Effects of technical factors on dimensional stability of porcelain stoneware body during sintering process: Isothermal kinetic study, Part II

• The dimensional stability range of porcelain stoneware bodies was studied.
• The effect of nepheline syenite on dimensional stability range was investigated.
• The effects of technical factors on microstructure were evaluated.
• The sintering rate evaluation was carried out by calculation average rate constant.
• The maximum thermal shrinkage was related to forming pressure.

The effect of technical factors on dimensional stability of porcelain stoneware bodies during the isothermal sintering was investigated by measuring linear shrinkage. Different milling times and forming pressures were considered in the preparation of specimens. The sintering process was isothermally carried out at different soaking times. It was observed that the presence of nepheline syenite in the composition negatively affects the dimensional stability range. In order to improve the dimensional stability of modified composition, the milling time should be increased up to 12 h. It was found that the pressure drastically influences the thermal shrinkage and dimensional stability range. The increment in pressure is able to reduce the defects of microstructure. In the next step, a modified kinetic model was applied to analyze the shrinkage variation. The heterogonous diffusion of liquid phase into the pores was confirmed from the computation of a dimensionless factor and calculation of average rate constant.

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