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The application value of refractory materials


 For refractory materials, including whether it is used for the channel induction furnace, or coreless induction furnace, he should meet the following requirements.

(1) Good resistance to thermal properties
This point is particularly important for the induction of a furnace. Because of the continuous cycle operation mode for "no furnace feeding - melting - baked process, lining material is subjected to repeated thermal shock. If the refractory thermal shock stability is poor, it is very easy to crack and crack propagation, the liquid metal in the short term will penetrate into the coil, causing the whole lining scrap.

(2) have good chemical stability
Metal aluminum and aluminum alloy not only high chemical activity, and the flow of the molten liquid is excellent. The viscosity of molten aluminum at 750 DEG C for only 1.04 CPS, and 20 DEG C when the viscosity of water (1 CPS) quite close, this is easy to penetrate the lining and the internal chemical reaction is the main reason. The effect of aluminum on the reducing agent is the temperature of the aluminum liquid and the refractory material. TiO2, FeO, SiO2 and other oxides in the refractory are reduced by aluminum. Between the liquid aluminum with refractory materials was not only the quality of the products are affected, but also makes the lining surface nodulation, bulging and precipitate, by liquid aluminum impregnation and the original brick interface crack danger caused by spalling will shutdown. Therefore, the lining material in contact with molten aluminum, must have high chemical stability and minimal impregnation.

(3) have good resistance to erosion.
In order to make the general electrical efficiency is high, the furnace wall materials are designed to be thin, but the operation process, because of the electromagnetic force, the furnace molten metal kept churning and mixing, constantly scour and wear of lining. In the induction furnace, the erosion and abrasion of the refractory are more serious because of the jet flow pattern. Therefore, the requirements of the refractory materials must have high mechanical strength and hardness.

(4) is not easy to be wetted by the metal liquid and penetrate
As is well known, refractory materials are brittle materials, in the process of heating and cooling, it is inevitable to produce cracks. But one of the key factors that determine the life span is the crack size and the speed of crack propagation. While the crack growth and the metal liquid to the contact material's wettability and the penetration ability. The worse wettability, the more favorable.

(5) there is a higher density and volume stability
As the refractory materials used in the melting furnace, in the case of material, it is hoped to obtain higher density and volume stability. The height of body density, the amount of the porosity in the body, especially the degree of sintering. The higher the volume stability of the material, the smaller the possibility of the cracks in the process of sintering and the use of the material, the smaller the width of the crack, the stronger the resistance to penetration.

(6) is not easy to produce a furnace tumor
A furnace tumor is rarely formed due to the presence of impurities (e.g., Al2O3) on the surface of the molten material. Because the furnace tumor can make the furnace capacity is reduced significantly, and the metal tumor itself is dense, tough, is very difficult to get rid of.