Wilson Abrasive Co.,Ltd
The amount of aluminum sulfide produced depends on the amount of pyrite added. The melting point of corundum furnace liquid decreases with the increase of aluminum sulfide content. The shape of the silicon carbide abrasive crystal has a great relationship with the content of aluminum sulfide in the furnace liquid. When the content of aluminum sulfide in the melt is close to 4%, the corundum crystallized from the melt is mainly equiaxed crystal, and the particle shape is particularly good. When the content of aluminum sulfide in the melt is 6.5%, in addition to equiaxed crystals, there are slender particles.
Generally speaking, the surface layer of the green silicon carbide crystal tube has low strength, and the quality of different parts of the crystal tube is also different. Generally, the less the sic content in the outer layer, the smaller the crystal size. Use a graded shovel to shovel the amorphous and secondary aluminum oxide grit at the same time; clean up the crystal tube, and manually shovel the fine crystals into a pile, lift it away with a grab, and store it in centralized storage for preparation Crushing and processing.
The smoke removal method of the corundum electric furnace mainly adopts a smoke exhaust hood method. That is, a large smoke exhaust hood is set above the furnace body. In this way, the crown cover is mainly composed of a furnace cover, a chimney and a furnace cover. The upper cover of the furnace is a double-layer structure welded with 6-8mm steel plates. The green silicon carbide middle interlayer can pass cooling water and is provided with air vents to prevent explosion accidents caused by the expansion of superheated steam. The side wall of the furnace cover is welded by steel plates and lined Refractory brick. According to the way of dust removal, soot purification equipment can be divided into two categories: wet and dry.
White corundum quality appraisal is now commonly used by stick method. The stick method is judged from two aspects. On the one hand is the stick-like color and crystal luster. The color is white, and those with shiny crystal stars are better. The aluminum oxide abrasive color is dark and the quality is not good. It is necessary to extend the smelting time. On the other hand, look at the stick-like thickness. A thin pass and a thick pass indicate that the hearth temperature is low and it takes some time. Before stopping the furnace, the thickness of the stick-like sample is 1.5 ~ 2.5mm. It is normal. If the thickness is more than 3mm, the sample is too thick.
The end point of smelting of white corundum has not been based on strict judgment so far. Should gradually reduce the current, gradually reduce power, and slowly shut down the furnace. The black silicon carbide is naturally cooled after the furnace is stopped. It is cooled slowly for a period of time to allow sufficient time for the crystallization of sodium perchlorate to segregate, and finally concentrated in the middle and upper part of the frit. Then water can be used to quickly cool the frit.
Various compounds in alumite are combined together in particulate form. It is impossible to identify various oxides by visual inspection, and it is difficult to separate the various oxides by beneficiation. Due to the different chemical composition and different cementitious substances, the color of brown corundum varies greatly, mainly gray, tan and brown. For example, Guangxi apple ore deposits are dark gray, Henan and Shanxi mines are gray, Guizhou bauxite deposits are white and light gray, and Shandong Tianzhuang bauxite deposits are chlorite.
Artificial corundum is divided into brown fused alumina (A), white corundum (WA), chrome corundum (PA), zirconium corundum (ZA), black corundum (BA), single crystal corundum (SA), microcrystalline corundum (MA) and the like. The brown corundum is mainly made of bauxite, iron filings and anthracite in the electric arc furnace by smelting and reducing impurities. The white corundum is obtained by melt crystallization of the aluminum oxide powder in the electric arc furnace. The other corundum is in the melting process with different alumina contents.
A certain amount of other oxide-derived substances having different properties are added. A large number of corundum applications are brown corundum and white corundum. A variety of abrasives such as white corundum, brown aluminum oxide, green silicon carbide, and black silicon carbide are also in full swing. In 1934, boron carbide with hardness higher than corundum and silicon carbide appeared. In 1936, a semi-crunchy corundum between white corundum and brown corundum appeared. At the same time, a metal bond natural diamond grinding wheel was produced.
In 1946, single crystal corundum was born. In 1954, the United States GE, Kaplenden and Norton worked together to make a device that can reproduce diamonds. Abrasives as a special industry, there are problems of abrasive smelting in energy saving and emission reduction. At present, there is overcapacity in domestic brown fused alumina price. With the implementation of national energy conservation and emission reduction policies, the next policy focus will be to eliminate the corundum industry. Outdated production capacity.
In the past five years, the development of emerging industries has brought more opportunities for super-hard materials, and super-hard materials have developed toward a wider and more sophisticated application. In recent years, white corundum abrasives and abrasives have been continuously improved, and the domestic machine tool industry has become an important “pointer” to break foreign monopoly. At the same time, in the fields of shipbuilding and aerospace industry, a group of high-tech abrasives and abrasives enterprises have shown their talents.
Domestically produced products have gradually replaced imported products, and their performance has even surpassed that of foreign products of the same type. Although we have made major breakthroughs in many fields of black corundum abrasives, overall, there is still a big gap between the high-end of abrasives and the world’s advanced level. Machining surface quality refers to the microscopic unevenness of the machined surface after machining, also called roughness.
The surface quality after machining directly affects the physical, chemical and mechanical properties of the machined part. The performance, reliability and longevity of the pink corundum product depend to a large extent on the surface quality of the main part. Therefore, it is of great significance to correctly understand the connotation of the surface quality of the parts, analyze various process factors affecting the quality of the machined surface during machining, improve the surface quality and improve the performance of the products.
At present, the situation of domestic brown fused alumina is overcapacity. The next step of the national policy will be to eliminate the backward production capacity of the white aluminium oxide industry, shut down some high-energy small and medium corundum production enterprises, eliminate the low-power smelting furnace, and encourage the advantageous enterprises to become stronger. Be big. Zhang Wei, secretary-general of the Guiyang Abrasives Association, bluntly said that some of the domestic abrasives companies still have some backward production equipment that is banned from use in the country, and will continue to be used for this part of the enterprise.