05-24 | 1958-09-02 | Parker Rust Proof Co | Composition for and methods of forming oxalate coatings on metallic surfaces |
DE1191657B (en) * | 1953-03-05 | 1965-04-22 | Manfred Freud Dit Jean Herbert | Descaling paste for iron, cast iron and steel |
US3216866A (en) * | 1961-03-06 | 1965-11-09 | Allied Decals Inc | Treatment of anodized aluminum |
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GB335868A (en) * | 1930-01-27 | 1930-10-02 | Willy Boehmer | Method of protecting iron from rust |
GB336854A (en) * | 1929-11-29 | 1930-10-23 | Gustav Adolph | A process of preserving aluminium from attack by alkalies |
US1924311A (en) * | 1931-01-06 | 1933-08-29 | Westinghouse Electric & Mfg Co | Insulating material |
US2077450A (en) * | 1935-01-08 | 1937-04-20 | Alrose Chemical Company | Method and composition for coating iron and steel articles |
GB464656A (en) * | 1936-01-11 | 1937-04-22 | Eugene Rivoche | Improvements in and relating to the process of blackening iron and steel, and protecting the same from rust |
US2148331A (en) * | 1937-02-25 | 1939-02-21 | Alrose Chemical Company | Method and composition for coating iron and steel articles |
US2154607A (en) * | 1937-06-29 | 1939-04-18 | Electro Metallurg Co | Method of stabilizing manganese alloys |
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1944
- 1944-02-17 US US522802A patent/US2431728A/en not_active Expired - Lifetime
Patent Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
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GB336854A (en) * | 1929-11-29 | 1930-10-23 | Gustav Adolph | A process of preserving aluminium from attack by alkalies |
GB335868A (en) * | 1930-01-27 | 1930-10-02 | Willy Boehmer | Method of protecting iron from rust |
US1924311A (en) * | 1931-01-06 | 1933-08-29 | Westinghouse Electric & Mfg Co | Insulating material |
US2077450A (en) * | 1935-01-08 | 1937-04-20 | Alrose Chemical Company | Method and composition for coating iron and steel articles |
GB464656A (en) * | 1936-01-11 | 1937-04-22 | Eugene Rivoche | Improvements in and relating to the process of blackening iron and steel, and protecting the same from rust |
US2148331A (en) * | 1937-02-25 | 1939-02-21 | Alrose Chemical Company | Method and composition for coating iron and steel articles |
US2154607A (en) * | 1937-06-29 | 1939-04-18 | Electro Metallurg Co | Method of stabilizing manganese alloys |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2579752A (en) * | 1950-03-11 | 1951-12-25 | Newell Isaac Laird | Process for blackening iron and steel and composition of matter therefor |
US2680081A (en) * | 1950-09-14 | 1954-06-01 | Rolls Royce | Silicate impregnation of porous castings |
US2665232A (en) * | 1950-12-18 | 1954-01-05 | United States Steel Corp | Method and solution for treating zinc surfaces to inhibit formation of white rust |
DE1191657B (en) * | 1953-03-05 | 1965-04-22 | Manfred Freud Dit Jean Herbert | Descaling paste for iron, cast iron and steel |
US2800421A (en) * | 1954-05-28 | 1957-07-23 | Parker Rust Proof Co | Composition and method for coating stainless metals |
US2850417A (en) * | 1955-05-24 | 1958-09-02 | Parker Rust Proof Co | Composition for and methods of forming oxalate coatings on metallic surfaces |
US3216866A (en) * | 1961-03-06 | 1965-11-09 | Allied Decals Inc | Treatment of anodized aluminum |
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