Fabrication and characteristics of porous ceramics from ZrTiO₄based ceramic material

Abstract

Cordierite has a very low thermal expansion coefficient, but has problem that it has a weak mechanical strength and is apt to be attacked by acid such as sulfur for using as a diesel particulate filter support. The physical properties of ZrTiO₄modified with SiO₂, Al₂O₃, MoOx, Cr₂O₃ and Nb₂O5 were investigated with XRD, SEM, UTM and thermal expansion, etc. in this paper. ZrTiO₄powder was synthesized as a monoclinic structure with processes that starting materials of TiO₂ and ZrO₂were mixed with ball mill and calcined above 1240℃ for 3 hr. Additive modified ZrTiO₄specimens for flexural strength and thermal expansion measurement were obtained by mixing ZrTiO₄ powder with additives, pressing and firing at 1300℃ for 3 hr. The porosity of additive modified ZrTiO₄decreased monotonically with increasing additive content by 5 wt% regardless of additive types and saturated for further increase of additive by 10wt. The flexural strength of Al2O3 (5, 10 wt%) modified ZrTiO₄shows a large increase, but that of other additives modified ZrTiO₄decreased. The thermal expansion coefficient of additive modified ZrTiO4 except Nb₂O5 decreased continuously with the content of additive. In particular, the lowest thermal expansion coefficient of ZrTiO₄was obtained for the additive of SiO₂.