Ultra-low Temperature Glaze Preparation And Firing Mechanism Research

Nowdays, low-temperature quick firing technology is an effective way to save energy, reduce fuel consumption and improve the production efficiency in the ceramic industries.The defectives in the ceramic production line have greatly reduced the profits of many manufactures. Some industries choose to remove the spots and covered with glaze on the ceramic surface, and then calcined to be a perfect one. This method will greatly improve the yield of ceramic products. Since avoide to destroy the original glazes and embryos, the glazes must be calcined at an ultra-low temperature. This method can greatly reduce the energy consumption and the production cost.In this paper, a glaze with a melting temperature below 800℃was obtained on the basis of lots of experimental designs. By DSC-TG, XRD, SEM and Raman analysis, the structure, microstructure and forming process of glazes were discussed, and the physical properties of the glazes were also tested. Finally the calcined mechanism and the calcined system of these glazes were discussed.The conclusions showed that, when the mass proportion of B2O3: SiO2 is 1.367:1, and the content of ZnO is 11.74%, the new glazes are melted at about 780℃with great glossy, the best transparency and high thermal stabilities, and the embryo glaze layer was generated. Compeared with the glazes melted at 1180℃, the initial melting temperature of new glazes is reduced by 500℃, the temperature width of melting process is increased by 20℃, and the weight loss coursed by the emission of CO2 is reduced by 80℃.510℃-600℃, Na2B4O7 and NaBO2 firstly begin to melt, and at the same temperature ZnO, feldspar, talc, calcite, BaCO3 and other minerals also begin to melt, and at about 710℃these minerals melt down; Melting of quartz and a small amount of silicate begin at 600℃-715℃, and at 780℃all of the glaze have been gone into the melt. In the calcined process,600℃-780℃, when the heating rate is 6℃/min, glazes with great glossy can be made; 800℃-500℃, when the cooling rate is 20-25℃/min, glazes with little recrystallization and good transparency can be obtained; below the initial melting temperature, when the cooling rate is 2-5℃/min, the glazes are heated equably and with little crack.