US2474680A - Method of rectifying a neutral molten salt treating bath - Google Patents
Method of rectifying a neutral molten salt treating bath Download PDFInfo
- Publication number
- US2474680A US2474680A US584490A US58449045A US2474680A US 2474680 A US2474680 A US 2474680A US 584490 A US584490 A US 584490A US 58449045 A US58449045 A US 58449045A US 2474680 A US2474680 A US 2474680A
- Authority
- US
- United States
- Prior art keywords
- bath
- molten salt
- rectifying
- neutral
- treating bath
- 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
Links
- 230000007935 neutral effect Effects 0.000 title description 10
- 150000003839 salts Chemical class 0.000 title description 8
- 238000000034 method Methods 0.000 title description 7
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 12
- 235000002639 sodium chloride Nutrition 0.000 description 8
- NEHMKBQYUWJMIP-UHFFFAOYSA-N chloromethane Chemical compound ClC NEHMKBQYUWJMIP-UHFFFAOYSA-N 0.000 description 6
- QVQLCTNNEUAWMS-UHFFFAOYSA-N barium oxide Chemical compound [Ba]=O QVQLCTNNEUAWMS-UHFFFAOYSA-N 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- 229910000831 Steel Inorganic materials 0.000 description 4
- 229910052799 carbon Inorganic materials 0.000 description 4
- 150000001875 compounds Chemical class 0.000 description 4
- 239000010959 steel Substances 0.000 description 4
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 3
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 description 3
- 229910052801 chlorine Inorganic materials 0.000 description 3
- 239000000460 chlorine Substances 0.000 description 3
- 229910052731 fluorine Inorganic materials 0.000 description 3
- 239000011737 fluorine Substances 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 150000004820 halides Chemical class 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 229940050176 methyl chloride Drugs 0.000 description 3
- KKCBUQHMOMHUOY-UHFFFAOYSA-N sodium oxide Chemical compound [O-2].[Na+].[Na+] KKCBUQHMOMHUOY-UHFFFAOYSA-N 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- ZCYVEMRRCGMTRW-UHFFFAOYSA-N 7553-56-2 Chemical compound [I] ZCYVEMRRCGMTRW-UHFFFAOYSA-N 0.000 description 2
- WKBOTKDWSSQWDR-UHFFFAOYSA-N Bromine atom Chemical compound [Br] WKBOTKDWSSQWDR-UHFFFAOYSA-N 0.000 description 2
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 2
- 239000005977 Ethylene Substances 0.000 description 2
- 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 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 description 2
- GDTBXPJZTBHREO-UHFFFAOYSA-N bromine Substances BrBr GDTBXPJZTBHREO-UHFFFAOYSA-N 0.000 description 2
- 229910052794 bromium Inorganic materials 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 2
- 238000005261 decarburization Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000002347 injection Methods 0.000 description 2
- 239000007924 injection Substances 0.000 description 2
- 229910052740 iodine Inorganic materials 0.000 description 2
- 239000011630 iodine Substances 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 125000000325 methylidene group Chemical group [H]C([H])=* 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 229910010271 silicon carbide Inorganic materials 0.000 description 2
- 239000010802 sludge Substances 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- 229910052708 sodium Inorganic materials 0.000 description 2
- 229910001948 sodium oxide Inorganic materials 0.000 description 2
- VZGDMQKNWNREIO-UHFFFAOYSA-N tetrachloromethane Chemical compound ClC(Cl)(Cl)Cl VZGDMQKNWNREIO-UHFFFAOYSA-N 0.000 description 2
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical class [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- XSTXAVWGXDQKEL-UHFFFAOYSA-N Trichloroethylene Chemical group ClC=C(Cl)Cl XSTXAVWGXDQKEL-UHFFFAOYSA-N 0.000 description 1
- 150000001350 alkyl halides Chemical class 0.000 description 1
- 229910052788 barium Inorganic materials 0.000 description 1
- WDIHJSXYQDMJHN-UHFFFAOYSA-L barium chloride Chemical compound [Cl-].[Cl-].[Ba+2] WDIHJSXYQDMJHN-UHFFFAOYSA-L 0.000 description 1
- 229910001626 barium chloride Inorganic materials 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 150000001639 boron compounds Chemical group 0.000 description 1
- 150000001642 boronic acid derivatives Chemical class 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 150000001805 chlorine compounds Chemical class 0.000 description 1
- NEHMKBQYUWJMIP-NJFSPNSNSA-N chloro(114C)methane Chemical compound [14CH3]Cl NEHMKBQYUWJMIP-NJFSPNSNSA-N 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- PXBRQCKWGAHEHS-UHFFFAOYSA-N dichlorodifluoromethane Chemical compound FC(F)(Cl)Cl PXBRQCKWGAHEHS-UHFFFAOYSA-N 0.000 description 1
- 235000019404 dichlorodifluoromethane Nutrition 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000002360 explosive Substances 0.000 description 1
- 150000002497 iodine compounds Chemical class 0.000 description 1
- -1 methyl halide Chemical class 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 231100000614 poison Toxicity 0.000 description 1
- 230000007096 poisonous effect Effects 0.000 description 1
- 235000011164 potassium chloride Nutrition 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- UBOXGVDOUJQMTN-UHFFFAOYSA-N trichloroethylene Natural products ClCC(Cl)Cl UBOXGVDOUJQMTN-UHFFFAOYSA-N 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/34—Methods of heating
- C21D1/44—Methods of heating in heat-treatment baths
- C21D1/46—Salt baths
Definitions
- the present invention relates to the heat treating of steel in a neutral molten salt bath, and particularly to a method of maintaining such baths in a neutral condition to avoid decarburization of the steel.
- Boron compounds form complex borates with the oxides of the bath. These are insoluble. Some of them float on the surface and others sink to the bottom as a sludge which must be removed at frequent intervals. Those which float as a scum often stick to the work and present a diflicult cleaning problem.
- chlorine and fluorine are likewise each effective but are somewhat less desirable for commercial use because of their poisonous character which necessitates use of extreme care to avoid gas leaks.
- anhydrous hydrochloric acid which is also effective as a neutralizer.
- Iodine or iodine compounds cannot be used because iodine does not produce compounds with barium or sodium which are stable at heat treating temperatures.
- Liquids such as bromine, carbon tetrachloride, or trichloroethylene are also efiective but they must be vaporized before they are injected into the bath, in order to prevent an explosive expansion. It is for this reason that materials which are gaseous at room temperature are preferred to the liquids.
- the amount of rectifying material which must be injected in a. gaseous state depends upon the condition of the bath. A continuous injection of very small quantities is sufficient to maintain the bath in a neutral condition. If desired, the as may be injected intermittently from time to time as required by the condition of the bath. In no case should the amount be sufiicient to blow any of the molten salt out of the pot.
- the methyl chloride CH3C1 breaks down into hydrochloric acid and methylene or ethylene.
- the methylene or ethylene burn at the surface of the bath and the hydrochloric acid reacts with the barium oxide or sodium oxide, as follows:
- the method of rectifying a neutral molten salt heat treating bath. containing undesirable oxides which includes injecting ina gaseous state into the bath while it is in a heat treating pot a 4 methyl halide of the halide group consisting of chlorine, fluorine, bromine.
Description
Patented June 28, 1949 METHOD OF RECTIFYING A NEUTRAL MOLTEN SALT TREATING BATH Paul H. Kramer, Detroit, Mich., assignor to Park Chemical Company, Detroit, Mich., a corporation of Michigan No Drawing. Application March 23, 1945, Serial No. 584,490
2 Claims. 1
The present invention relates to the heat treating of steel in a neutral molten salt bath, and particularly to a method of maintaining such baths in a neutral condition to avoid decarburization of the steel.
In the heat treatment of steel, and particularly the hardening of the medium and high carbon steels, it is particularly important that no decarburization result. For this reason neutral molten salt baths are widely used for such heat treating operations, and a number of different types give satisfactory results. Among them are barium chloride baths and baths comprising mixtures of sodium and potassium chlorides.
While these neutral salt baths give satisfactory results when made up fresh from pure chemicals, all are subject to the disadvantage that on continued use at high temperatures some breakdown of the chlorides to oxides occurs. The resulting oxides have a definite decarburizing effect upon the steel, and accordingly it is essential and common practice to add rectifiers to such baths from time to time in order to maintain them in a. neutral condition. Among the rectifiers which have been used commercially are carbon, compounds of boron, and silicon or its compounds. Carbon operates to form a cover for the bath and hence to exclude atmospheric oxygen. Because it must necessarily be disturbed from time to time it does not provide complete protection and, in addition, it cannot be used satisfactorily for the work treated in baskets, due to the tendency to remove excess quantities of the carbon cover.
Boron compounds form complex borates with the oxides of the bath. These are insoluble. Some of them float on the surface and others sink to the bottom as a sludge which must be removed at frequent intervals. Those which float as a scum often stick to the work and present a diflicult cleaning problem.
Silicon and silicon carbide, as Well as silica, form a sludge which settles to the bottom of the pot and must be removed at regular intervals.
In accordance with the present method oonvennot be vaporized before they are injected into since it is relatively inexpensive, easy to obtain,
and relatively safe. Other equally satisfactory but slightly more expensive alkyl halide gases are dichlorodifiuoromethane and dichloromonofiuoromethane (Freon 12 and Freon 21, respectively).
The elements chlorine and fluorine are likewise each effective but are somewhat less desirable for commercial use because of their poisonous character which necessitates use of extreme care to avoid gas leaks. The same is true of anhydrous hydrochloric acid which is also effective as a neutralizer.
Iodine or iodine compounds cannot be used because iodine does not produce compounds with barium or sodium which are stable at heat treating temperatures.
Liquids such as bromine, carbon tetrachloride, or trichloroethylene are also efiective but they must be vaporized before they are injected into the bath, in order to prevent an explosive expansion. It is for this reason that materials which are gaseous at room temperature are preferred to the liquids.
The amount of rectifying material which must be injected in a. gaseous state depends upon the condition of the bath. A continuous injection of very small quantities is sufficient to maintain the bath in a neutral condition. If desired, the as may be injected intermittently from time to time as required by the condition of the bath. In no case should the amount be sufiicient to blow any of the molten salt out of the pot.
It is believed that the reactions which occur on the injection of methyl chloride are as follows:
First, the methyl chloride CH3C1 breaks down into hydrochloric acid and methylene or ethylene. The methylene or ethylene burn at the surface of the bath and the hydrochloric acid reacts with the barium oxide or sodium oxide, as follows:
From the above it is apparent that the hydrochloric acid, which results from the breakdown of the methyl chloride, will restore either barium oxide or sodium oxide to their original chloride for-m, thus leaving the bath in its initial state free from any addition agents. The water formed in the reaction passes off immediately as steam.
From the above reactions it is apparent how anhydrous hydrochloric acid likewise will rectify the bath. Since all primary halides break down into hydrochloric acid on heating they will result in similar reactions. In the case of chlorine and fluorine, which do not break down into hydrochloric acid, it is believed that a direct reaction results in a substitution of the halide for the oxygen in the barium or sodium oxide compounds in the bath.
No particular or unusual apparatus is required to carry out the process, exceptthat it is found that the use of a ceramic delivery tubefor the gas where it enters the heat treating potavoids plug;- ging of the tube by carbon.
While a number of elements or compounds have been specifically referred to, it is apparent that others of the broad class set forthi'n the specification may be employed within the spirit of the invention and the scope of the appended claims.
What is claimed is:
1. The method of rectifying a neutral molten salt heat treating bath. containing undesirable oxides which includes injecting ina gaseous state into the bath while it is in a heat treating pot a 4 methyl halide of the halide group consisting of chlorine, fluorine, bromine.
2. The method of rectifying a neutral molten salt heat treating loath containing undesirable oxides which includes injecting methyl chloride into the bath while it is in a heat treating pot.
PAUL H. KRAMER.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Number Name Date 1,241,113 Hayes Sept. 25, 1917 2,375,758 Bates May 15, 1945 FOREIGN PATENTS Number Country Date 494,274 Great Britain Oct. 24, 1938 OTHER REFERENCES Gregory: Uses and Applications of Chemicals and Related Materials, Reinhold Pub. Corp, N. Y. C., N. Y. (1939), page 315.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US584490A US2474680A (en) | 1945-03-23 | 1945-03-23 | Method of rectifying a neutral molten salt treating bath |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US584490A US2474680A (en) | 1945-03-23 | 1945-03-23 | Method of rectifying a neutral molten salt treating bath |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US2474680A true US2474680A (en) | 1949-06-28 |
Family
ID=24337529
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US584490A Expired - Lifetime US2474680A (en) | 1945-03-23 | 1945-03-23 | Method of rectifying a neutral molten salt treating bath |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | US2474680A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4009112A (en) * | 1975-09-05 | 1977-02-22 | Park Chemical Co. | Pelletized rectifier for molten neutral salt baths and method |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1241113A (en) * | 1916-03-31 | 1917-09-25 | Carnot Dev Corp | Solution for the treatment of iron or steel. |
| GB494274A (en) * | 1936-10-01 | 1938-10-24 | Aluminium Lab Ltd | Improvements in or relating to the thermal treatment of aluminium and aluminium base alloys |
| US2375758A (en) * | 1940-09-27 | 1945-05-15 | Houdry Process Corp | Control of heat transfer salts |
-
1945
- 1945-03-23 US US584490A patent/US2474680A/en not_active Expired - Lifetime
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1241113A (en) * | 1916-03-31 | 1917-09-25 | Carnot Dev Corp | Solution for the treatment of iron or steel. |
| GB494274A (en) * | 1936-10-01 | 1938-10-24 | Aluminium Lab Ltd | Improvements in or relating to the thermal treatment of aluminium and aluminium base alloys |
| US2375758A (en) * | 1940-09-27 | 1945-05-15 | Houdry Process Corp | Control of heat transfer salts |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4009112A (en) * | 1975-09-05 | 1977-02-22 | Park Chemical Co. | Pelletized rectifier for molten neutral salt baths and method |
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