Zirconia is a white, powdered metal oxide. Like other common dental crown materials, it is a ceramic. Zirconia is made from zirconium, a metal with similar properties to titanium.
Zirconia ceramics, ZrO2 (zirconium dioxide) ceramics, have high melting and boiling points, high hardness, insulators at room temperature, and electrical conductivity at high temperatures. Pure ZrO2 is white, yellow or gray when it contains impurities, and generally contains HfO2, which is not easy to separate. The world's proven zirconium resources are about 19 million tons, and zirconium oxide is usually made from zirconium ore.
There are three crystal states of pure ZrO2 under normal pressure: monoclinic zirconia, tetragonal zirconia and cubic zirconia. The above three crystal types exist in different temperature ranges and can be transformed into each other: the relationship between temperature and density.
(1) The temperature of monoclinic zirconia is <950℃, and the density is 5.65g/cc
(2) The temperature of tetragonal zirconia is 1200-2370℃, the density is 6.10g/cc
Zirconia ceramics are widely used in the field of structural ceramics because of their high toughness, high bending strength and high wear resistance, excellent thermal insulation performance, and thermal expansion coefficient close to steel. Mainly include: Y-TZP grinding balls, dispersion and grinding media, nozzles, ball valve seats, zirconia molds, miniature fan shafts, optical fiber pins, optical fiber sleeves, drawing dies and cutting tools, clothing buttons, watch cases and watches Belts, bracelets and pendants, ball bearings, light golf clubs and other room temperature wear-resistant parts.
Comparison results of zirconia ceramics and alumina ceramics Compared with alumina ceramics, zirconia ceramics are more wear-resistant. The reason is that the sintering temperature of zirconia ceramics is higher. The density is twice as high as alumina ceramics.