Black Silicon Carbide Applications

Black silicon carbide, due to its stable chemical properties, high thermal conductivity, low thermal expansion coefficient, and excellent wear resistance, has many other applications besides being used as an abrasive. For instance, applying silicon carbide powder with special technology to the inner wall of a turbine runner or cylinder can enhance its wear resistance and double its service life. When used to produce refractory materials, it offers excellent heat resistance, compact size, light weight, and high strength, resulting in good energy-saving effects. Low-grade silicon carbide (containing about 85% SiC) serves as a good deoxidizer, accelerating the steelmaking process and facilitating the control of chemical composition, thereby improving the quality of steel. Additionally, silicon carbide is extensively used in the production of electrical heating elements like silicon carbide rods.

Silicon carbide has high hardness, excellent thermal conductivity, is a semiconductor, and can resist oxidation at high temperatures.

Silicon carbide (SiC) is produced by high-temperature smelting in a resistance furnace from raw materials such as quartz sand, petcoke (or coke), and wood shavings. Silicon carbide also exists in nature as a rare mineral, moissanite.

Silicon carbide, also known as carborundum, is widely used and economically viable among the advanced refractory raw materials like carbon, nitrogen, and boron, which are non-oxides. It can be referred to as either steel slag sand or refractory sand.

Silicon carbide is produced by smelting quartz sand, petcoke (or coal coke), and wood shavings (with salt added for green silicon carbide production) in a resistance furnace at high temperatures. In China, industrially produced silicon carbide is available in two types: black and green, both of which are hexagonal crystals with a specific gravity of 3.20 to 3.25 and a microhardness of 2840 to 3320 kg/mm².

Including black silicon carbide and green silicon carbide, among which: Green silicon carbide is produced primarily from petcoke and quartz stone, with added salt as an additive, through high-temperature smelting in a resistance furnace. It has a hardness between corundum and diamond, and a higher mechanical strength than corundum. Common silicon carbide abrasives come in two different crystals: green silicon carbide, containing over 97% SiC, primarily used for grinding hard gold-containing tools. The other is black silicon carbide, with a metallic luster, containing over 95% SiC, stronger than green silicon carbide but with lower hardness, mainly used for grinding cast iron and non-metallic materials.

Black silicon carbide is produced from quartz sand, pet coke, and high-quality silicon stone, refined through high-temperature smelting in a resistance furnace. It has a hardness between that of corundum and diamond, with higher mechanical strength than corundum, and is brittle yet sharp.

Silicon carbide comes in two common types: black silicon carbide and green silicon carbide, both belonging to α-SiC. ① Black silicon carbide contains about 98.5% SiC and has higher toughness than green silicon carbide, making it suitable for processing materials with low tensile strength, such as glass, ceramics, stone, refractory materials, cast iron, and non-ferrous metals. ② It has excellent self-sharpening properties and is commonly used for processing hard alloys, titanium alloys, and optical glass, as well as for honing cylinder liners and finishing high-speed steel cutting tools. Additionally, there is cubic silicon carbide, which is a yellow-green crystal obtained through special processes. The abrasive tools made from it are suitable for ultra-fine machining of bearings, capable of reducing surface roughness from Ra32 to 0.16 micrometers in a single pass to Ra0.04 to 0.02 micrometers.