Covering Agent

In casting production, the covering material that covers the surface of the molten metal in order to prolong the solidification time of the molten metal is called covering agent. There are two types, insulation covering agent and heating covering agent.


Covering Agent
Covering Agent

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Riser Covering Agent

The riser insulation covering agent is composed of low thermal conductivity materials, such as expanded perlite, expanded graphite, etc., covering the surface of the metal liquid to play the role of thermal insulation; the heating covering agent is to add a certain proportion of heating materials in addition to low thermal conductivity materials Under the heat action of the molten metal, the oxidant provides oxygen to oxidize the reducing agent to generate heat, prolonging the solidification time of the molten metal.

Riser Covering Agent Physicochemical Indexes











Insulation Materials

Acidified graphite 2.5 times expansion when heated, low thermal conductivity
Fly ash Formation of liquid slag to prevent carbon infiltration and heating insulation

Flake graphite


Gray-black scales, high melting point, not immersed in steel castings

Expanded perlite

Soften to glass state at high temperature, reducing heat loss is good for heat preservation
Heating material


Aluminum powder, iron oxide powder


Thermite reaction generates a large amount of heat and reduces heat loss
Covering agent for sale
Covering agent for sale

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Tundish Covering Agent

The tundish covering agent has the functions of heat insulation and preventing crusts on the molten steel surface, as well as the function of insulating the air, preventing the secondary oxidation of molten steel and absorbing non-metallic inclusions on the molten steel surface.

Most of the commonly used at present are thermal insulation slag. The single type (carbonized rice husk, rice husk ash) has a small bulk density and low thermal conductivity, but it is not easy to form a liquid slag layer, has poor anti-secondary oxidation effect, is easy to add carbon to molten steel, and is nearly eliminated; the composite type is a mixture of multiple components. The thermal insulation performance is greatly improved. The liquid slag layer can prevent the secondary oxidation of the molten steel and absorb the inclusions, and has a good application prospect.

There are four types of tundish covering agents: acidic, neutral, alkaline, and double-dregs.

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Tundish Covering Agent Physicochemical Indexes

Category Material Characteristics
Acidic Charred rice husk Good thermal insulation, low cost, but unfavorable for inclusions, chemical reaction at steel slag interface
Neutral Al2O3-SiO2 Certain thermal performance and lower cost
Alkaline MgO or dolomite slightly poor thermal insulation, easy to crust when used alone
Double slag Carbonized rice husk + alkaline residue Possibly add carbon to molten steel
Covering Agent Sales
Covering Agent Sales

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Zhengzhou Rongsheng Kiln Refractory Co.,Ltd main products are all kinds of shaped, unshaped refractories and metallurgical auxiliary materials, which are widely used in building materials, metallurgy, nonferrous metals, chemical industry, electric power and other industries. The company has the high temperature tunnel kiln production line, the product sells well at home and abroad, receives the customer the widespread high praise, if has the need, invites the consultation!

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