In modern industrial, metallurgical, and semiconductor sectors, Silicon Carbide (SiC) plays an indispensable role. As a synthetically produced compound, it is highly valued for its extreme hardness, excellent thermal conductivity, and chemical stability. Today, SiC is widely utilized in abrasives, refractory materials, and rapidly growing new energy sectors.
This comprehensive guide will walk you through the core definition, primary classifications, and rigorous manufacturing process of Silicon Carbide, helping you make informed decisions for your procurement and application needs.
What is Silicon Carbide?
Silicon Carbide, commonly referred to in the industry as Carborundum, is a covalent compound composed of silicon and carbon (Chemical Formula: SiC).
SiC is highly favored across various industries due to its outstanding physical and chemical properties:
? Extreme Hardness: With a Mohs hardness of 9.5, it is second only to boron carbide and diamond, making it an ideal abrasive material.
? High Thermal Conductivity: It dissipates heat rapidly and maintains structural stability even at extreme temperatures.
? Chemical Inertness: Highly resistant to acids, alkalis, and oxidation at high temperatures.
? Thermal Shock Resistance: Capable of withstanding drastic temperature changes without fracturing.
In recent years, beyond traditional abrasives and refractories, Silicon Carbide has emerged as a new-type strong composite deoxidizer in metallurgy—replacing traditional silicon-carbon powders. Furthermore, it shows massive potential in LED semiconductor substrates and EV power electronic devices.
Primary Classifications of Silicon Carbide
In industrial applications, Silicon Carbide is generally categorized into three main types based on raw materials, crystal structure, and color:
1. Black Silicon Carbide (Black SiC)
Black SiC typically contains over 95% SiC. It offers higher toughness but slightly lower hardness compared to its green counterpart. Due to its microstructure, Black SiC is primarily used for processing materials with lower tensile strength, such as cast iron, non-ferrous metals (copper, aluminum), stone, glass, ceramics, and non-metallic refractories.
2. Green Silicon Carbide (Green SiC)
Green SiC has a higher purity, typically containing over 97% SiC. It is harder and more brittle than Black SiC, featuring excellent thermal conductivity and semiconductor properties. Green SiC is predominantly used for processing hard and brittle materials, such as cemented carbides, optical glass, precision cutting tools, and high-end ceramic glazes.
3. Cubic Silicon Carbide (Cubic SiC / β-SiC)
This is a yellow-green microcrystalline powder synthesized through special processes. It possesses extreme purity and fine grinding capabilities. Grinding tools made of Cubic SiC are specifically designed for super-precision machining of bearings, achieving a mirror-like surface roughness of Ra 0.04-0.02 micrometers.
*(Note: Structurally, SiC is divided into α-SiC [hexagonal/rhombohedral structure, like black/green SiC] and β-SiC [cubic structure].)*
How is Silicon Carbide Produced?
The production of industrial-grade Silicon Carbide is a highly energy-intensive and technically demanding process. The most mainstream method used globally is the Acheson Process. The entire workflow consists of four core steps:
Step 1: Raw Material Mixing and Furnace Loading
The core raw materials include:
Silica (SiO2): Typically high-purity quartz sand.
Carbon (C): Typically petroleum coke or anthracite coal.
Additives: Wood chips (to increase gas permeability) and salt (to remove impurities like aluminum oxide and iron oxide).
These materials are strictly proportioned and packed around large graphite electrodes inside a massive resistance furnace.
Step 2: High-Temperature Smelting Reaction
Once powered on, the internal temperature of the furnace rapidly climbs to between 1700°C and 2500°C. Under these extreme conditions, the silica is reduced by carbon, triggering the core chemical reaction:
SiO? + 3C → SiC + 2CO↑
Step 3: Cooling and Crystallization
After dozens of hours of reaction, the power is cut, and the furnace enters a long natural cooling phase. During this time, SiC vapor crystallizes around the core, eventually forming a massive, solid cylindrical ingot. This ingot features distinct radial layers:
Outer Layer: Unreacted raw materials and impurities.
Middle Layer: Metallurgical-grade SiC and some β-SiC.
Inner Layer: High-purity, coarse-crystal α-SiC (the commercially viable Black/Green SiC).
Core: A highly graphitized core.
Step 4: Sorting, Crushing, and Processing
After cooling, skilled workers perform precise manual sorting to strip away the useless outer layers and extract the high-grade SiC crystals.
These lumps are then sent to crushers for size reduction, followed by water washing and acid washing (chemical processing) to remove residual impurities. Finally, advanced screening systems classify the material into specific grit sizes (e.g., F16 to F1200 micro-powders) before being packaged as finished products.
Conclusion
Understanding the definition, classifications, and production process of Silicon Carbide is the first step toward smart procurement. Different application scenarios—whether for deoxidization, refractories, grinding, or semiconductors—require vastly different SiC purities, grit sizes, and crystal morphologies.
As a professional Silicon Carbide supplier, LSFerroalloy strictly controls every stage from raw material selection to final crushing and screening, providing Black and Green SiC products that meet international standards.
Need the latest Silicon Carbide prices or detailed technical data sheets? Contact us today.