What’s stabilized zirconia?
- info16151
- Nov 20, 2018
- 2 min read
Stabilized Zirconia is widely used in ceramics industry. Why use stabilized zirconia instead of pure zirconia?
Zirconia (ZrO2) mineral materials are mainly zircon. Zircon series igneous rock deep layer mineral, color has light yellow, brown yellow, yellow-green, etc., specific gravity is 4.6-4.7, hardness is 7.5, has a strong metallic luster, can be used as raw material for ceramic glaze. Pure zirconia is a kind of high-grade refractory material. Its melting temperature is about 2900 C. It can increase the high temperature viscosity of glaze and enlarge the temperature range of viscosity change. It has good thermal stability.
When the content of zirconia is 2% - 3%, it can improve the crack resistance of glaze. Because of its high chemical inertia, it can improve the chemical stability and acid-base resistance of glaze, and also play the role of emulsifier. Zircon is commonly used in building ceramic glaze, and the general dosage is 8% - 12%. Zirconia is a good color aid for yellow-green pigments. Pure zirconia must be used to obtain better vanadium-zirconium yellow pigments.
At present, zirconia ceramic bearings have been used in miniature cooling fans. Their product life and noise stability are better than traditional ball and sliding bearing systems. Foxconn took the lead in using zirconia ceramic bearings in computer cooling fans.
Here is the reason, pure zirconium oxide undergoes a phase transformation from monoclinic to tetragonal and then to cubic when temperature changes: monoclinic (1173 °C) tetragonal (2370 °C) cubic (2690 °C) melt
The volume will change during the phase transformation. The transition from tetragonal to monoclinic will lead to about 9% volume increase, which will lead to crack for the ceramics.
To solve this problem, stabilization of the cubic polymorph of zirconia over wider range of temperatures is needed. Adding some stabilizer can make it. The process is accomplished by the substitution of some of the Zr4+ ions (ionic radius of 0.82 Å) in the crystal lactice with slightly larger ions, e.g., those of Y3+ (ionic radius of 0.96 Å). The new formed materials are stabilized zirconia.
Most common stabilizer includes calcia (CaO), magnesia (MgO), ceria (CeO2) or alumina (Al2O3) or hafnia (HfO2).
Stanford Advanced Materials offers several different stabilized zirconia powders in bulk quantity for ceramics industry as below:
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