Effects of ammonium molybdate additive and sintering temperature on the properties of foam ceramics based on ceramic tile polishing waste

Abstract

In this study, the foam ceramics based on ceramic tile polishing waste (CTPW) were successfully prepared by a simple solid phase sintering method. The CTPW was used as the main raw material, SiC inside CTPW as the foam agent and (NH₄)₆Mo₇O₂₄ as the sintering additive. Effects of the amounts addition of (NH₄)₆Mo₇O₂₄ (0–6 wt %) and sintering temperature (1080–1200°C) on the sintering properties, structural evolution, phase composition and mechanical properties have been investigated. During the sintering process, the SiC inside CTPW could react with oxygen and then produce the gases such as CO and CO₂, which caused a closed-pore structure. After adding (NH₄)₆Mo₇O₂₄ and increasing the sintering temperature, a better porous structure with suitable pore size and high compressive strength could be obtained. It was found that the foam ceramics doped with 2 wt % (NH₄)₆Mo₇O₂₄ and sintered at 1200°C for 30 min showed excellent properties: a low bulk density (0.362 g/cm³), the appropriate pore size (0.94 mm), a uniform pore size distribution and a very high compressive strength (8.16 MPa).