Combustion synthesis of TiB2-TiC-WB powders by coupling weak with strong exothermic reactions

Abstract

Abstract TiB 2 -TiC-WB composite ceramic powders have been prepared by fast combustion synthesis from Ti, W and B 4 C, by coupling the weak exothermic reaction of W + B = WB with strong ones of Ti + 2B = TiB 2 and Ti + C = TiC. With increasing W/(Ti + W) ratio, the reaction temperature and heating rate decrease while the content of WB increases, and unreacted W appears for W/(Ti + W) = 0.24. The addition of excessive B 4 C leads to lower reaction temperature, smaller grain size, and formation of WB 2 . The products show a homogeneous microstructure without element segregation on the scale of agglomerates, and in most products the average grain size is smaller than 1 µm.