Sintering and thermal shock resistance properties of LaPO4 based composite refractories

Abstract

Monazite type rare earth phosphates (REPs) are low thermal conducting (<5 W.m(-1).K-1) high temperature stable polycrystalline ceramics showing unique 'damage tolerant property' due to its layered structure and ductile nature. Lanthanum phosphate (LaPO4) is a candidate 'thermal ceramics' among many REPs due to its low reactivity with Al2O3 and ZrO2. Unfortunately phase pure LaPO4 has poor creep resistance, low mechanical strength at elevated temperatures and low micro hardness (<4 GPa). These undesirable engineering properties limit the potential use of LaPO4 as refractories. Therefore composite approach is suggested in recent days. In this work, we report the conventional sintering of Al2O3-LaPO4 thermal ceramics and the role of LaPO4 on the thermal shock resistance of Al2O3 ceramic nano composites.