In the grinding and polishing industry, White fused aluminum oxide is one of the oldest abrasives. Is it different from other abrasives? Below we will compare the characteristics of various abrasives in the two areas of abrasive blasting and abrasive tool manufacturing:
1. Sandblasting Media
White fused aluminum oxide. It is an abrasive that melts aluminum-oxygen powder into a liquid and condenses by cooling. The higher its Al2O3 composition ratio (the Al2O3 content of white fused alumina is 99%), the stronger the hardness and cutting and grinding ability. Since mass production began in the early 20th century, White fused aluminum oxide have been used in most grinding jobs. White fused alumina can be used for fine grinding of aluminum alloy, stainless steel, metal, surface cleaning of carbon steel, chromium alloy, molybdenum alloy, cemented carbide and other metals, and can also be used for non-metallic materials such as acrylic, plastic, bamboo products, wood Surface passivation of manufactured products and glass.
Brown fused aluminum oxide. The composition ratio of brown fused alumina is slightly lower than that of white corundum, and the purity of the first grade is 93-96%. It is also an artificial abrasive made by melting method. However, the raw material of brown fused alumina is bauxite, not alumina with higher purity. In addition, the smelted products of brown corundum are usually divided into different grades, which is caused by the difference in the formation of crystals in different parts of the smelting road. 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 as a basic high-hardness abrasive for different usage scenarios. For large-scale sandblasting of metals, carbon steel, glass and other materials, brown fused alumina is a good choice.
Garnet abrasive. The hardness of garnet abrasive is the leader among natural abrasives. It is a kind of natural emery sand. The hardness of garnet with high purity is also Mohs 8.5. The front surface is prepared for sandblasting, etc., which is economical. Some garnets have associated minerals such as ommatite, which can affect the purity of the garnet, which in turn affects the blasting efficiency.
Black silicon carbide. It is an abrasive with a higher hardness than corundum-based abrasives. The smelting process of black silicon carbide abrasives is a process of mixing quartz sand and anthracite (or petroleum coke) 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, the brittleness is large, and the particles are continuously broken during the grinding process to form new cutting edges. Therefore, the grinding ability is higher than that of corundum-based abrasives. It is suitable for cleaning and sandblasting of ceramics, marble and granite, and can also be used for fine grinding of glass, aluminum alloy, copper products and jade.
Green silicon carbide. The production process of green silicon carbide 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 99%. Its Mohs hardness is 9.4-9.5, which makes green silicon carbide the second most abrasive after synthetic diamond. For magnesium alloys, titanium alloys, and tungsten carbide alloys with high hardness, green silicon carbide can be cut quickly, showing high sharpness. In addition, for special non-metallic materials, such as calcium silicate glass, quartz glass, borosilicate glass, optical glass, jewelry and jade, etc., it also shows excellent grinding performance.
Glass bead blasting media. The hardness of glass beads is Mohs 5-6, and their spherical particle shape will not cause destructive scratches on the workpiece surface. The glass beads used for surface shot peening are soda lime glass produced by the flame flotation method after the recycled glass is remelted in the furnace. The influence of the quality of raw materials on glass beads lies in the residue of heavy metals. Glass beads with high metal content will affect the smoothness of sandblasting, and it is also easy to react with the workpiece material. Glass beads are economical in price and can be used for surface beautification of various metal materials. The effect of sandblasting is brighter than the previous angular abrasives.
Ceramic beads blasting meida(zirconia beads). Ceramic beads is also an artificial abrasive produced by fusion method, and the particle shape is spherical. The main raw material for the production of ceramic beads is zircon sand, which is doomed to be very expensive. Nevertheless, ceramic beads is widely used for fine polishing of electronic parts, aviation parts, stainless steel materials, magnesium aluminum alloys, titanium alloys and other products due to its advantages of being unbreakable, non-polluting, high brightness shot peening effect and long service life. It can beautify the surface of the product and improve the added value of metal products. In the field of aviation, it can also improve the fatigue resistance of metals and eliminate surface stress, and the development prospect is very broad.
Walnut shell sand. Walnut sand, also known as walnut shell sand, is a process of breaking dry walnuts, removing their shells, and then grinding them into particles of different sizes. The hardness of walnut sand abrasive is 2.5-3.0, which varies according to different varieties of peach pits. Good quality walnut shells are weathered Changbai Mountain wild walnut shells, and the hardness is higher than that of artificially planted walnut shells. Although the hardness of walnut shell abrasive is not high, its remarkable feature is its strong oil absorption. Good oil absorption, can be used for surface treatment of stained materials, such as engines with oil stains, to improve cleaning efficiency. In addition, walnut shell sand is also used for surface beautification of surgical instruments, metal musical instruments, golf clubs and other products, and the abrasive will not cause damage to the workpiece.
Sodium bicarbonate blasting media. (Baking Soda abrasive) Sodium bicarbonate abrasive is an abrasive particle made by a physical synthesis method. It is soluble in water, does not produce sparks during sandblasting, and does not damage the workpiece under the primer. Its Mohs hardness is 2.5-3.0, and it is commonly used in car paint cleaning and oil tanker cleaning in the petrochemical industry. In foreign countries, sodium bicarbonate is also used as a dental sandblasting material. After sandblasting with sodium bicarbonate, it is easy to clean with water and will not cause pollution.
2. Abrasives tools industry
White fused aluminum oxide. The abrasive code is WA/WFA, it is also be called white corundum. And its self-sharpening is relatively high among traditional abrasives. It is suitable for the production of various cutting, rough grinding, fine grinding, rough polishing and fine polishing abrasive products. White aluminum oxide grain can be found in various abrasive products such as vitrified grinding wheels, grinding heads, resin cutting discs, grinding discs, coated abrasives, and whetstones. These abrasives are mainly aimed at ordinary metal products. White fused aluminum oxide occupies a large proportion in the abrasive market, and various manufacturers have been working hard for many years, which is of great help to the quality improvement of white corundum. White corundum abrasives are not only complete in particle size, but also in the direction of low sodium and high bulk density. In addition, the iridium-plated white corundum developed on the basis of white corundum has higher toughness and hydrophilicity than ordinary white corundum, which can be used as a choice for improving the quality of abrasive tools.
Brown fused aluminum oxide. The abrasive code is A. It is also called brown corundum. Its toughness is higher than that of WA, and its self-sharpening is not as good as that of white aluminum oxide. The basic properties and high toughness of brown fused alumina make it is suitable for grinding discs, barren grinding wheels, polishing coated abrasives, etc. In addition, brown corundum also has broad prospects in making high-end abrasive products together with zirconium aluminum oxide. Thirdly, calcining brown fused alumina 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. The abrasive code is C, also be called black carborundum. Black silicon carbide has the characteristics of higher hardness than corundum. It is mainly used for the production of abrasive tools for marble, concrete and cement grinding. Black carborundum grit is mainly used for coated abrasives, mainly using black silicon carbide P sand series, which is used for manual grinding of metal, wooden surfaces and bamboo products.
Green silicon carbide. The abrasive code is GC, also be called green carborundum. GC is harder than black silicon carbide and grinds more efficiently. It is mainly used in abrasive tools for granite, ceramics, glass and tile dressing, and is also suitable for the production of multi-functional grinding wheels, bearing steel whetstones, refining whetstones, PVC grinding wheels and other products. In addition, because green carborundum is the abrasive with the highest hardness among non-superhard abrasives, it is often added to diamond abrasives to reduce costs and fill.
Pink fused alumina/Ruby fused aluminum oxide. The abrasive code is PA. The other name of PA is chrome fused aluminum oxide. Pink fused alumina is also a fused alumina abrasive. When 0.5-2% chromium oxide is added during the smelting process, the crystal structure of alumina will change, showing better mechanical strength, toughness and specific gravity than white corundum. Pink fused alumina is suitable for the production of bonded abrasives such as vitrified grinding wheels and resin bonded grinding wheels, and is rarely used in coated abrasives. The materials targeted are also mainly metal materials. The unique crystal structure of pink fused alumina can remove heat during grinding, reduce the clogging of the metal surface, and improve the sharpness of the grinding wheel.
Single crystal corundum. The abrasive code is MA. The other name is Monocrystalline Alumina. The smelting of single crystal corundum is a process of fusion of white fused alumina and alloy products. The smelted particles are independent crystals, and the division of different particle sizes has not been mechanically broken. Therefore, the toughness and strength of the abrasive particles are better than those of WA and PA. And can be more closely bonded with the binder. Monocrystalline Alumina is mainly used in the production of 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 abrasive tools have been greatly improved.
Zirconia fused aluminum oxide. The abrasive code is ZA. Zirconia fused aluminum oxide is an ordinary abrasive with the highest wear resistance (relatively super-hard abrasive) so far. It is made of zirconium material and alumina through high temperature smelting and rapid cooling. A typical use of zirconia alumina is the production of heavy duty grinding wheels. The particle crushing mechanism of zirconium corundum is also through the shedding of abrasives to form a new cutting edge surface. Each time the particles fall off, the zirconium corundum crystals fall off. The crystal size of zirconia aluminum oxide is one-twentieth of that of white aluminum oxide, its toughness is dozens of times that of brown aluminum oxide, and its compressive strength and bulk density are much higher than those of ordinary aluminum oxide grains. Zirconium fused aluminum oxide can be used for centerless grinding vitrified grinding wheels, heavy-duty grinding wheels, resin cutting grinding wheels, railway rail grinding grinding wheels and other bonded abrasives and polishing discs, flexible nylon grinding wheels and other coated abrasives in machine tool processing, and its performance is greatly improved. obvious. Zirconia fused aluminum oxide is more suitable for grinding with heavy machine loads, such as high-power cutting machines, heavy-duty grinders, and smart equipment grinding.
Ceramic aluminum oxide (SG abrasive/Sol-gel aluminum oxide). The abrasive code is SG. The production process of SG abrasive grain is more complicated, and it also subverts the traditional abrasive smelting method. It is made by chemically dissolving the raw materials, adding additives to make a jelly, and cooling and calcining. The grinding mechanism of ceramic aluminum oxide is the breaking and falling off of the nano-scale particles. It is conceivable how revolutionary this is for the improvement of abrasive self-sharpening and longevity. Not only that, advanced ceramic aluminum oxide manufacturers have also made more innovations in the shape of the particles. Triangular flake particles, triangular pyramid particles, and columnar particles are all new forms of ceramic corundum. SG abrasive grain was invented by 3M Company, and internationally famous abrasive companies such as Saint-Gobain and German horse ring have developed their own ceramic corundum products, but the performance is not as good as 3M Cubitron series. Ceramic abrasive grain can be used for fine grinding of special steels such as aerospace sheet grinding, high-hardness bearing steel, nickel-chromium alloy, and titanium alloy. The promotion of ceramic corundum makes it possible to improve grinding efficiency, save labor and subsequent polishing costs. The work efficiency of vitrified grinding wheels, coated grinding wheels and resin grinding wheels made of it has been improved by an order of magnitude, creating conditions for robotic grinding and cutting.
