Carborundum Stone For Stained Glass? Best 66 Answer

Extremely hard semiconductor containing silicon and carbon

“Carborundum” redirects here. Not to be confused with corundum

Chemical compound

Silicon carbide (SiC), also known as carborundum ( ), is a hard chemical compound containing silicon and carbon. A semiconductor, it occurs naturally as the extremely rare mineral moissanite, but has been mass-produced as a powder and crystal for use as an abrasive since 1893. Grains of silicon carbide can be bonded together by sintering to form very hard ceramics that are widely used in applications requiring high durability, such as B. Car brakes, car clutches and ceramic plates in bulletproof vests. Large single crystals of silicon carbide can be grown using the Lely method and cut into a gemstone known as synthetic moissanite.

Electronic applications of silicon carbide such as light emitting diodes (LEDs) and detectors in early radios were first demonstrated around 1907. SiC is used in semiconductor electronic devices that operate at high temperatures or high voltages or both.

Natural occurrence[edit]

Moissanite single crystal (approx. 1 mm in size)

Naturally occurring moissanite occurs only in minute amounts in certain types of meteorites, corundum deposits, and kimberlite. Almost all silicon carbide sold worldwide, including moissanite jewels, is synthetic.

Natural moissanite was first identified in 1893 as a small component of the Canyon Diablo meteorite in Arizona by Dr. Ferdinand Henri Moissan, after whom the material was named in 1905.[7] Moissan’s discovery of naturally occurring SiC was initially controversial because his sample may have been contaminated by silicon carbide saw blades already on the market at the time.[8]

While silicon carbide is rare on Earth, it is remarkably common in space. It is a common form of stardust found around carbon-rich stars, and examples of this stardust have been found in pristine condition in primitive (unaltered) meteorites. The silicon carbide found in space and in meteorites is almost exclusively the beta polymorph. Analysis of SiC grains found in the Murchison meteorite, a carbonaceous chondrite meteorite, has revealed anomalous isotopic ratios of carbon and silicon, suggesting that these grains formed outside the solar system.[9]

history [edit]

Early experiments[ edit ]

Non-systematic, less recognized, and often unverified syntheses of silicon carbide include:

César-Mansuète Despretz conducts electric current through a carbon rod embedded in sand (1849)

Robert Sydney Marsden’s dissolution of silica in molten silver in a graphite crucible (1881)

Paul Schützenberger’s heating a mixture of silicon and silicic acid in a graphite crucible (1881)

Albert Colson’s heating of silicon under a stream of ethylene (1882).[10]

Mass production [ edit ]

Large scale production is credited to Edward Goodrich Acheson in 1890.[11] Acheson attempted to create artificial diamonds when he heated a mixture of clay (aluminum silicate) and coke powder (carbon) in an iron bowl. He named the blue crystals that formed carborundum because he believed it was a new compound of carbon and aluminum, similar to corundum. Moissan also synthesized SiC in several ways, including dissolving carbon in molten silicon, melting a mixture of calcium carbide and silicon dioxide, and by reducing silicon dioxide with carbon in an electric furnace.

Acheson patented the process for making silicon carbide powder on February 28, 1893.[12] Acheson also developed the electric batch furnace, which is still used to produce SiC today, and founded the Carborundum Company to manufacture SiC in large quantities, initially for use as an abrasive.[13] In 1900, the company came to terms with the Electric Smelting and Aluminum Company when a judge’s decision gave its founders “large priority” to “reduce ores and other substances by the annealing method.”[14] It is said that Acheson was attempting to dissolve carbon in molten corundum (alumina) and discovered the presence of hard, blue-black crystals which he believed to be a compound of carbon and corundum: hence carborundum. He may have named the material “Carborundum” in analogy to corundum, which is also a very hard substance (9 on the Mohs scale).

The first use of SiC was as an abrasive. Electronic applications followed. At the beginning of the 20th century silicon carbide was used as a detector in the first radios.[15] In 1907, Henry Joseph Round made the first LED by applying a voltage to a SiC crystal and observing yellow, green, and orange emission at the cathode. The effect was later rediscovered by O. V. Losev in the Soviet Union in 1923.[16]

production [edit]

Synthetic SiC crystals with a diameter of ~3mm

Two six-inch silicon carbide wafers

Since natural moissanite is extremely scarce, most silicon carbide is synthetic. Silicon carbide is used as an abrasive, as well as a gem quality semiconductor and diamond simulant. The simplest method of producing silicon carbide is to combine silica sand and carbon in an Acheson Graphite Resistance Furnace at a high temperature of between 1,600°C (2,910°F) and 2,500°C (4,530°F). Fine SiO 2 particles in plant material (e.g. rice hulls) can be converted to SiC by heating the excess carbon from the organic material.[17] The silica fume, which is a byproduct of the production of silicon metal and ferrosilicon alloys, can also be converted to SiC by heating with graphite at 1,500 °C (2,730 °F).[18]

The purity of the material formed in the Acheson furnace varies depending on the distance from the graphite resistor heat source. Colorless, pale yellow, and green crystals have the highest purity and are closest to the resistor. The color changes to blue and black as the distance from the resistor increases, and these darker crystals are less pure. Nitrogen and aluminum are common impurities and affect the electrical conductivity of SiC.[19]

Synthetic SiC Lely crystals

Pure silicon carbide can be produced by the Lely process[20] in which SiC powder is sublimated into high-temperature species of silicon, carbon, silicon dicarbide (SiC 2 ), and disilicon carbide (Si 2 C) in an argon gas environment at 2500 °C and on a slightly colder substrate to flake-like single crystals[21] with a size of up to 2 × 2 cm. This process yields high quality single crystals, mostly from the 6H-SiC phase (because of the high growth temperature).

A modified Lely process using induction heating in graphite crucibles yields even larger single crystals with a diameter of 10 cm (4 inches) and a cross-section 81 times larger than the conventional Lely process.[22]

Cubic SiC is typically grown by the more expensive chemical vapor deposition (CVD) process from silane, hydrogen, and nitrogen.[19][23] Homoepitaxial and heteroepitaxial SiC layers can be grown in both the gas and liquid phases.[24]

To form complex-shaped SiC, preceramic polymers can be used as precursors, which form the ceramic product through pyrolysis at temperatures in the range of 1000–1100 °C.[25] Precursor materials to obtain silicon carbide in this way include polycarbosilanes, poly(methylsiline), and polysilazanes.[26] Silicon carbide materials obtained by pyrolysis of preceramic polymers are known as polymer-derived ceramics, or PDCs. The pyrolysis of preceramic polymers is most commonly carried out under an inert atmosphere at relatively low temperatures. Compared to the CVD process, the pyrolysis process is advantageous because the polymer can be formed into various shapes before thermalization in the ceramic.[27][28][29][30]

SiC can also be processed into wafers by cutting a single crystal either with a diamond wire saw or with a laser. SiC is a useful semiconductor for power electronics.[31]

Structure and properties[edit]

Structure of the main SiC polytypes. (β)3C-SiC 4H-SiC (α)6H-SiC

Silicon carbide, image under a stereo microscope.

Silicon carbide exists in about 250 crystalline forms.[32] Silicon carbide in a glassy amorphous form is also produced by the pyrolysis of preceramic polymers in an inert atmosphere.[33] The polymorphism of SiC is characterized by a large family of similar crystalline structures called polytypes. They are variations of the same chemical compound, identical in two dimensions and different in the third. Therefore, they can be viewed as layers stacked in a specific order.[34]

Alpha silicon carbide (α-SiC) is the most common polymorph and is formed at temperatures above 1700°C and has a hexagonal crystal structure (similar to wurtzite). The beta-modification (β-SiC) with a zincblende crystal structure (similar to diamond) is formed at temperatures below 1700 °C.[35] Until recently, the beta form had relatively few commercial applications, although there is now increasing interest in its use as a support for heterogeneous catalysts due to its higher surface area compared to the alpha form.

Properties of the most important SiC polytypes[5][27] Polytype 3C (β) 4H 6H (α) Crystal structure zinc blende (cubic) Hexagonal Hexagonal Space group T2 d -F 4 3m C4 6v -P6 3 mc C4 6v -P6 3 mc Pearson- Symbol cF8 hP8 hP12 Lattice Constants (Å) 4.3596 3.0730; 10.053 3.0810; 15.12 Density (g/cm3) 3.21 3.21 3.21 Band Gap (eV) 2.36 3.23 3.05 Bulk Modulus (GPa) 250 220 220 Thermal Conductivity (W⋅m−1⋅K−1) @ 300 K (see [36] [37] for temperature dependence) 320 348 325

Pure SiC is colorless. The brown to black color of the industrial product results from iron impurities. The crystals’ rainbow-like luster is due to thin-film interference of a silicon dioxide passivation layer that forms on the surface.

SiC’s high sublimation temperature (around 2700 °C) makes it useful for bearings and furnace parts. Silicon carbide does not melt at any known temperature. It is also chemically very inert. Currently, there is much interest in its use as a semiconductor material in electronics, where its high thermal conductivity, high electric field breakdown strength, and high maximum current density make it more promising than silicon for high-power devices.[38] SiC also has a very low coefficient of thermal expansion (4.0 × 10−6/K) and does not experience phase transitions that would lead to thermal expansion discontinuities.[19]

Electrical conductivity [ edit ]

Silicon carbide is a semiconductor that can be n-doped with nitrogen or phosphorus and p-doped with beryllium, boron, aluminum, or gallium.[5] Metallic conductivity has been achieved through heavy doping with boron, aluminum, or nitrogen.

Superconductivity has been demonstrated in 3C-SiC:Al, 3C-SiC:B, and 6H-SiC:B at similar temperatures of ~1.5 K.[35][39] However, a decisive difference can be observed for the magnetic field behavior between aluminum and boron doping: 3C-SiC:Al is type II. In contrast, 3C-SiC:B is Type I, as is 6H-SiC:B. Thus, the superconducting properties appear to depend more on the dopant (B vs. Al) than on the polytype (3C- vs. 6H-). In an attempt to explain this dependence, it was found that B is substituted at C sites in SiC, but Al is substituted at Si sites. Therefore, Al and B “see” different environments in both polytypes.[40]

Used[ edit ]

SiC cutting discs

In art, silicon carbide is a popular abrasive in modern lapidary due to the durability and low cost of the material. Due to its hardness, it is used in production for abrasive machining processes such as grinding, honing, water jet cutting and sandblasting. Silicon carbide particles are laminated onto paper to make sandpaper and skateboard grip tape.[41]

In 1982, an exceptionally strong composite of alumina and silicon carbide whiskers was discovered. It took just three years to develop this laboratory-made composite into a commercial product. In 1985, the first commercial cutting tools made from this composite material reinforced with alumina and silicon carbide whiskers were introduced.[42]

Structural material[ edit ]

Silicon carbide is used in ballistic vest trauma plates

In the 1980s and 1990s, silicon carbide was studied in several high-temperature gas turbine research programs in Europe, Japan and the United States. The components were intended to replace nickel superalloy turbine blades or vanes.[43] However, none of these projects resulted in a production volume, mainly because of its low impact strength and low fracture toughness.[44]

Like other hard ceramics (namely alumina and boron carbide), silicon carbide is used in composite armor (e.g. Chobham armor) and in ceramic plates in bulletproof vests. Dragon Skin, manufactured by Pinnacle Armor, used silicon carbide discs.[45] Improved fracture toughness in a SiC armor can be facilitated by the phenomenon of abnormal grain growth or AGG. The growth of unusually long silicon carbide grains can serve to impart a toughening effect through crack wake bridging similar to whisker reinforcement. Similar AGG hardening effects have been reported for silicon nitride (Si 3 N 4 ).[46]

Silicon carbide is used as a support and deposit material in high-temperature furnaces, e.g. B. for firing ceramics, for glass melting or for glass casting. SiC furnace shelves are significantly lighter and more durable than traditional alumina shelves.[47]

In December 2015, the infusion of silicon carbide nanoparticles into molten magnesium was mentioned as a way to produce a new strong and plastic alloy suitable for use in aerospace, automotive, and microelectronics.[48]

Car parts [ edit ]

The silicon carbide “carbon ceramic” disc brake of the Porsche Carrera GT

Silicon-infiltrated carbon-carbon composite is used for high-performance “ceramic” brake discs because of their ability to withstand extreme temperatures. The silicon reacts with the graphite in the carbon-carbon compound to form carbon fiber reinforced silicon carbide (C/SiC). These brake discs are used on some road sports cars, supercars as well as other high performance cars including the Porsche Carrera GT, Bugatti Veyron, Chevrolet Corvette ZR1, McLaren P1,[49] Bentley, Ferrari, Lamborghini and some specific high performance cars from Audi. Silicon carbide is also used in sintered form for diesel particulate filters.[50] It is also used as an oil additive [dubious – discuss][clarification needed] to reduce friction, emissions and harmonics.[51][52]

Ladle [ edit ]

SiC is used in crucibles to hold molten metal in both small and large foundry applications.

Electrical systems[ edit ]

The earliest electrical application of SiC was in lightning rods in electrical power systems. These devices must exhibit high resistance until the voltage across them reaches a certain threshold V T , at which point their resistance must drop to a lower value and remain at that value until the applied voltage falls below V T .[55]

It was recognized early on that SiC has such a voltage-dependent resistance, and so columns of SiC pellets were connected between high-voltage power lines and ground. If a lightning strike on the line raises the line voltage sufficiently, the SiC pillar will conduct, allowing the strike current to flow harmlessly to earth instead of along the power line. The SiC columns proved to be very conductive at normal mains operating voltages and therefore had to be connected in series with a spark gap. This spark gap is ionized and rendered conductive when lightning raises the voltage of the power line conductor, effectively connecting the SiC pillar between the power line and ground. Spark gaps used in lightning conductors are unreliable, either failing to strike an arc when needed or failing to shut down thereafter, in the latter case due to material failure or contamination from dust or salt. The use of SiC columns was originally intended to make the spark gap in lightning rods redundant. SiC arresters with gaps were used for lightning protection and sold under the brand names GE and Westinghouse, among others. The gapped SiC arrester has been largely superseded by no-gap varistors that use columns of zinc oxide pellets.[56]

Electronic circuit elements[ edit ]

Silicon carbide was the first commercially important semiconductor material. A “carborundum” (synthetic silicon carbide) crystal radio detector diode was patented by Henry Harrison Chase Dunwoody in 1906. It found much earlier use in ship receivers.

Power Electronic Devices[edit]

In 1993, silicon carbide was considered in both research and early mass production as a semiconductor offering advantages for high-temperature and/or high-voltage fast devices. The first devices available were Schottky diodes, followed by junction gate FETs and MOSFETs for high power circuits. Bipolar transistors and thyristors are currently[when?] under development.[38]

A major problem in the commercialization of SiC has been the elimination of defects: edge dislocations, screw dislocations (both hollow and closed core), triangular defects, and basal plane dislocations.[57] As a result, devices made from SiC crystals initially showed poor reverse blocking performance, although researchers have found experimental solutions to improve breakdown performance.[58] Aside from crystal quality, problems with the SiC to silicon dioxide interface have hampered the development of SiC-based power MOSFETs and insulated gate bipolar transistors. Although the mechanism is still unclear, nitriding has drastically reduced the defects causing the interface problems.[59]

In 2008, the first commercial JFETs with a voltage rating of 1200 V were released,[60] followed by the first commercial MOSFETs with a voltage rating of 1200 V in 2011. JFETs are now available with a voltage rating of 650 V to 1700 V and a resistance as low as 25 mΩ .[61] In addition to SiC switches and SiC Schottky barrier diodes (also known as Schottky Barrier Diodes, SBD) in the popular TO-247 and TO-220 packages, companies have earlier started to manufacture the Implement bare chips in their power electronics modules.

SiC SBD diodes found wide market acceptance and were used in PFC circuits and IGBT power modules.[62] Conferences such as the International Conference on Integrated Power Electronics Systems (CIPS) regularly report on the technological progress of SiC power components. The major challenges to fully unleashing the capabilities of SiC power devices are:

Gate Drive: SiC devices often require gate drive voltage levels that differ from their silicon counterparts and can even be unbalanced, e.g. B. +20 V and -5 V. [63]

Packaging: SiC chips may have higher power densities than silicon power devices and are able to handle higher temperatures, exceeding silicon’s 150°C limit. New die-attach technologies such as sintering are required to efficiently remove heat from the devices and ensure a reliable connection.[64]

Starting with Tesla Model 3, the inverters in the power unit use 24 pairs of silicon carbide (SiC) MOSFET chips, each rated at 650 volts. In this case, silicon carbide gave Tesla a significant advantage over silicon chips in terms of size and weight. A number of car manufacturers are planning to incorporate silicon carbide into the power electronics of their products. A significant increase in silicon carbide production is forecast, starting with a large plant being planned by Wolfspeed in upstate New York.

Ultraviolet LED

LEDs[edit]

The phenomenon of electroluminescence was discovered in 1907 using silicon carbide and the first commercial LEDs were based on SiC. Yellow LEDs made of 3C-SiC were produced in the Soviet Union in the 1970s[67] and blue LEDs (6H-SiC) worldwide in the 1980s.[68]

LED production soon ceased when another material, gallium nitride, showed 10 to 100 times brighter emission. This difference in efficiency is due to SiC’s unfavorable indirect band gap, while GaN has a direct band gap that favors light emission. Nevertheless, SiC is still one of the most important LED components—it is a popular substrate for the growth of GaN devices and also serves as a heat spreader in high-power LEDs.[68]

astronomy [edit]

The low coefficient of thermal expansion, high hardness, rigidity and thermal conductivity make silicon carbide a sought-after mirror material for astronomical telescopes. The growth technology (chemical vapor deposition) has been scaled up to produce polycrystalline silicon carbide disks up to 3.5 m (11 ft) in diameter, and several telescopes such as the Herschel Space Telescope are already equipped with SiC optics [69][70 ]. ], the Gaia Space Observatory spacecraft’s subsystems are also mounted on a rigid silicon carbide frame that provides a stable structure that will not expand or contract due to heat.

Thin filament pyrometry[ edit ]

Test flame and glowing SiC fibers. The flame is about 7 cm high.

Silicon carbide fibers are used to measure gas temperatures in an optical technique called thin filament pyrometry. A thin filament is introduced into a hot gas stream. Radiant emissions from the filament can be correlated to filament temperature. Filaments are SiC fibers with a diameter of 15 microns, about one-fifth the diameter of a human hair. Because the fibers are so thin, they hardly disturb the flame and their temperature stays close to that of the local gas. Temperatures of about 800–2500 K can be measured.[71][72]

Heating elements [ edit ]

Evidence of silicon carbide heating elements has existed since the early 20th century when they were manufactured by Acheson’s Carborundum Co. in the USA and EKL in Berlin. Silicon carbide offered increased operating temperatures compared to metallic heaters. Silicon carbide elements are now used in melting of glass and non-ferrous metals, heat treatment of metals, float glass manufacture, manufacture of ceramic and electronic components, igniters in pilot lights for gas heaters, etc.[73]

Nuclear Fuel Particles and Shells[ edit ]

Silicon carbide is an important material in TRISO-coated fuel particles, the type of nuclear fuel found in high-temperature gas-cooled reactors such as the Pebble Bed Reactor. A layer of silicon carbide provides structural support to the coated fuel particles and is the main diffusion barrier for the release of fission products.[74]

Silicon carbide composites have been investigated for use as replacements for Zircaloy cladding in light water reactors. One of the reasons for this study is that Zircaloy experiences hydrogen embrittlement as a result of the corrosion reaction with water. This leads to a decrease in fracture toughness with increasing volume fraction of radial hydrides. This phenomenon increases drastically with increasing temperature at the expense of the material.[75] Silicon carbide claddings do not experience the same mechanical degradation but instead maintain their strength properties with increasing temperature. The composite consists of SiC fibers wrapped around an inner SiC layer and surrounded by an outer SiC layer.[76] Problems with the ability to bond the parts of the SiC composite have been reported.[77]

Jewelry [ edit ]

As a gemstone, silicon carbide is called “synthetic moissanite” or simply “moissanite” after the mineral name. Moissanite is similar to diamond in several important respects: it is transparent and hard (9-9.5 on the Mohs scale compared to 10 for diamond) with a refractive index between 2.65 and 2.69 (compared to 2.42 for diamond). Moissanite is slightly harder than regular zirconia. Unlike diamond, moissanite can be highly birefringent. For this reason, moissanite jewels are cut along the optical axis of the crystal to minimize birefringence effects. It is lighter (density 3.21 g/cm3 vs. 3.53 g/cm3) and much more heat resistant than diamond. This results in a stone with higher luster, sharper facets and good resilience. Loose moissanite stones can be placed directly into wax ring molds for the lost-wax casting process, as can diamonds,[78] since moissanite is undamaged by temperatures up to 1,800 °C (3,270 °F). Moissanite has become popular as a diamond substitute and can be misidentified as diamond because its thermal conductivity is closer to diamond than any other substitute. Many diamond thermal probers cannot distinguish moissanite from diamond, but the gem can be distinguished by its birefringence and a very slight green or yellow fluorescence under ultraviolet light. Some moissanite stones also have curved, cord-like inclusions that diamonds never have.[79]

Steel production[ edit ]

Piece of silicon carbide used in steelmaking

Silicon carbide dissolved in a basic oxygen steelmaking furnace is used as a fuel. The extra energy released allows the furnace to process more scrap with the same batch of pig iron. It can also be used to increase tap temperatures and adjust carbon and silicon levels. Silicon carbide is cheaper than a combination of ferrosilicon and carbon, produces cleaner steel and lower emissions due to low levels of trace elements, has low gas content, and does not lower the temperature of steel.[80]

Catalyst support[ edit ]

The inherent resistance to oxidation of silicon carbide, as well as the discovery of new ways to synthesize the cubic β-SiC form with its increased surface area, has led to considerable interest in its use as a support for heterogeneous catalysts. This form has been used as a catalyst support for the oxidation of hydrocarbons such as n-butane to maleic anhydride.[81][82]

Carborundum printmaking[edit]

Silicon carbide is used in the Carborundum printing technique – a collagraph printing technique. Carborundum grit is applied in a paste to the surface of an aluminum plate. When the paste is dry, ink is applied and trapped in its grainy surface and then wiped off the bare areas of the plate. The color plate is then printed onto paper in a roller bed press used for gravure manufacture. The result is a print of painted marks embossed into the paper.

Carborundum grit is also used in stone lithography. Its uniform particle size makes it possible to “grain” a stone that removes the previous image. In a process similar to grinding, coarser grit carborundum is applied to the stone and worked with a levigator, then finer and finer grit is gradually applied until the stone is clean. This creates a fat-sensitive surface.[83]

Graph production [ edit ]

Silicon carbide can be used in graphene fabrication due to its chemical properties that promote the epitaxial production of graphene on the surface of SiC nanostructures.

During its production, silicon is mainly used as a substrate to allow the graphene to grow. But there are actually several methods that can be used to grow the graphene on the silicon carbide. The CCS (Confinement Controlled Sublimation) growth process consists of a SiC chip that is heated with graphite under vacuum. Then the vacuum is released very gradually to control the growth of graphene. This method yields the highest quality graphene layers. However, other methods have also been reported to give the same product.

Another way to grow graphene would be to thermally decompose SiC at high temperature in a vacuum.[84] But this method yields graphene sheets that contain smaller grains within the sheets.[85] Hence, efforts have been made to improve the quality and yield of graphene. One such method is to perform ex situ graphitization of silicon-terminated SiC in an atmosphere consisting of argon. Es hat sich gezeigt, dass diese Methode Graphenschichten mit größeren Domänengrößen liefert als die Schicht, die mit anderen Methoden erreichbar wäre. Diese neue Methode kann sehr praktikabel sein, um qualitativ hochwertigeres Graphen für eine Vielzahl von technologischen Anwendungen herzustellen.

Wenn es darum geht zu verstehen, wie oder wann diese Methoden der Graphenproduktion eingesetzt werden sollen, produzieren oder züchten die meisten von ihnen dieses Graphen hauptsächlich auf dem SiC in einer wachstumsfördernden Umgebung. Aufgrund der thermischen Eigenschaften von SiC wird es am häufigsten bei etwas höheren Temperaturen (z. B. 1300 °C) eingesetzt.[86] Es wurden jedoch bestimmte Verfahren durchgeführt und untersucht, die potenziell zu Methoden führen könnten, die niedrigere Temperaturen verwenden, um die Herstellung von Graphen zu unterstützen. Genauer gesagt wurde beobachtet, dass dieser andere Ansatz für das Graphenwachstum Graphen in einer Temperaturumgebung von etwa 750 °C produziert. Dieses Verfahren beinhaltet die Kombination bestimmter Verfahren wie chemische Gasphasenabscheidung (CVD) und Oberflächenabscheidung. Und was das Substrat betrifft, würde das Verfahren darin bestehen, ein SiC-Substrat mit dünnen Filmen eines Übergangsmetalls zu beschichten. Und nach der schnellen Wärmebehandlung dieser Substanz würden die Kohlenstoffatome dann an der Oberflächengrenzfläche des Übergangsmetallfilms häufiger vorkommen, was dann Graphen ergeben würde. Und es stellte sich heraus, dass dieser Prozess Graphenschichten ergab, die über die gesamte Substratoberfläche durchgehender waren.[87]

Quantenphysik [ bearbeiten ]

Siliziumkarbid kann Punktdefekte im Kristallgitter beherbergen, die als Farbzentren bekannt sind. Diese Defekte können bei Bedarf einzelne Photonen erzeugen und dienen somit als Plattform für Einzelphotonenquellen. Ein solches Gerät ist eine grundlegende Ressource für viele neue Anwendungen der Quanteninformationswissenschaft. Wenn man ein Farbzentrum über eine externe optische Quelle oder elektrischen Strom pumpt, wird das Farbzentrum in den angeregten Zustand gebracht und entspannt sich dann mit der Emission eines Photons.[88][89]

Ein wohlbekannter Punktdefekt in Siliziumkarbid ist die Divacancy, die eine ähnliche elektronische Struktur wie das Stickstoff-Leerstellenzentrum in Diamant hat. In 4H-SiC hat die Divacancy vier verschiedene Konfigurationen, die vier Null-Phonon-Linien (ZPL) entsprechen. Diese ZPL-Werte werden unter Verwendung der Schreibweise V Si – V C und der Einheit eV geschrieben: hh(1.095), kk(1.096), kh(1.119) und hk(1.150).[90]

Angelrutenführer [ bearbeiten ]

Siliziumkarbid wird wegen seiner Haltbarkeit und Verschleißfestigkeit bei der Herstellung von Angelführern verwendet.[91] Siliziumkarbid-Ringe werden in einen Führungsrahmen eingepasst, der typischerweise aus Edelstahl oder Titan besteht und verhindern, dass die Schnur den Rutenrohling berührt. Die Ringe bieten eine reibungsarme Oberfläche, die die Wurfweite verbessert und gleichzeitig eine angemessene Härte bietet, die Abrieb durch geflochtene Angelschnur verhindert.[92]

See also[edit]

Amid all that’s going on in the world, I think now would be the perfect time to speak head-on about things other than the weirdness of our current reality. With we all confined to our homes, now more than ever is the time to focus on the things we love to do and are grateful for. For me, this is stained glass, so I want to do what I can to share some positivity and guidance for those of you stuck at home who also need to use this time to create glass work, or who stained glass thanks to a new one Don’t know hobbies yet Haha. In my last post I shared my recommendations for cutting glass, so of course the next step when working on your stained glass project is: sanding!

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FIRST TIME GLASS GRINDER?

Alright, so you’ve cut out all your pieces, excellent! But like anyone working with a material as fragile as glass, your cuts aren’t flawless and your project doesn’t come together perfectly. This is where an amazing tool called the grinder comes in and saves you the day and LOTS of time (the alternative is to grind by hand with a stone like they did in medieval times…no thanks). A glass grinder is a type of wet grinder designed specifically for grinding glass. It features a diamond bur to help slowly sand away the unwanted excess glass on your pieces, turning them into perfect puzzle pieces that fit together. If a wet grinder is a new concept, you’re not alone. I was completely confused when I first saw one – er mix electricity with water – what? Anyhow, they’re perfectly safe (worst thing they can do is shave off your fingernail) and I promise not as dangerous as those wood sanders you vaguely remember dreading in middle school . Your grinder has a diamond bit that sits in the center and spins quickly as soon as you flip the power switch. It is usually touched by a sponge as it rotates. The sponge is designed to prevent glass dust from becoming airborne by supplying water to catch the glass particles. The sponge that touches the bit is also in contact with the water reservoir below to provide constant water against your grinder and glass piece. Grinders aren’t terribly loud, are surprisingly small, and flatten glass MUCH slower than you’d think. Some manufacturers find this part of the process tedious, but I don’t think having loud music playing in the background is too bad.

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The chemical formula of silicon carbide, also known as carborundum, is SiC. It is made by the carbothermal reduction of silica to form an ultra-hard, covalently bonded material. It is extremely rare in nature but can be found in the mineral moissanite, which was first discovered in Arizona in 1893.

Precision machined sintered silicon carbide component machined by Insaco.

Machining of silicon carbide

In all of the applications described above, where high-precision engineering components are required, it is important to recognize the difficulties involved in machining silicon carbide. Despite the high hardness values, it is still a relatively brittle material and can only be processed using diamond grinding techniques.

Consequently, it is beneficial to have a knowledgeable and experienced operator perform the machining operations, as improper procedures can create subsurface damage and microcracks that can lead to premature failure once the component is subjected to operational stresses.

Synthesis of silicon carbide

Typically, silicon carbide is produced by the Acheson process, in which silica sand and carbon are heated to high temperatures in an Acheson graphite resistance furnace. It can be formed as a fine powder or a bound mass that needs to be crushed and ground before it can be used as a powder feedstock. Once the silicon carbide is in powder form, the grains of the compound can be sintered together to form a very useful engineering ceramic that has a wide range of applications in many manufacturing industries.

The structure of silicon carbide

Many structures or polytypes have been identified for silicon carbide. These polytypes have different stacking arrangements for the silicon and carbon atoms in the compound. One of the simplest structures is the diamond structure known as b-SiC. There are more complex hexagonal or rhombic structures of the compound and these are referred to as a-SiC.

The discovery of silicon carbide

dr Edward Goodrich Acheson was a scientist who once worked for Thomas Edison. He first synthesized silicon carbide by accident while attempting to create artificial diamonds. Diamonds could, in theory at least, be burned in the lab, so he decided to try synthesizing them using carbon-based materials. In his experiment, he attached a cable from a dynamo to a plumber’s bowl filled with clay and powdered coke.

When the mixture was exposed to the high heating temperature of the dynamo lead, he didn’t produce any diamonds, but he did notice some bright spots at the end of the lead. He took the lead and dragged it across a pane of glass and it cut the pane like a diamond. What he had achieved was the first artificial substance hard enough to cut through glass.

He was also attempting to dissolve carbon in molten corundum or aluminum oxide when he discovered the blue-black colored crystals, which he believed to be a compound of corundum and carbon, hence naming the material carborundum. This became the popular name for silicon carbide and was also the name of the company that Acheson founded. Although the compound was initially used as an abrasive, it was later developed for use in electronic applications and many other engineering applications.

Types of Silicon Carbide

For use in commercial engineering applications, silicon carbide products are manufactured in three forms. These are:

Sintered Silicon Carbide (SSC)

Nitride Bonded Silicon Carbide (NBSC) and

Reaction Bonded Silicon Carbide (RBSC)

Other compound variations include clay bonded silicon carbide and SiAlON bonded silicon carbide. There is also chemical vapor deposited silicon carbide called CVD silicon carbide which is an extremely pure form of the compound.

In order to sinter the silicon carbide, it is necessary to add sintering aids that help form a liquid phase at the sintering temperature that allows the silicon carbide grains to bond together.

Key Properties of Silicon Carbide

Silicon carbide has a refractive index greater than diamond. It has high thermal conductivity and a low coefficient of thermal expansion. This combination of these properties gives it excellent thermal shock resistance, making it useful in many industries. It is also a semiconductor and is suitable for a wide range of applications due to its electrical properties. It is also known for its extreme hardness and is very resistant to corrosion.

The table below provides additional sample data for sintered silicon carbide.

Table 1. Properties of sintered silicon carbide.

Property Minimum Value (SI) Maximum Value (SI) Units (SI) Minimum Value (Imp.) Maximum Value (Imp.) Units (Imp.) Atomic Volume (Average) 0.0062 0.0064 m3/kmol 378.347 390.552 in3/kmol Density 3 3.2 Mg /m3 187.284 199.77 lb/ft3 Energy Content 150 200 MJ/kg 16250.8 21667.7 kcal/lb Bulk Modulus 181 189.8 GPa 26.2518 27.5281 106 psi Compressive Strength 3047.4 3359.9 MPa 441.988 487.312 ksi Ductility 0.00076 0.00084 0.00076 0.00084 NULL Elastic Limit 304.7 336 MPa 44.193 48.7327 KSI -Endurance Limit 259.17 302.37 MPA 37.5894 43.855 KSI Fracture Hardness 4.28 4.72 MPA.M1/2 3.895 4.29542 KSI.in1/2 Hardness 23800 26250 MPA 3451.9 3807.24 KSI Loss Coefficient 2e -00055 -007.24 KSI Loss Coefficient 2e-00555 2- 005-005-007.24 KSI Loss Coefficient 2e-005555 2-005-007.24 KSI Loss Coefficients 365.7 403.2 MPa 53.0403 58.4792 ksi NULus Poisson’s Ratio 1.305 ULL 10 1.50 Shear Modulus 1.13 171.15 179.8 GPa 24.8232 26.0778 106psi Tensile Strength 304.7 336MPa 44.193 48.7327 ksi Young’s Modulus 390.2 410 GPa 56.5937 59.4654 106 psi Latent Heat of Fusion 930 1050 kJ/kg 399,826 45 1.416 BTU/lb Maximum Operating Temperature 1738 1808 K 2668.73 2794.73 °F Melting Point 2424 2522 K 3907.3 °F Minimum Operating Temperature 0 0 K -459.67 -459.67 °F Specific Heat 663 677 J/kg.K 0.513068 0.52.0 BTU39 0.52.0 F Thermal Conductivity 90 110 W/m.K 168.483 205.924 BTU.ft/h .ft2.F Thermal Expansion 2.7 2.8 10-6/K 4.86 5.04 10-6/°F Breakdown Potential 5 10 MV/m 127 254 V/mil Dielectric Constant 7 9 7 9 ZERO Resistance 1e+ 009 3.16e+010 10-8 Ohm.m 1e+009 3.16e+010 10-8 Ohm.m

Main Applications of Silicon Carbide

There are many applications of silicon carbide in different industries. Its physical hardness makes it ideal for use in abrasive machining processes such as grinding, honing, grit blasting and water jet cutting.

Silicon carbide’s ability to withstand very high temperatures without cracking or deforming is used in the manufacture of ceramic brake discs for sports cars. It is also used in bulletproof vests as an armor material and as a gasket material for sealing pump shafts, where it often runs at high speed in contact with a similar silicon carbide seal. One of the main advantages in these applications is the high thermal conductivity of silicon carbide, which is able to dissipate the frictional heat generated on a friction surface.

The high surface hardness of the material means that it is used in many engineering applications where high levels of resistance to sliding, erosion and corrosion wear are required. Typically this can occur in components used in pumps or, for example, as valves in oil field applications where conventional metal components would exhibit excessive wear rates leading to rapid failures.

The compound’s unique electrical properties as a semiconductor make it ideal for the fabrication of ultra-fast and high-voltage light-emitting diodes, MOSFETs and thyristors for high-power circuits.

The material’s low coefficient of thermal expansion, hardness, rigidity and thermal conductivity make it an ideal mirror material for astronomical telescopes. Silicon carbide fibers, known as filaments, are used to measure gas temperatures in an optical technique called thin filament pyrometry.

It is also used in heating elements where extremely high temperatures must be accommodated. It is even used in nuclear power to provide structural support in high-temperature gas-cooled reactors.

Precision manufacturing through Design Play

This information was obtained, verified and adapted from materials provided by INSACO Inc.

For more information on this source, visit INSACO Inc.

You can use the rotary Dremel tool to grind glass with special bits designed for use with glass such as: B. the diamond or silicon carbide whetstones. To be safe, apply water to the glass when grinding. This will prevent glass dust from splashing into your eyes and nose and will help cool and lubricate the glass surface during grinding. Use a slow, steady speed and gentle pressure. Do not try to rush the work or you risk breaking the glass.

Precisely grind small pieces of glass art – without losing your fingers!

Sometimes you need to be able to accurately cut small pieces of stained glass to get a good fit or detailed designs. The small pieces get your fingers in the path of the grinder bit and can be tricky to work with, especially if your fingers are immobile.

I asked how others tackle the tricky problem of hand-cutting stained glass and had some interesting ideas exchanged. Let me know if any of these are helpful, or if you have another trick up your sleeve that you’d like to add in the comments below.

1. Stained Glass Mill Cookies

Milly’s recommendation:

This is the tool I use to painlessly and accurately sand small pieces of stained glass. It looks a bit like an unsuccessful flying saucer, but it actually does a good job of holding small pieces of glass in place while grinding.

I was a bit skeptical at first and figured my fingers would do the job just fine, thanks. But I’ve been trying them for a few years and now I think they’re great.

Because you have more control over the grinding process, there is less breakage. For the same reason, they seem to help get the grinder insert.

The Cookie grinder is comfortable to hold, you don’t have to hold anything, so it’s good if you struggle with dexterity.

It is also good for grinding shapes that taper to thin points. I bought a couple for my class and tried using two together which meant I didn’t have to hold the glass at all. The Glass Grinder Cookie also prevents you from wiping the pen lines with your fingers, which is a huge plus.

Best of all, it’s easy on your nails and fingertips and reduces the cramps you sometimes get when grinding tiny pieces of glass.

All in all I am corrected. This is a very useful addition to a stained glass kit and is recommended.

Stained Glass Cookie Mill (*paid link)

The following suggestions were kindly shared by members of my Stained Glass Hub community and readers – big thanks to everyone!

Tips on Alternatives to Art Glass Cookie Grinders from Readers:

This is a great idea for a cheap, effective DIY version:

I use the Stained Glass Grinder Cookie you show, but for even smaller pieces of glass I made a pusher out of a paint stirrer. I put a nickel sized “U” in it and it works fine.

2. Grinders Mate & other stained glass grinding tools

You may find the following tips and discussions about different stained glass grinders useful:

I was recently loaned a Nick’s Grinders Mate for testing. I have to say I LOVE it. If you haven’t tried it yet, I highly recommend it. The jaws grip exceptionally well and hold even the smallest piece fairly securely. I’ve read that others don’t like that the piece is lifted off the grinding surface and makes contact with the bit at a raised point. This is not a disadvantage for me.

I have the Grinders Mate and it works fine but tiny little bits get lost in it.

I have Grinders Mate but I found the soft rubber doesn’t carry well, really small bits “get lost”.

Grinder’s Pal (*paid link)

Comment from Milly: There are replacement heads for these glass grinding pliers, so the wear and tear described above is not the end of the pliers, just a bit of a nuisance!

Grinders Mate replacement heads (*paid link)

My art glass grinding pliers are the yellow Morton pliers (*paid link), you have to clamp the piece of glass with your hand all the time. I would recommend the Grinder’s Mate though as it stays locked in place – no hand grip required.

While working on a skylight, I stumbled across Griffin Glass Gripper (made in Germany) grinding pliers marketed by Glastar. Like the Morton, you have to hold them together to grab the jar, but so far I’ve found them superior because they hold super small pieces well. They appear to be a heavier plastic and there is no soft rubber to wear out and affect grip. The downside is the price – they’re significantly more expensive than Grinder’s Mate or Morton.

Just so you know, if you click the link and make a purchase within 24 hours, I will receive a small percentage from Amazon (not you!). Thanks in advance but don’t worry if you have a local shop – I would always support them first 🙂

3. Additional grinding tips

Here are some clever ideas from Stained Glass Hub member Denise Whittle, with a nifty storyboard to help you understand:

I use a +/- 1 or 2 inch piece of strip scrap so I have something to hold on to. Grind that scrap to be safe.

Sand around 3 sides, then score and break the 4th side and sand it. This way you only have to hold a tiny bit for one side.

I also have a cookie grinder that holds it against the bit, but if it’s too small it will disappear into the bottom of the grinder.

Another thing I do is either hold it directly against the 1/4 or 1/8 bit with my fingers or use the grinding pliers. You have to hold on because you don’t have a work surface to support your little piece.

Image Denise Whittle

Here’s a genius cork idea, although I’m wondering how safe it is to insert a small piece of glass into a cork, so be careful if you try this.

I make a slit in a wine cork… insert the tiny piece of glass and hold the cork while I grind :-). I have to save people for myself as I also use them for polishing foil on heavily textured glass.

4. Cheap and cheerful finger guard

I was fed up with polished fingertips – the solution? rubber thimbles! Easily found in stationery stores. Get larger ones made of plastic suitable for quilting for your thumb. Here are some on Amazon (*paid link)

Alternatively, use duct tape – tape it over and back over the top of your fingers and then around the perimeter of your finger/thumb to hold it in place.

I’ve been making stained glass since 2002. I buy the rubber finger guards you would use for flipping through papers etc for sanding. I buy them in different sizes. I always have them on each thumb and either my index or middle finger (that way either the index or middle finger depending on what finger guard you’re wearing can be clear to pick up the pieces. This works better than duct tape they leave very easy to put on and take off.

Idea Ron – “I avoid finger dragging (as best I can) by using 2 erasers per image attached. You grip the glass well.”

So here are some suggestions to help you sand small pieces of stained glass more easily and accurately without putting your precious fingers at risk! Let me know how you get on below if you try any of these suggestions or if you have others. Thanks in advance.

Glass mill for precise shapes

Get stained glass to match

When it comes to cast glass, it often doesn’t make much sense to hold the piece on a surface grinder or against a belt sander for any length of time. Cast glass can be very heavy and unwieldy, and your arms, hands and back can suffer. It can then be advantageous to bring the grinder to the glass and this is where water-fed angle grinders come into play. When it comes to right angle grinders, there are a number of choices, from electric grinders, which do not require an air compressor but weigh more and can tire the user more quickly, to pneumatic, air-powered grinders, which are lighter and more versatile but require larger air compressors to operate She.

Even within the electric or pneumatic options, there is a choice of grinder size and weight and their subsequent price points. When it comes to pneumatic grinders, there’s even a choice between the larger grinders, which can accommodate backing pads from 3″ all the way up to 5″ in diameter, and the smaller, lightweight, and versatile LXB-10 grinder, which we’ll show you in the videos are accepted just a 2 inch diamond disc.

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carborundum sample

Carborundum is an artificial crystal also known as silicon carbide. Carborundum is a very charming crystal with black spiky crystals like a castle, beautiful rainbow-like luster, dazzling colors of green, blue, purple, pink, yellow, etc. Pure Silicon Carbide is very rare on Earth but abundant in space and meteorites , a common form of stardust found around carbon-rich stars. The rainbow colors in carborundum are associated with the seven chakras. Carborundum energetically cleanses the mind, body and soul and promotes intuition and judgment. Carborundum enhances communication, transmits thoughts, conducts electrical impulses, and can enhance energy transfer from the healer and healing minerals.

Carborundum is a powerful vitality booster and is useful for relieving headaches, eye strain, and computer injuries. Carborundum helps solve shoulder and neck problems. It can be helpful in treating bone deformities, problems with the skeletal system, healing fractures, and can be used to strengthen teeth.

This large piece of carborundum weighs 1.050 kg (2.3 lb) and measures 4.5 in. x 4.5 in. x 4 in. (L x W x H).