The cover material in order to extend the solidification time of the liquid metal in the riser cover the surface of the riser metal during casting production is called cover agent. There are two kinds of covering agent: thermal insulation covering agent and heating covering agent.
Advantages of covering agent:
1, Insulation material covering agent is made of low thermal conductivity material composition, such as: expanded perlite, expanded graphite.
2.In addition to the low thermal conductivity material, by adding a certain percentage of the heating material, and under the heat of the metal liquid, the oxidant provides oxygen to oxidize the reducing agent and prolong the solidification time of the metal liquid in the riser.
3.In the case of different insulation covering agent, the mouth shrinks into a "dish-shaped flat or hemispherical bottom, which is shaped like a U-shaped throat.
4.Significantly prolonged the time of the top of the riser, so that the molten steel in the riser for a long time under the action of atmospheric pressure, greatly improving the feeding efficiency of the feeder is conducive to the casting of gas and inclusions float to achieve the purpose of purifying molten steel , And access to sound steel, reducing the rejection rate.