EP0147011A2 - Bain de sel sans cyanure et procédé de carburation de métaux et alliages ferreux - Google Patents
Bain de sel sans cyanure et procédé de carburation de métaux et alliages ferreux Download PDFInfo
- Publication number
- EP0147011A2 EP0147011A2 EP84306336A EP84306336A EP0147011A2 EP 0147011 A2 EP0147011 A2 EP 0147011A2 EP 84306336 A EP84306336 A EP 84306336A EP 84306336 A EP84306336 A EP 84306336A EP 0147011 A2 EP0147011 A2 EP 0147011A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- mixture
- bath
- temperature
- strontium
- composition
- 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.)
- Withdrawn
Links
- 229910052751 metal Inorganic materials 0.000 title claims abstract description 16
- 239000002184 metal Substances 0.000 title claims abstract description 16
- 229910045601 alloy Inorganic materials 0.000 title claims abstract description 5
- 239000000956 alloy Substances 0.000 title claims abstract description 5
- 238000000034 method Methods 0.000 title claims description 26
- -1 ferrous metals Chemical class 0.000 title abstract description 4
- 150000002825 nitriles Chemical class 0.000 title description 2
- 239000000203 mixture Substances 0.000 claims abstract description 43
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 34
- 229910002804 graphite Inorganic materials 0.000 claims abstract description 25
- 239000010439 graphite Substances 0.000 claims abstract description 25
- XFXPMWWXUTWYJX-UHFFFAOYSA-N Cyanide Chemical compound N#[C-] XFXPMWWXUTWYJX-UHFFFAOYSA-N 0.000 claims abstract description 20
- 229910001514 alkali metal chloride Inorganic materials 0.000 claims abstract description 12
- 239000012190 activator Substances 0.000 claims abstract description 11
- 229910052788 barium Inorganic materials 0.000 claims abstract description 9
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 claims abstract description 9
- 239000011833 salt mixture Substances 0.000 claims abstract description 9
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 claims abstract description 8
- 150000001875 compounds Chemical class 0.000 claims abstract description 8
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 6
- 239000001301 oxygen Substances 0.000 claims abstract description 6
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 6
- 150000003438 strontium compounds Chemical class 0.000 claims abstract 2
- 238000005255 carburizing Methods 0.000 claims description 16
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M potassium chloride Inorganic materials [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 claims description 12
- 229910052712 strontium Inorganic materials 0.000 claims description 10
- CIOAGBVUUVVLOB-UHFFFAOYSA-N strontium atom Chemical compound [Sr] CIOAGBVUUVVLOB-UHFFFAOYSA-N 0.000 claims description 10
- 229910052799 carbon Inorganic materials 0.000 claims description 9
- 238000007654 immersion Methods 0.000 claims description 8
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical group 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 claims description 7
- 235000011164 potassium chloride Nutrition 0.000 claims description 6
- KQAGKTURZUKUCH-UHFFFAOYSA-L strontium oxalate Chemical compound [Sr+2].[O-]C(=O)C([O-])=O KQAGKTURZUKUCH-UHFFFAOYSA-L 0.000 claims description 6
- FAPWRFPIFSIZLT-UHFFFAOYSA-M sodium chloride Inorganic materials [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 5
- KWGKDLIKAYFUFQ-UHFFFAOYSA-M lithium chloride Chemical compound [Li+].[Cl-] KWGKDLIKAYFUFQ-UHFFFAOYSA-M 0.000 claims description 4
- 239000001103 potassium chloride Substances 0.000 claims description 4
- 239000011734 sodium Substances 0.000 claims description 4
- 239000011780 sodium chloride Substances 0.000 claims description 3
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 claims description 2
- 239000011591 potassium Substances 0.000 claims description 2
- QVQLCTNNEUAWMS-UHFFFAOYSA-N barium oxide Chemical group [Ba]=O QVQLCTNNEUAWMS-UHFFFAOYSA-N 0.000 claims 2
- IATRAKWUXMZMIY-UHFFFAOYSA-N strontium oxide Chemical compound [O-2].[Sr+2] IATRAKWUXMZMIY-UHFFFAOYSA-N 0.000 claims 2
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 claims 1
- GXUARMXARIJAFV-UHFFFAOYSA-L barium oxalate Chemical compound [Ba+2].[O-]C(=O)C([O-])=O GXUARMXARIJAFV-UHFFFAOYSA-L 0.000 claims 1
- 229940094800 barium oxalate Drugs 0.000 claims 1
- 238000004519 manufacturing process Methods 0.000 claims 1
- 150000003839 salts Chemical class 0.000 abstract description 14
- 235000002639 sodium chloride Nutrition 0.000 description 15
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 10
- 229910000831 Steel Inorganic materials 0.000 description 7
- 239000010959 steel Substances 0.000 description 7
- 229910001026 inconel Inorganic materials 0.000 description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 4
- 235000021053 average weight gain Nutrition 0.000 description 4
- 230000006698 induction Effects 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 235000019786 weight gain Nutrition 0.000 description 4
- 230000004584 weight gain Effects 0.000 description 4
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 3
- 238000013019 agitation Methods 0.000 description 3
- 238000010791 quenching Methods 0.000 description 3
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 3
- 229910010271 silicon carbide Inorganic materials 0.000 description 3
- 229910000788 1018 steel Inorganic materials 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- 229910002091 carbon monoxide Inorganic materials 0.000 description 2
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 150000001247 metal acetylides Chemical class 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 229910052708 sodium Inorganic materials 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 1
- FLVIGYVXZHLUHP-UHFFFAOYSA-N N,N'-diethylthiourea Chemical compound CCNC(=S)NCC FLVIGYVXZHLUHP-UHFFFAOYSA-N 0.000 description 1
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 1
- 229910000534 SAE 1117 Inorganic materials 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 1
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052810 boron oxide Inorganic materials 0.000 description 1
- 239000012267 brine Substances 0.000 description 1
- 239000004202 carbamide Substances 0.000 description 1
- 150000005323 carbonate salts Chemical class 0.000 description 1
- 150000007942 carboxylates Chemical class 0.000 description 1
- 150000003841 chloride salts Chemical class 0.000 description 1
- 150000001805 chlorine compounds Chemical class 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 150000001913 cyanates Chemical class 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- QGBSISYHAICWAH-UHFFFAOYSA-N dicyandiamide Chemical compound NC(N)=NC#N QGBSISYHAICWAH-UHFFFAOYSA-N 0.000 description 1
- 230000003203 everyday effect Effects 0.000 description 1
- 239000007770 graphite material Substances 0.000 description 1
- 159000000011 group IA salts Chemical class 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 description 1
- 229910052808 lithium carbonate Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000005121 nitriding Methods 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 150000002897 organic nitrogen compounds Chemical class 0.000 description 1
- 150000003891 oxalate salts Chemical class 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- 239000010802 sludge Substances 0.000 description 1
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 230000004580 weight loss Effects 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
- the present invention relates to a non-cyanide molten salt bath composition and process for the carburization of objects made of ferrous metals or alloys utilizing said composition.
- Carburization of ferrous metal parts in molten salt baths has been known for many years.
- the conventional method involves using a substantial amount of a cyanide salt in a molten chloride bath.
- metal parts treated in the cyanide baths exhibit a high degree of surface hardness when quenched, the difficulty of safe handling and waste disposal have presented severe problems.
- non-cyanide carburizing processes are described in Holt US Patent 2,049,806; Muller, US Patent 3,194,696 and Jakubowski et al US Patent 4,268,323. These processes involve the addition of organic nitrogen compounds such as urea, cyanates and dicyanodiamide. Such baths introduce both carbon and nitroqen into the treated parts, and in many applications, nitriding is not desired.
- non-cyanide carburizing baths using metal carbides in molten salt are described in Albrect, US Patent 1,992,931; Solakian, US Patent 2,249,581; Steigerwald, US Patent 2,254,328 and British Patent 1,223,952.
- silicon carbide is preferred for good carburization.
- silicon carbide reacts with alkaline salts to form a silicate which is corrosive to steel and further gives rise to the objectionable formation of sludge or scum.
- Another object of the present invention is to provide a non-cyanide carburizing process capable of carburizing at a rate equal to or faster than the conventional cyanide process.
- a further object of the invention is to provide a carburizing process employing readily available materials which are economical, require no special handling and create no waste disposal problems.
- Yet another object of the present invention is to provide a carburizing process which can utilize equipment currently employed in cyanide processing.
- a molten salt bath for carburizing ferrous metal surfaces is provided.
- the molten salt bath maintained at a temperature of 900°C to 1050°C, comprises, based on the weight of the bath:
- a noncyanide carburizing molten salt bath operated at a temperature in the range of 900°C - 1050 0 C may be prepared, based on the total weight of the bath, to comprise:
- the alkali metal chloride may be sodium, potassium or lithium chloride used individually or in combination with one another.
- the alkali metal chloride is a mixture of sodium and potassium chlorides, and most preferably, a 50:50 by weight mixture of sodium and potassium chlorides.
- Compounds useful as an activator are selected from oxygen containing compounds of barium or strontium.
- the oxygen containing compound of barium or strontium suitable as activators should produce the corresponding oxides of barium or strontium on being calcined, such as: the oxides, the hydrated chlorides, or carboxylates of barium and strontium.
- the preferred compounds suitable as activators are the oxides or oxalates of barium or strontium, especially preferred is strontium oxalate.
- the graphite used in the process according to the invention should be of standard industrial quality and finely divided, i.e. with a particle size between 80 mesh and 300 mesh. Especially preferred is a graphite known as Carbon 1264 available from Asbury Graphite Mills, Inc., New Jersey.
- the amount of graphite according to the present invention should be sufficient to provide a continuous cover over the molten salts. Generally, approximately 1% is sufficient initially. However, for a newly prepared molten salt mixture, during the induction period, more graphite may need to be added to maintain a continuous cover on the surface of the molten salt mixture. It has been found that 3% to 8% by weight of additional graphite has been found to be satisfactory.
- the graphite is consumed and more graphite is needed to continuously cover the molten salt mixture with a layer of graphite such that no molten salt surface is exposed.
- approximately 1-3% by weight, based on the weight of the bath, of additional graphite is required.
- the bath can be continuously used for 9-10 working days as long as more graphite, 1% to 3% by weight, is added every day.
- the bath can then be reactivated by adding another allotment of the activator.
- the bath should be operated at a temperature in the range of 900°C - 1050°C. It has been found that for efficient and effective, i.e. optimum, carburization, the temperature of the bath is critical, and is dependent on the type of chloride and amount of activator in the bath. If potassium chloride is used together with 2% strontium oxalate, the temperature of the bath may be lower. At approximately 900°C, it takes approximately 6 hours of immersion to achieve a Rockwell hardness of Rc 60-67; at 925°C, it takes approximately 4 hours of immersion to achieve a Rockwell hardness of Rc 64-67; and at 950°C, it takes approximately 2 hours of immersion to achieve a Rockwell hardness of Rc 63-67.
- the molten salt is a mixture of sodium and potassium chloride, in particular a 50-50 mixture with about 1% strontium oxalate
- the temperature of the bath should be higher, the optimum temperature being 950°C. It has been observed at times that when the bath is operating optimally, the gases on the surface of tho bath tends to flare into flame, similar in appearance to that observed in conventional cyanide baths.
- the amount of graphite added to provide a continuous cover on the bath was 7% over a 6 hour period.
- One of the panels was etched with 10% hydrochloric acid with 0.2% diethylthiourea. The solution was analyzed by atomic absorption and the presence of strontium was indicated.
- a mixture of the following composition was prepared and heated to 950 0 C in an Inconel pot, and held at this temperature for about an hour. The amount of graphite added over a period of 6 hours was about 4%.
- Six SAE 1010 panels with the same dimension as Example 1 were cleaned and weighed and immersed in the bath. Two panels were removed after 1 hour and immediately water quenched. These two panels showed an average gain in weight of 94 mg and an average Rockwell hardness of Rc 45. Four panels were removed after two hours and water quenched. These four panels showed an average weight gain of 187.8 mg. and an average Rockwell hardness of Rc 65.
- the mixture was molten and heated to a temperature of 900°C in an Inconel pot and held at this temperature for one hour. A total of 4% graphite was added over a period of 6 hours.
- Four panels of SAE 1010 steel with the same dimensions were cleaned and weighed and immersed in the bath. One panel was removed after 1 hour, one panel was removed after 2 hours, one panel was removed after 4 hours and the last panel was removed after 6 hours. All of the panels were immediately quenched with cold water. The results obtained are as follows: the first panel after one hour immersion showed a weight gain of 24.5 mg. and a Rockwell hardness of Ra 47-75. The second panel with two hours immersion showed a weight gain of 53.7 mg. and a Rockwell hardness of Ra54-85.
- the rockwell hardness on the C scale could not be measured.
- the third panel with four hours immersion showed a weight gain of 107.6 mg and a Rockwell hardness of Rc 35-66.
- the fourth panel with six hours immersion showed a weight gain of 179.9 mg and a Rockwell hardness of Rc 60-67.
- a mixture of the following composition was prepared and heated to 950°C in a mild steel pot. The molten salt mixture was held at this temperature for 1 hour.
- the amount of graphite added over a period of 6 hours was 2%.
- a mixture of the following composition was prepared and heated to 950 0 C in an Inconel pot and held at this temperature for 1 hour. 2% more graphite was added over a 5 hour period.
- Two identical panels immersed in the bath for 2 hours showed an average weight gain of 180 mg. and an average Rockwell hardness of Rc 65.
- the bath was heated to 950°C and held at this temperature forl hour.
- Five soft steel panels were immersed in the bath for 2 hours followed by a cold water quench. These showed an average weight gain of 147.5 mg. and an average Rockwell hardness of Rc 56. Further, the readings were widely scattered in the range of Rc 39-67.
- the composition was heated to 925°C and held at this temperature for 1 hour.
- test bars For comparison purposes, two test bars, one made of 1117 steel and one made of 1018 steel, were treated in a conventional cyanide bath at 950°C. Two identical test bars were treated by the process using strontium oxalate according to the present invention, also at a temperature of 950°C. all of the test bars were immersed for 2 hours, removed, cooled, and the depth of carburization measured. The depth of carburization was measured by making successive 0.005" (0.0127 cm) cuts of the surface of the test bars. Each 0.005" layer was analyzed for percent by weight of carbon. The results obtained are as follows:
- Example 9 shows that the non-cyanide process according to the present invention is comparable or better than the conventional cyanide process.
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)
- Treatment Of Steel In Its Molten State (AREA)
- Carbon And Carbon Compounds (AREA)
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US56628883A | 1983-12-28 | 1983-12-28 | |
| US566288 | 1983-12-28 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0147011A2 true EP0147011A2 (fr) | 1985-07-03 |
| EP0147011A3 EP0147011A3 (fr) | 1986-03-26 |
Family
ID=24262267
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP84306336A Withdrawn EP0147011A3 (fr) | 1983-12-28 | 1984-09-17 | Bain de sel sans cyanure et procédé de carburation de métaux et alliages ferreux |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP0147011A3 (fr) |
| CA (1) | CA1244748A (fr) |
| ES (1) | ES8606522A1 (fr) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6093303A (en) * | 1998-08-12 | 2000-07-25 | Swagelok Company | Low temperature case hardening processes |
| US6165597A (en) * | 1998-08-12 | 2000-12-26 | Swagelok Company | Selective case hardening processes at low temperature |
| US6547888B1 (en) | 2000-01-28 | 2003-04-15 | Swagelok Company | Modified low temperature case hardening processes |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE627008C (de) * | 1931-12-13 | 1936-03-06 | Degussa | Aus indifferenten Salzen, fein verteilter Kohle und nicht zementierend wirkenden alkalischen Stoffen bestehendes Zementationsbad |
| US2492803A (en) * | 1946-03-23 | 1949-12-27 | Du Pont | Carburizing steel articles |
| CA944665A (en) * | 1971-10-06 | 1974-04-02 | Park Chemical Company | Cyanide free carburizing composition apparatus and process |
-
1984
- 1984-09-17 EP EP84306336A patent/EP0147011A3/fr not_active Withdrawn
- 1984-09-19 CA CA000463590A patent/CA1244748A/fr not_active Expired
- 1984-12-27 ES ES539095A patent/ES8606522A1/es not_active Expired
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6093303A (en) * | 1998-08-12 | 2000-07-25 | Swagelok Company | Low temperature case hardening processes |
| US6165597A (en) * | 1998-08-12 | 2000-12-26 | Swagelok Company | Selective case hardening processes at low temperature |
| US6461448B1 (en) | 1998-08-12 | 2002-10-08 | Swagelok Company | Low temperature case hardening processes |
| US6547888B1 (en) | 2000-01-28 | 2003-04-15 | Swagelok Company | Modified low temperature case hardening processes |
Also Published As
| Publication number | Publication date |
|---|---|
| CA1244748A (fr) | 1988-11-15 |
| ES539095A0 (es) | 1986-04-01 |
| EP0147011A3 (fr) | 1986-03-26 |
| ES8606522A1 (es) | 1986-04-01 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
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