US2175417A - Salt bath for case-hardening - Google Patents
Salt bath for case-hardening Download PDFInfo
- Publication number
- US2175417A US2175417A US199533A US19953338A US2175417A US 2175417 A US2175417 A US 2175417A US 199533 A US199533 A US 199533A US 19953338 A US19953338 A US 19953338A US 2175417 A US2175417 A US 2175417A
- Authority
- US
- United States
- Prior art keywords
- bath
- composition
- sodium
- hardening
- cyanide
- 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
- 150000003839 salts Chemical class 0.000 title description 4
- 239000000203 mixture Substances 0.000 description 15
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical class [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 12
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 6
- 238000005255 carburizing Methods 0.000 description 6
- KXZJHVJKXJLBKO-UHFFFAOYSA-N chembl1408157 Chemical compound N=1C2=CC=CC=C2C(C(=O)O)=CC=1C1=CC=C(O)C=C1 KXZJHVJKXJLBKO-UHFFFAOYSA-N 0.000 description 6
- 229910000029 sodium carbonate Inorganic materials 0.000 description 6
- 235000017550 sodium carbonate Nutrition 0.000 description 6
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 description 5
- 229910000831 Steel Inorganic materials 0.000 description 5
- PUZPDOWCWNUUKD-UHFFFAOYSA-M sodium fluoride Chemical compound [F-].[Na+] PUZPDOWCWNUUKD-UHFFFAOYSA-M 0.000 description 5
- 239000010959 steel Substances 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 4
- 239000000047 product Substances 0.000 description 4
- 229910001631 strontium chloride Inorganic materials 0.000 description 4
- AHBGXTDRMVNFER-UHFFFAOYSA-L strontium dichloride Chemical compound [Cl-].[Cl-].[Sr+2] AHBGXTDRMVNFER-UHFFFAOYSA-L 0.000 description 4
- 239000007795 chemical reaction product Substances 0.000 description 3
- 239000004615 ingredient Substances 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 150000002825 nitriles Chemical class 0.000 description 3
- 239000011780 sodium chloride Substances 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- XFXPMWWXUTWYJX-UHFFFAOYSA-N Cyanide Chemical compound N#[C-] XFXPMWWXUTWYJX-UHFFFAOYSA-N 0.000 description 2
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 230000035515 penetration Effects 0.000 description 2
- 239000001103 potassium chloride Substances 0.000 description 2
- 235000011164 potassium chloride Nutrition 0.000 description 2
- 239000010802 sludge Substances 0.000 description 2
- MNWBNISUBARLIT-UHFFFAOYSA-N sodium cyanide Chemical compound [Na+].N#[C-] MNWBNISUBARLIT-UHFFFAOYSA-N 0.000 description 2
- 235000013024 sodium fluoride Nutrition 0.000 description 2
- 239000011775 sodium fluoride Substances 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- 101100493705 Caenorhabditis elegans bath-36 gene Proteins 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- BDAGIHXWWSANSR-NJFSPNSNSA-N hydroxyformaldehyde Chemical compound O[14CH]=O BDAGIHXWWSANSR-NJFSPNSNSA-N 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000003381 stabilizer Substances 0.000 description 1
- 229910000018 strontium carbonate Inorganic materials 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
- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C8/40—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using liquids, e.g. salt baths, liquid suspensions
- C23C8/42—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using liquids, e.g. salt baths, liquid suspensions only one element being applied
- C23C8/44—Carburising
- C23C8/46—Carburising of ferrous surfaces
Definitions
- my improved salt bath is based principally upon the presence therein of a cyanide modified by the influence of one or 'more suitable accelerators, the latter being chosen with a view not only of speeding up the rate of cementation, but also for producing only such residue products of the reaction or double reactions taking place during the case hardening process as will be readily soluble in water.
- my improved bath composition is that it may be used at relatively high working temperatures without serious decomposition or breaking down of the active carburizing agents therein. Temperatures of 1350 F. to 1750 F. are safe working limits since on test my bath 36 composition has remained stable at a temperature of 1800 F. for as long as one hundred hours. 4
- my bath composition is so constituted that sludge of residue products is not formed at the bottom of the pot which would 40 tend to insulate the transfer'of heat to the bath when in use.
- the principal ingredient of my bath composition is a cyanide and preferably sodium cyanide (NaCN) because it gives a soluble characteristic to the composition and products thereof and is also more stable than other 10 cyanide compounds which otherwise might be used.
- NaCN sodium cyanide
- strontium chloride SrCl-z
- the accelerator strontium chloride is also preferably added in a liberal proportion so that unless restrained the initial activity of said reaction might, be faster than desired.
- This sodium carbonate is also chosen because 25.
- a bath of the above composition for case hardening would give a case too high in carbon and preferably should be diluted for best results
- the further compounds added as determined by low cost, considerations of solubility, low fusing temperatures, stability, etc. are preferably sodium chloride (NaCl), potassium chloride (KCl), and sodium fluoride (NaF).
- the last named fills the function of a'cleaner for foreign matter such as scale (iron oxide) that may be introduced into the bath on the work being treated.
- Sodium fluoride ingredient is not so important as the others and may in some cases be omitted.
- the foregoing bath composition fuses at approximately 1075" F. and its normal or most commonly used working temperature is about 1550 F. As heretofore stated, however, it can be successfully used at temperatures up to 1750 F. or 1800" F. without breakdown.
- carburizing steels for case hardening its rate of penetration is from fifty to one hundred per cent faster than the ordinary and commonly used cyanide salt baths, the depth of penetration depending upon the duration of the steel immersion therein.
- the bath is prepared for the market in the usual way by fusing together the ingredients in the proportions above stated and breaking up the solidified product into condition suitable for shipment.
- a fusible salt bath composition for carburizing steels of relatively low carbon content comprising in approximate proportions by weight the following:
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
Description
Patented a. 10, i 939 1 SALT BATH FOR GASE-HARDENING Ernest A. Walen, Springfield, Mass, assignor The Heatbath Corporation, West Springfield,
Mass, a corporation of Massachusetts N0 Drawing. Application April 1, 1938,
Serial No. 199,533
\ 1 Claim.
The action of my improved salt bath is based principally upon the presence therein of a cyanide modified by the influence of one or 'more suitable accelerators, the latter being chosen with a view not only of speeding up the rate of cementation, but also for producing only such residue products of the reaction or double reactions taking place during the case hardening process as will be readily soluble in water.
An objectionable characteristic of cyanide salt baths either with or without accelerators as heretofore used is that when the steel articles are removed therefrom after the carburizing treatment, special cleaning processes must be resorted.
to for removinginsoluble end products adhering to the articles so treated, due to the fact that said end products are not soluble. In the use of my improved bath composition hereinafter described, the articles after being treated may be thoroughly cleaned simply by washing in water which is a considerable saving in expense over old methods.
Another advantage of my improved bath composition is that it may be used at relatively high working temperatures without serious decomposition or breaking down of the active carburizing agents therein. Temperatures of 1350 F. to 1750 F. are safe working limits since on test my bath 36 composition has remained stable at a temperature of 1800 F. for as long as one hundred hours. 4
Furthermore, my bath composition is so constituted that sludge of residue products is not formed at the bottom of the pot which would 40 tend to insulate the transfer'of heat to the bath when in use. i
In the continuous use of any bath with work being repeatedly immersed therein and withdrawn therefrom a gradual depletion thereof 45 takes place due to the so called drag-out or portion of the bath adhering to the withdrawn work. In the replenishment of my bath a composition of the same original proportions is added since neither the drag-out loss nor the reac- 50 tions of working the bath changes the original composition. A further advantage of my bath is that its combustibility is very low, there being only a very slow oxidizing thereof at the surface in contact with air. For this reason my bath does not diminish in its active carburizing 7 strength over long periods, and it has been found in practice that the replenishment of the dragout loss even when infrequently made will be entirely suflicient to keep the bath in its full working carburizing strength. 5 As has been stated, the principal ingredient of my bath composition is a cyanide and preferably sodium cyanide (NaCN) because it gives a soluble characteristic to the composition and products thereof and is also more stable than other 10 cyanide compounds which otherwise might be used. To the sodium cyanide I add as the principal accelerator, strontium chloride (SrCl-z) which in combination with the sodium cyanide carburizes the steel. While the sodium cyanide predominates in quantity in the composition the accelerator strontium chloride is also preferably added in a liberal proportion so that unless restrained the initial activity of said reaction might, be faster than desired. Accordingly I add to 20 the aforesaid (Na-300a) as a stabilizer which acts to level out the intensity of said reaction, prolong the life of the bath, and make its action more uniform.
This sodium carbonate is also chosen because 25.
of its soluble character since it is important in. my bath that all end products of the reacting bath shall be soluble in water for easy cleaning by washing. An equivalent of the sodium carbonate for my composition is strantium carbon- 31) ate, and this latter might be used except for the fact of its much higher cost at the present time.
The foregoing compounds are the chief working parts of my improved bath composition and are fused together in the approximate propor- 35 tions by weight as follows:
Parts Sodium cyanide (NaCN) 4 Strontium chloride (SrClz) 2 Sodium carbonate (Na2CO3) 40 and/or 1 Strontium carbonate (SICOs) However, a bath of the above composition for case hardening would give a case too high in carbon and preferably should be diluted for best results, The further compounds added as determined by low cost, considerations of solubility, low fusing temperatures, stability, etc. are preferably sodium chloride (NaCl), potassium chloride (KCl), and sodium fluoride (NaF). The last named fills the function of a'cleaner for foreign matter such as scale (iron oxide) that may be introduced into the bath on the work being treated. It tends to dissolve these things and keep them in solution rather than peringredients sodium carbonate mitting them to accumulate in the bottom of the pot as an objectionable and insulating sludge. Sodium fluoride ingredient is not so important as the others and may in some cases be omitted.
-A typical example in approximate percentages of my preferred 'and complete composition is given as follows:
' Per cent Sodium cyanide (NaCN) -f 40 Strontium chloride (SrC12).. 20 Sodium carbonate (NazCO3) and/or 10 Strontium carbonate (SrCOa) Sodium chloride (NaCl) 20.45 Potassium chloride (KCl) 5 Sodium fluoride *(NaF); 4.55
The foregoing bath composition fuses at approximately 1075" F. and its normal or most commonly used working temperature is about 1550 F. As heretofore stated, however, it can be successfully used at temperatures up to 1750 F. or 1800" F. without breakdown. In carburizing steels for case hardening its rate of penetration is from fifty to one hundred per cent faster than the ordinary and commonly used cyanide salt baths, the depth of penetration depending upon the duration of the steel immersion therein. The bath is prepared for the market in the usual way by fusing together the ingredients in the proportions above stated and breaking up the solidified product into condition suitable for shipment.
What I claim is:
A fusible salt bath composition for carburizing steels of relatively low carbon content comprising in approximate proportions by weight the following:
Per cent Sodium -cyanide 40 Strontium chloride 20 Sodium carbonate 10 Sodium chloride 20.45 Potassium chloride 5 Sodium fluoride 4.55
ERNEST A. WALEN.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US199533A US2175417A (en) | 1938-04-01 | 1938-04-01 | Salt bath for case-hardening |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US199533A US2175417A (en) | 1938-04-01 | 1938-04-01 | Salt bath for case-hardening |
Publications (1)
Publication Number | Publication Date |
---|---|
US2175417A true US2175417A (en) | 1939-10-10 |
Family
ID=22737934
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US199533A Expired - Lifetime US2175417A (en) | 1938-04-01 | 1938-04-01 | Salt bath for case-hardening |
Country Status (1)
Country | Link |
---|---|
US (1) | US2175417A (en) |
-
1938
- 1938-04-01 US US199533A patent/US2175417A/en not_active Expired - Lifetime
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