"form) or aloxite in the mining, ceramic, and materials science communities, aluminium oxide finds wide use. Annual world production of aluminium oxide in 2015 was approximately 115 million tonnes, over 90% of which is used in the manufacture of aluminium metal. The major uses of speciality aluminium oxides are in refractories, ceramics, polishing and abrasive applications. Large tonnages of aluminium hydroxide, from which alumina is derived, are used in the manufacture of zeolites, coating titania pigments, and as a fire retardant/smoke suppressant. Over 90% of the aluminium oxide, normally termed Smelter Grade Alumina (SGA), produced is consumed for the production"
"oxygen. Corundum occurs as a mineral in mica schist, gneiss, and some marbles in metamorphic terranes. It also occurs in low silica igneous syenite and nepheline syenite intrusives. Other occurrences are as masses adjacent to ultramafic intrusives, associated with lamprophyre dikes and as large crystals in pegmatites. It commonly occurs as a detrital mineral in stream and beach sands because of its hardness and resistance to weathering. The largest documented single crystal of corundum measured about , and weighed . The record has since been surpassed by certain synthetic boules. Corundum for abrasives is mined in Zimbabwe, Pakistan, Afghanistan, Russia,"
"Chromium(III) oxide Chromium(III) oxide (or chromia) is the inorganic compound of the formula . It is one of the principal oxides of chromium and is used as a pigment. In nature, it occurs as the rare mineral eskolaite. adopts the corundum structure, consisting of a hexagonal close packed array of oxide anions with of the octahedral holes occupied by chromium. Similar to corundum, is a hard, brittle material (Mohs hardness 8 to 8.5). It is antiferromagnetic up to 307 K, the Néel temperature. It is not readily attacked by acids. occurs naturally in mineral eskolaite, which is found in chromium-rich"
"substance in existence, is actually softer than fullerite and even harder aggregated diamond nanorods, both of which have been synthesised in laboratories, but no commercial process has yet been developed. Diamond itself is expensive due to scarcity in nature and the cost of synthesising it. Bauxite is a very common ore which, along with corundum's reasonably high hardness, contributes to corundum's status as a common, inexpensive abrasive. Thought must be given to the desired task about using an appropriately hard abrasive. At one end, using an excessively hard abrasive wastes money by wearing it down when a cheaper, less hard"
"10.0 and moissanite falling somewhere in between corundum (ruby) and diamond in hardness. Sapphire, ruby, and pure corundum are α-alumina, the most stable form of AlO, in which 3 electrons leave each aluminum ion to join the regular octahedral group of six nearby O ions; in pure corundum this leaves all of the aluminum ions with a very stable configuration of no unpaired electrons or unfilled energy levels, and the crystal is perfectly colorless. When a chromium atom replaces an occasional aluminum atom, it too loses 3 electrons to become a chromium ion to maintain the charge balance of the"
"of the growing oxide. One of the most significant effects, is that the oxide is partially converted from amorphous alumina into crystalline forms such as corundum (α-AlO) which is much harder. As a result, mechanical properties such as wear resistance and toughness are enhanced. The part to be coated is immersed in a bath of electrolyte which usually consists of a dilute alkaline solution such as KOH. It is electrically connected, so as to become one of the electrodes in the electrochemical cell, with the other ""counter-electrode"" typically being made from an inert material such as stainless steel, and often"
"is comparable with corundum (α-) in hardness and can only be polished and finished with abrasives of superior hardness such as cubic boron nitride and diamond powder, wheels, and compounds. Historically referred to as Wolfram, ""Wolf Rahm"", wolframite ore discovered by Peter Woulfe was then later carburized and cemented with a binder creating a composite now called ""cemented tungsten carbide"". Tungsten is Swedish for ""heavy stone"". Colloquially among workers in various industries (such as machining and carpentry), tungsten carbide is often simply called ""carbide"", despite the imprecision of the usage. Among the lay public, the growing popularity of tungsten carbide"
"or more of the following other than titanium in varying amounts. These are molybdenum, vanadium, niobium, tantalum, zirconium, manganese, iron, chromium, cobalt, nickel, and copper. The titanium alloys have excellent formability and can be easily welded. Beta titanium is nowadays largely utilized in the orthodontic field and was adopted for orthodontics use in the 1980s. This type of alloy replaced stainless steel for certain uses, as stainless steel had dominated orthodontics since the 1960s. It has strength/modulus of elasticity ratios almost twice those of 18-8 austenitic stainless steel, larger elastic deflections in springs, and reduced force per unit displacement 2.2"
"much lower values for both the hardness (7–20 GPa, which makes it softer than common oxides like corundum AlO and rutile TiO) and bulk modulus (~300 GPa). The oxides are commercially important ores of titanium. The metal can also be mined from other minerals such as ilmenite or leucoxene ores, or one of the purest forms, rutile beach sand. Star sapphires and rubies get their asterism from rutile impurities present in them. Titanium dioxide (B) is found as a mineral in magmatic rocks and hydrothermal veins, as well as weathering rims on perovskite. TiO also forms lamellae in other minerals."
"within a 60-70 Rockwell hardness C range which is comparable only to hardened carbon steel alloys, but considerably inferior to the hardness of natural and synthetic corundum. Instead, with plasma electrolytic oxidation, the coating is porous only on the surface oxide layer while the lower oxide layers are much more compact than with standard DC anodizing procedures and present a higher crystallinity due to the oxide layers being remelted and densified to obtain α-Al2O3 clusters with much higher coating hardness values circa 2000 Vickers hardness. Alumina is used to manufacture tiles which are attached inside pulverized fuel lines and flue"
"is soluble in these metals to give carbides. Polycrystalline c-BN (PCBN) abrasives are therefore used for machining steel, whereas diamond abrasives are preferred for aluminum alloys, ceramics, and stone. When in contact with oxygen at high temperatures, BN forms a passivation layer of boron oxide. Boron nitride binds well with metals, due to formation of interlayers of metal borides or nitrides. Materials with cubic boron nitride crystals are often used in the tool bits of cutting tools. For grinding applications, softer binders, e.g. resin, porous ceramics, and soft metals, are used. Ceramic binders can be used as well. Commercial products"
"fewer Zr(III) compounds are known, and Zr(II) is very rare. The most common oxide is zirconium dioxide, ZrO, also known as ""zirconia"". This clear to white-coloured solid has exceptional fracture toughness and chemical resistance, especially in its cubic form. These properties make zirconia useful as a thermal barrier coating, although it is also a common diamond substitute. Zirconium monoxide, ZrO, is also known and S-type stars are recognised by detection of its emission lines in the visual spectrum. Zirconium tungstate has the unusual property of shrinking in all dimensions when heated, whereas most other substances expand when heated. Zirconyl chloride"
"superalloys but it could not be used effectively on steels because carbon tends to dissolve in iron at high temperatures. Aluminium oxide was the conventional abrasive used on hardened steel tools. Borazon replaced aluminium oxide for grinding hardened steels owing to its superior abrasive properties, comparable to that of diamond. Borazon is used in industrial applications to shape tools, as it can withstand temperatures greater than 2000 °C (3632 °F), much higher than that of a pure diamond at 871 °C (1600 °F). Other uses include jewellery designing, glass cutting and laceration of diamonds. CBN-coated grinding wheels, referred to as"
"involved in corundum synthesis, large quantities of these crystals have become available on the market causing a significant reduction of price in recent years. Apart from ornamental uses, synthetic corundum is also used to produce mechanical parts (tubes, rods, bearings, and other machined parts), scratch-resistant optics, scratch-resistant watch crystals, instrument windows for satellites and spacecraft (because of its transparency in the ultraviolet to infrared range), and laser components. Corundum crystallizes with trigonal symmetry in the space group ""R""""c"" and has the lattice parameters a = 4.75 Å and c = 12.982 Å at standard conditions. The unit cell contains six"
"and American researchers found that the British Museum skull was worked with a harsh abrasive substance such as corundum or diamond, and shaped using a rotary disc tool made from some suitable metal. The Smithsonian specimen had been worked with a different abrasive, namely the silicon-carbon compound carborundum (Silicon carbide) which is a synthetic substance manufactured using modern industrial techniques. Since the synthesis of carborundum dates only to the 1890s and its wider availability to the 20th century, the researchers concluded ""[t]he suggestion is that it was made in the 1950s or later"". None of the skulls in museums come"
"small size of the difference in density and difficulties in measuring it accurately, but, with increased accuracy in factors used for calculating density X-ray crystallographic data yielded densities of 22.56 g/cm for iridium and 22.59 g/cm for osmium. Iridium is the most corrosion-resistant metal known: it is not attacked by almost any acid, aqua regia, molten metals, or silicates at high temperatures. It can, however, be attacked by some molten salts, such as sodium cyanide and potassium cyanide, as well as oxygen and the halogens (particularly fluorine) at higher temperatures. Iridium forms compounds in oxidation states between −3 and +9;"
"(turning it yellow or brown over time). Lanthanum oxide has replaced thorium dioxide in almost all modern high-index glasses. Thorium dioxide Thorium dioxide (ThO), also called thorium(IV) oxide, is a crystalline solid, often white or yellow in color. Also known as thoria, it is produced mainly as a by-product of lanthanide and uranium production. Thorianite is the name of the mineralogical form of thorium dioxide. It is moderately rare and crystallizes in an isometric system. The melting point of thorium oxide is 3300 °C – the highest of all known oxides. Only a few elements (including tungsten and carbon) and"
"glassmaking and also as a glaze for ceramics. Green chromium oxide is extremely lightfast and as such is used in cladding coatings. It is also the main ingredient in infrared reflecting paints, used by the armed forces to paint vehicles and to give them the same infrared reflectance as green leaves. Natural rubies are corundum (aluminum oxide) crystals that are colored red (the rarest type) due to chromium (III) ions (other colors of corundum gems are termed sapphires). A red-colored artificial ruby may also be achieved by doping chromium(III) into artificial corundum crystals, thus making chromium a requirement for making"
"Ukraine) of sapphire monocrystals for hip joint endoprostheses. Sapphire Sapphire is a precious gemstone, a variety of the mineral corundum, consisting of aluminium oxide () with trace amounts of elements such as iron, titanium, chromium, copper, or magnesium. It is typically blue, but natural ""fancy"" sapphires also occur in yellow, purple, orange, and green colors; ""parti sapphires"" show two or more colors. The only color that sapphire cannot be is red – as red colored corundum is called ruby, another corundum variety. Pink colored corundum may be either classified as ruby or sapphire depending on locale. Commonly, natural sapphires are"
"he had in view, he produced a compound which is known as TUNGUM. Recognising that its close likeness to 22 carat gold would make it a marketable commodity the inventor carried out a series of tests which satisfied him that he had discovered a wonderful alloy."" The material is now mainly used in commercial diving and offshore applications, for the material's resistance to salt water corrosion. UNS C69100 UNS C69100, also known as Tungum alloy, CW700R and CZ127, is a bronze copper alloy. It has a naturally occurring oxide layer, which on exposure to reagents develops into a very thin"
"clay, especially Armenian bole, have been used in gilding. Hematite is also used in art such as in the creation of intaglio engraved gems. Hematine is a synthetic material sold as ""magnetic hematite"". Hematite Hematite, also spelled as haematite, is the mineral form of iron(III) oxide (FeO), one of several iron oxides. It is the oldest known iron oxide mineral that has ever formed on earth, and is widespread in rocks and soils. Hematite crystallizes in the rhombohedral lattice system, and it has the same crystal structure as ilmenite and corundum. Hematite and ilmenite form a complete solid solution at"
"often form mixtures, generally containing six-coordinate Al centers that feature both halide and aquo ligands. When aluminium and fluoride are together in aqueous solution, they readily form complex ions such as , , and . In the case of chloride, polyaluminium clusters are formed such as [AlO(OH)(HO)]. Aluminium forms one stable oxide with the chemical formula AlO It can be found in nature in the mineral corundum. Aluminium oxide is also commonly called alumina. Sapphire and ruby are impure corundum contaminated with trace amounts of other metals. The two oxide-hydroxides, AlO(OH), are boehmite and diaspore. There are three trihydroxides: bayerite,"
"for high pressure systems (3,000 p.s.i.) and aluminium tubing for low pressure systems. Titanium Titanium is a chemical element with symbol Ti and atomic number 22. It is a lustrous transition metal with a silver color, low density, and high strength. Titanium is resistant to corrosion in sea water, aqua regia, and chlorine. Titanium was discovered in Cornwall, Great Britain, by William Gregor in 1791, and was named by Martin Heinrich Klaproth after the Titans of Greek mythology. The element occurs within a number of mineral deposits, principally rutile and ilmenite, which are widely distributed in the Earth's crust and"
"etc.). Corundum (alpha-AlO), the only stable form of aluminum oxide, does not have such a chemically active surface and is not used as a sorbent. Activated alumina is used for a wide range of adsorbent and catalyst applications including the adsorption of catalysts in polyethylene production, in hydrogen peroxide production, as a selective adsorbent for many chemicals including arsenic, fluoride, in sulphur removal from fluid streams (Claus Catalyst process). Used as a desiccant, it works by a process called ""adsorption"". The water in the air actually sticks to the alumina itself in between the tiny passages as the air passes"
"Titanium Titanium is a chemical element with symbol Ti and atomic number 22. It is a lustrous transition metal with a silver color, low density, and high strength. Titanium is resistant to corrosion in sea water, aqua regia, and chlorine. Titanium was discovered in Cornwall, Great Britain, by William Gregor in 1791, and was named by Martin Heinrich Klaproth after the Titans of Greek mythology. The element occurs within a number of mineral deposits, principally rutile and ilmenite, which are widely distributed in the Earth's crust and lithosphere, and it is found in almost all living things, water bodies, rocks,"
"UNS C69100 UNS C69100, also known as Tungum alloy, CW700R and CZ127, is a bronze copper alloy. It has a naturally occurring oxide layer, which on exposure to reagents develops into a very thin protective coating. Tungum resists both pitting and crevice corrosion in marine environments/atmospheres. This offers excellent service-life, even at intermittent duty in the corrosive ""splash"" zone. Tungum is non-magnetic and has non-sparking properties. This allows Tungum to be used in high pressure gas pipework systems (oxygen and inert gases). Unusually for a copper alloy, it can be precipitation hardened using heat treatment techniques. This enables its physical"
"Hematite Hematite, also spelled as haematite, is the mineral form of iron(III) oxide (FeO), one of several iron oxides. It is the oldest known iron oxide mineral that has ever formed on earth, and is widespread in rocks and soils. Hematite crystallizes in the rhombohedral lattice system, and it has the same crystal structure as ilmenite and corundum. Hematite and ilmenite form a complete solid solution at temperatures above . Hematite is colored black to steel or silver-gray, brown to reddish brown, or red. It is mined as the main ore of iron. Varieties include ""kidney ore"", ""martite"" (pseudomorphs after"
"spot of cost per ounce). Rhodium is a so-called noble metal, resistant to corrosion, found in platinum- or nickel ores together with the other members of the platinum group metals. It was discovered in 1803 by William Hyde Wollaston in one such ore, and named for the rose color of one of its chlorine compounds, produced after it reacted with the powerful acid mixture aqua regia. The element's major use (about 80% of world rhodium production) is as one of the catalysts in the three-way catalytic converters of automobiles. Because rhodium metal is inert against corrosion and most aggressive chemicals,"
"and are sometimes cut and polished. An almandine in which the ferrous oxide is replaced partly by magnesia is found at Luisenfeld in German East Africa. In the United States there are many localities which yield almandine. Fine crystals of almandine embedded in mica-schist occur near Wrangell in Alaska. The coarse varieties of almandine are often crushed for use as an abrasive agent. Connecticut has almandine garnet as its state gemstone. Almandine Almandine (), also known incorrectly as almandite, is a species of mineral belonging to the garnet group. The name is a corruption of alabandicus, which is the name"
"yttrium oxide and lanthanum oxide, for example forming KSc(OH) with KOH. In this, scandium shows more similarity with aluminium oxide. Natural scandia, although impure, was recently described as mineral kangite Scandium oxide Scandium(III) oxide, ScO, or scandia, is a high melting rare earth oxide. It is used in the preparation of other scandium compounds as well as in high-temperature systems (for its resistance to heat and thermal shock), electronic ceramics, and glass composition (as a helper material). Scandium(III) oxide adopts a cubic crystal structure (point group: tetrahedral (T), space group: Ia) containing 6-coordinate metal centres. Powder diffraction analysis shows Sc−O"
"form, it is described as a dark, shiny gray like high-grade steel or titanium. It is almost impossible to destroy or fracture in this state, and when molded to a sharp edge, it can penetrate most lesser materials with minimal force. The Marvel Comics character Wolverine discovers an adamantium-laced skull in the character Apocalypse's laboratory and says it seems to have been there for eons. Adamantium appears in various Marvel Comics publications and licensed products, where it is found in: In the Marvel Comics Ultimate Marvel imprint, adamantium is highly durable and can shield a person's mind from telepathic probing"
"Sapphire Sapphire is a precious gemstone, a variety of the mineral corundum, consisting of aluminium oxide () with trace amounts of elements such as iron, titanium, chromium, copper, or magnesium. It is typically blue, but natural ""fancy"" sapphires also occur in yellow, purple, orange, and green colors; ""parti sapphires"" show two or more colors. The only color that sapphire cannot be is red – as red colored corundum is called ruby, another corundum variety. Pink colored corundum may be either classified as ruby or sapphire depending on locale. Commonly, natural sapphires are cut and polished into gemstones and worn in"
"common ingredient for many glazes in its white powdered form. When a glaze containing this material is fired in a kiln, the whiting acts as a flux material in the glaze. Ground calcium carbonate is an abrasive (both as scouring powder and as an ingredient of household scouring creams), in particular in its calcite form, which has the relatively low hardness level of 3 on the Mohs scale of mineral hardness, and will therefore not scratch glass and most other ceramics, enamel, bronze, iron, and steel, and have a moderate effect on softer metals like aluminium and copper. A paste"