THE EFFECT OF DIFFERENT CRYSTAL PHASES ON THE MECHANICAL PROPERTIES OF GLAZES
ERGANI E. 1,2, DA? GENÇO?LU P. 2, TURAN S. 1,2
1 Eskisehir Technical University, Eskisehir, Turkey; 2 Ceramic Research Center, Eskisehir, Turkey
Glass–ceramics are ceramic materials produced through controlled crystallisation (nucleation and crystal growth) of a parent glass. The great variety of compositions and the possibility of developing special microstructures with specific technological properties have allowed glass-ceramic materials to be used in a wide range of applications. An important application of glass-ceramics has been the preparation of glass-ceramic glazes with high hardness and wear resistance to improve the performance of traditional glazes. Great efforts have been shown towards improvement of mainly aesthetic functions of floor tiles so far. Technical features of these glazed floor tiles are determined by the glaze characteristics. However, there is an increasing demand of new ceramic tiles with improved properties of glazes such as high resistance to wear by abrasion, high surface hardness, low level of closed porosity and good chemical resistance. Therefore, wide-spread research is going on in the world to find out a ceramic tile with a glaze layer of improved properties. Until now, glass-ceramics had never been sufficiently used in the ceramic tile industry and were used only as components to obtain opacified or matt glazes. Now, glass-ceramics are of growing interest for preparing tile coatings compared to traditional amorphous glazes. A high softening point, good coating capability for clay support and high chemical and abrasion resistance of glass-ceramics have made them attractive alternative glaze material for tiles. The main objective of this study was to obtain new glass-ceramic glazes with improved mechanical properties. The research is concentrated on to check the suitability of different types of glass-ceramic material as glaze layer on ceramic floor tile. Crystalline glazes are produced with in-situ formed and ex-situ added crystal phase contents such as anorthite, diopside, mullit, cordierite, gehlanite, zircon, quartz. The hardness and the wear resistance of crystalline glazes with different crystal phase content were compared both among themselves and with amorphous glazes.