Refractory materials are special products that are able to retain their strength at high temperatures. They are used to make crucibles and refractory linings, which line furnaces, kilns and incinerators. The refractory material is the surface in the vessel or furnace that comes in direct contact with the extremely hot metal, glass or other material that is being processed. Therefore, refractory materials need to be strong at high temperatures, resistant to thermal shock, chemically inert, and also have low thermal conductivities and coefficients of expansion. Refractories must be chosen based on the conditions that they will face in service. Alumina, which is the oxide of aluminum, is an important refractory material used throughout the world in a wide variety of industries, such as steel production, cement production, petrochemicals, non-ferrous metal production and glass production. Alumina-based refractories are valued by industry due to their superior mechanical strength and thermal shock resistance at the extreme temperatures used in materials production.
Ceramics are inorganic non-metallic materials formed as a result of the action of heat. Originally the most important ceramics were mined clays – which were made into pottery, bricks and tiles - along with cements and glass. Alumina and more advanced ceramic materials have expanded the many uses for ceramics.
Today technical ceramics play an important role in our lives. A large number of household appliances could not function without ceramic insulating elements. Insulators, fuses and circuit-breaker components made of technical ceramics are essential aspects of ensuring a safe and reliable power supply. Ceramic substrates and components are used in an extensive range of devices and subassemblies across all fields of electronics, while ceramic seals and regulator discs provide for wear-free operation and proper sealing in many valves and household water taps. These brief examples illustrate the importance of technical ceramics in the world today. As these ceramic components form parts of larger functional units in plant and equipment, machinery and motor vehicles, they are not usually highly visible. Consequently, whilst we rely on technical ceramics in our everyday life we are seldom aware of their presence.
The process of creating a smooth surface is known as polishing. Quite often the objective behind polishing is to create a shiny surface that looks highly appealing. Alumina is one of the most important abrasive materials for polishing. Examples include the metal polishing of a motorbike or a cooking pot. For metallic medical instruments, the polished surface removes any minute grooves or surface imperfections where bacteria could easily grow. Household cleaners are formulated to remove stains from porcelain or other materials, while automotive polishes return a finish to its original luster. Stones are polished to enhance their natural beauty, while our teeth are polished to give them a whiter appearance. And for all of these needs, Polishing Aluminas are widely utilized and valued. Alumina, with a Mohs' hardness of 9, is second only to the diamond on the hardness scale and is able to polish many softer materials.