Calcined zinc oxide has a large specific gravity and good fluidity. The glaze produced with it has small shrinkage, and the glaze surface is not prone to pinholes and cracks. Except for the specific gravity, the product quality standards of calcined zinc oxide are the same as those of grade zinc oxide.
Zinc oxide calcined at high temperature appears light yellow, and its melting point is 1975°C.
Calcined zinc oxide is an important ceramic chemical flux raw material, especially in building ceramic wall and floor tile glazes, low-temperature porcelain glazes and ceramic pigments. It is also widely used in art ceramic glazes.
Role and use in glaze: ZNO has a strong fluxing effect in glaze, which can reduce the expansion coefficient of the glaze, improve the thermal stability of the product, and at the same time increase the gloss and whiteness of the glaze. degree and improve the elasticity of the glaze. It can increase the brilliance of glaze color while expanding the melting range. However, use with caution in black glazes containing chromium. Generally speaking, ZNO is mainly used in the following aspects:
1. Used as a flux: When ZNO is used as a flux in low-temperature frit glaze, the general dosage is between 5% and 10%. The dosage in raw material glaze is generally about 5%.
2. Used as opacifying agent: Adding zinc oxide to glazes containing higher AlO can improve the opacification of the glaze. Because ZNO can form zinc spinel crystals with AlO. In zinc-containing opacifying glazes, AlO can improve the whiteness and opacification of the glaze. SiO2 can improve the gloss of the glaze.
3. Used as crystallizing agent: ZNO is an indispensable crystallizing agent in art glaze crystallizing glaze. When the molten glaze is rapidly cooled, it forms larger crystal patterns, which are very beautiful. In crystalline glaze, the dosage of ZNO is as high as 20-30%.
4. Used to make cobalt sky blue glaze: ZNO is a very important flux in cobalt sky blue glaze. It can make cobalt oxide form beautiful sky blue in the glaze.
5. Use as ceramic pigment: Due to its strong fluxing effect, ZNO can be used as a flux, mineralizer and glaze color carrier for ceramic pigments. As the main raw material in the brown ceramic color series
6. Used as a glass additive: Zinc oxide added with aluminum, gallium and nitrogen has a transparency of 90% and can be used as a glass coating to allow visible light to pass through. Reflects infrared rays. Coatings can be applied to the inside or outside of window glass to provide insulation or insulation.
China Ferroalloy Online