The Synthesis of Silicon Carbide

Silicon carbide (SiC) is one of the world’s premier ceramic materials with numerous industrial applications due to its superior thermal and chemical stability. SiC boasts many desirable characteristics such as high strength and hardness, corrosion resistance, refractoriness and great wear resistance – qualities which have led to widespread adoption worldwide.

Edward Goodrich Acheson first synthesized moissanite in 1891 during an attempt to create artificial diamonds, and its natural source is the Canyon Diablo meteorite in Arizona where it’s known by the mineral name moissanite.

Chemical Reactions

Silicon Carbide (SiC) is a chemical compound made of silicon and carbon that forms an extremely hard hexagonal crystal structure. When in its purest form, SiC acts like an electrical insulator; however, by controlling impurity levels or adding dopants it can act like a semiconductor; doping with aluminium results in P-type properties while doping nitrogen/phosphorus gives rise to N-type properties allowing SiC to be utilized across many applications.

SiC is typically created through either reacting silica and carbon at high temperatures in an electric furnace or by reducing silicon with carbon in an electric arc reactor, although natural sources also contain moissanite which was first discovered at Arizona’s Canyon Diablo meteor crater in 1893 and broad-scale production was begun by American inventor Edward G. Acheson in 1891.

Acheson developed his method for producing silicon carbide powder by heating a mixture of clay (aluminium silicate) and powdered coke in an iron bowl, later naming the blue crystals produced carborundum which later came to be known as silicon carbide.

Silicon carbide naturally exhibits an enormous band gap compared to silicon, making it an extremely robust semiconductor material with wide band gaps. Due to this characteristic, silicon carbide makes an excellent replacement material in power electronics applications due to its fast switching and blocking voltage capabilities; making it suitable for replacement of traditional silicon devices.

Reaction-bonded SiC is an economical material suitable for many electronic applications, including LEDs, light emitting diodes and detectors. To produce it, mix powdered mixture of silicon carbide and carbon with plasticizer before shaping into desired shapes before burning off any remaining plasticizer and infusing with liquid or gaseous silicon at high temperature – known as carbothermal reduction.

Recently developed methods of synthetic material synthesis include detonating silicon and carbon together. A mild steel pressure vessel filled with TNT and RDX charges is ignited using a spark plug before detonation takes place due to build-up of kinetic energy in the system – creating an explosion that creates SiC nanopowder which can then be studied using HRTEM on a JEM-2010 electron microscope.

Electrolysis

Electrolysis is a chemical decomposition process that employs direct electric current to dissolve an ionic compound into its component parts. To conduct electrolysis successfully, you need a suitable electrolyte, electrodes and external power source; additionally the compound must remain contained so as not to diffuse too close to either electrode during electrolysis. Cations are reduced at the cathode while anions are oxidized at the anode; some electrolytes also contain partitions or ion exchange membranes which prevent two reactants coming into contact during electrolysis processes.

Silicon carbide can be produced using various techniques. Solvothermal synthesis produces 1D nanorods and nanobelts as well as 2D structures like nanosheets and nanowires, while microwave sintering is widely used for producing polytype-b SiC. Calcination, carbothermal redox reactions and other similar processes may also be employed when synthesizing silicon carbide.

Direct electrochemical reduction of solid silicon oxides can be used to produce both amorphous and crystalline SiC. This process resembles electrolytic titanium dioxide production but differs in that silicon oxide is an insulator and cannot gain four electrons during reaction. Direct electrochemical reduction of SiO2 begins when an appropriately large cathodic overpotential is applied to a conducting collector; this causes ions within the oxide phase to gain electrons and migrate toward the silica/molten salt interface, where silica particles can be reduced into crystalline Si and oxygen deposits at an anode.

Molten salt electrolysis is another means of producing silicon carbide, using porous nano-silica as its raw material. After exposure to an electric current and subsequent redox reaction with molten sodium chloride solution, amorphous silicon undergoes redox reactions which produce 3PIs that can then be further converted to crystalline SiC by means of high temperature sintering.

One of the most promising sources for gathering materials necessary to synthesize silicon carbide is municipal solid waste (MSW). Solventomal pyrolysis of MSW has proven successful at producing SiC nanopowder with both one- and two-dimensional structures such as nanorods and belts as well as sheets and wires; using extra carbon from organic precursors allows us to lower processing temperature significantly with this approach.

Calcination

Silicon carbide (SiC) can be produced through reacting silica with carbon at high temperatures in a multistep process that can take years. Raw materials used include industrial byproducts or natural deposits. Properties of the final material depend on factors like reaction conditions, processing temperature and particle size; for instance calcining raw materials may influence density and surface area of final products.

Silicon carbide has a four-sided structure made up of covalently bound silicon and carbon atoms in three-dimensional crystal structure, creating a hard and brittle material with very high mechanical tensile strength and nanoscale hardness. Additionally, it boasts thermal conductivity properties as well as insulation. Calcination temperature also affects its pore size with lower temperatures producing smaller pores while higher ones produce larger ones.

Crystallinity of SiC is determined by both calcination temperature and duration; additionally, sintering and reorganization processes take place during calcination that alter its morphology, giving rise to various subtypes with unique properties.

Rajarao and Sun have developed an efficient method for producing porous b-SiC. Their technique involves using waste macadamia shells as the carbon source and silica as starting material, producing an end product with an impressive specific surface area of 100m2g-1.

Pyrolising organo-silicas is another approach to synthesizing b-SiC and can yield SiC with high surface area and low density, and may help modify agglomeration by adding substances like tetraethyloxysilane to the mixture during synthesis.

One use for b-SiC is in electricity generation. Due to its unique atomic structure, b-SiC can produce silicon trioxide (SiO2) cells with high efficiency at minimal costs – ideal for solar cell production that produces clean energy while minimising environmental impacts.

Detonation

Silicon carbide (SiC) is an exceptionally robust chemical compound composed of the elements silicon and carbon. Featuring hexagonal crystal structure and wide band-gap semiconductor properties allowing electrons to exit their orbits around its nucleus with minimal energy loss, making this material highly hard and resistant to high temperatures and thermal shock – properties which made it one of the key industrial ceramic materials of the industrial revolution – Silicon carbide remains widely used today as an abrasive, steel additive, structural ceramic, as well as emergence as an important semiconductor material in next-gen electronics devices.

Edward Acheson can be credited for pioneering SiC synthesis through large-scale production. In 1891 he discovered this compound while trying to artificially produce diamonds using electric current passing through carbon rods in clay, only to discover instead blue-colored crystals which he named carborundum and began manufacturing commercially.

Natural moissanite can be found in small quantities in meteorites and kimberlite deposits; however, all of the SiC that finds large-scale applications is synthetically produced using various techniques like calcination or microwave sintering. Detonation synthesis could potentially significantly lower costs by employing the explosive reaction between nitrogen and hydrogen gas molecules to form SiC.

Recently, researchers conducted a study aimed at creating facilities for detonation synthesis of nano-sized alpha variant SiC that is difficult to produce with conventional calcination methods. After optimizing explosive composition and temperature to maximize yield of nanomaterial, their team achieved first successful nanomaterial synthesis in this range of SiC a-SiC.

Detonation-produced a-SiC was evaluated using X-ray diffraction (XRD). Diffraction patterns show that it’s a single phase material with no amorphous carbon particles present, while energy dispersive X-ray spectroscopy detected impurities including cerium, hafnium, niobium and indium oxides as well as trace amounts of oxygen – supporting the hypothesis that detonation synthesis methods could be applied towards creating other high performance materials.