Effects of Quartz Addition on Firing Process of Bone China Body

Abstract

This investigation represented the effects of addition of quartz on firing process of bone china prepared by use of bone phosphate.
Thermal expansion and shrinkage curves of green bodies consisting of bone phosphate, limestone, clays, feldspar, and quartz were discussed. Microstructure of the fired bodies were investigated by X-ray diffraction method and observation with a polarization microscope and scanning electron microscope. Bulk density, transverse strength, and modulus of elasticity of fired bodies were measured, and furthermore, they were discussed with effect of grain size distribution of raw materials on these firing process and properties of bodies.
During firing, quartz grains dissolved into the melt formed in the bodies. The dissolution promoted the vitrification and lowered the vitrification temperature of the bodies. Below 1250°C, about 10% quartz were completely dissolved into the melt. Addition of quartz did not affect the mechanical strength of the bodies, but extended the temperature range of their vitrification. The finer the materials of the bodies were used, the larger their transverse strength became.