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The Material Structure and Properties of Silicon Carbide Sintered at Atmospheric Pressure
Release time:
2022-01-19
Among modern high-tech refractory raw materials such as C, N, and B—non-oxide materials— Atmospheric-pressure sintered silicon carbide It is widely used and economically viable—often referred to as carborundum or refractory sand. Pure silicon carbide is a colorless, transparent crystal. So what are the material structure and properties of silicon carbide? Below, we’ll introduce you to pressureless sintered silicon carbide!
Material structure of silicon carbide sintered under atmospheric pressure:
For industrial use Atmospheric-pressure sintered silicon carbide Depending on the type and content of impurities, silicon carbide can appear in shades of pale yellow, green, blue, or black; its transparency varies with differing degrees of purity. The crystal structure of silicon carbide is classified into hexagonal or rhombohedral polytypes and cubic polytype-SiC. Due to differences in the stacking order of carbon and silicon atoms within their crystal structures, polytype-SiC exhibits numerous polymorphs—more than 70 have been identified. Beta-SiC transforms into alpha-SiC above 2100°C. Industrially, silicon carbide is produced by refining high-quality quartz sand and petroleum coke in a resistance furnace. The refined silicon carbide blocks are then crushed, subjected to acid-alkali cleaning, magnetic separation, sieving, or water sorting to yield products of various particle sizes.
Material properties of silicon carbide sintered at atmospheric pressure:
Silicon carbide boasts excellent chemical stability, thermal conductivity, thermal expansion coefficient, and wear resistance. Therefore, in addition to its use as an abrasive material, it has a wide range of other applications. For example, when silicon carbide powder is applied using a special process to the inner surfaces of turbine impellers or cylinder blocks, its wear resistance is significantly enhanced, extending the service life by a factor of one to two. Made from high-grade refractory materials that are heat-resistant, compact in size, lightweight, and highly strong, silicon carbide offers outstanding energy efficiency. Lower-grade silicon carbide (containing approximately 85% SiC) serves as an excellent deoxidizer, accelerating steelmaking processes and enabling easy control of chemical composition to improve steel quality. Moreover, atmospheric-pressure sintered silicon carbide is extensively used in the manufacture of electrical components, such as silicon-carbon rods.
Silicon carbide is extremely hard. Its Mohs hardness rating is 9.5, second only to that of the world’s hardest material—diamond (which rates a perfect 10). It is a semiconductor with excellent thermal conductivity and can resist oxidation even at high temperatures. Silicon carbide has at least 70 different crystalline forms. Plutonium silicon carbide is a common polymorph that forms at temperatures above 2000°C; it features a hexagonal crystal structure (similar to that of wurtzite). Silicon carbide sintered under atmospheric pressure...
Applications of Silicon Carbide in the Semiconductor Industry
The silicon carbide semiconductor industry chain primarily includes high-purity silicon carbide powder, single-crystal substrates, epitaxial wafers, power components, module packaging, and end-use applications.
1. Single-crystal substrates serve as supporting materials, conductive materials, and epitaxial growth substrates for semiconductors. Currently, the methods for growing SiC single crystals include the physical vapor transport (PVT) method, the liquid-phase epitaxy (LPE) method, and the high-temperature chemical vapor deposition (HTCVD) method. Atmospheric-pressure sintering of silicon carbide.
2. Epitaxial silicon carbide wafers—single-crystal films (epitaxial layers) grown on silicon carbide substrates, with the crystal orientation of the substrate being consistent with certain requirements for silicon carbide substrates. In practical applications, wide-bandgap semiconductor devices are almost always fabricated using epitaxial layers; silicon wafers themselves are used solely as substrates, including those serving as substrates for GaN epitaxial layers.
3. High-purity silicon carbide powder—high-purity silicon carbide powder is the raw material used to grow silicon carbide single crystals via the PVT method. The purity of the product directly affects the growth quality and electrical properties of the silicon carbide single crystals.
4. Power devices made from silicon carbide materials offer wide-bandwidth power capabilities and exhibit characteristics of high temperature, high frequency, and high efficiency. Depending on the device’s operating mode, SiC power devices primarily include power diodes and power switching transistors.
5. In third-generation semiconductor applications, silicon carbide semiconductors offer advantages that complement those of gallium nitride semiconductors. Thanks to their high conversion efficiency, low heat generation, and lightweight characteristics, demand from downstream industries continues to rise, and there is a growing trend toward replacing SiO2 devices with SiC devices.
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