0
391views
Write preparation properties and uses of - (i) Dolomite bricks (ii) Silicon carbide
1 Answer
0
0views

1. Dolmite bricks

  • Preparation: Dolmite bricks are made by mixing calcined dolmite (CaO+MgO mixture in equimolecular preparations) with silicate binder. They are fired at 1500 °C for about 24 hours
  • Properties: Dolmite bricks possess less strength, more softness and porosity, greater shrinkage and high hygroscopicity than magnasite bricks. However, they can withstand a load of 3.5 kg/cm2 at 1650 °C. They are also not very resistant to thermal shocks.
  • Uses: Dolmite is rarely used as a direct refractory, but it is useful as repair material.
  • Stabilized dolmite bricks are, however used for basic electric furnace linings.
  • Bessemer converters, open-hearth furnaces, ladle-linings etc. and as a cheap substitute for magnesite bricks.

2. Silicon carbide:

  • Preparation: It is a bluish-black crystalline artificial mineral with hardness between corundum and diamond.
  • It is made by subjecting a mixture of silica and carbon (coke or coal) to high temperature (1650-2200 °C) in an electric furnace

  • It is very hard, chemically unreactive, can withstand the action of high temperature without damage, but it is not tough and is somewhat brittle. It is mainly used in cutting-wheels, abrasive papers and clothes. It is extensively used for grinding of materials of low tensile strengths like cast iron, brass, bronze and many more.

Please log in to add an answer.