Effects of SiC_W on porous Al₂TiO₅ SiC_W composites by reaction sintering

Porous Al₂TiO₅-SiC_w composites were prepared by reaction sintering with γ-AlOOH, TiO₂ and SiC_w as raw materials.The effects of SiC_w on phases, microstructures, porosity and compressive strength of Al₂TiO₅-SiC_w composites were investigated.The results show that the main phases of the reaction products are Al₂TiO₅, Al₆Si₂O₁₃, TiC and SiO₂.SiC_w reacts completely with TiO₂ to form TiC and SiO₂ because of the fast decomposition of slender SiC_w.With the addition of SiC_w, the microstructures of Al₂TiO₅ composites are significantly refined.The fine regular TiC grains and Al₆Si₂O₁₃ grains which distribute between the grain boundaries of Al₂TiO₅ can impede the growth of Al₂TiO₅ grains and improve the compressive strength of the porous Al₂TiO₅ composites.Moreover, because SiC_w changes the packing form of the raw materials and increases the pore size, its porosity increases notably.In addition, some SiO₂ existing among the crystalline grains makes the walls of pores denser and increases the compressive strength of Al₂TiO₅ composites, but the compressive strength will decrease when the content of SiC_w is excessive for the appearance of more glass phase.