Zirconia ceramic is a non-metallic inorganic material sintered at high temperature. It is widely used in various industries for its excellent properties of high temperature resistance, corrosion resistance, wear resistance and thermal shock resistance. In this article, the major factors that can affect zirconia ceramic properties are briefly introduced.

1. Purity of zirconia powder

The raw material of zirconia ceramic is high purity zirconia powder. Different grades of purity have a dramatic effect on properties of industrial zirconia ceramics.

It is inevitable to add impurities when preparing zirconia powder. During the sintering process, the irregular shaped pores formed due to the organic impurities were burnt away, while at high temperature sintering stage, the inorganic impurities could react with ceramic powder, or remain in ceramic body where the tiny cracks formed.

The microstructural defects that are caused by impurities have a significant effect on the densification of zirconia ceramics, therefore it is crucial to use high purity zirconia powder for preparing excellent performance zirconia ceramics.

2. Grain size of zirconia powder

Powder grain size also gives a great impact on properties of ceramic products. Only if zirconia powder is fine enough, can the final finished products be sintered into microcrystalline structured ceramic, which has excellent performance of wear resistance.

The finer powder is more active, which can accelerate the sintering process and help to obtain finished ceramic with higher strength.

Small grains can minimize the stress concentrations on grain boundary that is caused by the different coefficient of linear expansion of corundum and glass. So, finer zirconia powder can decrease the risk of cracking.

3. Moulding process of zirconia ceramic green bodies

Zirconia ceramics with low porosity and high density shows excellent properties. High density ceramic bodies have a compact grain structure, which can withstand external compressive strength and corrosion. However, the moulding process is the key point to obtain high density ceramic green bodies.

Commonly applied moulding process of zirconia ceramic includes dry pressing, isostatic pressing, and hot die casting. Different moulding processes have their own characteristics. Generally, complex shaped items apply slip casting and hot die casting, while simple shaped items apply dry pressing. Besides, the density of items which apply dry pressing is higher than that of the item which apply hot die casting.

4. Sintering process of zirconia ceramic green bodies

Sintering process of ceramic refers to the densification of ceramic green bodies that sinter at high temperature. As the firing temperature rises and time increases, bonding occurs between powder grains, then the strength of sintered ceramic green bodies enhances.