1.The performances of ZrO2, Pure ZrO2 is white, and appears yellow or grey when containing impurities, the  density   of  ZrO2 is 5.6g/cm3, melting point being 2715℃. ZrO2 has good performance of heat  esistance,  insulation and good corrosion resistance.

The generally used ZrO2 is TZP, the added Y2O3 inhibits the crystal transformations of ZrO2, and TZP has the best toughness in all PSZ even in all polycrystalline ceramics. The density of ZrO2 ceramics is 5.95-6.05 g/cm3, in the four generally used ball ceramics (Si3N4, SiC, Al 2O3,ZrO2), ZrO2 has the best toughness (more than 8MPa·m1/2) and its coefficient of thermal expansion (10.5×10-6/℃) is near that of metals, and matches well with metals, however the dimension stability of ZrO2 is not well, the dimensions variation with temperature is bigger than that of the other three ball ceramics. The rolling contact failure form is crushing, in some key component the stability of ZrO2 ceramics is not as well as that of Si3N4. ZrO2 ceramics is self-lubricating material, and can well settle the problem of pollution and inconvenience of adding lubricant.  2.  Field of application ZrO2 ceramics can be used in the manufacture equipment of semiconductor, LCD; the manufacture equipment of electric plating, synthetic fibre, and optical film; the heat treating furnace, vacuum facility, etc.ZrO2 ceramics can also be used in the fields of ball bearings, machining tools, various guide wheel, kinds of valves and kinds of severe conditions. The production of silicon nitride ceramic balls Now the difficulty and the price of ceramic ball bearings all depend on the production technology of ceramic balls. Outside, the ceramic ball bearings have been researched since 1960s-1970s. In this period, the main producer of hot-pressed Si3N4 bland ball (marked NC-132) is Norton The ceramic balls we produced use superfine high-pure home-made Si3N4 powders, the uniformly mixed powders are molded to near net size, and then sintered by GPS-HIP, the produced ceramic balls have excellent material performance and good spherical shape, this highly reduces the processing cost and shortens the processing periods from formerly several hundreds of hours to current several tens of hours, furthermore, we have explored a complete set of technology of processing ceramic balls, established a complete production line, and now we can produce large batches of kinds of gauges of G5 ceramic balls, and some gauges can be processed to G3. The usually used ceramic materials to produce ceramic bearings are Si3N4,SiC, Al2O3 and ZrO2. in the four typical materials, SiC has its obvious characteristics: 1. SiC has the maximum upper limit of working temperatures, SiC has good strength at high temperatures, when the temperature is above 1200℃, the strength of SiC start exceeding that of Si3N4. 2. SiC has the best heat conductivity, about 150 W/m·K, in the rotation of bearings the heat produced can drop off quickly. 3. SiC has the best thermal-shock resistance, and can be used in the situation of rapid changes of temperature. 4. SiC has low coefficient of thermal expansion (only a little bigger than that of Si3N4), so it can keep good dimension precision at high temperature. 5. SiC has the maximum elastic ratio, and can reach 420GPa, this can increase the bearing’s dynamic stiffness, SiC can be used in the situation of high stiffness, such as machine tool main arbor. 6. SiC has the best corrosion resistance, it can resist the corrosion of strong acid and strong alkali, especially the corrosion of HF acid. The key applications of SiC ceramic bearings Industry Working conditions Characteristic Oil High temperature, high pressure Resistance to high temperature, corrosion and wear Chemistry Strong acid, strong alkali Resistance to corrosion and wear High temperature and oxidation Resistance to high temperature and corrosion Mechanism Engine Resistance to high temperature,  thermal-shock resistance, good strength Grinding Resistance to wear Light industry Paper stuff and its wastewater Resistance to corrosion and wear High temperature Resistance to high temperature, Good heat conductivity Large power rejection of heat Good heat conductivity Nucleus, laser High temperature water with boron, Large power Resistance to radiation, good strength and good stability Metallurgy High temperature gas Resistance to high temperature, corrosion and oxidation Other Machine-shaping Resistance to corrosion and wear