What Is Zirconium Oxide?
Zirconium oxide, an odorless white inorganic compound, is recognized for its significant properties and applications.
It is classified under domestic laws and regulations as a hazardous and toxic substance to be labeled and to be notified under the Safety and Health Law, yet not under other major regulations such as the Fire Service Law.
Uses of Zirconium Oxide
Zirconium oxide’s unique properties lend it to diverse applications:
- High Melting Point, Heat Resistance, and Chemical Erosion Resistance: Used in manufacturing cutting tools, refractory materials, and more.
- Hardness and Durability: Applied in dental materials, ceramic knives, and jewelry as imitation diamonds.
- Oxygen Ion Conductivity: Essential for solid electrolyte fuel cells.
Known for its extreme hardness, often compared to diamonds, zirconium oxide is about ten times harder than common ceramics. It is also utilized in electronic components like piezoelectric elements and ceramic capacitors, and as an additive in optical glass and quasi-drugs like catalysts and cosmetics.
Characteristics of Zirconium Oxide
Zirconium oxide, a ceramic material with the chemical formula ZrO2, features a melting point of 2715°C, boiling point of 4300°C, density of 5.68 g/cm3, and a refractive index of 2.13.
It boasts low thermal conductivity, heat resistance, corrosion resistance, and high strength, but can degrade with temperature-induced structural changes.
Zirconium oxide transitions from a monoclinic structure at room temperature to tetragonal and cubic structures with increased temperature. Stabilizers like yttrium oxide (Y2O3), calcium oxide (CaO), cerium oxide (CeO2), and magnesium oxide (MgO) help maintain a stable cubic crystal structure at room temperature, enhancing its conductivity of oxygen ions.
Other Information on Zirconium Oxide
1. Production Methods
Zirconium oxide is produced mainly through wet and dry refining from ores like zircon and haddelite. Wet refining involves melting ores with caustic soda, decomposition with hydrochloric acid, followed by calcination of zirconium hydroxide to produce zirconium oxide powder. Dry refining entails crushing the ore, removing impurities, and ore dressing to yield pure zirconium oxide.
2. Comparison with Zirconium
Unlike metallic zirconium, zirconium oxide is a ceramic bonded by strong covalent bonds, granting it superior corrosion resistance, hardness, and heat resistance due to its high melting point and strong bond formation.