Ceramics of Engineering Importance

Alumina (Al₂O₃):

Alumina is used quite commonly in Spark Plugs and Electrical Insulators. Other typical uses include Tank Armour, Cockpit windows (in single crystal form), Prosthetic applications etc. In the industry, Alumina is sold in several grades based on the purity of the material. Typical grades include 90, 96 and 99.5% pure Alumina. The 90 grade is regularly used as insulation bases, liners etc.. The 96.5 grade has in addition good chemical resistance and mechanical strength. Hence they are used in applications like machinery seal rings, bushings, bearing for special environment and electronic substrates. 99.5 is the highest grade of Alumina available which is used in specialised fields like Laser system, semiconductor industry and TFT-LCD processing related parts.

Boron Carbide (B₄C):

Attractive for it’s low density and high hardness, used in applications similar to Alumina. Typical uses include Lightweight Armours, Sandblasting nozzles etc.

Silicon Carbide (SiC):

The hardness of SiC is almost as high as Diamond. In addition, it has very high electrical insulation and mechanical strength. The most popular use of SiC is in the field of semiconductor industry. Starting from the use as lightning arrestors in power lines, it now has a vast application in power devices, thyristors and LEDs. As a structural material, Use of SiC as a substitute of metallic super alloys in high performance turbine blades is still limited to laboratory-based studies. However, current industrial uses are mostly in the fields of disc-brakes, cutting tools, dies and molds for high surface quality casting alloys.