Ceramic coating materials(Ⅰ)

1, The emergence of high-performance ceramic coating

The rapid development of modern science and technology, especially the high technologies such as aerospace, aviation, electronics and military which poses the new requirements for  better materials. Especially the aerospace industry has more strict requirements for the materials. The first is to require stable material properties, while light weight, high temperature resistance, erosion resistance, radiation resistance and other comprehensive excellent performance. Thus high-performance ceramic coating came into being.

The ceramic coating is a new composite material developed on the basis of the traditional ceramic materials, it keeps a high temperature resistance, wear resistance, corrosion resistance and other advantages of the traditional ceramic material while keep the structure strength of the matrix material. Since the ceramic coating thickness is usually within a millimeter, it greatly reduces the negative weight the parts.And its thermal shock resistance is better than the overall ceramic.

The application of plasma spraying technology in industry in the 1950s and the high speed oxygen fuel spraying technology (HVOF) developed later on the basic of flame spraying technology provide a good process for ceramic coating molding.

2, Ceramic coating classification

According to the chemical composition of the material, ceramic coating has oxides, carbides, nitrides, boride ceramics.

There are a wide variety of oxide ceramics. The most commonly used coating materials are Al2O3; TiO2; ZrO2; Cr2O3; SiO2; MgO; BeO; Y2O3; Al2O3.SiO2; MgO.ZrO2 and so on.

Carbide ceramics are mainly: SiC; WC; B4C; TiC and so on.

Nitride ceramics are mainly: Si3N4iTiN; BN; AlN and so on.

The application of boride ceramics is not widely used, such as TiB, ZrB2 and so on.

Figure (1) Alumina ceramic coating, It plays a role in wear-resistant insulation.

 

3, The forming methods of Ceramic coating

The main method of forming ceramic coating are the following:

3.1  Wet chemical method: the main sol - gel method; chemical plating and chemical composite plating.

3.2  Vapor deposition method: the main physical vapor deposition (PVD); chemical vapor deposition (CVD).

3.3  Solid deposition method; mainly self-propagating high temperature synthesis method; enamel coating.

3.4  Thermal Spray Method . Mainly include plasma spraying, flame spraying and so on.

Thermal spray coating accounted for about 50% of the ceramic coating market in the four kinds of ceramic coating molding process.