Elastic deformation of zirconia ceramics

Zirconia ceramics are a new type of special ceramic material in recent years, with phase change toughening and microcrack toughening, so it has high strength and toughness, and is known as "ceramic steel".

Zirconia has the highest fracture toughness among all industrial ceramics. By optimizing the zirconia formulation and process using room temperature mechanical properties, we have obtained zirconia ceramics with fine crystal structure and high hardness, high strength and high toughness. The high hardness, high strength, and high toughness ensure that zirconia ceramics have incomparable wear resistance compared to other conventional structural ceramics. The fine crystal structure of ceramics can be processed to obtain a very low surface roughness (<0.1um). As a result, the coefficient of friction on the ceramic surface is reduced, thereby reducing friction and improving the quality of the product.

Zirconia ceramics are white, yellow or gray when they contain impurities, and generally contain HfO2, which is not easily separated. Elastic deformation refers to the deformation of the material by a certain amount under the action of external force, and after the external force is removed, the material can restore the deformation of the original shape. The modulus of elasticity and coefficient of thermal expansion is similar to those of steel and thus can be organically combined with steel parts to form a composite workpiece that will not be damaged or blown up by inconsistent thermal expansion. So what is the elastic deformation characteristic of zirconia ceramics?

1. Under static tensile load at room temperature, metal materials generally undergo two stages of elastic deformation and plastic deformation before fracture, while ceramic materials generally do not appear in the plastic deformation stage, tiny strains of elastic deformation immediately after the brittle fracture, elongation and surface shrinkage are almost zero.

2. The modulus of elasticity in compression is much higher than that in tension, i.e., E compression > E tension. At the same time, ceramic materials can also produce a small amount of compressive plastic deformation when compressed. Usually, metal materials, even very brittle cast iron, the tensile strength of compressive strength of 1/3 to 1/4. But the tensile strength of ceramic materials is often less than 1/10 of the compressive strength.

3. The modulus of elasticity of ceramic materials is much larger than that of metals, often 1 to several times higher. The modulus of elasticity of ceramic materials is not only related to the bonding but also the type of its constituent phases, distribution ratio and porosity because the forming and sintering process of ceramics has a significant impact on the modulus of elasticity.

4. The strength of ceramic materials is much greater in compression than in tension. This is a characteristic or advantage of brittle materials.

5. Compared with metallic materials, zirconia ceramics have good resistance to creep at high temperatures and also have some plasticity at high temperatures.