Calculation of pyroplastic deformation number of feldspar–kaolin–quartz system porcelain clays

Abstract

In the design of feldspar–kaolin–quartz system of porcelain clays, norm calculations based on the chemical composition of the raw materials are used to predict the degree of pyroplastic deformation by plotting the ratio of the three components onto an existing contour diagram. However, there is no method to quantify the degree of pyroplastic deformation of a porcelain body clay directly from norm calculations. This study presents a direct method for calculating pyroplastic deformation numbers (PDN) from norm calculation. Two methods of calculating PDN were considered: color map diagram reference and finite element analysis. A study of the relationship between the amount of firing deformation and PDN of the porcelain clay actually used in Mino ware showed a negative correlation. Correlation coefficients (CC) based on color map diagram references ranged from −0.62 to −0.66, and those based on finite element analysis ranged from −0.68 to −0.72. Feldspar as an ore is a solid solution of potash feldspar, soda feldspar, and lime feldspar, and its eutectic point varies with the proportion of minerals it is composed of. When corrected for the co-melting point of feldspar, the CC ranged from −0.69 to −0.74. Porcelain clay products were wet overground from 21 to 275 h to determine the relationship between particle size and fired deformation, with a CC of 0.81. Adding a correction for the particle size of the porcelain clay, the CC ranged from −0.70 to −0.78.