Properties of Zirconia and Common Preparation Methods|
What is zirconia
Zirconium is a primary oxide with the chemical formula ZrO2. Normal conditions produce a white, odorless crystal. It's insoluble in hydrochloric and dilute acid, but it can be dissolved in water. The chemical properties of the crystal are inactive. The high melting temperature, high resistivity and high refractive indices, as well as the low thermal expansion coefficient make it a ceramic sunscreen, ceramic insulating materials and a material that can withstand high temperatures. It is also used as the primary raw materials for artificial drills.
How to prepare zirconia
1. Chemical Method (Alkali Metal Method)
It is necessary to add zircon concentrate to caustic soap at high temperatures to cause it to react and produce sodium zirconate. The sodium zirconate, washed in concentrated hydrochloric to produce zirconium dioxide (ZH), Cl2, is then dried with a slurry of ammonia water. The zirconium oxide SH2OX is dissolved in water and then ammonia-water is added to precipitate the Zr(OH). You can burn Zr(OH1S), to get zirconia.
It is possible to add hydrochloric, or sulfuric, acid to the precipitate after melting zircon (Na2ZrO3, or Na2SiO3, or undecomposed products) by adding water to leaching. Zr(OH), prepared by acid leaching followed by precipitation removal and ammonia-water, is obtained after removing precipitation. The zircon can also be added to alkaline earth metal carbonates or oxides, then calcined into calcium zirconate. Finally, it is boiled in hydrochloric to remove the impurities and obtain zirconia.
2. Electrofusion method for Zirconia preparation
Reduced desalination and zirconium enrichment are achieved by melting and reducing zircon. At 2700 degrees, zircon decomposes completely into liquid ZrO2 (and SiO2), while SiO2 decomposes to gaseous SiO2 or O2. This is a reversible chemical reaction.
Two methods are available for the preparation of stable zirconia using the electric melt method: primary melting and secondary melting. For the primary electric melting method, you need to mix zircon powder with graphite and a stabilizer (usually CaCO3). Add them to an electric furnace and melt. After the ZrO2 is fused, it is quenched in order to promote crystallization. In the second electric melting method the zircon powder is mixed with graphite, melted and quenched in an electric furnace, then burned lightly (about 1400degC), resulting in mZrO2. It is necessary to mix the m-ZrO2 with a stabiliser according to the specified proportion, mix it uniformly and then add the mZrO2 to an electric arc melting furnace to perform secondary electric melt.
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