SILICON CARBIDE (SIC) CERAMICS belong to an important class of structural materials for high temperature applications. The specific attributes that account for their utility as engineering ceramics are the high value of thermal conductivity and a lower thermal expansion coefficient and hence, better thermal shock resistance. Being a covalent solid, the heat treatment operations need to be carried out at exceedingly high temperatures for achieving full densification. Various approaches are thus followed, such as reaction bonding, pressureless sintering, hot pressing, etc., Incorporation of certain additives is known to promote the densification process as well as generates a favourable bimodal microstructure. The latter provides an effective in situ toughening mechanism in to the matrix phase. Several workers have studied the influence of aluminium, boron and carbon, in densification and phase transformation reaction of SiC ceramics.
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