The superior performance of silicon carbide stems from its covalent crystal structure (silicon atoms are tightly bonded to carbon atoms, with a bond energy as high as 432 kJ/mol). Its core advantages are as follows:
Ultra-high hardness and wear resistance: With a Mohs hardness of 9.2-9.5, second only to diamond, and a microhardness of 2800-3300 HV, its wear resistance is 10-20 times that of ordinary steel, capable of withstanding strong friction and impact, making it suitable for wear-resistant parts applications.
Excellent high-temperature stability: With a melting point as high as 2700℃, it remains stable in air environments below 1600℃ without significant oxidation deformation; its coefficient of linear expansion is only 4.5 × 10⁻⁶/℃ (20-1000℃), far lower than that of metallic materials, exhibiting excellent dimensional stability at high temperatures.
Strong chemical corrosion resistance: It does not react with conventional corrosive media such as acids, alkalis, and salts at room temperature, only reacting slightly with a mixture of concentrated nitric acid and hydrofluoric acid at high temperatures, making it suitable for highly corrosive chemical environments.
Excellent thermal conductivity and electrical properties: Room temperature thermal conductivity reaches 120-200 W/(m·K), which is 3-5 times that of ordinary ceramics and 4-6 times that of steel, resulting in outstanding heat dissipation efficiency. As a semiconductor material, its bandgap (3.26 eV) is 3 times that of silicon, and its breakdown electric field strength is 10 times that of silicon, making it suitable for high-voltage and high-frequency electronic devices.
High mechanical strength and impact resistance: Room temperature flexural strength reaches 400-500 MPa, and fracture toughness is 3-5 MPa·m¹/², exhibiting stronger impact resistance and less brittleness than traditional ceramic materials.
Core Types of SiC Materials (Subdivided by Classification Dimensions)
(1) Classification by Color and Purity (Most Commonly Used in Industry)
| Type | Core Component (SiC Purity) | Key Characteristics | Typical Application Scenarios |
| Black silicon carbide | 95%-97% | High toughness, moderate cost | Used for processing low tensile strength materials (glass, ceramics, stone, cast iron), manufacturing grinding wheels, and sandblasting abrasives |
| Green silicon carbide | ≥97% (high purity up to 99%) | Higher hardness, better self-sharpening properties | For machining high-hardness materials (hard alloys, titanium alloys, high-speed steel) and precision grinding (bearing ultra-precision machining, optical glass polishing) |
(2) Classification by Crystal Structure (Determines Performance Differences)
α-SiC (Hexagonal Crystal):
High-temperature stable phase (stable above 1400℃), the main form of industrial silicon carbon alloy, possessing high hardness and high-temperature strength, suitable for structural materials and high-temperature components (such as furnace liners, rocket nozzles);
β-SiC (Cubic Crystal):
Low-temperature phase (stable below 1400℃), synthesized through special processes, with a uniform crystal structure and superior semiconductor performance, suitable for electronic devices and third-generation semiconductor chip substrates;
γ-SiC (Cubic Crystal):
A rare low-temperature variant, requiring extremely high purity, mainly used in scientific research and high-end electronics fields.
(3) Classification by Product Form (Adapted to Different Application Scenarios)
Powder:
size 100-3000 mesh, used in abrasives, ceramic raw materials, and metallurgical deoxidizers;
Blocks/Plates:
Used in furnace liners, supports, and high-temperature structural components;
Ceramic Products:
Molded components such as sealing rings, bearings, and thermocouple protection tubes;
Semiconductor Wafers:
High-purity β-SiC single crystal wafers, used in the manufacture of power devices and RF devices.
Typical Application Scenarios of Silicon Carbide Materials (Subdivided by Industry)
(1) Machinery and Abrasive Industry
Utilizing high hardness and wear resistance, it is used to manufacture grinding wheels, cutting discs, and sandblasting abrasives for the processing of metals, stone, and glass;
Producing wear-resistant ceramic sealing rings and bearings, suitable for rotating machinery such as water pumps and valves, with a service life 5-10 times that of metal seals.
(2) Metallurgy and High-Temperature Industries
As high-temperature components such as furnace liners, crucibles, and trays, it is suitable for high-temperature scenarios below 1600℃, such as non-ferrous metal smelting and semiconductor material synthesis;
Used in aluminum electrolysis cells and zinc powder furnace arc plates, utilizing its high-temperature resistance and corrosion resistance to extend equipment lifespan.
(3) Electronics and Semiconductor Industries
High-purity β-SiC wafers are used to manufacture high-voltage power devices (such as new energy vehicle inverters and photovoltaic inverters), reducing energy consumption and increasing power density;
As a substrate for radio frequency devices, it is suitable for high-frequency scenarios such as 5G communication and satellite communication.
(4) Aerospace and High-End Manufacturing
Manufacturing high-temperature components such as rocket nozzles and gas turbine blades, which withstand extreme temperatures above 2000℃ and airflow impact;
Used in high-temperature coatings for aero-engines, improving the high-temperature oxidation resistance and wear resistance of components.
(5) Chemical Industry
Production of corrosion-resistant pipes, valves, and heat exchangers, suitable for conveying and reacting strong acids, strong alkalis, and high-temperature media;
As a catalyst carrier, utilizing its high specific surface area and chemical stability to improve catalytic reaction efficiency.
Selection Principles for Different Types of Silicon Carbide
Selection based on "hardness requirements":
Select green silicon carbide for processing high-hardness materials, and black silicon carbide for general processing;
Selection based on "temperature scenarios":
Select α-SiC for high-temperature structural parts above 1400℃, and β-SiC for electronic devices;
Selection based on "morphological requirements":
Select powder form for abrasives and deoxidizers, block/plate form for structural parts, and ceramic products for precision components.
