Removal of veinlike defects in ceramic sanitaryware

In this thesis, veinlike defects; slip meeting marks, tracks of hallow - drain cast zones and deformations on ceramic sanitaryware surfaces were investigated in order to eliminate them. Furthermore, diffrent packing method and its effects on drying and sintering behaviour of the final product were researched. Experimental trials were performed under industrial conditions in Eczacıbaşı - Vitra Co. At first, present production stages and strategies were taken as a referance and then modifications of mould designs, casting rates, drying and firing positions were changed. It was found that, slip meeting marks were dependent on mould filling behaviour of slip and its? confusing characteristics in mould cavity. By changing moulding designs, with the changing places, radius and directions of slip feeding nozzles, slips in mould cavity had mixed effectively and slip meeting marks either removed or de-escalated. Difference of packing mechanism and dead load of products were most common factors on evolution of hallow - drain cast tracks. It was observed that, respectively pyroplastic deformation during firing, hydroplastic deformation on ambient drying conditions and drying shrinkage rate and positions of product at controlled drying had importance to constitution of hallow-drain cast tracks. By changing moulding designs, defects were removed. New ceramic sanitaryware formulations were prepaired by addition of wollastonite and K-feldspar-calcite based mix. According to results, it was observed that addition of wollastonite, presence of needle-like particules makes better cast packing and deformation tendency of both drying and firing become lower. Presence of K-feldspar and calcite raises activation of glassy phase fraction at low temperature and due to obtained high viscosity, resistance to deformation increases. Additionaly, the achievement of a lower deformation value in the experimental compositions in comparison to the reference composition and thinner casting suggest that the smooth product surfaces without deformations and hollow - drain cast zone tracks.