Silicon carbide (SiC), also known as silicon carbide or corundum, is a compound composed of silicon and carbon. Here are some key facts about silicon carbide:

• Structure: Silicon carbide has a variety of crystal structures, the most common of which are α-SiC and β-SiC. α-SiC has a hexagonal structure, while β-SiC has a cubic structure.
• Hardness: As mentioned earlier, silicon carbide is very hard, second only to diamond and cubic boron nitride. It is usually rated 9 to 9.5 on the Mohs hardness scale.
• application:
  • Abrasives: Due to its extremely high hardness, silicon carbide is often used in abrasives such as sandpaper, grinding wheels, etc.
  • Semiconductors: Silicon carbide has a wide range of applications in high-temperature, high-frequency, and high-power electronic devices because it can maintain its electrical properties under extreme conditions.
  • Refractory materials: Due to its high melting point (about 2730 degrees Celsius), silicon carbide is used as a refractory material and high-temperature structural material.
  • Ceramics: Silicon carbide ceramics are used to manufacture bearings, seals, and automotive parts due to their high hardness and wear resistance.
• Manufacturing: Silicon carbide can be manufactured by several methods, the most common of which is to react silicon dioxide (such as quartz sand) with carbon (such as coke) at high temperatures to produce SiC.
• Properties: In addition to hardness, silicon carbide also has high thermal conductivity, low coefficient of thermal expansion, chemical stability and corrosion resistance.

Silicon carbide rod

is silicon carbide a ceramic​

Yes, Silicon Carbide (SiC) can be considered a ceramic material.

• Definition: Ceramics usually refer to materials made of inorganic non-metallic materials (such as oxides, nitrides, carbides, etc.) through high-temperature sintering. Silicon carbide meets this definition.
• Properties: Silicon carbide has many typical ceramic properties, including:
  • High hardness: As mentioned before, silicon carbide is very hard.
  • High melting point: about 2730 degrees Celsius, much higher than the melting point of most metals.
  • High temperature resistance: Silicon carbide maintains its physical and chemical properties at high temperatures.
  • Corrosion resistance: It has good corrosion resistance to most chemicals.
  • Low thermal expansion coefficient: This means that silicon carbide changes less in volume when the temperature changes.
• Application: In the application of ceramics, silicon carbide is used to make refractory materials, wear-resistant ceramics, structural ceramics, electronic ceramics, etc. For example:
  • Structural ceramics: used to manufacture bearings, seals, cutting tools, etc.
  • Electronic ceramics: used as substrate materials or packaging materials in semiconductor devices.

is silicon carbide harder than aluminum oxide​

Yes, Silicon Carbide (SiC) is harder than Aluminum Oxide (Al₂O₃). The Mohs hardness of Silicon Carbide is between about 9 and 9.5, while the Mohs hardness of Aluminum Oxide is usually around 9. Therefore, Silicon Carbide is generally considered to be a harder material than Aluminum Oxide.

Silicon carbide plate

how is silicon carbide made​

how to make silicon carbide​? There are many ways to prepare silicon carbide (SiC). Here are some of the main production processes:

1. Acheson Process:
   • Raw materials: Quartz sand (mainly silicon dioxide, SiO₂), coke (carbon, C) and salt.
   • Process: Mix quartz sand and coke, add a small amount of salt (as a flux), and then heat to about 2000-2500 degrees Celsius in an electric furnace. A temperature gradient is formed inside the electric furnace, with the highest temperature in the center and lower temperature at the edge. At high temperature, SiO₂ in quartz sand reacts with C in coke to form SiC:
     [
     SiO₂ + 3C \rightarrow SiC + 2CO \uparrow
     ]
   • Product: The obtained SiC grains are of different sizes and need further processing.
2. Chemical Vapor Deposition (CVD):
   • Gas source: Use gases such as silane (SiH₄) and methane (CH₄) as reactants.
   • Process: At high temperature (usually 1000-1500°C) and low pressure, the gas is decomposed by chemical reaction, and Si and C atoms are deposited on the surface of the substrate to form a SiC film or coating.
   • Application: Used to manufacture high-purity, fine-structured SiC materials, such as semiconductor devices.
3. Sol-Gel Process:
   • Raw materials: Use organic precursor solutions containing silicon and carbon, such as tetraethoxysilane (TEOS).
   • Process: Form SiC particles or films through steps such as hydrolysis, condensation, gelation and sintering.
4. Laser Sintering:
   • Method: Use laser to quickly heat and cool SiC powder to achieve rapid sintering.
5. Liquid phase method:
   • Raw materials: Use liquid precursors, such as polycarbosilane (PCS).
   • Process: The liquid precursor is heated to polymerize, crosslink, and eventually convert into SiC.
6. Reaction sintering:
   • Method: SiC powder is mixed with silicon (Si), and after a sintering process, Si and C react to form SiC.

Silicon carbide pillar

what is silicon carbide used for​

1.Abrasive

• Sandpaper and grinding tools: Silicon carbide is used as an abrasive due to its high hardness to make sandpaper, grinding wheels, grinding stones, etc.
• Polishing: Used for polishing metals, glass, ceramics and other materials.

2.Refractory Materials

• Kiln lining: Due to its high melting point and high temperature resistance, silicon carbide is used as a lining material for kilns.
• High temperature structural material: Silicon carbide can maintain its mechanical strength in high temperature environments.

3. Semiconductor Materials

• Electronic devices: Silicon carbide has excellent electrical properties and is suitable for manufacturing high-temperature, high-frequency and high-power semiconductor devices such as MOSFET, diodes, LEDs, etc.
• Optoelectronic devices: Used to manufacture light-emitting diodes (LEDs), laser diodes, etc.

4. Ceramic Materials

• Structural ceramics: used to manufacture bearings, seals, cutting tools, heat exchangers, etc.
• Bulletproof materials: Silicon carbide ceramics have high hardness and impact resistance and are used to manufacture bulletproof vests and armor.

5. Wear-resistant coating

• Coating materials: Silicon carbide coatings are used to improve the wear resistance and corrosion resistance of components, such as turbine blades, automotive parts, etc.

6. High temperature heating elements

• Heating elements: Silicon carbide is used as a heating element material due to its high thermal conductivity and high temperature resistance.

Silicon carbide sagger

7. Metallurgical Industry

• Smelting furnace: used to make lining materials for smelting furnaces.
• Casting mold: Silicon carbide is used to make casting molds.

8. Chemicals

• Filter material: Silicon carbide ceramic filter element is used for high temperature gas filtration.
• Catalyst carrier: It is used as a carrier material for catalysts.

9. Automotive

• Brake pads: Silicon carbide is used to make high-performance brake pads.
• Engine parts: such as cylinder liners, piston rings, etc.

10. Optics

• Lenses and Windows: Silicon carbide is light-transmitting in infrared optical applications.

11. Aerospace and aviation

• High-temperature components: Silicon carbide is used to manufacture components for spacecraft and aerospace engines due to its resistance to high temperatures and corrosion.

12. energy

• Solar cells: Silicon carbide is used as a transparent conductive layer in solar cells.
• Fuel cells: As an electrode material.

The application areas of silicon carbide are still expanding, and with the development of technology, new application areas are also being explored and developed.

Silicon carbide beam