What is yttria stabilized zirconia?

YSZ is a ceramic material, by adding yttrium oxide to change the phase transition temperature range of zirconia, resulting in room temperature stable cubic crystals and tetragonal crystals.

Pure zirconia is a monoclinic phase at room temperature. When the temperature rises to about 1173℃, it becomes a tetragonal phase. When the temperature rises to 2370℃, it becomes a square phase and becomes a liquid phase at 2690℃.

Monoclinic phase (phase transition temperature :1173°C) tetragonal phase (phase transition temperature :2370°C) cubic phase (melting point/freezing point :2690°C) liquid.

When pure zirconia is cooled from high temperature to room temperature, the square crystal is converted into monoclinic crystal after the phase transformation temperature. Due to the drastic change in its volume, the sintered product contains micro cracks and is often unable to use. Zirconia does not exist in the cubic phase (fluorite crystal structure) at room temperature, but by adding other oxides, the stable temperature range of zirconia in the cubic phase can be greatly increased. Zirconia doped with phase stabilizers is called stabilized zirconia.

Advantages of yttrium oxide stabilization of zirconia YSZ

Common zirconia stabilizers are usually alkaline earth oxides or rare earth oxides, such as yttrium oxide, cerium oxide, calcium oxide, and magnesium oxide. These stabilizers are similar in substance to stabilize zirconia, but have different properties. Zirconia doped with yttrium oxide has good comprehensive properties and is the most widely used solid electrolyte. The stable zirconia doped with cerIA has the best electrical conductivity, but its mechanical properties are relatively poor. The stable zirconia doped with calcium oxide has better performance and cheaper price than other stabilizers, but it is easy to be decalcified and unstable. The stable zirconia doped with magnesium oxide has general conductivity and low price, but its long-term performance is poor and it is generally used as a consumable product.

Yttrium oxide is used as a stabilizer, and this material is mainly tetragonal structure. Zirconia has the highest bending strength of any material, especially when sintered. Yttrium stabilized zirconia has a small grain, and is suitable for cutting tools because of its high wear resistance, which is used to achieve cutting a very sharp corner part. Excellent grain makes the production of ceramics dense density, without many pores, with excellent mechanical strength, corrosion resistance, impact toughness, thermal shock resistance and very low thermal conductivity. Because of these characteristics, yttrium stabilized zirconia is used mainly in wear resistant parts, cutting tools and thermal barrier coatings.

Examples of typical applications of yttrium stabilized zirconia:

1. Solid oxide fuel cell SOFC

Solid oxide fuel cell is an all-solid chemical power generation device which can directly convert the chemical energy stored in fuel and oxidizer into electric energy efficiently and environmentally friendly at medium and high temperature. In the SOFC system, the anode support body is U706 ZRO2-8Y. YSZ is an excellent oxygen ion conductor and stable in both oxidation and reduction atmosphere, making it an ideal material for solid oxide fuel cells.

2. Biological ceramics, electronic ceramics, structural ceramics

U703 ZRO2-3Y biological grade denture with yttrium stabilized zirconia features high fracture strength, high fracture toughness and high light transmittance. Jade has a strong sense of quality and is highly whitening, which can match the color of human teeth well. And extremely suitable for milling with manual grinder or CAD/CAM equipment.

3. Artificial gemstones, colored ceramic jewelry

The hardness of zirconia color ceramic jewelry is close to natural diamond, lighter than metal, never wear, never change color, never rust, beautiful and durable, bright and bright, texture, visual otherworldly.

4. Refractory materials

Yttrium stabilized zirconia as a refractory, used in electronic ceramic firing support plate, refractory for melting glass, metallurgical metal.

5. Oxygen sensor

Oxygen sensor is the standard configuration of the automobile, it is the use of ceramic sensitive elements to measure the oxygen potential in the automobile exhaust pipe, calculated the corresponding oxygen concentration by the principle of chemical balance, to monitor and control the combustion air-fuel ratio, to ensure product quality and exhaust emission standards of the measurement element. The element zirconia in the sensor acts like an electrolyte.

6. More applications

Worn parts, heat barrier coatings, optical fibers, ferrules and bushings, grinding media.