EP0173913B1 - Verfahren zur Behandlung von Gusseisenschmelzen mit Siliciumcarbid - Google Patents

Verfahren zur Behandlung von Gusseisenschmelzen mit Siliciumcarbid Download PDF

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Publication number
EP0173913B1
EP0173913B1 EP85110449A EP85110449A EP0173913B1 EP 0173913 B1 EP0173913 B1 EP 0173913B1 EP 85110449 A EP85110449 A EP 85110449A EP 85110449 A EP85110449 A EP 85110449A EP 0173913 B1 EP0173913 B1 EP 0173913B1
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EP
European Patent Office
Prior art keywords
silicon carbide
cast iron
sic
grains
temperatures
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
Application number
EP85110449A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0173913A1 (de
Inventor
Theodor Dr. Dipl.-Ing. Benecke
Benno Prof. Dr. Dipl.-Ing. Lux
Wolf-Dieter Dr. Dipl.-Ing. Schubert
An Tuan Dipl.-Ing. Ta
Gerhard Dipl.-Ing. Kahr
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Elektroschmelzwerk Kempten GmbH
Original Assignee
Elektroschmelzwerk Kempten GmbH
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Elektroschmelzwerk Kempten GmbH filed Critical Elektroschmelzwerk Kempten GmbH
Priority to AT85110449T priority Critical patent/ATE41176T1/de
Publication of EP0173913A1 publication Critical patent/EP0173913A1/de
Application granted granted Critical
Publication of EP0173913B1 publication Critical patent/EP0173913B1/de
Expired legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C1/00—Refining of pig-iron; Cast iron
    • C21C1/08—Manufacture of cast-iron
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys

Definitions

  • silicon carbide for the treatment of cast iron melts, such as for siliciding, carburizing, deoxidizing and inoculating, has long been state of the art (cf. US-A-2 020 171, DE-C-2 215 266 and DE-A-2 746 478).
  • metallurgical silicon carbide is usually used, the SiC content of which varies in the range of approximately 85-95% by weight and which, from the production point of view, still contains approximately 2-5% by weight of free carbon and approximately 2-3% by weight.
  • Has silicon dioxide which is available in the form of grain sizes in the range up to 20 mm with a maximum grain size distribution of ⁇ 10 mm.
  • Such a product which originates from large-scale SiC production in the resistance furnace, has a strongly fluctuating composition in terms of manufacture and the individual SiC grains are surrounded by an SiO 2 skin in the surrounding area, which makes contact with the liquid Prevents iron and is also of particular importance for its resistance to oxygen-containing gases at high temperatures (cf. Th. Benecke in "Foundry", Vol. 68 (1981), pages 344-349).
  • Th. Benecke refers to the work of G. Wiebke in reports Deutsche Keramische Deutschen, vol. 37 (1960), pages 219-226, in which the oxidation of purified silicon carbide in oxygen as a function of time, temperature and Grain size was measured. It was found that the oxide skin only grows very slowly and that even in pure oxygen at 1500 ° C. and with a grain size of only 63 ⁇ m, only 6% SiC had been oxidized after 9 hours. It follows from this that SiC of technical purity (metallurgical SiC), the grains of which are already surrounded by a very thin SiO 2 skin from manufacture, is certainly not further oxidized when stored in air at room temperature.
  • the individual SiC grains are not completely surrounded by a layer containing uniformly thick silicon dioxide, but that this layer is interrupted at individual points on the grain surface, ie either completely missing at these points or only very thin is.
  • This can be achieved, for example, by exposing a granular silicon carbide to an oxidizing atmosphere, such as air, oxygen or water vapor, in a static bed at temperatures in the range from 900 ° C. to 1000 ° C.
  • the individual grains are oxidized on the free surfaces to form the Si0 2 layer and agglomerated at the same time.
  • the agglomerates are then subjected to gentle comminution in order to expose the silicon carbide surfaces which were completely or partially removed from the oxidative attack due to the formation of the agglomerates. Then the silicon carbide pretreated in this way, the individual grains of which are partially surrounded by a shell containing silicon dioxide, is introduced into the cast iron melt.
  • a silicon carbide with grain sizes of 0.5 mm and finer, in particular in the range from 0.1 mm to 0.5 mm, and an SiC content of at least 95% by weight in a stationary bed is used of flowing air at temperatures of 1250 ° C - 1300 ° C subjected to the oxidizing treatment.
  • Layer thicknesses of the silicon dioxide-containing shell up to about 15 microns, in particular in the range 0.5 microns to 5 microns, are generated.
  • the degree of oxidation can be determined from the decrease in the original SiC content.
  • the subsequent comminution under gentle conditions can be carried out in a mortar, for example.
  • the process according to the invention is not limited to this preferred embodiment, but it is within the scope of the invention that both the parameters for the oxidizing treatment and for the silicon carbide which is subjected to this treatment can be varied within a wide range.
  • the silicon carbide pretreated according to the invention can be introduced into the cast iron melt in a customary known manner, such as by addition in the melting unit, in and before the holding unit or in the forehearth or by addition to the type before melting. Furthermore, it can be used both in the form of a loose granulation and in the form of pellets or briquettes which have been compacted in the customary known manner.
  • Crystalline silicon carbide with an SiC content of 98.5% by weight, an SiO 2 content of 0.26% by weight and a grain size of 0.1-0.5 mm was used as the starting material, which was freshly ground and had been screened.
  • This SiC was stored as a loose bed in an electrically heated tube furnace and oxidized for 72 hours at 1,250 ° C - 1,300 ° C under a slight negative pressure (0.4 - 0.6 bar) in a flowing air atmosphere. After cooling, the agglomerated product was removed from the oven and crushed in a mortar by gentle breaking.
  • the SiC content was 93.9% by weight and the Si0 2 content was 4.6% by weight.
  • the degree of oxidation ie the percentage of oxidized SiC, calculated from the decrease in the SiC content and corresponding to the increase in the Si0 2 content, was thus 3%.
  • the layer thickness of the Si0 2 coating was a maximum of 5 microns.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Carbon And Carbon Compounds (AREA)
  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
EP85110449A 1984-08-24 1985-08-20 Verfahren zur Behandlung von Gusseisenschmelzen mit Siliciumcarbid Expired EP0173913B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT85110449T ATE41176T1 (de) 1984-08-24 1985-08-20 Verfahren zur behandlung von gusseisenschmelzen mit siliciumcarbid.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19843431263 DE3431263A1 (de) 1984-08-24 1984-08-24 Verfahren zur behandlung von gusseisenschmelzen mit siliciumcarbid
DE3431263 1984-08-24

Publications (2)

Publication Number Publication Date
EP0173913A1 EP0173913A1 (de) 1986-03-12
EP0173913B1 true EP0173913B1 (de) 1989-03-08

Family

ID=6243848

Family Applications (1)

Application Number Title Priority Date Filing Date
EP85110449A Expired EP0173913B1 (de) 1984-08-24 1985-08-20 Verfahren zur Behandlung von Gusseisenschmelzen mit Siliciumcarbid

Country Status (5)

Country Link
US (1) US4642135A (enrdf_load_stackoverflow)
EP (1) EP0173913B1 (enrdf_load_stackoverflow)
JP (1) JPS6164809A (enrdf_load_stackoverflow)
AT (1) ATE41176T1 (enrdf_load_stackoverflow)
DE (2) DE3431263A1 (enrdf_load_stackoverflow)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4865806A (en) * 1986-05-01 1989-09-12 Dural Aluminum Composites Corp. Process for preparation of composite materials containing nonmetallic particles in a metallic matrix
EP0409853B1 (en) * 1988-03-11 1994-12-07 Deere & Company Production of manganese carbide and ferrous alloys
US20040103755A1 (en) * 2002-08-12 2004-06-03 Beyerstedt Ronald Jay Method of producing cast iron
FR3003577B1 (fr) * 2013-03-19 2016-05-06 Ferropem Inoculant a particules de surface

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2527829A (en) * 1948-11-12 1950-10-31 Electro Refractories & Alloys Foundry additives
US2569146A (en) * 1949-11-30 1951-09-25 American Metaliurgical Product Metallurgical addition agent
US2771356A (en) * 1953-09-25 1956-11-20 United States Steel Corp Method of deoxidizing semi-killed steel
FR1242864A (fr) * 1959-04-17 1960-10-07 Ct Technique Des Ind Fonderie Procédé d'incorporation de différents éléments et en particulier de carbone, à un bain métallique
US3051564A (en) * 1959-08-12 1962-08-28 Carborundum Co Composition for metallurgical use and process of using the same
US3158465A (en) * 1961-09-07 1964-11-24 Kerchner Marshall & Company Metallurgical material and process for treating iron therewith
US3764298A (en) * 1969-09-02 1973-10-09 Meehanite Metal Corp Method of melting cast iron
DE2215266C3 (de) * 1972-03-29 1978-04-20 Elektroschmelzwerk Kempten Gmbh, 8000 Muenchen Verfahren zur Beschleunigung der Auflösegeschwindigkeit von Siliciumcarbid in Eisenschmelzen

Also Published As

Publication number Publication date
DE3431263A1 (de) 1986-03-06
EP0173913A1 (de) 1986-03-12
JPS6310203B2 (enrdf_load_stackoverflow) 1988-03-04
ATE41176T1 (de) 1989-03-15
JPS6164809A (ja) 1986-04-03
DE3568592D1 (en) 1989-04-13
US4642135A (en) 1987-02-10

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