Selection of the right material for operating conditions is a challenge in high-performance material-using industries. If you are searching materials suitable for fields like aerospace, semiconductor manufacturing or wear-resistant applications, this article will explain the properties, uses and advantages of silicon carbide ceramics. You’ll learn how silicon carbide meet your demands for durability, high-temperature and wear resistance, helping you make informed decisions for your projects.

What is Silicon Carbide Ceramic?

The definition of silicon carbide is: a compound formed from carbon and silicon. The formula for silicon carbide is SiC. Silicon carbide ceramic is an inorganic non-metallic material with silicon carbide as the principal component.

Silicon carbide ceramics are also priced with great value. It is able to sustain high-temperature, corrosive and high-wear conditions. This is beneficial compared with metals and common ceramics. It is suitable for strategic industries such as aerospace, new energy and semiconductors, taking the place of common materials to conserve energy and enhance reliability, providing a huge assistance.

Major Properties of Silicon Carbide Ceramics

Being a high-performance ceramic, silicon carbide ceramics assure the best performance under severe working conditions owing to their superior characteristics.

Mechanical Properties of Silicon Carbide

• Hardness of Silicon Carbide

Silicon carbide is second only to diamond in hardness, with a Mohs hardness of 9.5, giving it excellent wear and abrasion resistance.

• Wear Resistance of Silicon Carbide

Due to its high hardness, silicon carbide presents good wear resistance. The material can withstand long exposure to abrasive environments without noticeable degradation.

• Elastic Modulus of Silicon Carbide

Silicon carbide is quite rigid, maintaining its shape under stress. It has an elastic modulus that falls between 300 to 420 GPa.

Thermal Properties of Silicon Carbide

• Thermal Conductivity of Silicon Carbide

The high thermal conductivity of silicon carbide makes it excellent in dissipating heat, hence ensuring stability from thermal stress in electronics and power systems.

• High-Temperature Stability of Silicon Carbide

Silicon carbide, with a melting point above 2700℃ and having a strength of 280 MPa at 1200℃, performs very well in high-temperature applications such as kilns.

• Thermal Expansion of Silicon Carbide

Silicon carbide has low thermal expansion, ensuring minimal dimensional change during temperature fluctuations. It enables precision in dimension accuracy for applications where such properties are needed.

Chemical Properties of Silicon Carbide

• Corrosion Resistance of Silicon Carbide

Silicon carbide is highly resistant to corrosion, with resistance to most acids, bases, and salts. Therefore, it is ideal for usage in harsh chemical surroundings within the petrochemical and energy industries.

• Oxidation Resistance of Silicon Carbide

With high temperatures, it creates a protective silica layer that enhances its durability against oxidation conditions, for instance, in furnaces or exhaust systems.

Other Properties of Silicon Carbide

• Density of Silicon Carbide

With a density of 3.1 g/cm³, silicon carbide is lighter compared to most metals, which makes it ideal in the aerospace and automotive sectors where weight sensitivity is crucial.

• Electrical Properties of Silicon Carbide

Silicon carbide’s electrical property can be modified. It acts as an insulator when it is in pure form, acts as a semiconductor when doped. The elasticity like this makes it capable of following different purposes.

• Brittleness of Silicon Carbide

Silicon carbide ceramics are not all positive. Its most known limitation is that it is brittle. Having low fracture toughness of about 3.5 MPa·m^1/2, it is prone to spontaneous fractures when subjected to impact or stress. This limits its use in dynamic environments.

Process of Silicon Carbide Ceramics

The production of silicon carbide ceramics includes several stages. Each is meticulously controlled to meet specific performance requirements.

Raw Material Preparation

It usually needs high-purity silicon carbide powder (>99% purity) mixed with sintering aids like boron, carbon, and alumina. This step can optimize densification and mechanical performance of the products.

Forming

Various methods can shape the raw materials into desired parts.

Dry Pressing: For simple shapes, like seals, nozzles.

Hot Pressing: Adds pressure to improve density and reduce grain size.

Injection Molding: For precision small parts.

Extrusion: Used for parts with uniform cross-sections, like pipes.

Sintering

Sintering densifies the material and enhances its mechanical properties. The commonly used methods include:

Reaction Sintering (RBSiC): Forms net-shaped products at lower temperatures. It is ideal for large parts, but with limited high-temperature strength.

Pressureless Sintering (PSSiC): Cost-effective method, but leads to products with lower density.

Hot Pressing (HPSiC): Applies pressure during heating to achieve higher density and improved properties.

Hot Isostatic Pressing (HIPSiC): Uses high pressure and temperature for near-complete densification, ideal for complex shapes.

Recrystallization Sintering (RSiC): Achieves dense, high-performance materials, excellent for high-temperature applications.

Spark Plasma Sintering (SPSSiC): Rapidly heats and densifies materials, ideal for nano-structured products.

Oscillatory Pressure Sintering (OPSiC): Enhances densification rate and improves mechanical properties.

Post-Processing

After sintering, precision machining (grinding, polishing, or drilling) ensures the final product meets required surface finish and dimensional accuracy. Quality control tests key parameters like density, strength, and porosity to verify reliability for specific applications.

Depending on the industry, different silicon carbide products have different processing requirements. At the end of this article, we provide some information on the customization requirements for industrial products. Please refer to the end of the article if you needed.

Application Fields of Silicon Carbide Ceramics

Because of its multi-functionality and excellent properties such as high strength, corrosion and high temperature resistance, silicon carbide ceramics possess an unreplacable location in various leading fields.

High-Temperature Applications

In applications needs long-term high-temperature operations like sintering, kilns demands highly for the heat resistance of load-bearing parts. Silicon carbide beams and rollers are increasingly becoming good alternatives. Supporting the products, they meet the stringent demands by 3 point.

First, their high-temperature strength. In kiln with temperatures ranging from 1380℃ to 1600℃, they can maintain stable mechanical properties. Their bending strength remains high at 1200℃, resistant to deformation under long-term load. Second, their thermal shock resistance. It enables them to withstand rapid temperature changes during kiln start-up and shutdown without cracking. Third, they have good thermal conductivity, helping to ensure even temperature distribution inside the kiln, improving the sintering quality. Their high-temperature resistance also significantly extends the lifespan of the equipment, far outlasting traditional refractory materials.

Semiconductor Manufacturing

The semiconductor manufacturing has strict requirements for material purity and stability. Silicon carbide boats and chucks, with their precisely matched properties, have become critical components in semiconductor equipment. Silicon carbide boats are used in high-temperature processes such as diffusion and oxidation to carry and transport silicon wafers. Silicon carbide chucks are used in photolithography and etching to adsorb and fix the wafers stably.

The choice of silicon carbide ceramics is driven by several factors. First, its high-purity meet ultra-clean processing requirements, preventing contamination of expensive silicon wafers. Second, the combination of low thermal expansion and high thermal conductivity ensures that thermal stress does not cause wafer displacement and deformation during high-temperature processes. Third, silicon carbide has etching resistance to withstand plasma erosion. Moreover, its service life exceeds many other alternative materials. High rigidity and lightweight properties make it suitable for the ultra-precise motion requirements of semiconductor manufacturing.

Wear-Resistant Applications

In the high-wear environment, such as mining and metallurgy, the wear-resistant component serves to guarantee continuous operation. Silicon carbide wear-resistant bricks can extend the equipment service life greatly. Their advantages are mainly manifested in hardness, wear resistance, and strength.

Silicon carbide bricks are of a Mohs hardness of 9.5 and wear resistance 266 times higher compared to manganese steel. Their wear rates are thus extremely lower than that of conventional wear-resistant materials. Silicon carbide bricks, insensitive to the angle of abrasive attack, enjoy stable wear resistance under conditions like high-speed scouring and particle impact. Besides, they have excellent resistance to corrosion, with the exception of hydrofluoric acid, and are resistant to corrosion by all forms of corrosive media. Moreover, their resistance to bending is more than 20 MPa, allowing them to bear high-load impacts without distorting. They are able to serve in high temperatures greater than 1350℃ with excellent thermal shock resistance. Having a density of about half that of steel leads to a reduction in load on the equipment and thus enhances the efficiency of heat exchange. Hence, silicon carbide bricks find wide applications under extreme conditions-for example, blast furnace linings in steel industries and pipelines in mineral processing plants.

Military

In personal protective gear and armored vehicle defense, silicon carbide bulletproof plates have become essential materials for military protection for their core advantages of strong protection and lightweight. As the core layer of bulletproof vests, it uses two mechanisms to resist projectile impact.

Through the combination of high hardness and high strength, the bullethead is quickly blunted upon impact, while the impact energy is dispersed across the entire plate, absorbing the shock efficiently. The lightweight feature is also significant. With the same level of protection, silicon carbide bulletproof plates are about 20% lighter than alumina plates, improving operational mobility. Additionally, silicon carbide bulletproof plates are more cost-effective. They provide 80%-90% of the protection capability of the top-tier bulletproof material, boron carbide, but at a much lower cost. Therefore, silicon carbide is widely used in military equipment such as armored vehicles, bulletproof vehicles and vests.

Mechanical Sealing

Mechanical seals require components that are highly resistant to corrosion, wear, and high temperature. Silicon carbide ceramics boast corrosion and wear resistance, high thermal conductivity and low density that are the keys in different products.

Silicon carbide is widely used to manufacture mechanical seals such as seal rings and shaft sleeves. These ceramic seals perform much better under extreme conditions of pressure, speed, and corrosion than their metal counterparts and last longer. These are applied in industries such as the petrochemical industry and the pump valve industry. Silicon carbide bearings are preferred in high-speed applications or when strong acids or alkalis exist, showing better wear resistance compared to metal bearings and higher operating temperatures (up to 1600°C) than zirconia. Because of this, silicon carbide ceramics have been adopted in place of conventional materials, solving the problem of short-lived seals against their lifetimes in demanding sectors.

Other Fields

Silicon carbide ceramics also play a critical role in several other industrial sectors. The chemical industry employs them for corrosion-resistant pipelines, linings and desulfurization nozzles, potentially increasing their service life 3-5 times compared to alumina and decreasing maintenance costs. In aerospace, their lightweight and high-temperature stability make them ideal for high-temperature components, such as rotors and nozzles, capable of enduring the extreme conditions. They also find application in the automotive manufacturing industry in rotors and brake systems for meeting particular requirements.

In the future, more application areas for silicon carbide will emerge. Material performance and economic feasibility can be promoted by low-temperature processes, such as spark plasma sintering, enabling traditional material substitution in extreme conditions. Further breakthroughs in cost-effective production technologies of complex components will promote market penetration. As the technology of sintering techniques and composite research improves, the advantages of silicon carbide in lightweight design will accelerate the upgrading of traditional industries and new fields such as new energy and high-end manufacturing.

Prospects of Silicon Carbide Ceramics

Silicon carbide ceramics, with their high strength, high-temperature resistance and corrosion resistance, have been applied in many fields deeply. They not only address the performance shortcomings of traditional materials under extreme conditions, but also provide efficient solutions for industrial kilns, semiconductor manufacturing, mechanical seals and military defense.

With the development of emerging industries, the demand for silicon carbide ceramics continues to grow. It has an irreplaceable status in the high-end materials. Through process optimization and upgrades, silicon carbide ceramics will continue to drive technological and efficiency improvements in related industries in the future. They are definitely becoming a more and more important material support for the advancement of high-end manufacturing.

If you have any questions about silicon carbide ceramics, feel free to contact us. Newthink New Materials always ready to provide silicon carbide products tailored to your needs. If you are finding custom silicon carbide ceramic products, please provide us with the following information to receive a customized quote:

• What is your application industry?
• What material are you currently using?
• What substances will silicon carbide bricks come into contact with during the application?
• Do you need us to provide a bonding solution?
• What problems have you encountered in your current use?

References

[1] Presser, V., & Nickel, K. G. (2008). Silica on silicon carbide. Critical reviews in solid state and materials sciences, 33(1), 1-99.

[2] Vasilevskiy, K., & Wright, N. G. (2020). Historical introduction to silicon carbide discovery, properties and technology. Advancing Silicon Carbide Electronics Technology II: Core Technologies of Silicon Carbide Device Processing, 69(1).

[3] Xu, M., Girish, Y. R., Rakesh, K. P., Wu, P., Manukumar, H. M., Byrappa, S. M., & Byrappa, K. (2021). Recent advances and challenges in silicon carbide (SiC) ceramic nanoarchitectures and their applications. Materials Today Communications, 28, 102533.

[4] Yamada, K., & Mohri, M. (1991). Properties and applications of silicon carbide ceramics. In Silicon Carbide Ceramics—1: Fundamental and Solid Reaction (pp. 13-44). Dordrecht: Springer Netherlands.