Introduction of Silicon Carbide Ceramic

Silicon Carbide (SiC or Carborundum) is a strong material with exceptional thermal performance. Silicon carbide ceramics are characterized by great hardness, high thermal conductivity, low coefficient of thermal expansion, excellent thermal shock resistance, and impressive resistance to corrosion and wear.

SiC ceramics find application in a variety of industries. It is used in the production of heaters in the metallurgical and refractory industries. Additionally, this tough ceramic is often applied to manufacture wear-resistant components and wear parts. SiC ceramics are also employed in the automotive and semiconductor industries.

Figure 1. Silicon Carbide Powder

Now let’s talk once again about Silicon Carbide ceramics and start this article with how they are made.

1. Reaction Bonded Silicon Carbide (RBSC)

Reaction bonding is one of the earliest methods of manufacturing silicon carbide ceramics. The manufacturing process is listed as follows.

1. First, mix and heat coarse silicon carbide, silicon, and plasticizer.
2. Next, make the combination into the desired shape.
3. Burn these materials and prepare them for further processing.
4. Completing these steps will result in an inexpensive and easily machinable silicon carbide ceramic.

Reaction Bonded Silicon Carbide is manufactured on a large scale in many areas. Due to the low manufacturing cost, this method has many potential applications. RBSC has good thermal shock resistance and is used to make kiln furniture. This ceramic is also used as wear parts due to its excellent resistance to wear, corrosion, and high temperatures. 

Yet, RBSC has some limitations. It ends up with a lot of free silicon, which adversely affects the quality of the final product. Also, RBSC only applies to low temperatures. Be sure to adjust the heating chamber to 1400°C or less.

2. Sintered Silicon Carbide (SSC)

SSC is a traditional manufacturing method that can be used at high temperatures.

1. First, mix fine and pure silicon carbide powder with a non-oxide sintering aid.
2. These raw materials are then heated and ground to the desired tolerance using diamond precision grinding technology.
3. Make sure the whole process is done at 2000℃.
4. SiC ceramics with high purity and low porosity are made by sintering.

• SSC is the best option for manufacturing sealing parts due to its wear and corrosion resistance. For vehicles, there are sintered silicon carbide seal faces that meet US and European requirements. We also have many SSC mechanical seals and pumps.
• SSC has been found in bulletproof vests because of its high hardness and low density.
• SSC is the best material for nozzles and valves with a longer service life and excellent corrosion resistance.

3. Recrystallized Silicon Carbide (RSIC)

High-purity silicon carbide ceramics can also be obtained by recrystallization. Recrystallized Silicon Carbide (RSIC) is manufactured in three steps.

• First, prepare high-purity silicon carbide which is not crystallized yet.
• Heat the mixture to a high temperature of 2000℃.
• RSIC is then obtained through evaporation and aggregation.

RSIC ceramic has several advantages. First, these silicon carbide ceramics have superior thermal conductivity and thermal shock resistance compared to other superior manufacturing methods. It also has a high porosity (10-15%), which results in very low shrinkage. 

Conclusion

Silicon carbide ceramics have a variety of manufacturing processes and are used in many industries. These major methods involve reactive bonding that occurs at low temperatures. Sintering occurs at high temperatures. Recrystallization yields higher-purity silicon carbide products. If you have any trouble choosing the SiC ceramic type suitable for your application, please contact our sales team for further recommendations. 

Advanced Ceramic Materials (ACM) offers quality silicon carbide ceramics manufactured by a variety of manufacturing methods. Send us an inquiry if you are interested.