White corundum, brown corundum, chrome corundum, zirconium corundum, and ceramic corundum are all commonly used abrasives in the grinding industry. Below we will compare the characteristics of various abrasives in the two fields of grinding sandblasting and abrasive tool manufacturing:
1. Sandblasting industry
White corundum abrasive. It is an abrasive that melts aluminum oxide powder into liquid and then cools and condenses. The higher the Al2O3 content (the Al2O3 content of white corundum is 99), the stronger the hardness and cutting and grinding ability. Since mass production began in the early 20th century, white corundum abrasives have been used in most grinding work. White corundum abrasives can be used for fine grinding of aluminum alloys, stainless steel, and metals, surface cleaning of carbon steel, chrome alloys, molybdenum alloys, cemented carbides and other metals, and can also be used for surface passivation of non-metallic materials such as acrylic, plastics, bamboo products, wooden products, and glass.
Brown corundum abrasive. Brown corundum abrasive has a slightly lower proportion of aluminum oxide than white corundum. The purity of the first grade is 93-96%, and it is also an artificial abrasive made by the melting method. However, the raw material of brown corundum is bauxite, not the higher purity aluminum oxide. In addition, the smelting products of brown corundum are usually divided into different grades, which is caused by the difference in crystal formation in different parts of the smelting process. Therefore, the quality of brown corundum varies greatly. The toughness of first-grade brown corundum is higher than that of white corundum, which makes brown corundum abrasive abrasive a basic high-hardness abrasive for different use scenarios. For large-scale sandblasting of metal, carbon steel, glass and other materials, brown corundum is a good choice.
Garnet abrasive. Garnet sand abrasive has a moderate hardness of 7.5-8.0. It is a natural mineral sand. The hardness of high-purity garnet is also up to Mohs 8.5. It is economical for sandblasting of pipelines, large steel components, ship cleaning sandblasting, and surface preparation before anodizing. Some garnets have associated minerals such as omphacite, which will affect the purity of garnet and thus the efficiency of sandblasting.
Black silicon carbide abrasive. It is an abrasive with higher hardness than corundum abrasives. The smelting process of black silicon carbide abrasive is to mix quartz sand and anthracite (or petroleum coke) and put them into a large graphite resistance furnace for reaction. The hardness of first-grade black silicon carbide is very high, reaching Mohs 9.2, and the SiC content can reach 98%. At the same time, it is very brittle, and the particles are constantly broken during the grinding process to form new cutting edges. Therefore, the grinding ability is higher than that of corundum abrasives. It is suitable for cleaning and sandblasting of ceramics, marble, and granite, and can also be used for fine grinding of glass, aluminum alloys, copper products, and jade.
Green silicon carbide abrasive. The production process of green silicon carbide abrasive is similar to that of black silicon carbide, but green silicon carbide usually does not use anthracite, but uses petroleum coke as the main raw material, and adds salt. The purity of green silicon carbide is higher than that of black silicon carbide, and the SiC content is above 98.5. Its Mohs hardness is 9.4-9.5, which makes green silicon carbide the abrasive second only to artificial diamond. For magnesium alloys, titanium alloys, and tungsten carbide alloys with high hardness, green silicon carbide can cut quickly and show high sharpness. In addition, for special non-metallic materials, such as calcium silicate glass, quartz glass, borosilicate glass, optical glass, jewelry and jade, it also shows excellent grinding performance.
2. Abrasive Industry
White corundum abrasive. The abrasive code is WA. Its self-sharpening property is relatively high among traditional abrasives. It is suitable for producing various abrasive products for cutting, rough grinding, fine grinding, rough polishing and fine polishing. White corundum can be found in various abrasive products such as ceramic grinding wheels, grinding heads, resin cutting discs, grinding discs, coated abrasives, oilstones and other products. These abrasives are mainly aimed at ordinary metal products. White corundum accounts for a large proportion in the abrasive market. Various manufacturers have been deeply engaged in it for many years, which is of great help to improve the quality of white corundum. White corundum abrasives not only have a complete range of particle sizes, but also develop in the direction of low sodium and high bulk density. In addition, iridium-plated white corundum developed on the basis of white corundum has higher toughness and hydrophilicity than ordinary white corundum, and can be used as an option to improve the quality of abrasives.
Brown corundum abrasive. The abrasive code is A. Its toughness is higher than that of white corundum, but its self-sharpening property is not as good as that of white corundum. The basic properties and high toughness of brown corundum make it suitable for grinding sheets, rough grinding wheels, polishing coated abrasives, etc. In addition, brown corundum also has broad prospects for making high-end abrasive products with zirconium corundum. Thirdly, calcining brown corundum at a certain temperature can enhance the hydrophilicity and strength of brown corundum, reduce the thermal expansion coefficient of brown corundum, and improve the service life and performance of abrasive products.
Black silicon carbide abrasive. The abrasive code is C. Black silicon carbide has the characteristics of higher hardness than corundum. It is mainly used to produce abrasives for grinding marble, concrete, and cement. It can also be used to produce water sandpaper, remove paint surfaces, and remove welding points. Cleaning wheels. Black silicon carbide is mainly used for coated abrasives. The black silicon carbide P sand series is used for manual grinding of metal, wooden surfaces, and bamboo products.
Green silicon carbide abrasive. The abrasive code is GC. It has a higher hardness than black silicon carbide and is more efficient in grinding. It is mainly used in abrasive tools for granite, ceramics, glass, and tile finishing. It is also suitable for the production of multi-functional grinding wheels, bearing steel oilstones, fine grinding oilstones, PVC grinding wheels and other products. In addition, since green silicon carbide is a hard abrasive in non-superhard abrasive tools, it is often added to diamond abrasive tools to reduce costs and fill.
Chrome corundum abrasive. The abrasive code is PA. Chrome corundum is also a molten aluminum oxide abrasive. When 0.5-2% chromium oxide is added during its smelting process, the crystal structure of aluminum oxide will change, showing better mechanical strength, toughness and specific gravity than white corundum. Chrome corundum is suitable for the production of ceramic grinding wheels, resin grinding wheels and other consolidated abrasive tools, and is rarely used in coated abrasive tools. The materials targeted are also mainly metal materials. The unique crystal structure of chrome corundum can take away heat during grinding, reduce blockage on the metal surface, and improve the sharpness of the grinding wheel.
Single crystal corundum. The abrasive code is SA. The smelting of single crystal corundum is the process of fusion of white corundum and alloy products. The particles after smelting are independent crystals. The division of different particle sizes has not been mechanically crushed. Therefore, the toughness and strength of the abrasive particles are better than those of white corundum and chrome corundum, and they can be more closely bonded with the binder. Single crystal corundum is mainly used to produce ceramic grinding wheels and cutting grinding wheels. For the grinding of bearing steel, titanium alloy, vanadium alloy, austenitic stainless steel, and anti-fingerprint plates, the efficiency and service life of the grinding tools have been greatly improved.
Zirconium corundum. The abrasive code is ZA. Zirconium corundum is the most common abrasive (relatively superhard abrasive) with the best wear resistance so far. It is made of zirconium material and alumina after high temperature smelting and then rapid cooling. The typical use of zirconium corundum is to produce heavy-duty grinding wheels. The particle crushing mechanism of zirconium corundum is also to form a new cutting edge surface through the shedding of grinding abrasives. Each shedding of particles is the shedding of zirconium corundum crystals. The crystal size of zirconium corundum is one twentieth of that of white corundum, its toughness is dozens of times that of brown corundum, and its compressive strength and bulk density are much higher than those of ordinary corundum. Zirconium corundum abrasives can be used for centerless ceramic grinding wheels, heavy-load grinding wheels, resin cutting grinding wheels, railway guide grinding wheels and other consolidated abrasives and polishing discs, flexible nylon grinding wheels and other coated abrasives in machine tool processing, and their performance has been significantly improved. Zirconium corundum is more suitable for grinding with large machine loads, such as high-power cutting machines, heavy-load grinders, and intelligent equipment grinding.
Ceramic corundum abrasive (SG abrasive). The abrasive code is SG. The production process of ceramic corundum is relatively complicated, and it also subverts the traditional abrasive smelting method. It adopts the method of chemically dissolving the raw materials first, adding additives to make a jelly, and cooling and calcining. The grinding mechanism of ceramic corundum is the nano-level crushing and shedding of particles. It can be imagined how revolutionary this is to the improvement of abrasive self-sharpening and life. Not only that, ceramic corundum manufacturers have also made more innovations in the shape of particles. Triangular flake particles, triangular pyramid particles, and columnar particles are all new forms of ceramic corundum. Since SG abrasives were invented by 3M, international SG abrasive companies such as Saint-Gobain and German Horse Circle have developed their own ceramic corundum products, but their performance is not as good as the 3M Cubitron series. Ceramic corundum can be used for fine grinding of special steels such as aviation leaf grinding, high-hardness bearing steel, nickel-chromium alloy, and titanium alloy. The promotion of ceramic corundum provides the possibility of improving grinding efficiency, saving labor and subsequent polishing costs. The working efficiency of ceramic grinding wheels, coated grinding wheels, and resin grinding wheels made of it has increased by an order of magnitude, creating conditions for robot grinding and cutting.