Role of Zinc Oxide in Ceramic Manufacturing

Zinc oxide is an important ceramic chemical flux raw material. In the ceramic industry, zinc oxide is widely used in brick and tile glaze. In the construction industry, zinc oxide is also used in ceramic wall and floor tile glaze.

The glaze is directly introduced in the form of zinc oxide or zinc carbonate. The purpose is that zinc oxide has a strong melting aid effect in the glaze, which can reduce the expansion coefficient of the glaze, improve the thermal stability of the product, increase the luster and whiteness of the glaze and improve the elasticity of the glaze. It can increase the luster of glaze while expanding the melting range. ZnO is an indispensable component in the red glaze of architectural ceramics and artistic ceramics. 

Generally speaking, zinc oxide is mainly used in the following aspects.

Used as flux

When zinc oxide is used as flux in low-temperature frit glaze, the general dosage is between 5% ~ 10%, and about 5% in low-temperature raw glaze.

Used as an opacifier

Adding zinc oxide to the glaze with high Al2O3 can improve the opacification of the glaze. Because zinc oxide can form zinc spinel ZnO · Al2O3 crystal with Al2O3. In the zinc containing opaque glaze, Al2O3 can improve the whiteness and turbidity of the glaze. SiO2 can improve the luster of glaze.

Used as crystallizer

Zinc oxide is an indispensable crystallizer in artistic glaze. When the molten glaze cools rapidly, it forms a large crystal pattern, which is very beautiful. The amount of zinc oxide in crystalline glaze is as high as 20 ~ 30%.

Making cobalt sky blue glaze

Zinc oxide is a very important flux in cobalt sky blue glaze. It can make cobalt oxide form beautiful sky blue in the glaze.

Used as ceramic pigment

Zinc oxide can be used as flux, mineralizer and glaze carrier of ceramic pigments because of its strong melting aid.

Cautions

The following points should be paid attention to in the use of zinc oxide:

1. It must be calcined at high temperature before use, and the calcination temperature is about 1200 ℃. The reasons are: calcination reduces the shrinkage in the sintering process; Reduce bare glaze, bubble, pinhole and other defects due to shrinkage, increase its density, avoid paste and improve the performance of green glaze.

2. Too much zinc oxide in the glaze will affect the glaze gloss. And will improve the fire resistance, viscosity, so that the glaze is not easy to melt.

3. Zinc oxide has a poor effect on some colored glaze, especially chromium glaze. It plays an auxiliary role in cyan, prevents the tendency of being green when mixed with chromium, increases the luster of glaze and avoids glaze cracking.

After understanding the main functions of zinc oxide in pottery products, I believe you are no longer unfamiliar with the chemical additive zinc oxide of art. The amount of zinc oxide must be controlled during use. 

Coastal Zinc provides selected grades of zinc oxide for advanced customers in ceramics, pharmaceuticals, personal care, animal nutrition and rubber. 

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