Different types of stabilizers added to zirconia result in different types of stabilized zirconia products. Although the essence of each stabilizer is roughly the same, the properties of the obtained ZrO2 products vary. Additionally, the performance of products prepared by adding different amounts of stabilizers to zirconia also differs. Let's take a look together.
1.Y-TZP: Yttria-stabilized tetragonal zirconia ceramic
Y-TZP is the most researched TZP material to date. This material exhibits good mechanical properties, high strength, and excellent fracture toughness. The material has fine and uniform grain size distribution, attracting considerable attention. The atomic fraction of stabilizer Y2O3 in Y-TZP ceramic ranges from 2% to 3%.
Compared to other ceramics, Y-TZP offers the advantage of low sintering temperature, approximately between 1400-1500°C, with good sintering performance and high density. This ceramic possesses excellent room temperature mechanical properties, with a flexural strength of over 1000 MPa and fracture toughness between 10-15 MPa.m1/2. Moreover, Y-TZP exhibits good wear resistance, corrosion resistance, and biocompatibility. Various multi-element composite special ceramics have been developed based on Y-TZP and applied in practice.
2.CSZ: Calcium-stabilized zirconia
Calcium-stabilized zirconia is one of the earliest researched zirconia ceramics. CSZ ceramics have high ionic conductivity, low thermal conductivity, excellent high-temperature chemical stability, and resistance to thermal shock. They possess high strength and find wide applications in oxygen sensors, oxygen pumps, and high-temperature heating elements. Additionally, the cost of CaO is relatively low, which further justifies the continued research on calcium-stabilized zirconia. However, controlling the phase of sintered CSZ ceramics is difficult, resulting in low density and comprehensive performance inferior to yttria-stabilized zirconia.
3.Mg-PSZ: Magnesia partially stabilized zirconia
Compared to Y-TZP, Mg-PSZ offers the advantage of good mechanical properties and creep resistance at relatively high temperatures. It belongs to mid-temperature structural ceramic materials with a usage temperature below 800°C.
However, the solubility temperature of MgO in the cubic phase of ZrO2 is as high as 1700°C, resulting in a high sintering temperature for Mg-PSZ materials (generally between 1700°C to 1800°C). Moreover, Mg-PSZ is prone to crystallographic decomposition and significant tetragonal phase instability at 1000°C, limiting its application at high temperatures. Research focuses on reducing the sintering temperature to achieve low-temperature sintering while improving mechanical properties at high temperatures to expand applications.
4.Ce-TZP: Ceria-stabilized zirconia
CeO2 is an ideal zirconia stabilizer. Compared to Y2O3, its advantage lies in its low price and the formation of a tetragonal solid solution with zirconia over a wide temperature range. Additionally, the critical grain size of Ce-TZP is larger than that of Y-TZP, allowing the production of high-performance zirconia ceramic materials without the need for ultrafine powders.
Ce-TZP exhibits high fracture toughness and good resistance to low-temperature hydrothermal aging, but its hardness and strength are relatively low. The hardness and fracture toughness of Ce-TZP strongly depend on grain size, with larger grains resulting in better mechanical properties. Therefore, the key to Ce-TZP research lies in controlling grain growth.
