However, alumina calcined at 1650 ~ 1750 ° C requires 4 to 7 rinses to take effect. The reason may be that the black corundum calcined at high temperature, impurities and alumina are firmly combined and difficult to transfer to the solution. The total amount of impurities such as Fe2O3, SiO2 and Na2O remaining after washing with alumina calcined at 1650 ~ 1750 ℃ is 0.01% ~ 0.07% higher than that calcined at 1450 ~ 1550 ℃. A certain amount of reducing agent is added, and carbon is generally used as the reducing agent.
In summary, the physical and chemical changes in the bauxite calcination process are restricted by various factors, among which the Al2O3 content, mineral composition and distribution, and the level of the calcination temperature determine the sintering characteristics of the bauxite. China is a country with abundant bauxite resources in the world, but due to the natural law of ore deposit formation, the distribution of its super-grade ore is not concentrated, the mechanized mining is severely mixed, and the natural type of ore is complex and difficult to strictly classify.
The reaction between carbon and SiO2 is the reaction between carbon and impurities: SiO discharged from the solution is combined with oxygen in the air to form SiO2 (silica fume). , Iron, titanium impurities and black silicon carbide form a ferrosilicon alloy sinking at the bottom of the furnace and separated from the zirconium-rich liquid. Thereby, the desiliconization error is obtained by the enrichment of ZrO2. Fused cast corundum products are attractive for desilicon zirconium, which improves product performance.
Grinding wheel wear is reduced and grinding heat is reduced. At higher wheel speeds, the metal removal rate can be increased, the grinding force can be reduced, and the power consumption can be reduced. Under the same surface roughness of the workpiece, the grinding efficiency can be improved. Increasing the speed of the CBN grinding wheel will improve the surface roughness of the workpiece. The higher the grinding wheel speed, the better the surface roughness of the workpiece, which will reduce the tangential and normal grinding forces.
Lamination method can be divided into lamination with mold and lamination without mold. Then increase the roll distance to make the forming material automatically roll off, divide it into several parts after cooling, press the blocks separately, sprinkle the talcum powder, and park it for use. The silicon carbide abrasive crosslinking reaction is in the stage of thermal vulcanization, and the crosslinking begins to produce network structure. At present, there are two kinds of binders used in rubber abrasives in China: natural rubber and synthetic rubber.
The forming pressure of the abrasive formula is determined according to the abrasive particle size, hardness and organization. Each formula has a fixed unit pressure. Only by pressing according to the converted gauge pressure can the quality of the product be guaranteed. The pressed parts can achieve the uniform density of the upper and lower structures, which ensures the quality of the products. This can not only overcome the shortcomings of manual unloading, but also ensure the quality of the parts.
The raw materials used for rubber abrasive tools are very complex, and there are usually more than ten kinds of them, which are generally divided into three parts, namely, abrasive, rubber and admixture. The abrasives used in rubber abrasives are the same as those used in ceramic abrasives and resin abrasives, usually aluminum oxide grit and white corundum, with a small amount of microcrystalline corundum, green silicon carbide and black silicon carbide. Lamination is mainly due to the high thickness ( 20 mm) of solid rubber.