Refractories are high temperature resistant materials that constitute the linings for high-temperature industrial furnaces and reactors and other processing units. In addition to being resistant to thermal stress and other physical phenomena induced by heat, refractories must also withstand physical wear and corrosion by chemical agents. Refractories are more heat resistant than metals and are required for heating applications above 1000°F(538°C).
While this definition correctly identifies the fundamental characteristics of refractories–their ability to provide containment of substances at high temperature– refractories comprise a broad class of materials having the above characteristics to varying degrees, for varying periods of time, and under varying conditions of use. There are a wide variety of refractory compositions fabricated in a vast variety of shapes and forms which have been adapted to a broad range of applications. The common denominator is that when used they will be subjected to temperatures above1000°F(538°C) when in service. Refractory products fall into two categories: brick or fired shapes, and specialties or monolithic refractories. Refractory linings are made from these brick and shapes, or from specialties such as plastics, castables, gunning mixes or ramming mixes, or from a combination of both.
Many refractory products, in final shape, resemble a typical construction brick. However, there are many different shapes and forms. Some refractory parts are small and may possess a complex and delicate geometry; others are massive and may weigh several tons in the form of precast or fusion cast blocks.
The oxides of magnesium (magnesite) and calcium (lime) are the most important refractory materials, though fireclay is widely used as well. Zirconia is used when the material must withstand extremely high temperatures. Silicon carbide is another refractory material. It is very strong at high temperatures, but will burn in the presence of oxygen, if the protective silica coating comes off. Refractories must be chosen according to the conditions they will face. For example, carbon cannot be used when it will be in contact with oxygen, as it will burn. Acidic refractories cannot be used in a basic environment and basic refractories cannot be used in acidic environment because they will be eroded. Zircon, fireclay and silica are acidic, dolomite and magnesite are basic and alumina, chromite, silicon carbide, carbon and mullite are neutral. Refractory materials must be strong at high temperatures, resistant to thermal shock, chemically inert, and have low thermal conductivities and coefficients of expansion.”
Check our product list Go for list !