The refractory should meet requirements

Refractory lining, whether it is used for induction channel furnace, or coreless induction furnace, should meet the following requirements.
(1) good chemical stability;
Aluminum and aluminum alloys not only high chemical activity, but also excellent melt fluidity. The viscosity of the molten aluminum at 750 ° C when only 1.04 centipoise, fairly close to 20 ° C when the viscosity of water (1.0 centipoise), which is its easy penetration and chemical reactions occur mainly due to the inside of the lining. The temperature of liquid aluminum in contact with refractories, aluminum strong reducing effect. Refractory SiO2, TiO2, FeO oxide to aluminum reduction. Liquid aluminum and the reaction between the refractory lining is not only affected the quality of the product, and the lining surface nodulation, drum kits and precipitation debris, impregnated portion of the liquid aluminum and the original brick interface cracks shutdown also cause spalling. Therefore, contact with liquid aluminum lining material, you must have a high chemical stability and the least possible amount of impregnation.
(2) have a good erosion resistance;
Usually, in order to make the furnace has a higher electrical efficiency, the thin design of the furnace wall material, but the furnace during operation, due to the electromagnetic force, the molten metal in the furnace kept somersault and stirred continuous erosion and wear lining . Induction channel furnace, with a jet-type melt channel, erosion and wear of the melt channel refractories are more serious. Therefore, the requirements of the refractory material used must have a high mechanical strength and hardness.
(3) have a higher density and volume stability;
As a smelting furnace refractories in the case of certain materials, are hoped to obtain a higher density and volume stability. Bulk density level, and the reaction of the internal porosity of the molded body content, in particular the degree of sintering is good or bad. The higher the stability of the volume of material, the possibility of cracks during sintering and use the smaller, the smaller the width of the cracks, the stronger the resistance to penetration ability.
(4) not easy to produce furnace tumor;
Furnace tumors rarely possible due to the surface of the melt, the presence of impurities or internal (for example, Al2O3) is formed. A significant reduction in the furnace tumor causes the furnace capacity, and metal tumor itself dense, tough, it is very difficult to get rid of.
(5) can not easily be wetting and penetration of the liquid metal;
As well known, the refractory material is a brittle material, inevitable cracks in the heating and cooling process. But one of the key factors that determine their life is the size of the crack and the crack propagation rate. Crack propagation with liquid metal wetting and penetration ability of the contact materials. Wetting ability is worse, the more favorable.
(6) good resistance to thermal shock performance;
This is a coreless induction furnace is especially important. Because no furnace practices feeding - Melting - baked "process cycle, the lining material is subjected to repeated thermal shock. Refractory thermal shock resistance is poor, you can easily cracks and crack propagation, the liquid metal penetration in the short term to the coil at the entire lining scrapped.