Effect of substitution of sand stone dust for quartz and clay in triaxial porcelain composition

Abstract

Quartz and kaolin were partially substituted by sand stone dust (a siliceous byproduct of Indian stone cutting and polishing industries) in a traditional triaxial porcelain composition consisting of kaolin, quartz and feldsper. The effect of substitution upon heating at different temperatures (1050–1150\(\boldsymbol{^\circ}\)C) were studied by measuring the linear shrinkage, bulk density, porosity and flexural strength. Qualititative phase and microstructural analysis on selected samples were carried out using XRD and SEM/EDX technique. The results show that the samples of all the batches achieved higher density (2\(\boldsymbol\cdot\)50 g/cc) and almost full vitrification (\(\boldsymbol <\)0\(\boldsymbol{\cdot}\)1% apparent porosity) at around 1115\(\boldsymbol{^\circ}\)C compared to around 1300\(\boldsymbol{^\circ}\)C for traditional triaxial porcelain composition. As high as 70 MPa flexural strength was obtained in most of the vitrified samples. No significant variation in physico-mechanical properties was observed in between the composition. XRD studies on selected samples show presence of mainly quartz phase both at low and high temperatures. SEM photomicrographs of the 1115\(\boldsymbol{^\circ}\)C heated specimen show presence of quartz grain and glassy matrix. Few quartz grains (20–40\(\boldsymbol{\mu}\)m) are associated with circumferential cracks around them.