The composition and properties of commonly used abrasives

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In various industries, the use of abrasives is essential for tasks like grinding, polishing, and surface preparation. Different abrasives offer unique properties that cater to specific applications. This article aims to shed light on the composition and properties of commonly used abrasives, helping readers make informed decisions when selecting the right abrasive for their needs.

1. Brown-Fused Alumina: The main chemical component is Al2O3, which is produced by melting alumina, iron scraps, and anthracite in an electric arc furnace. Brown fused alumina abrasive has a brown color, hence its name. This abrasive has a certain hardness and toughness, providing strong grinding capability and the ability to withstand high pressure. It possesses characteristics such as high-temperature resistance, oxidation resistance, corrosion resistance, and good chemical stability. Due to its high tensile strength, it is suitable for grinding materials with high tensile strength, including carbon steel, high carbon steel, and alloy steel. It can be used for processing hardwood and can serve as a substitute when other abrasives are insufficient. It is widely regarded as a universal abrasive and is the most widely used abrasive.

2. White Fused Alumina: The main chemical component is Al2O3. It is produced by melting alumina powder, derived from pre-processed alumina used in brown fused alumina, in an electric arc furnace. It has a white color, hence its name. The texture of white fused alumina is purer compared to brown fused alumina. The alumina powder used as raw material is primarily composed of β-AL2O3 (without grinding ability), which is then transformed from β-AL2O3 to α-AL2O3 during the smelting process. The resulting α-AL2O3 possesses strong grinding power.

3. Black Silicon Carbide: The main chemical component is SiC. It is produced by melting petroleum coke, quartz sand, wood chips, etc., in a resistance furnace. Black silicon carbide has a black color, hence its name. Its texture is more brittle compared to corundum abrasives, and it has higher hardness. Its toughness is inferior to corundum abrasives, making it particularly suitable for processing materials with low tensile strength, such as non-metallic materials (various types of boards such as wood-based panels, particle boards, high, medium, and low-density fiberboards, bamboo boards, calcium silicate boards, leather, glass, ceramics, stone, etc.) and non-ferrous metals (aluminum, copper, lead, etc.). It is also ideal for processing hard and brittle materials.

4. Green Silicon Carbide: The main chemical component is SiC. The raw materials used in its production are generally similar to those used in black silicon carbide production. Additionally, industrial salt is added as a reactant and promoter during the reaction in the resistance furnace. It is named green silicon carbide due to its green color. Green silicon carbide has a purer texture compared to black silicon carbide and has higher hardness. It has the same grinding applications as black silicon carbide but is more suitable for precision grinding tasks such as grinding threads and measuring tools. It is more widely used for grinding hard alloy and diamond products. The production cost of green silicon carbide is higher than that of black silicon carbide due to different raw material ratios, the addition of auxiliary materials such as table salt, as well as differences in power consumption and processing processes. Therefore, the price of green silicon carbide products is higher than that of black silicon carbide. As a result, when comparing green silicon carbide with black silicon carbide, it is generally not chosen for non-metallic and non-ferrous metal materials. Instead, it is mainly selected for grinding hard alloys and precision grinding. It is less commonly used in abrasive belts and other coated abrasives.

5. Microcrystalline Corundum: The main chemical component is Al2O3. The production raw materials used are the same as those for brown fused alumina. However, the rapid cooling process is employed to obtain microcrystalline corundum with a small crystal size and fine structure. It has excellent hardness, toughness, and self-sharpening properties, making it suitable for precision grinding and polishing applications. Microcrystalline corundum is widely used in the manufacturing of abrasive tools, such as grinding wheels, cutting discs, and polishing stones, especially for materials that require high surface finish and dimensional accuracy.

6. Pink Fused Alumina: Pink fused alumina is produced by adding chromium oxide to the raw material during smelting. It has a pink color, hence its name. The addition of chromium oxide results in improved toughness and self-sharpening ability compared to other fused alumina abrasives. Pink fused alumina is commonly used for precision grinding, fine polishing, and producing high-quality abrasives. It is particularly suitable for grinding hardened steel, high carbon steel, and alloy steel, as well as for precision grinding of measuring tools, optical instruments, and jewelry.

7. Zirconia Alumina: Zirconia alumina is a composite material composed of zirconium oxide (ZrO2) and aluminum oxide (Al2O3). It combines the toughness and self-sharpening characteristics of alumina with the high hardness and wear resistance of zirconia. Zirconia alumina abrasives are known for their high grinding efficiency and long service life. They are widely used in heavy-duty grinding operations, such as grinding stainless steel, high-alloy steel, and hard-to-grind materials. They are also suitable for cutting and grinding applications in the metal fabrication industry.

8. Silicon Carbide Abrasives: Silicon carbide abrasives are produced by smelting a mixture of silica sand and petroleum coke in an electric furnace. Silicon carbide has a high hardness, excellent thermal conductivity, and low thermal expansion coefficient. It is widely used for grinding and polishing hard and brittle materials, such as cast iron, ceramics, and non-ferrous metals. Silicon carbide abrasives are available in both black and green varieties, with black silicon carbide being more commonly used for general-purpose grinding and green silicon carbide preferred for precision grinding applications.

Selecting the right abrasive is crucial for achieving optimal results in grinding, polishing, and surface preparation tasks. Understanding the composition and properties of commonly used abrasives empowers individuals to make informed decisions. Whether it's the versatility of aluminum oxide, the toughness of zirconia alumina, or the unmatched hardness of diamond and CBN, each abrasive brings unique benefits to specific applications. By considering the specific requirements and materials involved, professionals can confidently choose the most suitable abrasive for their needs, ensuring efficient and effective results.