Heat-preservation and flame-retardant casting covering slag

Abstract

The invention relates to heat-preservation and flame-retardant casting covering slag. The covering slag comprises, by weight, 50%-70% of a suspending agent, 30%-40% of a flame retardant and 5%-10% of high-aluminum bauxite powder. A binder with the total quantity of 3%-5% can further be added to the covering slag. Silica sol or aluminum phosphate can be used as the binder. Artificial mica, bentonite, diatomite, palygorskite clay and the like can be used as the suspending agent. Alkyl sodium sulfonate, boric acid and the like can be used as the flame retardant. The covering slag has high heat preservation performance, flame retardance and coating performance, also has an excellent suspension property and is not prone to precipitation in the using process. The covering slag reduces the hot crack tendency of an aluminum-magnesium alloy casting. During casting, the covering slag forms a layer of reductive protective atmosphere on the molten magnesium interface of a riser, so that aluminum-magnesium alloy is protected against oxidization and is prevented from burning in a casting mould during casting; sequential cooling of the aluminum-magnesium alloy is guaranteed, the feeding effect in the solidification process of the aluminum-magnesium alloy is improved, and the aluminum-magnesium alloy casting free of inside crystal orientation defects, smooth in surface and free of oxidized wrinkled skin is obtained.

Description

technical field [0001] The invention relates to the technical field of refractory materials, in particular to a heat-insulating and flame-retardant casting mold slag. Background technique [0002] As we all know, the chemical properties of magnesium are very active, and liquid magnesium can easily react with oxygen, nitrogen in the atmosphere and water in the mold. The surface films such as magnesium oxide and magnesium nitride formed as a result of the reaction have low density coefficients and poor thermal conductivity, and the large amount of heat released by the reaction cannot be dissipated quickly, resulting in a rapid rise in temperature on the reaction interface and accelerated oxidation of magnesium, which intensifies Magnesium burning. As a result, holes or oxide wrinkles appear on the surface of the casting, and in severe cases, the casting is scrapped. Therefore, preventing the burning of aluminum-magnesium alloys in the mold during the pouring process is one o...

AI Technical Summary

Problems solved by technology

The surface films such as magnesium oxide and magnesium nitride formed as a result of the reaction have low density coefficients and poor thermal conductivity, and the large amount of heat released by the reaction cannot be dissipated quickly, resulting in a rapid rise in temperature on the reaction interface and accelerated oxidation of magnesium, which intensifies burning of magnesium

As a result, holes or oxide wrinkles appear on the surface of the casting, and the casting is scrapped in severe cases