Self-propagation High-temperature Synthesis of Porous TiB2-TiC Multiphase Ceramics

Abstract:

Porous TiB₂-TiC multiphase ceramics were prepared by Self-propagation High-temperature Synthesis (SHS) and the reactant mole ratios of Ti:B₄C were 3:1, 3.5:1 and 4:1. The combustion characteristics, phase composition, microstructure,porosity and oxidation resistance of the products were investigated. The results show that the highest combustion temperature is 2458 K and the combustion products are mainly composed of TiB₂ and TiC. The open porosity of the porous products are within the range of 30.67%~31.19% and TiB₂-TiC multiphase ceramics possess good high temperature oxidation resistance at 923 K in air. The main pore formation mechanism includes the residual pores among the particles of the green powder compacts, and the in-situ pores owing to the molten titanium particles flowing during the combustion synthesis reaction. The large pores are formed by the interstitial hole combining with the in-situ pores, and the small pores are formed during the solution-precipitation process.