Silicon carbide has been the most widely used material for the use of structural ceramics. Characteristics such as relatively low thermal expansion, high force-to-weight radius, high thermal conductivity, hardness, resistance to abrasion and corrosion, and most importantly, the maintenance of elastic resistance at temperatures up to 1650 ° C, have led to a wide range of uses.
Silicon carbides for structural use can be classified as: Sintered, bonded by reaction, liquid phase, and sintered solid state. SiC4 bonded by reaction is a compound of a continuous matrix of SiC having silicon from 5 to 20%, and metal that fills the remaining volume. To form this material, a powder preform containing coal is added as a powder or as the decomposition product of a resin from the carbon source, is infiltrated with silicon around 1500 ° C with direct contact or using silicon vapor.
The silicon reacts with the carbon preform to form a structure that bridges the SiC. The remaining silica excess fills the residual pore space and gives a completely dense product that has structural integrity up to 1370 ° C. The silicon melts at 1410 ° C. The preform can be manufactured by any of the traditional ceramic processes. On the other hand, the low temperatures (1500 ºC) used during the linking by reaction, combined with the flexibility of size and purity of the powder, provide a good quality product with a reasonable cost.
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