The present invention relates to an unsintered composite powder composition comprising silicon carbide and aluminium nitride, a sintering process and a sintered silicon carbide material obtained or obtainable therefrom, as well as a SiC—AlN composite ceramic, uses thereof and articles comprising the same. In one aspect, the present invention provides an unsintered composite powder composition comprising from 90.0% to 99.9% by weight silicon carbide and from 0.1% to 10% by weight of aluminium nitride. In another aspect, the present invention provides a SiC—AlN composite ceramic material having the formula x(SiC)—1-x (AlN), wherein 0.999≥x≥0.900; and wherein the composite ceramic material has a fracture toughness of greater than 4.5 MPa·m1/2; and a thermal conductivity of greater than 120 W/m K.