US3728107A - Additives for production of cast irons - Google Patents
Additives for production of cast irons Download PDFInfo
- Publication number
- US3728107A US3728107A US00214961A US3728107DA US3728107A US 3728107 A US3728107 A US 3728107A US 00214961 A US00214961 A US 00214961A US 3728107D A US3728107D A US 3728107DA US 3728107 A US3728107 A US 3728107A
- Authority
- US
- United States
- Prior art keywords
- silicon carbide
- hardness
- chromite
- pelleted
- cast
- 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
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/006—Making ferrous alloys compositions used for making ferrous alloys
Definitions
- the homogenization of the microstructure improves the final product because of the uniform physical-chemical behavior of the workpiece in all the points thereof. There is also greater resistance to thermal shock in the finished piece.
- the hardness may be controlled in order to obtain specific properties for various types of finished products. The hardness is controlled in order to:
- the hardness and the homogenization have for some time been controlled by additives which are introduced together with the charge into cupolas or furnaces which process cast irons. Another technique normally used is to control the charges conveyed into furnaces by the addition of scrap iron. Pan (fore-crucible) additives are also used.
- the invention relates to cast iron which is understood to include any carbon iron alloy containing more than 1.7% total carbon and, more particularly, up to about 4% carbon.
- Such alloys may contain from 0.05 to 0.20% sulphur, from 0.5 to 3.0% silicon, from 0.50 to 1.0% manganese, and from 0.1 to 1.0% phosphorus and optionally other elements.
- the present invention disclosed herein permits homogenizing of the microstructure of cast ice iron to increase the hardness of a piece to the desired point by the addition of silicon carbide pelleted with chromite (Fe O -Cr O and, with the addition of catalytically activated silicon carbide to produce cast iron with a homogenized microstructure with a lower hardness of the finished piece.
- Additions of 050% silicon carbide pelleted with chromite has increased the hardness in such a way that the final product exceeded the desired specification (brake pans). Additions of only 0.10% silicon carbide pelleted with chromite noticeably improved the behavior of pieces of medium hardnesses.
- the addition of 0.50% of catalytically activated silicon carbide lowers the hardness of the pieces.
- the addition eliminates cementite hard points and facilitates the machining to thereby obtain a considerable improvement of the finished pieces.
- the pieces had a lesser index of foundry defects, greater resistance to thermal shock, increase of mechanical strength to stress and compression, particularly in engine blocks.
- silicon carbide pelleted with chromite and catalytical silicon carbide enables the production of pieces of high, medium and low hardness, with easy machinability and improved physical-chemical behavior from the same batch of cast iron. In all instances, the foundry (casting) defects were practically eliminated.
- SILICON CARBIDE PELLETED WITH CHROMITE A highly activated silicon carbide having a surface area of about 15 to 33 square meters per gram is used.
- the material preferably has a size grading which may vary from 80 mesh screen to impalpable powders or from 40 mesh Tyler screen to impalpable powders.
- This material is combined with fine chromite of a size less than 40 mesh Tyler screen, ideally 150 mesh Tyler screen, in colloidal conditions in an aqueous highly thixotropic suspension which includes a surface-active ingredient.
- the addition of the surfactant to silicon carbide facilities the penetration of the chromite into the pores of the crystals of this material. After curing the mass for 18 hours, it is pelletized by slowly extruding the cured material onto rotatory dishes.
- a combination between chromite and silicon carbide is thus obtained with a maximum contact between the two materials.
- a controlled pressure of more or less 15 kg./cm. of the extruded product and the adequate composition of the mixture aiford an appropriate mechanical strength to the pellets.
- the thixo'tropic agent is a consistent gel which fiuidifies by intense agitation or stirring.
- a surface-active agent is meant to include an organic surface-active compound capable of reducing the surface tension of mineral particles or to prevent repulsions by electrostatic forces.
- organic surface-active compound capable of reducing the surface tension of mineral particles or to prevent repulsions by electrostatic forces.
- anionic or nonionic character which do not introduce incompatible mineral elements such as organic sulphonates, particularly fatty alcohols, fatty acid condensation products, polyglycerine and polyglycol and fatty acid esters, alkylene oxide condensation products, especially ethylene oxide and the like are suitable.
- Silicon carbide to chromite proportions may vary from 20% to 50% silicon carbide to 80% to 50% chromite.
- the thixotropic ingredients are used in amounts ranging from 1 to 3%, while the surface-active ingredients for treating silicon carbide are used in an amount of approximately 0.50%.
- Temporary binders such as sodium lignin sulphonate; sodium silicate and dextrine may be employed in the range of 0.50 to 1.50% by weight, but the presence thereof is not critical.
- chromite does not sufier segregation, it is fully reduced and the binding or pick up of chromium can be foreseen with precision and the desired hardness of the finished piece can also be obtained with precision.
- the size of the pellets can vary from approximately 4 0.50 cm. to approximately 3.5 cm. in diameter and can have up to approximately 2 diameters length. Stick form of 0.20 cm. by 0.50 cm. up to 2 cm. by 7 cm. have been found satisfactory.
- a silicon carbide of high surface area up to 40 square meters per gram, less than mesh Tyler screen, in intimate mixture with lead chromate and potassium bichromate solution. After the solutions have been completely absorbed by the mass which optionally contains the above-mentioned binders and other ingredients with silicon carbide, the drying of the mixture is carried out in an abrasion resistant pulverization chamber. A reddish black powder is thus obtained, which is called component (A).
- component (A) 20% or more of component (A) is mixed with silicon carbide of mixed crystallization (alpha and beta), which may also embody a single crystalline system, to complete a total of
- the preformed mixture comprises 30% of a component (A) with 70% silicon carbide of mixed crystallization with a preferential size grading between 12 mesh and 80 mesh Tyler screens. Size gradings of from 6 mesh Tyler up to mesh Tyler screens may also be employed as maximum values. Percentages above 60% of component (A) with 40% of silicon carbide are violently reactive and may prove to be explosive.
- component (A) Upon adding the thus obtained product to cast irons there initially occurs a rapid decomposition of component (A) which liberates a great number of calories, increases the temperature in loco and causes the decomposition of the silicon carbide crystals.
- the silicon and carbon elements which are then free, deoxid-ized and liquefy the cast iron and disperse all of the microstructural elements, among which are graphite (elemental carbon) and cementite (Fe C).
- silicon carbide By mixing with component (A), silicon carbide suffers a positive catalysis and becomes highly reactive.
- An additive for use in the production of cast iron consisting essentially of a pelletized mixture of finely divided silicon carbide and chromite in the ratio of from 0.1 to 1.0 part silicon carbide to 1.0 part chromite.
- pelletized mixture includes a binder in an amount of 0.50 to 1.50% by weight, a thixotropic gel in an amount of 1 to 3% by weight, and a surface-active agent in an amount of about 0.5% by weight.
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Manufacture Of Alloys Or Alloy Compounds (AREA)
Abstract
Description
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US11569471A | 1971-02-16 | 1971-02-16 | |
US21496172A | 1972-01-03 | 1972-01-03 |
Publications (1)
Publication Number | Publication Date |
---|---|
US3728107A true US3728107A (en) | 1973-04-17 |
Family
ID=26813471
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US00214961A Expired - Lifetime US3728107A (en) | 1971-02-16 | 1972-01-03 | Additives for production of cast irons |
Country Status (1)
Country | Link |
---|---|
US (1) | US3728107A (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3899320A (en) * | 1973-02-23 | 1975-08-12 | Kempten Elektroschmelz Gmbh | Process for making iron sponge pellets containing silicon carbide |
US4072511A (en) * | 1976-11-26 | 1978-02-07 | Harold Huston | Method of producing silicon containing cast iron |
-
1972
- 1972-01-03 US US00214961A patent/US3728107A/en not_active Expired - Lifetime
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3899320A (en) * | 1973-02-23 | 1975-08-12 | Kempten Elektroschmelz Gmbh | Process for making iron sponge pellets containing silicon carbide |
US4072511A (en) * | 1976-11-26 | 1978-02-07 | Harold Huston | Method of producing silicon containing cast iron |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: KENNECOTT CORPORATION Free format text: MERGER;ASSIGNORS:BEAR CREEK MINING COMPANY;BEAR TOOTH MINING COMPANY;CARBORUNDUM COMPANY THE;AND OTHERS;REEL/FRAME:003961/0672 Effective date: 19801230 |
|
AS | Assignment |
Owner name: KENNECOTT MINING CORPORATION Free format text: CHANGE OF NAME;ASSIGNOR:KENNECOTT CORPORATION;REEL/FRAME:004815/0036 Effective date: 19870220 Owner name: STANDARD OIL COMPANY, 200 PUBLIC SQUARE, CLEVELAND Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:KENNECOTT MINING CORPORATION;REEL/FRAME:004815/0079 Effective date: 19870320 |