The use of MgO-coated SiC powders as low temperature densification materials

The densification of silicon carbide powders at relatively low temperatures (i.e. 1900 °C and below) has been investigated as a means of lowering the cost of the production route for dense silicon carbide components. The work has concentrated on the use of MgO, as a coating on α-SiC powder deposited by chemical methods to allow densification by a liquid phase mechanism. Samples of SiC containing additions of MgO, both alone and as a coating on the surface of the SiC powder have been either hot pressed at temperatures between 1500 and 1750 °C or pressureless sintered at temperatures up to 1750 °C. Densification of the MgO-coated powder was observed to take place below 1650 °C and in certain cases a considerable amount of densification had taken place at temperature as low as ∼1450 °C.