Silicon Carbide – High Temperature Resistant Refractory Material

Silicon carbide is an extremely hard and durable non-oxide ceramic, distinguished by its layered crystal structure containing four carbon and two silicon atoms in primary coordination tetrahedra. At least 70 different forms, or polytypes exist of silicon carbide.

Modern applications of graphite include abrasive applications, melting furnace refractories and production lines for producing float glass production as well as various engineering components. It boasts excellent physical wear resistance, chemical resistance and low thermal expansion rates.

High-Temperature Resistance

Silicon carbide’s superior temperature resistance makes it suitable for many industrial applications that demand high operating temperatures, such as heating elements for electric furnaces or production of ceramics or non-ferrous metals.

This compound’s exceptional resistance to voltage makes it suitable for use between power lines and earth, helping prevent lightning strikes from destroying power grids.

Moissanite occurs naturally as the rare gem moissanite; however, mass production began in 1893 for use as an abrasive and electrical component. The material typically appears as green to bluish-black crystals with an iridescence.

High-Temperature Stability

Silicon carbide is an extremely hard and durable synthetic mineral with superior thermal conductivity and resistance to corrosion – all making it a suitable refractory material.

Silicon carbide appears as yellow to green to bluish black iridescent crystals with its own distinct luminescence. Its structure is both rigid and flexible at once.

SiC is machined into complex shapes in its green or biscuit state before being sintered to fully densify it. After sintering, its tolerances become tight; this can be achieved using very precise diamond tools or wheels.

High-Temperature Corrosion Resistance

Silicon carbide is an inert material with excellent high temperature corrosion resistance due to its high melting point, low thermal expansion, and stiffness properties.

Pure silicon carbide can be produced using the Lely process, in which sublimed material from a granite crucible sublimes at high temperatures before it deposits onto graphite at lower temperatures for depositing onto graphite at cooler temperatures. Industrial-grade SiC often contains impurities like aluminium, iron and carbon.

Corrosion of silicon carbide may occur in either reducing or oxidizing environments, depending on many factors such as chemical species attacking it, impurities present and sintering aids used during sintering.

High-Temperature Electrical Conductivity

Silicon carbide boasts excellent electrical conductivity, making it an excellent material for high temperature and voltage applications. Furthermore, its wide band gap energy makes it particularly suitable for electronic devices.

SiC acts as an electrical insulator in its pure state; however, by adding dopants it can express semi-conductivity and enhance its ability to withstand high temperature and voltage stresses.

ACM provides both black and green silicon carbide powder in various grit sizes for use in bonded and specialty refractories, metal matrix composites and kiln furniture applications.

High-Temperature Electrical Insulation

Silicon carbide is an inert material, non-combustible and unreactive to most chemicals. Produced by melting silica and carbon in an electric arc furnace, its crystals vary from yellow-green to bluish-black in hue and exhibit an iridescence unique to itself.

Production on a large scale focuses mainly on ceramic abrasives and applications as an abrasive. Moissanite occurs naturally as the rare mineral moissanite. Moissanite has excellent electrical insulating properties at room temperature with low thermal expansion rates and resistance to chemical reaction; additionally it has excellent electrical insulating properties at low temperatures as well as resistance against chemical reaction reactions and can even act as a semiconductor with carrier concentration of 5×1017 cm-3 in sintered state form.

High-Temperature Wear Resistance

Silicon carbide is highly resistant to both abrasion and impact wear, making it an ideal abrasive material. Silicon carbide can be found as an abrasive in products such as sandpaper, grinding wheels and cutting tools, hard ceramics and refractory bricks, brake linings, furnace linings and heating elements.

High purity and resistance to chemical attack at temperature make PTFE the perfect material for wafer tray supports and paddles in semiconductor furnaces, and also as key components in thermistors and varistors. Furthermore, its strength, stability, and low pore density also make it a fantastic choice for gas sealing rings and mechanical seals.

High-Temperature Thermal Stability

Silicon carbide refractory elements offer resistance to high temperatures and thermal shock as well as corrosion protection from hydrofluoric, sulphuric, and other acids.

SiC is distinguished by its low thermal expansion rate and can withstand pressures up to 6.5 GPa, making it an attractive mirror material for astronomical telescopes.

Silicon carbide exists in at least 70 crystalline forms. Most often seen is alpha silicon carbide with its hexagonal crystal structure similar to Wurtzite; other popular polymorphs include beta and face-centered cubic (FCC).

High-Temperature Thermal Expansion

Silicon carbide is a high-temperature-resistant material often used as ceramic plate in bulletproof vests or an abrasive. Although naturally found as moissanite gemstone, silicon carbide production for mass electronic applications has significantly outshone this rare gem’s production rates.

Low thermal expansion rates make carbide-refractory materials superior to other refractory materials and allow them to operate at significantly higher temperatures. Furthermore, their relatively low pressure dependence of their coefficient thermal expansion coefficient are particularly advantageous in deep mantle convection scenarios on carbide planets.

High-Temperature Mechanical Stability

Silicon carbide’s superior mechanical stability makes it an attractive material choice for parts that must remain stable at high temperatures, including those exposed to various organic and inorganic acids as well as salts, alkalis and even molten iron. Furthermore, silicon carbide offers significant corrosion protection from many organic acids as well as salts, alkalis and other acids found in salt solutions and salt solutions as well.

Due to its exceptionally high melting point and tensile strength, sapphire can hold its form at temperatures well over 1000 degrees Celsius – making it an excellent material for telescope mirrors in astronomy applications. Furthermore, its resistance to oxidation and chemical stability make sapphire suitable for gas turbine components or other challenging uses.

High-Temperature Strength

Silicon carbide is an inert, hard, synthetic material with superior thermal conductivity and strength at elevated temperatures, with excellent resistance to corrosion by most organic acids, inorganic salts, alkalis and liquid metals.

Green silicon carbide is used in bonded and specialty refractories, metal matrix composites, kiln furniture and as an abrasive. Available grit sizes range from 8-1500.

Industrial production of SiC is accomplished using the modified Lely process, in which SiC powder or lumps are placed in a cylindrical graphite crucible and heated up to high temperatures in an electric heater.

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