Silicon carbide (SiC), also known as carborundum, is a hard chemical compound containing silicon and carbon. A semiconductor, it occurs in nature as the extremely rare mineral moissanite, but has been mass-produced as a powder and crystal since 1893 for use as an abrasive. Grains of silicon carbide can be bonded together by sintering to form very hard ceramics that are widely used in applications requiring high endurance, such as car brakes, car clutches and ceramic plates in bulletproof vests. Large single crystals of silicon carbide can be grown by the Lely method and they can be cut into gems known as synthetic moissanite.
In materials science, a refractory is a material that is resistant to decomposition by heat, pressure, or chemical attack, and retains strength and form at high temperatures. Refractories are polycrystalline, polyphase, inorganic, non-metallic, porous, and heterogeneous. They are typically composed of oxides or carbides, nitrides etc. of the following elements: silicon, aluminium, magnesium, calcium, boron, chromium and zirconium.
Titanium diboride (TiB2) is an extremely hard ceramic which has excellent heat conductivity, oxidation stability and wear resistance. TiB2 is also a reasonable electrical conductor, so it can be used as a cathode material in aluminium smelting and can be shaped by electrical discharge machining.
Tantalum carbides (TaC) form a family of binary chemical compounds of tantalum and carbon with the empirical formula TaCx, where x usually varies between 0.4 and 1. They are extremely hard, brittle, refractory ceramic materials with metallic electrical conductivity. They appear as brown-gray powders, which are usually processed by sintering.
Ceramic engineering is the science and technology of creating objects from inorganic, non-metallic materials. This is done either by the action of heat, or at lower temperatures using precipitation reactions from high-purity chemical solutions. The term includes the purification of raw materials, the study and production of the chemical compounds concerned, their formation into components and the study of their structure, composition and properties.
Aluminium carbide, chemical formula Al4C3, is a carbide of aluminium. It has the appearance of pale yellow to brown crystals. It is stable up to 1400 °C. It decomposes in water with the production of methane.
Nanocomposite is a multiphase solid material where one of the phases has one, two or three dimensions of less than 100 nanometers (nm) or structures having nano-scale repeat distances between the different phases that make up the material.
Zirconium diboride (ZrB2) is a highly covalent refractory ceramic material with a hexagonal crystal structure. ZrB2 is an ultra-high temperature ceramic (UHTC) with a melting point of 3246 °C. This along with its relatively low density of ~6.09 g/cm3 (measured density may be higher due to hafnium impurities) and good high temperature strength makes it a candidate for high temperature aerospace applications such as hypersonic flight or rocket propulsion systems. It is an unusual ceramic, having relatively high thermal and electrical conductivities, properties it shares with isostructural titanium diboride and hafnium diboride.
Solid is one of the four fundamental states of matter. The molecules in a solid are closely packed together and contain the least amount of kinetic energy. A solid is characterized by structural rigidity and resistance to a force applied to the surface. Unlike a liquid, a solid object does not flow to take on the shape of its container, nor does it expand to fill the entire available volume like a gas. The atoms in a solid are bound to each other, either in a regular geometric lattice, or irregularly. Solids cannot be compressed with little pressure whereas gases can be compressed with little pressure because the molecules in a gas are loosely packed.
In materials science, ceramic matrix composites (CMCs) are a subgroup of composite materials and a subgroup of ceramics. They consist of ceramic fibers embedded in a ceramic matrix. The fibers and the matrix both can consist of any ceramic material, whereby carbon and carbon fibers can also be regarded as a ceramic material.
Dymalloy is a metal matrix composite consisting of 20% copper and 80% silver alloy matrix with type I diamond. It has very high thermal conductivity of 420 W/(m·K), and its thermal expansion can be adjusted to match other materials, e.g. silicon and gallium arsenide chips. It is chiefly used in microelectronics as substrate for high power and high density multi-chip modules, where it aids with removal of waste heat.
AlSiC, pronounced "alsick", is a metal matrix composite consisting of aluminium matrix with silicon carbide particles. It has high thermal conductivity, and its thermal expansion can be adjusted to match other materials, e.g. silicon and gallium arsenide chips and various ceramics. It is chiefly used in microelectronics as substrate for power semiconductor devices and high density multi-chip modules, where it aids with removal of waste heat.
E-Material, also called E Material, is a metal matrix composite consisting of beryllium matrix with beryllium oxide particles. It has high thermal conductivity, and its thermal expansion can be adjusted to match other materials, e.g. silicon and gallium arsenide chips and various ceramics. It is chiefly used in microelectronics as substrate for power semiconductor devices and high density multi-chip modules, where it aids with removal of waste heat. E-materials have low weight and high strength, making them especially suitable for aerospace technology. Their high elastic modulus is favorable for absorbing vibrations and lowering material fatigue of attached modules and wire bonds.
Carbon nanotube metal matrix composites (CNT-MMC) are an emerging class of new materials that mix carbon nanotubes into metals and metal alloys to take advantage of the high tensile strength and electrical conductivity of carbon nanotube materials.
Ultra-high-temperature ceramics (UHTCs) are a type of refractory ceramics that that can withstand extremely high temperatures without degrading, often above 2,000 °C. They also often have high thermal conductivities and are highly resistant to thermal shock, meaning they can withstand sudden and extreme changes in temperature without cracking or breaking. Chemically, they are usually borides, carbides, nitrides, and oxides of early transition metals.
SiC–SiC matrix composite is a particular type of ceramic matrix composite (CMC) which have been accumulating interest mainly as high temperature materials for use in applications such as gas turbines, as an alternative to metallic alloys. CMCs are generally a system of materials that are made up of ceramic fibers or particles that lie in a ceramic matrix phase. In this case, a SiC/SiC composite is made by having a SiC matrix phase and a fiber phase incorporated together by different processing methods. Outstanding properties of SiC/SiC composites include high thermal, mechanical, and chemical stability while also providing high strength to weight ratio.
Cymat Technologies is an innovative materials technology company based out of Mississauga, Ontario, Canada, and one of the world leaders in the production of stabilized aluminum foam.
Al-Ca composite is a high-conductivity, high-strength, lightweight composite consisting of sub-micron-diameter pure calcium metal filaments embedded inside a pure aluminium metal matrix. The material is still in the development phase, but it has potential use as an overhead high-voltage power transmission conductor. It could also be used wherever an exceptionally light, high-strength conductor is needed. Its physical properties make it especially well-suited for DC transmission. Compared with conventional conductors such as aluminium-conductor steel-reinforced cable (ACSR), all aluminium alloy conductors (AAAC), aluminium conductor alloy reinforced (ACAR), aluminium conductor composite reinforced ACCR and ACCC conductor that conduct alternating current well and DC current somewhat less well, Al-Ca conductor is essentially a single uniform material with high DC conductivity, allowing the core strands and the outer strands of a conductor cable to all be the same wire type. This conductor is inherently strong so that there is no need for a strong core to support its own weight as is done in conventional conductors. This eliminates the "bird caging", spooling, and thermal fatigue problems caused by thermal expansion coefficient mismatch between the core and outer strands. The Al-Ca phase interfaces strengthen the composite substantially, but do not have a noticeable effect on restricting the mean free path of electrons, which gives the composite both high strength and high conductivity, a combination that is normally difficult to achieve with both pure metals and alloys. The high strength and light weight could reduce the number of towers needed per kilometer for long distance transmission lines. Since towers and their foundations often account for 50% of a powerline's construction cost, building fewer towers would save a substantial fraction of total construction costs. The high strength also could increase transmission reliability in wind/ice loading situations. The high conductivity has the potential to reduce Ohmic losses.
Silicon carbide fibers are fibers ranging from 5 to 150 micrometres in diameter and composed primarily of silicon carbide molecules. Depending on manufacturing process, they may have some excess silicon or carbon, or have a small amount of oxygen. Relative to organic fibers and some ceramic fibers, silicon carbide fibers have high stiffness, high tensile strength, low weight, high chemical resistance, high temperature tolerance and low thermal expansion. (refs) These properties have made silicon carbide fiber the choice for hot section components in the next generation of gas turbines, e.g. the LEAP engine from GE.
Nanotech metallurgy is an emerging interdisciplinary domain of materials science and engineering, manufacturing, and nanoscience and engineering to study how nanophases can be applied to significantly improve the processing/manufacturing, micro/nano-structures, and physical/chemical/mechanical behaviors of metals and alloys. This definition was first proposed by Xiaochun Li at the University of California, Los Angeles in 2018.
