Decreasing pyroplastic deformation of sanitaryware porcelain bodies

In this study, the effect of composition on mullite formation and body viscosity was investigated in order to decrease the pyroplastic deformation of sanitaryware porcelain. The deformation behaviour of the bodies was analyzed by means of fleximeter. By using the fleximeter data, the viscosity values of bodies at firing temperature were calculated. It was observed that, depending on the increase of mullite amount, the body viscosity increases, so does the resistance of body against deformation. While the viscosity of VC-STD body containing 20 % mullite by weight was 108,00 P, the viscosity of the K6 body containing 28 % mullite was found to be 108,34 P. The deformation of K6 body (25 mm) which had higher viscosity, was 44 % lower than the deformation of VC-STD (45 mm). The amount of glassy phase had no effect, however, the composition of glassy phase had a significant impact on pyroplastic deformation. The addition of spodumene into the system, increased the body viscosity by increasing the dissolution of SiO2 in the glassy phase. In addition, another outcome of the spodumene addition was that, although it did not change the amount and dimensions of mullite crystals, it increased the deformation resistance by expanding the crystallization areas. By decreasing the grain size of non-plastic raw materials, the sintering temperature was decreased, and depending on this condition, the resistance against deformation was increased.Keywords:Sanitaryware porcelain body, pyroplastic deformation, porcelain body viscosity, crystal phases