Technical Application of Calcined Zinc Oxide
In order to improve the physical properties of zinc oxide raw zinc oxide, such as direct zinc oxide and indirect zinc oxide, used in the ceramic glaze and its related chemical components, heavy calcined zinc oxide is obtained after high temperature processing and calcination.
Zinc oxide calcined is an important raw material for ceramic chemical fluxes, especially in the use of architectural ceramic tile glazes and low-temperature ceramic glazes and ceramic pigments. It is also widely used in art ceramic glazes. The role of calcined zinc oxide in the glaze and uses: calcined zinc oxide in the glaze has a strong fluxing effect, can reduce the expansion coefficient of the glaze, improve the thermal stability of the product, while increasing the glaze and whiteness of the glaze, Improve the elasticity of the glaze. The glaze color can be increased while expanding the melting range. However, use caution in black glazes containing chromium. In summary, calcined zinc oxide is mainly used in the following aspects:
First, as a flux: calcined zinc oxide used as a flux in the low-temperature frit glaze, the general amount of 5% to 10%, the amount of low-temperature raw material in the glaze is generally about 5%.
Second, as an opacifying agent: In the high glaze containing Al2O3 added zinc oxide, can improve the glaze emulsion. Because calcined zinc oxide can produce zinc spinel crystals with Al2O3. In zinc-containing opaque glaze, Al2O3 can improve the whiteness and opacity of the glaze. SiO2 can improve the gloss of the glaze.
Third, as a crystallization agent: In the art glaze crystalline glaze, calcined zinc oxide is an indispensable crystallization agent, in the cooling enamel chilling, it will form a larger crystal pattern, very beautiful. In the crystalline glaze, the amount of calcined zinc oxide is as high as 20 to 30%.
Fourth, to make cobalt sky blue glaze: calcined zinc oxide is a very important flux in cobalt sky blue glaze, it can make cobalt oxide in the glaze to form a beautiful sky blue.
Fifth, as a ceramic pigment: As a result of strong fluxing, calcined zinc oxide can be used as a flux ceramic pigments, mineralizers and glaze coloring carrier. Main raw material in brown ceramic pigment series
Sixth, used as a glass additive: The transparency of zinc oxide added with aluminum, niobium, and nitrogen is as high as 90%. It can be used as a glass coating to reflect visible light while reflecting infrared rays. Paint can be applied inside or outside the window glass to achieve insulation or thermal insulation.
The most important point of calcining zinc oxide is the antibacterial effect of ceramic surface glaze: calcined zinc oxide is an electronic structure of a semiconductor catalyst. Under light irradiation, when a photon with a certain energy or has more than this semiconductor band gap energy When an Eg photon strikes a semiconductor, one electron excites from the valence band NB to the conduction band CB leaving a hole. The excited-state conduction band electrons and valence band holes can be recombined to eliminate the input energy and heat. The electrons are trapped in the surface state of the material. The valence electrons transition to the conduction band. The valence band holes rob the OH electrons in the surrounding environment. The hydroxyls are turned into free radicals, and they complete the degradation of organics (or chlorine) as strong oxidants, killing germs and viruses.