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PROCESS FOR PRODUCING

DENSE ARTICLES FROM SILICON CARBIDE

Broad Area of Technology:	Powder Metallurgy
Narrow Field:	Reaction Sintering of Silicon Carbide
Purpose:	The process permits producing full-dense silicon carbide articles of a complex shape

Brief Description and Specific Features

The initial charge is composed of silicon and other ingredients. It is mixed with a molten binder (paraffin wax) to obtain a uniform slurry. A workpiece of a required shape is formed by slip casting (desirably under pressure). After that, the workpiece is placed into a powder media for pack carburizing, kept at elevated temperature to drive off the binder and then heated to 1100 °C to perform complete carburization (the compositions of the charge and the carburizing medium and the carburization regime constitute the "know-how"). To produce an article with increased strength, the starting mixture is compacted using high pressure and then heated in a carburizing atmosphere.

As a result of reaction sintering in these conditions, the silicon contained in the charge interacts with carbon atoms of the carburizing medium to give silicon carbide on the form of fine and coarse particles that fill all the pores of the workpiece. Subsequent annealing at 1300 °C permits obtaining a more uniform structure of the final silicon carbide article.

Advantages Over Known Methods

• the process is more economical due to the use of less expensive thermal equipment: the process temperature is lowered from the conventionally used value of 1600 - 2200 °C down to 1100 - 1300 °C
• it permit to produce articles of a complex shape and to decrease their brittleness
• the process is easy to implement, does not require high-skilled personnel and can easily be automatized

Results of Testing

The process was tested in laboratory conditions only. The samples of silicon carbide and titanium-silicon carbide composites produced by this process have been tested for heat resistance at 1300 °C. The heat resistance of silicon carbide is comparable with that of commercially available samples while the heat resistance of the Ti-SiC composite is higher by the factor of 2 to 10.

Possible Ways of Cooperation

(1) The process is available "as is".

(2) Additional investments are required for carrying out joint researches with a foreign partner in order to develop novel composite materials on the basis of Ti-Si-C and Mo-Si-C systems. Such composites will possess high heat resistance combined with high tensile and impact strength characteristics.

For more information please contact the author:

Dr Alexander Shmatov
Belarussia State Polytechnic Academy
65 F.Skorina Ave., built. 7
Minsk 220027
Belarus
Phone: (375) 17 2581066 (home), 2399260 (office)
Fax: (275) 17 2329137
E-mail: shmatov@infra.belpak.minsk.by

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