Main Production Methods of SIlicon Carbide Ceramics

Introduction to Silicon Carbide Ceramics

Silicon Carbide (SiC, or carborundum) is a strong material with great thermal performance. Silicon carbide ceramics stand out for their great hardness, which is second only to diamonds. SiC also offers high thermal conductivity, low thermal expansion index, and remarkable thermal shock resistance. It is known for corrosion resistance and abrasion resistance as well.

Because of these properties, silicon carbide ceramics found application in many industries. SiC is applied to make heating devices in metallurgy and refractories. Additionally, this tough ceramic is commonly used to make anti-abrasion components and wear parts. You can also find SiC ceramics in the automotive and semiconductor industry.

Here, we are going to have a further discussion about silicon carbide ceramics, and this article will start with their production methods.

1.   Reaction-bonded Silicon Carbide (RBSC)

Reaction bonding is one of the earliest methods to make silicon carbide ceramics. The manufacturing process of reaction-bonded silicon carbide (RBSC) can be divided into the following steps.

• First, combine coarse silicon carbide, silicon, and plasticizers and then heat them.
• Second, form the combination into a desirable shape.
• Burn off these materials and set them for further machining.

You can get cost-effective and easily machineable silicon carbide ceramics after completing these steps.

Reaction-bonded silicon carbide is produced at large scale for numerous fields. This method has a range of applications for its lower production cost. RBSC is used to make heating devices like kiln furniture thanks to its thermal shock resistance. Such ceramic is manufactured for wear components as well because of its good resistance to wear, corrosion, and high temperature. It is also an ideal choice for seals and vanes.

However, RBSC has some limits. First, it is also called siliconized silicon carbide (SiSiC) because there is lots of free silicon left at last, which hurts the quality of the final products. Besides, RBSC only applies to low temperatures. Remember to control the heating chamber under 1400℃.

2.   Sintered Silicon Carbide (SSC)

Sintering is another traditional manufacturing method, and it could be applied to higher temperatures.

• To get sintered silicon carbide (SSC), mix fine and pure silicon carbide powder and non-oxide sintering aids first.
• Thereafter, heat these raw materials and polish them to desired tolerances using precision grinding techniques for diamonds.
• Make sure the whole process takes place at 2000℃.

Silicon carbide ceramics of high purity and low porosity are formed through sintering, and they are employed for various sectors.

• SSC is a perfect option to make sealing components for its resistance to abrasion and corrosion. You can find seal faces made from sintered silicon carbide for vehicles, which meet the demands of the United States and Europe. There are lots of SSC mechanical seals and pumps as well.
• You can find SSC in bulletproof vests. Because of their high hardness and low density, SSC can withstand high-speed projectiles like bullets, missiles, and shrapnel.
• SSC is a great material for nozzles and valves. SSC nozzles have a longer life (50% over tungsten carbide nozzles). Sintered silicon carbide is also applied to make valves in harsh environments due to its outstanding corrosion resistance.

3.   Recrystallized Silicon Carbide (RSIC)

We also get high-purity silicon carbide ceramics through recrystallization. Recrystallized silicon carbide (RSIC) is produced in three steps.

• First, prepare highly pure silicon carbide in advance.
• Heat the mixture to a high temperature of 2000℃.
• Then, you can get RSIC after evaporation and conglomeration.

Recrystallized silicon carbide ceramics have several advantages. First, these silicon carbide ceramics have better thermal conductivity and thermal shock resistance compared with other prime production methods. Also, because of its high porosity (10-15%), it has very low shrinkage. Thus, related drawbacks could be avoided. With these properties, recrystallization serves as a great means to produce silicon carbide ceramics for different industries.

Conclusion

Silicon carbide ceramics have various manufacturing methods, and they are applied to several industries. Among these key methods, reaction bonding occurs at lower temperatures; sintering takes place at higher temperatures; recrystallization comes with silicon carbide products of higher purity. If you have problems choosing which type of SiC ceramics for your application, please send an inquiry to our Sales team for further recommendation. Advanced Ceramic Materials (ACM) provides quality silicon carbide ceramics obtained from different production methods. Hope that you can find suitable silicon carbide materials on our website.