The Strength and Thermal Conductivity of Silicon Carbide

Silicon carbide is an exceptionally hard, crystalline ceramic with outstanding strength and thermal conductivity, capable of withstanding high temperatures without thermal expansion and chemical stability.

Recently, we reported record-high isotropic room temperature phononic crystal thermal conductivity (k) values in wafer-scale 3C-SiC bulk crystals at temperatures greater than room temperature; our figure was over 50% higher than commercial 6H-SiC and AlN products.

1. Low thermal expansion

Silicon carbide ceramics have an ability to maintain their strength at elevated temperatures while resisting thermal shock, an important feature considering that sudden temperature shifts can create thermal stresses in materials, leading to microcracks.

Silicon carbide’s low thermal expansion rate makes it an excellent material for aerospace and space applications, while it is also frequently used as bulletproof armor because of its ability to withstand bullet impacts.

Silicon carbide’s wide bandgap is another key feature that distinguishes it as an outstanding semiconductor material. A bandgap is an energy barrier electrons must overcome to move from its valence band to conduction band; for silicon carbide this energy barrier exists between its valence band and conduction band; narrower than conductors but much wider than insulators which allows electricity to flow more readily between these bands. Silicon carbide can be made into p-type semiconductor by doping with aluminum, boron or gallium dopants while nitrogen or phosphorus dopants may also be added which will produce an n-type semiconductor.

2. High thermal conductivity

SiC’s excellent thermal conductivity enables it to dissipate heat quickly, helping protect electronic devices from performance degradation or shortening their lives due to excessively high temperatures.

Silicon carbide stands out as an ideal material for use in metallurgical applications due to its durable qualities, high mechanical strength, chemical inertness, low thermal expansion coefficient and superior thermal shock resistance. Furthermore, it features excellent corrosion resistance as well as being capable of withstanding very high temperatures.

Silicon carbide was first synthesized by Pennsylvanian Edward Acheson in 1891 by heating a mixture of clay and powdered coke in an iron bowl with a carbon electrode. Today, silicon carbide has become one of the world’s most used industrial ceramic materials; over 1 million tons a year are consumed worldwide. Silicon carbide’s excellent thermal shock resistance stems from its high thermal conductivity and low thermal expansion properties; it is thus widely used in mirrors used on astronomical telescopes as well as armor plates in bulletproof vests.

3. High thermal shock resistance

Silicon carbide offers excellent thermal shock resistance and can withstand sudden temperature shifts, making it suitable for use in harsh environments. Furthermore, it stands up well to exposure to acids and alkalis – further advantages in terms of chemical resistance.

Silicon carbide stands out among other refractory materials by not decomposing into oxides at high temperatures and being chemically inert, except with respect to water.

Pure silicon carbide behaves as an electrical insulator; however, by adding controlled impurities it can serve as a semiconductor. Doping with aluminium, boron or gallium creates P-type semiconductors with higher voltage resistance than standard silicon, making them suitable for electric vehicle applications or power generation systems as well as bulletproof vest plates. Refractories also use it to help manage current flows efficiently – an advantage over their insulating properties.

4. High thermal conductivity

Silicon carbide’s lattice structure of bonds between carbon and silicon atoms results in an exceptionally hard material with high thermal conductivity and low thermal expansion, making it capable of withstanding harsh conditions such as high temperature and voltage environments.

Sintered silicon carbide’s thermal conductivity depends on many variables, such as its sintering additive type, grain size and composition of phases and microstructure. Therefore, identifying its most critical aspects to improve thermal conductivity.

New research uncovered that 3C-SiC exhibits high phonon scattering due to its purity and crystal quality, providing it with excellent transport properties that could make it an excellent wide bandgap semiconductor for power electronics applications. With its resistance against chemical corrosion, oxidation, wear, dynamic sealing technology applications as well as industrial components; SiC also proves to be durable choice with regards to thermal management applications as it remains resistant against these factors.

5. Wide bandgap

Bandgap refers to the amount of energy electrons and holes need to transition from their valence band into the conduction band, with silicon carbide and gallium nitride having larger bandgaps than traditional semiconductor materials like silicon in order to accommodate higher voltages and temperatures.

Wide bandgap semiconductors like silicon carbide and gallium nitride have made inroads into power electronics and optoelectronics applications, where they improve efficiency while decreasing energy losses. Their high blocking voltage and low on resistance make these semiconductors well suited to higher switching speeds and radiation environments.

Wide-bandgap semiconductors’ excellent thermal conductivity is essential in applications where device temperature must be kept under control to avoid overheating and performance degradation. Their higher melting temperatures and reduced thermal expansion coefficients also allow heat to quickly escape the device.

6. High electrical conductivity

Silicon carbide’s excellent electrical conductivity makes it a fantastic material for high-performance electrical applications. It can withstand extreme temperatures while remaining strong under intense heat and pressure conditions.

Addition of specific additives during sintering can enhance the electrical conductivity of porous silicon carbide and help decrease resistance while also preventing oxidation of its porous structure.

However, this does not alter phonon conductivity and it can still be observed that with increasing neck size the conductivity decreases.

At the production stage of silicon carbide production, doping with aluminium, boron and gallium to form a p-type semiconductor is often employed. If desired, nitrogen and phosphorus doping may also be done to create an N-type semiconductor and thus control its electrical properties. This practice has become standard practice within the semiconductor industry for this reason.

7. High thermal conductivity

Silicon Carbide is one of the lightest, hardest and strongest advanced ceramics available today. It is widely used for wear-resistant parts due to its strength, resistance to corrosion and low thermal expansion as well as in refractories for its hardness and electronics for its high thermal conductivity.

SiC behaves as an electrical insulator in its pure state, but can be transformed into a semiconductor through controlled doping. Doping with aluminium, boron or gallium produces a p-type semiconductor while doping it with nitrogen and phosphorus creates an N-type one.

SiC is popular due to its wide bandgap, which allows electrons to move more easily between energy states. Coupled with higher electron mobility and reduced power losses, this makes SiC an excellent material choice for use in electronic devices like diodes and transistors – key factors contributing to its use in power electronics and optoelectronics applications.

8. High thermal conductivity

Silicon carbide’s superior thermal conductivity and low expansion coefficient make it resistant to rapid temperature changes, making it suitable for demanding applications in ceramic, metallurgical and chemical industries. Its hardness and rigidity also make it suitable for use.

Recently, it has been observed that liquid-phase sintered (LPS) polycrystalline SiC with Y2O3 and Sc2O3 additives has exhibited thermal conductivity up to 261.5 W/m-K; however, factors responsible for such performance remain poorly understood.

This research seeks to explore the correlation between phase composition, microstructure and thermal conductivity in LPS-SiC samples using x-ray diffraction, high-resolution scanning transmission electron microscopy and electron backscatter diffraction methods of analysis. These techniques also enable identification of chemical or structural defects that affect thermal conductivity. Results demonstrate that both phase composition and microstructure influence thermal conductivity significantly;

9. High thermal conductivity

Silicon carbide boasts high thermal conductivity thanks to its crystal lattice structure composed of bonds between carbon and silicon atoms, which gives rise to low thermal expansion rates and mechanical strength – two features which combine to make this material an excellent structural ceramic for industrial uses.

SiC is widely utilized as cladding material in nuclear reactors due to its resistance to radiation exposure, thermal conductivity and fracture toughness – qualities which have been verified through experiments and simulations.

Recently, it was reported that the room temperature thermal conductivity of polycrystalline SiC ceramic liquid-phase sintered (LPS) with Y2O3-Sc2O3 additives reached 261.5 W/m-K. Numerous factors are believed to affect this value, such as lattice oxygen/nitrogen content, porosity, grain size distribution, grain boundary structures and phase transformation, along with additive composition and additive formulations. This paper evaluates their influence on LPS-SiC thermal conductivity while uncovering any possible hidden connections among various factors.

10. High thermal conductivity

Silicon carbide is an ideal ceramic for high-temperature applications, offering purity, stiffness, chemical and oxidation resistance, low thermal expansion and thermal shock resistance – characteristics which make it suitable for industrial use. Silicon carbide has many applications including blast furnace lining blocks and bricks; guide rails; wave absorbers for nuclear fuel particles; protective coatings on metallurgical equipment and protective coatings used as protective coatings against wear & tear.

High-performance electronics and optoelectronics require efficient heat dissipation in order to function at their best. Unfortunately, localized heat generation degrades performance by raising device temperatures.

Researchers have recently made the surprising discovery that wafer-scale freestanding 3C-SiC crystals can achieve isotropic room-temperature thermal conductivities equivalent to their theoretical values, in part thanks to various factors including lattice oxygen/nitrogen levels, porosity levels, phase transformations, grain boundary structure changes and additive composition affecting its thermal conductivity value. Their work could aid the design of everyday electronic devices utilizing these semiconductors.