Investigation of methods to prevent pin-holing defect in tableware ceramic industry

Pin-holing is one of the major glazing defects that the tableware ceramic industry is experiencing. It is evident from this research work that the pin-holing defect can be prevented or at least reduced by optimizing composition and sintering profile, which in turn yields pin-hole-free tableware ceramics. Differential scanning calorimeter/thermo gravimetric analysis and dilatometer are found to be effective to understand the thermal behavior of specific ceramic tableware bodies and glaze. Dilatometry was employed to investigate the densification behavior and it was found that densification of the ceramic body reached completion by 1300°C. The final optimum firing temperature and soaking time, which are believed to influence the microstructure and mechanical properties of the ceramicware, were found to be 1300°C and 90 min, respectively. The microstructural change of the ceramic body and glaze sintered at different temperatures and times is observed under field emission scanning electron microscopy. It was found that the existence of pin-holing defect largely depends on the feldspar and quartz content in glaze raw material as well as the applied firing profile, and the result was found satisfactory when the ratio (quartz/feldspar) was ∼2.