Very specific requirements need to be met depending on the intended use of a component made of technical ceramics. In order to be able to fulfil these requirements perfectly, the appropriate choice of the right material is of crucial importance when manufacturing the component.
CVT use aluminium oxide in numerous applications because this material is extremely versatile and very economical in comparison with other high-performance ceramics, in many cases even more economical than carbides.
Aluminium oxide is distinguished by very good abrasion resistance and is approximately as hard as diamond. In addition, the material is characterised by a high chemical resistance, to acids and alkalis for example, a very high temperature resistance of up to 1,750°C, very good electrical insulation and dielectric strength. Furthermore, aluminium oxide displays high thermal conductivity.
The high purity of 99.7 % also made it possible to further improve the strength and corrosion resistance significantly.
Zirconium oxide (zirconium dioxide) is known as a high-performance material. It is characterised by a very high bending strength and impact strength. As a result, zirconium oxide is relatively “soft” in comparison with other high-performance ceramics. For this reason, the material is of particular interest for components used in mechanical engineering and is very suitable as a counterpart for steel or carbides, for example as a bezel.
However, zirconium oxide also offers other properties: for example, this material is biocompatible and is thus suitable for use in the food industry, but also in medical technology. Due to its low thermal conductivity, zirconium oxide is also used as a thermal insulator. Having roughly the same elastic modulus and the same thermal expansion as steel, it is suitable for incorporation in assemblies subject to temperature stresses.
The all-rounder among the high-performance ceramics offers a whole spectrum of advantages for the widest variety of applications. Its low density makes silicon nitride very light, which is of particular interest in installations with rotating or swivelling movements.
Silicon nitride, like aluminium oxide, is very hard and very chemically resistant. In terms of impact strength, silicon nitride comes close to zirconium oxide and is therefore used in all areas of mechanical and plant engineering.
However, the biggest advantage of silicon nitride lies in its high resistance to temperatures and temperature changes. This is why this material is used for example in induction plants. In addition, silicon nitride retains its full strength up to almost 1,000°C and hardly expands.
Glass ceramics are characterised in particular by a very low, even negative coefficient of thermal expansion, which prevents fracture due to temperature shock. Glass ceramics are therefore suitable for the manufacture of components which display outstanding thermal shock properties combined with very good mechanical strength.
Since conventional ceramics can only be ground with diamond after firing, machinable glass ceramics offer an economical solution in this case. The components can be manufactured quickly and precisely according to specifications using conventional metal machine tools. A further secondary firing is not necessary, leading to further savings in time and money during production.
Silicon carbide is the lightest and hardest material – similar to diamond – within the field of technical ceramics. In addition, silicon carbide displays good thermal conductivity, low thermal expansion and very good resistance to acids and alkalis. Since the properties of the material remain constant at temperatures of up to 1,400°C and it is also extremely light and stable in form, silicon carbide is outstandingly suitable as a construction material.
Components made of silicon carbide are for example used in chemical plants, as semiconductor material and in the field of optics. The material is also suitable for use within the foodstuffs industry. Generally, silicon carbide is suitable for use in demanding applications. In comparison with metal, the material offers very economical and durable solutions.