Silicon carbide (SiC) is a remarkable compound of carbon and silicon, initially produced through a high-temperature electrochemical reaction between sand and carbon. Its exceptional properties—including high-temperature strength, oxidation resistance, thermal shock resistance, and hardness—make it one of the most promising structural materials for diverse applications. SiC's superior performance stems from its unique atomic structure: tetrahedra of carbon and silicon atoms forming extremely strong bonds within the crystal lattice. This material has evolved from a simple abrasive to an advanced technical ceramic used in everything from grinding wheels to semiconductor components, with ongoing development expanding its structural and wear applications across multiple industries.
Silicon carbide (SiC) stands as one of the most promising structural materials for mechanical and thermomechanical applications. This exceptional compound—the only chemical combination of carbon and silicon—offers an impressive suite of properties: excellent high-temperature strength, superior oxidation resistance, exceptional thermal shock resistance, remarkable hardness, and low specific weight. Originally produced through a high-temperature electrochemical reaction of sand and carbon, SiC has evolved significantly since its discovery.
For over a century, silicon carbide has served as an excellent abrasive in grinding wheels and similar products. Today, it has developed into a high-quality technical ceramic with outstanding mechanical properties. Its applications span numerous fields, including abrasives, refractories, ceramics, and various high-performance uses. When processed appropriately, SiC can function as an electrical conductor, making it valuable for resistance heating, flame igniters, and electronic components. The development of structural and wear applications continues to expand, showcasing SiC's versatility.
The exceptional properties of silicon carbide derive from its fundamental atomic structure. The material consists of tetrahedra of carbon and silicon atoms forming extremely strong bonds within the crystal lattice. This arrangement creates a material with remarkable hardness and strength. The strong covalent bonds also contribute to SiC's chemical stability and resistance to extreme temperatures.
Silicon carbide is derived from powder or grain, produced through carbon reduction of silica. The initial product forms either as fine powder or as a large bonded mass that requires crushing. Purification involves washing with hydrofluoric acid to remove residual silica.
Commercial silicon carbide products are fabricated through three primary methods:
Each production method suits different applications, allowing manufacturers to tailor SiC products to specific requirements.
Silicon carbide exhibits numerous beneficial properties that make it ideal for demanding applications:
Table 1. Common values of Silicon Carbide properties
Property | SI Units | Values |
Physical/Mechanical | ||
Density | g/m³ | 3.1 |
Porosity | % | 0 |
Color | - | Black |
Flexural strength | MPa | 550 |
Elastic Modulus | GPa | 410 |
Shear Modulus | GPa | - |
Bulk Modulus | GPa | - |
Poisson’s ratio | - | 0.14 |
Compressive strength | MPa | 3900 |
Hardness | Kg/mm² | 2800 |
Fracture toughness KIc | MPa·m1/2 | 4.6 |
Max use temperature | °C | 1650 |
Thermal Properties | ||
Thermal Conductivity | W/m·K | 120 |
Coefficient of Thermal Expansion | 10⁻⁶/°C | 4.0 |
Specific heat | J/kg·K | 750 |
Electrical | ||
Volume Resistivity | Ohm·cm | 102 - 106 |
Silicon carbide's resistance to chemical attack is particularly notable. It remains unaffected by acids, alkalis, or molten salts up to 800°C. When exposed to air at 1200°C, SiC forms a protective silicon oxide coating, enabling use at temperatures up to 1600°C. The combination of high thermal conductivity with low thermal expansion and high strength gives this material exceptional thermal shock resistance.
Silicon carbide ceramics with minimal grain boundary impurities maintain their strength at extremely high temperatures, approaching 1600°C without degradation. This remarkable temperature stability makes SiC increasingly valuable for advanced applications.
The exceptional properties of silicon carbide have led to its adoption across numerous industries:
Chemical purity, resistance to chemical attack at elevated temperatures, and strength retention at high temperatures have made SiC popular for wafer tray supports and paddles in semiconductor furnaces.
The electrical conductivity of the material has led to its use in resistance heating elements for electric furnaces and as a key component in thermistors (temperature-variable resistors) and varistors (voltage-variable resistors).
Silicon carbide excels in applications requiring high performance under extreme conditions:
Monolithic SiC ceramics and SiC-based ceramic composites show promise for thermonuclear fusion reactor applications. Silicon carbide fiber-reinforced composites offer particular advantages, including low radioactivity through neutron transmutations, high stability after reactor shutdown, excellent high-temperature properties, low plasma contamination, and low specific weight.
Figure 1: Silicon Carbide products
Silicon carbide continues to demonstrate its value as an advanced material for challenging applications. Its unique combination of properties—thermal resistance, chemical stability, mechanical strength, and electrical characteristics—ensures its ongoing importance in established and emerging technologies. As manufacturing techniques continue to advance, we can expect to see silicon carbide playing an increasingly vital role in high-performance applications across multiple industries.
Total Materia Horizon contient les propriétés mécaniques et physiques de centaines de milliers de matériaux, à différentes températures, formes de livraison, conditions métallurgiques, et bien plus.
Profitez d’un compte d’évaluation GRATUIT sur Total Materia Horizon et rejoignez notre communauté qui compte plus de 500.000 utilisateurs dans plus de 120 pays.