US3218201A - Method of replenishing solutions for coating corrosion resistant alloys - Google Patents
Method of replenishing solutions for coating corrosion resistant alloys Download PDFInfo
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- US3218201A US3218201A US232616A US23261662A US3218201A US 3218201 A US3218201 A US 3218201A US 232616 A US232616 A US 232616A US 23261662 A US23261662 A US 23261662A US 3218201 A US3218201 A US 3218201A
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- Prior art keywords
- coating
- solutions
- corrosion resistant
- salts
- resistant alloys
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- 238000000576 coating method Methods 0.000 title claims description 43
- 239000011248 coating agent Substances 0.000 title claims description 38
- 238000000034 method Methods 0.000 title description 16
- 229910045601 alloy Inorganic materials 0.000 title description 10
- 239000000956 alloy Substances 0.000 title description 10
- 238000005260 corrosion Methods 0.000 title description 6
- 230000007797 corrosion Effects 0.000 title description 6
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 claims description 39
- 150000001768 cations Chemical class 0.000 claims description 14
- 235000006408 oxalic acid Nutrition 0.000 claims description 12
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims description 9
- 239000011593 sulfur Substances 0.000 claims description 9
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 8
- 229910052760 oxygen Inorganic materials 0.000 claims description 8
- 239000001301 oxygen Substances 0.000 claims description 8
- 150000002500 ions Chemical class 0.000 claims description 7
- 229910052717 sulfur Inorganic materials 0.000 claims description 7
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 5
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 claims description 5
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 5
- 150000001450 anions Chemical class 0.000 claims description 5
- 229910052791 calcium Inorganic materials 0.000 claims description 5
- 239000011575 calcium Substances 0.000 claims description 5
- 239000011701 zinc Substances 0.000 claims description 5
- 229910052725 zinc Inorganic materials 0.000 claims description 5
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims description 4
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 claims description 4
- 229910052793 cadmium Inorganic materials 0.000 claims description 4
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 claims description 4
- 229910052749 magnesium Inorganic materials 0.000 claims description 4
- 239000011777 magnesium Substances 0.000 claims description 4
- 229910052748 manganese Inorganic materials 0.000 claims description 4
- 239000011572 manganese Substances 0.000 claims description 4
- 229910052788 barium Inorganic materials 0.000 claims description 3
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 claims description 3
- 230000006872 improvement Effects 0.000 claims description 3
- LSNNMFCWUKXFEE-UHFFFAOYSA-L sulfite Chemical compound [O-]S([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-L 0.000 claims description 3
- DHCDFWKWKRSZHF-UHFFFAOYSA-L thiosulfate(2-) Chemical compound [O-]S([S-])(=O)=O DHCDFWKWKRSZHF-UHFFFAOYSA-L 0.000 claims 1
- 239000000243 solution Substances 0.000 description 35
- 239000003795 chemical substances by application Substances 0.000 description 13
- 150000003839 salts Chemical class 0.000 description 8
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 description 6
- -1 alkali metal salt Chemical class 0.000 description 6
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 4
- LSNNMFCWUKXFEE-UHFFFAOYSA-N Sulfurous acid Chemical class OS(O)=O LSNNMFCWUKXFEE-UHFFFAOYSA-N 0.000 description 4
- 239000007864 aqueous solution Substances 0.000 description 4
- 235000010260 calcium hydrogen sulphite Nutrition 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 229910000831 Steel Inorganic materials 0.000 description 3
- 230000002378 acidificating effect Effects 0.000 description 3
- 229910001413 alkali metal ion Inorganic materials 0.000 description 3
- 238000004458 analytical method Methods 0.000 description 3
- 235000010338 boric acid Nutrition 0.000 description 3
- LVGQIQHJMRUCRM-UHFFFAOYSA-L calcium bisulfite Chemical compound [Ca+2].OS([O-])=O.OS([O-])=O LVGQIQHJMRUCRM-UHFFFAOYSA-L 0.000 description 3
- 239000000470 constituent Substances 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 238000002425 crystallisation Methods 0.000 description 3
- 230000008025 crystallization Effects 0.000 description 3
- GRWZHXKQBITJKP-UHFFFAOYSA-N dithionous acid Chemical class OS(=O)S(O)=O GRWZHXKQBITJKP-UHFFFAOYSA-N 0.000 description 3
- 150000003891 oxalate salts Chemical class 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 229910001220 stainless steel Inorganic materials 0.000 description 3
- 239000010959 steel Substances 0.000 description 3
- 150000004764 thiosulfuric acid derivatives Chemical class 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 229910052783 alkali metal Inorganic materials 0.000 description 2
- 239000011260 aqueous acid Substances 0.000 description 2
- AJGPQPPJQDDCDA-UHFFFAOYSA-N azanium;hydron;oxalate Chemical compound N.OC(=O)C(O)=O AJGPQPPJQDDCDA-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 125000005619 boric acid group Chemical class 0.000 description 2
- GBAOBIBJACZTNA-UHFFFAOYSA-L calcium sulfite Chemical compound [Ca+2].[O-]S([O-])=O GBAOBIBJACZTNA-UHFFFAOYSA-L 0.000 description 2
- 235000010261 calcium sulphite Nutrition 0.000 description 2
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 230000008021 deposition Effects 0.000 description 2
- 238000007654 immersion Methods 0.000 description 2
- 238000007689 inspection Methods 0.000 description 2
- 238000009434 installation Methods 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- 159000000000 sodium salts Chemical class 0.000 description 2
- AKHNMLFCWUSKQB-UHFFFAOYSA-L sodium thiosulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=S AKHNMLFCWUSKQB-UHFFFAOYSA-L 0.000 description 2
- 235000019345 sodium thiosulphate Nutrition 0.000 description 2
- UJRAXLUXHBUNDO-UHFFFAOYSA-M sodium;hydron;oxalate Chemical compound [Na+].OC(=O)C([O-])=O UJRAXLUXHBUNDO-UHFFFAOYSA-M 0.000 description 2
- 239000010935 stainless steel Substances 0.000 description 2
- ZCYVEMRRCGMTRW-UHFFFAOYSA-N 7553-56-2 Chemical compound [I] ZCYVEMRRCGMTRW-UHFFFAOYSA-N 0.000 description 1
- WXHQGKBFLPYNSO-UHFFFAOYSA-L B(O)(O)O.S(=S)(=O)([O-])[O-].[Na+].[Na+] Chemical compound B(O)(O)O.S(=S)(=O)([O-])[O-].[Na+].[Na+] WXHQGKBFLPYNSO-UHFFFAOYSA-L 0.000 description 1
- LSNNMFCWUKXFEE-UHFFFAOYSA-M Bisulfite Chemical compound OS([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-M 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 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 1
- 229910000990 Ni alloy Inorganic materials 0.000 description 1
- DWAQJAXMDSEUJJ-UHFFFAOYSA-M Sodium bisulfite Chemical compound [Na+].OS([O-])=O DWAQJAXMDSEUJJ-UHFFFAOYSA-M 0.000 description 1
- 229920002472 Starch Polymers 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 230000001464 adherent effect Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 150000003863 ammonium salts Chemical class 0.000 description 1
- 239000012736 aqueous medium Substances 0.000 description 1
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 description 1
- 239000004327 boric acid Substances 0.000 description 1
- 230000003139 buffering effect Effects 0.000 description 1
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 1
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 1
- 239000000920 calcium hydroxide Substances 0.000 description 1
- 159000000007 calcium salts Chemical class 0.000 description 1
- 150000003841 chloride salts Chemical class 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
- 238000010960 commercial process Methods 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- LNGNZSMIUVQZOX-UHFFFAOYSA-L disodium;dioxido(sulfanylidene)-$l^{4}-sulfane Chemical compound [Na+].[Na+].[O-]S([O-])=S LNGNZSMIUVQZOX-UHFFFAOYSA-L 0.000 description 1
- TXKMVPPZCYKFAC-UHFFFAOYSA-N disulfur monoxide Inorganic materials O=S=S TXKMVPPZCYKFAC-UHFFFAOYSA-N 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- KRHYYFGTRYWZRS-UHFFFAOYSA-N hydrofluoric acid Substances F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 1
- 150000004679 hydroxides Chemical class 0.000 description 1
- 229910001026 inconel Inorganic materials 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 239000011630 iodine Substances 0.000 description 1
- 229910052740 iodine Inorganic materials 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 1
- 235000013980 iron oxide Nutrition 0.000 description 1
- VBMVTYDPPZVILR-UHFFFAOYSA-N iron(2+);oxygen(2-) Chemical class [O-2].[Fe+2] VBMVTYDPPZVILR-UHFFFAOYSA-N 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 150000002696 manganese Chemical class 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910001120 nichrome Inorganic materials 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 235000010267 sodium hydrogen sulphite Nutrition 0.000 description 1
- 229910001415 sodium ion Inorganic materials 0.000 description 1
- 235000019698 starch Nutrition 0.000 description 1
- 239000008107 starch Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 229910052815 sulfur oxide Inorganic materials 0.000 description 1
- PENRVBJTRIYHOA-UHFFFAOYSA-L zinc dithionite Chemical compound [Zn+2].[O-]S(=O)S([O-])=O PENRVBJTRIYHOA-UHFFFAOYSA-L 0.000 description 1
- ZTUVUXVSZXNSCL-UHFFFAOYSA-L zinc;hydrogen sulfite Chemical compound [Zn+2].OS([O-])=O.OS([O-])=O ZTUVUXVSZXNSCL-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
- C23C22/06—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
- C23C22/46—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 oxalates
Description
, METHOD OF REPLENISHING SOLUTIONS FOR COATING CORROSION RESISTANT ALLOYS George F. Otto, Oreland, Pa., amignor to Amchem Prodnets, Ind, Ambler, Pa., a corporation of Delaware No Drawing. Filed Oct. 23, 1962, Ser. No. 232,616 6 Claims. (Cl. 1486.24)
The present invention relates to the art of coating corrosion resistant alloys, and is particularly concerned with an improved method of replenishing solutions used in obtaining such coatings.
The term corrosion resistant alloys, as used in this specification as well as in the claims appended hereto, include the various stainless steels, such as those referred to as the 200, 300, 400 and 500 series, the Nichrome and Inconel"= alloys which are nickel based, and various other alloys of two or more of copper, nickel and chromium with or without iron.
Before outlining the objects of the present invention it is desired to refer to certain standard practices in the prior art in order to appreciate more fully the nature of the present invention.
Virtually all commercial processes for coating corrosion resistant alloys are based upon the use of aqueous solutions of oxalic acid. The coatings thus produced are an aid in the chipless deformation of such alloys. Similarly, virtually all of these aqueous oxalic acid solutions are prepared so as to contain therein an accelerating agent, which is usually a sulfur-bearing compound containing oxygen and which will liberate sulfur and/or sulfur dioxide under the acidic conditions of the coating solution.
Such accelerating agents are normally chosen from the class consisting of sulfites, bisulfites, hydrosulfites, thiosulfates and thionates, and are usually employed in the form of an alkali metal salt, particularly the sodium salt. A more detailed understanding of the use of these accelerating agents may be found in the teachings of my issued US. Patents 2,813,816 and 2,953,487, and also in US. Patents 1,911,537, 2,550,660 and 2,758,962.
Commercial installations for coating corrosion resistant alloys are frequently large size tanks, ranging from several hundred to several thousand gallons of coating solution. Over extended periods of time solutions, as above described, have been found to accumulate large quantities of soluble alkali metal ions, particularly sodium ions. Such ions have certain adverse effects upon the operation and maintenance of such oxalate coating solutions as will be hereinafter explained. For example, the accumulation of soluble alkali metal ions results in a buffering action within the coating solution, and acidity control of the bath, which is frequently maintained in a pH range of 0.4 to 1.0, becomes increasingly difiicult.
These alkali metal ions are also suspected of contributing to powdery coating formation on the treated work pieces.
However, of perhaps greatest significance is the deposition of large quantities of crystalline masses within the coating solution tanks, particularly when the coating bath has been allowed to cool to ambient temperatures, as occurs during normal Weekend plant shut-down. These crystalline deposits have been found to consist primarily of sodium acid oxalate (NaHC O l-l O), which is very difficult to dissolve from the crystalline state. This crystallization problem results in the removal of large quantities of the oxalic acid coating constituent from the treating solutions, thereby causing appreciable loss of acidity and compounding the problems of bath acidity control and replenishment.
*Trademarks for nickel alloys as described in Engineering Alloys (Woldman) published by ASTM, 1954 Edition.
3,218,201 Patented Nov. 16, 1965 This crystallization problem has been so severe in several heavily used commercial installations, that as much as one-half of the volume of the treating solutions, after having cooled to room temperature, has been observed to be a solid crystalline mass. Such crystalline deposition causes serious impediments in the treating tanks by virtue of the size and nature of these needle-like crystals, which grow from the sides and bottom of the tank thereby obstructing and impeding the free movement of work pieces therein.
A recent attempt to solve this problem involve a suggestion for using only ammonium salts of the sulfurbearing, oxygen containing accelerating agents, since ammonium acid oxalate is more soluble than the corresponding sodium salt in the acidic coating solutions. However, while this proposal offers some relief to the problem at hand, it falls short of providing adequate relief due to the fact that an appreciable amount of ammonium acid oxalate salt is still precipitated from the treating solution.
With the foregoing in mind, the principal object of the present invention may be said to reside in the provision of an improved method for replenishing the sulfur-bearing, oxygen containing accelerating ion content of aqueous oxalic acid coating solutions, which substantially minimizes or essentially overcomes the formation of large needle-like crystals in the treating tanks thereby avoiding the concomitant loss of acidity from precipitation of the essential coating constituents.
Other objects and advantages of the present invention will become apparent from a consideration of the following detailed disclosure.
The present invention is based upon the discovery that if the sulfur-bearing oxygen containing accelerating agents selected from the class consisting essentially of sulfites, bisulfites, hydrosulfites, thiosulfates and thionates, used for purposes of replenishing aqueous acid oxalate coating solutions, are added thereto as salts of certain divalent cations, the oxalate salts of which cations are substantially insoluble in the aqueous acid coating solutions, marked improvements will result in the behavior of the coating solutions with substantially reduced loss of the essential oxalate coating ions through precipitation therefrom.
Hereinafter in this specification, as well as in the claims appended hereto, use of the expression substantially insoluble shall refer to a solubility of certain divalent cation salts of oxalic acid of less than 1 gram/liter in the acid oxalate coating solutions.
The divalent cations which may be combined with the sulfur-bearing oxygen containing accelerating agents to form salts thereof, and which cations form substantially insoluble oxalates in the acidic coating solutions, are selected from the class consisting essentially of calcium, magnesium, barium, cadmium, zinc, manganese and ferrous iron.
A number of these salts are known commercially, such as for example, calcium sulfite or bisulfite, and zinc hydrosulfite. Moreover, these salts may easily be prepared from the oxides, hydroxides, chlorides or carbonates of the divalent cations by reacting same with sulfur dioxide, or with alkali metal salts of the desired accelerator anion. For example, calcium sulfite may be prepared from the interaction of sodium bisulfite with calcium hydroxide, and manganese or zinc bisulfite may be obtained by reacting the metallic carbonates with gaseous sulfur dioxide.
Although the method of preparation of several of these divalent cation salts of the sulfur-bearing oxygen containing accelerating compounds have been indicated, such preparations form no part of the present invention, and other methods, not listed herein, may be utilized in accordance with general chemical principles.
The amount of divalent cation salts of oxalate coating accelerating agents from the class described, which must be employed in order to obtain the desired coating results depends entirely upon the degree of bath loading. Since such. amounts are determined in accordance with prior art practice, no detailed teachings with respect to this usage are presented herewith.
So far as concerns the actual incorporation of these divalent cation salts, from the class described, into the oxalate coating solutions, this may be accomplished by the use of aqueous solutions or slurries of such salts, or simply by adding the requisite amount of a powdered or dry salt to the coating bath. Generally, it has been found that aqueous solutions or slurries are easier to handle, although with the exception of the bisulfite salts, the majority of these salts of accelerator agents are obtainable in solid or crystalline form due to their limited solubility in aqueous media.
In order to illustrate the improved results secured in accordance with the teachings of this invention there is presented below a detailed outline of a process run in accordance with the replenishing technique of this invention.
Stainless steel panels (type 304) were pickled in a nitric-hydrofluoric acid bath according to well established art practice. After water rinsing, these panels were sub jected to the coating action of the solution described below using 5 minute immersion cycles at 180 Grams Oxalic acid 4O Boric acid 20 Sodium thiosulfate 2.0
Water, to make 1 liter such solution being described and claimed in my issued US. Patent 2,953,487.
After 1 square foot of total surface area had been treated in this solution, bath analyses (as determined by titrating a ml. sample of the coating solution with 0.05 N iodine solution to a blue endpoint using starch indicator) showed a deficiency of accelerating agent, and 0.35 gram/liter of calcium bisulfite was added in the form of an aqueous solution thereof. Additional steel panels were processed through the coating solution which was replenished, as required with oxalic and boric acids, and with calcium bisulfite, until a total of 25 square feet of steel had been coated. inspection or" the coated panels showed fine crystalline coatings having weights of 426 mm/sq. foot.
In order to compare the foregoing with the standard replenishing technique of the prior art, a coating solution was prepared containing:
Grams Oxalic acid 4O Boric acid Sodium thiosulfate 2.6
Water, to make 1 liter such solution being exactly similar to the bath prepared for the experiment reported above.
Stainless steel (type 304) panels, pickled in nitrichydrofiuoric acid as before, were water rinsed and then subjected to the action of the oxalate coating solution using immersion times of 5 minutes at 180 F. Replenishment of the coating constituents was accomplished using oxalic and boric acids as before. However, the accelerating agent was supplied as sodium thiosulfate throughout the entire coating operation. After square feet of total surface area has been treated, the steel panels were found to contain fairly coarse crystalline coatings having weights or" 533 mg./sq. foot.
Both coating solutions were permitted to cool, and were then allowed to remain undisturbed at ambient temperatures for i5 hours. Subsequent inspection of the baths showed a solid /s inch layer of large needle-like crystalline deposits in the solution replenished with sodium thiosuliate; but only a /8 inch layer of a line, powdery non-adherent type precipitate which was freely distributed on the bottom of the coating solution tank in the solution replenished with calcium bisultite.
Analyses of thecrystalline deposit obtained from the sodium thiosulfite accelerated bath indicated the precipitated crystals were almost entirely hydrated sodium acid oxalate (NaHC OJ-I O). Analyses of the line powder from the calcium bisulfite accelerated bath indicatcd it to be about 32180 about Ctr-C 6, and about 22% FeC Q The balance of the fine powdery deposit was sulfur and iron oxides.
Comparison of the results obtained from these two processes clearly shows that the use of a salt of an accelerating agent, cation portion of which forms a substantially insoluble oxalate salt in oxalic acid coating solutions, successfully avoids the serious crystallization problems encountered in prior art processes. It has also been oberved that the use of calcium salts of accelerating agents yields a refinement in the coatings obtained on the metal work pieces. For this reason, it may sometimes be desirable to employ Zinc, cadmium, ferrous or manganese salts of the accelerating agents, since this refining elfect has not been observed from the use of these cations.
I claim:
1. in the replenishment of the accelerator ion content of aqueous oxalic acid coating solutions, said accelerator ion containing sulfur and oxygen and being selected from the class of anions consisting of sulfitcs, bisulfites, hydrosulfites, thiosulfates and thionates, the improvement which comprises adding such accelerator anions in association with a cation selected from the class consisting of calcium, magnesium, barium, cadmium, zinc. manganese and ferrous iron.
2. The method of claim it wherein the cation is calcium.
3. The method of claim it wherein the cation is zinc. The method of claim 1 wherein the cation is ferrous iron.
5. The method of claim 1 wherein the cation is magnesium.
e. The method of claim 1 wherein the cation is main ganesc.
References -Cited by the Examiner FOREIGN PATENTS 3/1955 Austria.
RICHARD D. NEVIUS, Primary Examiner.
,VELLIAM D. MARTIN, Examiner.
Claims (1)
1. IN THE REPLENISHMENT OF THE ACCELERATOR ION CONTENT OF AQUEOUS OXALIC ACID COATING SOLUTIONS, SAID ACCELERATOR ION CONTAINING SULFUR AND OXYGEN AND BEING SELECTED FROM THE CLASS OF ANIONS CONSISTING OF SULFITES, BISULFITES, HYDROSULFITES, THIOSULFATES AND THIONATES, THE IMPROVEMENT WHICH COMPRISES ADDING SUCH ACCELERATOR ANIONS IN ASSOCIATION WITH A CATION SELECTED FROM THE CLASS CONSISTING OF CALCIUM, MAGNESIUM, BARIUM, CADMIUM, ZINC, MANGANESE AND FERROUS IRON.
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US232616A US3218201A (en) | 1962-10-23 | 1962-10-23 | Method of replenishing solutions for coating corrosion resistant alloys |
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US232616A US3218201A (en) | 1962-10-23 | 1962-10-23 | Method of replenishing solutions for coating corrosion resistant alloys |
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Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3879237A (en) * | 1973-01-16 | 1975-04-22 | Amchem Prod | Coating compositions for stainless steels |
US20020062866A1 (en) * | 2000-11-29 | 2002-05-30 | Sadao Sumiya | Adjustment pipe for fuel injection valve, and press-fitting structure and press-fitting method for the same |
WO2020214592A1 (en) * | 2019-04-16 | 2020-10-22 | Ppg Industries Ohio, Inc. | Systems and methods for maintaining pretreatment baths |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
AT181478B (en) * | 1949-02-12 | 1955-03-25 | Parker Rust Proof Co | Process for the formation of oxalate coatings on stainless steels and for the preparation of a means for carrying out the same |
-
1962
- 1962-10-23 US US232616A patent/US3218201A/en not_active Expired - Lifetime
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
AT181478B (en) * | 1949-02-12 | 1955-03-25 | Parker Rust Proof Co | Process for the formation of oxalate coatings on stainless steels and for the preparation of a means for carrying out the same |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3879237A (en) * | 1973-01-16 | 1975-04-22 | Amchem Prod | Coating compositions for stainless steels |
US20020062866A1 (en) * | 2000-11-29 | 2002-05-30 | Sadao Sumiya | Adjustment pipe for fuel injection valve, and press-fitting structure and press-fitting method for the same |
US6834667B2 (en) * | 2000-11-29 | 2004-12-28 | Denso Corporation | Adjustment pipe for fuel injection valve, and press-fitting structure and press-fitting method for the same |
WO2020214592A1 (en) * | 2019-04-16 | 2020-10-22 | Ppg Industries Ohio, Inc. | Systems and methods for maintaining pretreatment baths |
US20200332420A1 (en) * | 2019-04-16 | 2020-10-22 | Ppg Industries Ohio, Inc. | Systems and methods for maintaining pretreatment baths |
US11566330B2 (en) * | 2019-04-16 | 2023-01-31 | Ppg Industries Ohio, Inc. | Systems and methods for maintaining pretreatment baths |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: AMCHEM PRODUCTS, INC. A CORP. OF DEL. Free format text: MERGER;ASSIGNORS:AMCHEM PRODUCTS, INC. (MERGED INTO);HHC, INC. (CHANGED TO);REEL/FRAME:004102/0461 Effective date: 19810320 |