Composition and properties of common abrasives

1. Brown corundum:
The main chemical composition is AL2O3, which is formed by smelting bauxite, iron filings and anthracite in the electric arc furnace. The color of brown corundum abrasive is brown. In terms of its color, it is named brown corundum. This kind of abrasive has certain hardness and toughness, has strong grinding ability, and can withstand great pressure. It has the characteristics of high temperature resistance, oxidation resistance, corrosion resistance and good chemical stability. Because of its high tensile strength, it is suitable for grinding materials with high tensile strength, for ordinary steel, high carbon steel and alloy steel, for processing hard wood, and for replacing other abrasives when they are insufficient. It is called universal abrasive and is the most widely used abrasive.
2. White corundum:
The main chemical composition is AL3O2, which is made by melting aluminum oxide powder in electric arc furnace. The color is white, and it is named white corundum in terms of its color. The texture of white corundum is more pure than that of brown corundum. The raw material of aluminum oxide powder used is made of bauxite used for brown corundum in advance, and its main physical composition is β- AL2O3 (no grinding ability), melted by electric arc furnace from β- AL2O3 converted to α- AL2O3。 Converted α- AL2O3 has strong grinding force.
3. Black silicon carbide:
The main chemical composition is SiC. It is made by melting petroleum coke, quartz sand, sawdust and other raw materials in a resistance furnace. The color of black silicon carbide is black. In terms of its color, it is named black silicon carbide. Black silicon carbide is more brittle and hard than corundum abrasive, and its toughness is also inferior to corundum abrasive. It is especially suitable for processing materials with low tensile strength, such as non-metallic materials (various kinds of plates, such as wood plywood, particle board, high, medium and low density fiberboard, bamboo board, calcium silicate board, leather, glass, ceramics, stone, etc.) and non-ferrous metals (aluminum, copper, lead, etc.), It is also an ideal abrasive for processing hard and brittle materials.
4. Green silicon carbide:
The main chemical composition is SiC. The raw material used in manufacturing is roughly the same as that used in the production of black silicon carbide. In addition, industrial salt is used as a reactant and accelerator to react in the resistance furnace. Its color is green, so it is named green silicon carbide. Green silicon carbide is more pure than black silicon carbide, and its hardness is higher than black silicon carbide. In addition to the same grinding purpose as black silicon carbide, it is more suitable for fine grinding of materials, such as thread grinding, measuring tool grinding, etc. In grinding materials, it is more widely used for hard alloy and diamond products. Because the production cost of green silicon carbide is higher than that of black silicon carbide, such as different proportions of raw materials, salt auxiliary materials, power consumption and processing differences, the price of green silicon carbide is higher than that of black silicon carbide. Therefore, in comparison with black silicon carbide, green silicon carbide is generally not selected for non-metallic and non-ferrous materials, but mainly used for grinding of cemented carbide and precision grinding, and less green silicon carbide is used as grinding material on abrasive belt and other coated abrasive tools.
5. Microcrystalline corundum:
The main chemical composition is AL2O3, and the raw material used for production is the same as that of brown corundum. Only in the smelting process, the process of rapid cooling is used to obtain the effect of fine crystallization. The mechanical strength of fine crystalline corundum is higher than that of ordinary corundum. Abrasive tools made of microcrystalline corundum are often used for rough grinding of cast steel, high toughness titanium nickel alloy steel and other difficult grinding materials, but they are rarely used for manufacturing coated abrasive tools.
6. Chromium corundum:
It is to add the mixture of Cr2O3 in the production process of white corundum to make this corundum form a co-melt of white corundum and Cr2O3, and change the properties and structure of corundum. The toughness of chrome corundum is higher than that of white corundum, and its hardness is about the same as that of white corundum. The quantity of Cr2O3 added is also slightly different from the performance of the produced chromic corundum, and its color is also different. Due to the different content of Cr2O3 added in chromic corundum, its use is different. Therefore, in chromic corundum, abrasives are divided into several grades according to the different addition of Cr2O3. Chromium corundum grinding materials are often used for the grinding of hardened steel, alloy steel and deformed steel and the precision grinding of instrument parts. Chromium corundum is often used in the production of consolidated abrasives, but rarely used in the production of coated abrasives.
7. Hollow ball abrasive:
The so-called hollow ball abrasive refers to an aggregate of spherical abrasive formed by evenly coating the abrasive on the surface of the hollow ball made of plastic with a straight diameter of 0.05-mm, and then coating the made hollow ball abrasive on the surface of the substrate in a general conventional way.
Hollow ball abrasives are generally used in making fine-grained products. Because the abrasive is very fine, if it is directly coated on the surface of the substrate, the abrasive layer is very thin, the abrasive involved in grinding is less, the grinding efficiency is poor, and the abrasive is very fine, the surface porosity of the abrasive belt is very low, and it is easy to block during grinding. If the hollow ball abrasive is used, the abrasive belt surface will form a very "rough" grinding surface, and the surface porosity will be greatly increased, so the abrasive belt surface will be beneficial to eliminate the grinding blockage. More importantly, the number of abrasive particles on the abrasive belt surface participating in grinding will increase by several times or tens of times, and the increase depends on the ratio of ball diameter to particle size. The larger the ratio, the larger the added abrasive particles, thus greatly improving the grinding efficiency and durability.
8. New ceramic abrasive with microcrystalline structure:
It is a sintered ceramic abrasive made by the gel method. Its crystal size is about 1-3 microns. It is hard and tough. When grinding, the tiny crystals gradually fall off and expose new crystals, maintaining the sharpness of the entire abrasive grain. 3M Corporation of the United States put it on the market in 1981 and named the abrasive belt made of Cubutron. The grinding hammer head is 71% higher than the cutting efficiency of zirconium corundum abrasive belt, and the efficiency of nickel coated stainless steel is 150% higher than the cutting efficiency of zirconium corundum abrasive belt
9. Zirconia abrasive:
It is a high toughness abrasive with ZrO2 and 20 micron crystal size. There are 40% and 25% ZrO2 added. The abrasive tool used for coating should have sharp abrasive particles, especially suitable for processing stainless steel parts and titanium alloy parts.
However, zirconia corundum abrasive belt is not only used as abrasive belt, but also widely used in consolidation abrasive tools.
10. Composite abrasive:
It refers to the mechanical combination of one abrasive and another abrasive rather than the combination of chemical reaction. When the abrasive tool is manufactured, the two abrasives are mechanically added to the molding material, and the various abrasives still maintain their unique physical and chemical properties. In use, take advantage of its advantages and achieve better results. In order to achieve the purpose of grinding, composite abrasive is often used to produce abrasive tools for hard to process materials at home or abroad. This is a method of creating a brand name and brand name. Common composite abrasives include the combination of brown corundum and white corundum, the combination of corundum and green silicon carbide, the combination of brown corundum and black silicon carbide, etc.
Composite abrasives are commonly used in bonded abrasives, but rarely used in the manufacture of coated abrasives.