Silicon Carbide

Silicon carbide ceramics not only have excellent mechanical properties at room temperature, such as high flexural strength, excellent oxidation resistance, good corrosion resistance, high wear resistance and low friction coefficient, but also high temperature mechanical properties (strength, creep resistance) properties, etc.) is the best known ceramic materials. The high temperature strength of hot pressing sintering, pressureless sintering and hot isostatic pressing sintered materials can be maintained up to 1600 ℃, which is the material with the best high temperature strength among ceramic materials. The oxidation resistance is also the best among all non-oxide ceramics.

Silicon carbide ceramics have excellent mechanical properties, excellent oxidation resistance, high wear resistance and low friction coefficient. The disadvantage of SiC ceramics is that the fracture toughness is low, that is, the brittleness is relatively large. For this reason, multiphase ceramics based on SiC ceramics, such as fiber (or whisker) reinforcement, heterogeneous particle dispersion strengthening, and gradient functional materials have appeared one after another. , which improves the toughness and strength of the monomer material.

Core performance of silicon carbide ceramic materials

1. High temperature stability

High temperature strength: The bending strength remains 500-600 MPa at 1600℃, far exceeding that of alumina (the strength at 1400℃ drops significantly), and is suitable for scenes such as aircraft engine turbine blades.

Antioxidation: A dense SiO₂ protective film is formed at high temperatures, and the anti-oxidation performance is better than most non-oxide ceramics.

1. Mechanical properties

Hardness and wear resistance: The hardness reaches 2400–2800 HV, the friction coefficient is low, and it is widely used in wear-resistant parts such as sealing rings and bearings.

Brittle defects: The fracture toughness is low, and the toughness needs to be improved by fiber reinforcement (such as carbon fiber) or particle dispersion (such as graphite).

2. Thermal and electrical properties

Thermal conductivity: The thermal conductivity is 120–200 W/m·K (second only to beryllium oxide in ceramics), suitable for heat dissipation substrates of high-power devices.

Conductive adjustability: The insulator → conductor transformation is achieved through doping (conductivity 10²–10⁵ S/m), which is used for high-temperature electrodes and semiconductor devices.

Low thermal expansion coefficient: Reduce thermal stress cracks and improve thermal shock resistance.

Application

High temperature and energy fields

Aerospace: turbine blades, combustion chamber components (resistant to 1700℃ gas).

Energy equipment: gas turbine components, nuclear reactor cores (radiation resistance, corrosion resistance).

Heating elements: high-temperature furnace heat exchangers, thermocouple sleeves (thermal conductivity + oxidation resistance).

Electronics and semiconductors

Heat dissipation substrates: 5G base stations, high-power LED heat sinks (high thermal conductivity + insulation).

Wafer manufacturing: lithography machine worktable, ceramic suction cup (low thermal expansion + high rigidity).

Grinding parts: SiC grinding disc (hardness matches silicon wafer, improves polishing accuracy).

Chemical and mechanical

Corrosion-resistant parts: magnetic pump sealing ring, desulfurization nozzle (resistant to strong acid/alkali).

Wear-resistant parts: nozzle, bearing (life is 3-5 times that of alumina).

Special protection and optics

Bulletproof armor: lightweight bulletproof plate (ballistic performance reaches 70-80% of boron carbide, lower cost).

Space reflector: low expansion coefficient + high rigidity, used for remote sensing satellites.

Silicon carbide ceramics have become the core materials of high-end industries such as aerospace, semiconductors, and new energy due to their extreme environmental adaptability (high temperature, corrosion, wear) and adjustable functional characteristics (thermal/electrical conductivity).