The generation of residual stress in ABS type glaze of commercial bone china

We investigated why residual stress is generated in the glaze of a commercial bone china product. Because of the difference between the coefficient of thermal expansion (CTE) of the glaze and the body, the residual stress in the glaze was expected to be 15MPa or lower. However, the measured value exceeded 50MPa. During glost firing, an interface layer appeared between the glaze and body, and it was thought to be hydroxyapatite (HAp) or β-tricalcium phosphate (TCP). A simulation confirmed that the CTE of the interface layer should be higher than 14×10−6/°C and its thickness should be 30μm or more to match the measured strain value of 50MPa. Thus, it was thought that the difference in the CTE between the glaze and the interface had a stronger influence than that between the glaze and the body with respect to developing residual compressive stress in the glaze of bone china.