Zirconium carbides

Electric Furna.ce, Zircon and coke have reacted in an electric arc furnace to produce a cmde zirconium carbide nitride [12713-24-5] (ca 6 wt %... 

Zirconium oxide is fused with alurnina in electric-arc furnaces to make alumina—zirconia abrasive grains for use in grinding wheels, coated-abrasive disks, and belts (104) (see Abrasives). The addition of zirconia improves the shock resistance of brittle alurnina and toughens the abrasive. Most of the baddeleyite imported is used for this appHcation, as is zirconia produced by burning zirconium carbide nitride. 

Carbide. Zirconium carbide [12020-14-3] nominally ZrC, is a dark gray brittle soHd. It is made typically by a carbothermic reduction of zirconium oxide in a induction-heated vacuum furnace. Alternative production methods, especially for deposition on a substrate, consist of vapor-phase reaction of a volatile zirconium haHde, usually ZrCl, with a hydrocarbon in a hydrogen atmosphere at 900—1400°C. 

Once initiated, zirconium and carbon powders react exothermically in a vacuum or inert atmosphere to form zirconium carbide. With the greater availabiHty of relatively pure metal powders, this technique is coming into common use for the production of several refractory carbides. Zirconium carbide is not a fixed stoichiometric compound, but a defect compound with a single-phase composition ranging from ZrCQ to ZrCQ at 2400°C. 

Zirconium carbide is inert to most reagents but is dissolved by hydrofluoric acid solutions which also contain nitrate or peroxide ions, and by hot concentrated sulfuric acid. Zirconium carbide reacts exothermically with halogens above 250°C to form zirconium tetrahaHdes, and with oxidizers to zirconium dioxide in ak above 700°C. Zirconium carbide forms soHd solutions with other transition-metal carbides and most of the transition-metal... 

As a hard, high melting carbide and possible constituent of UC-fueled reactors, zirconium carbide has been studied extensively. The preparation, behavior, and properties of zirconium and other carbides are reviewed in Reference 132, temperature-correlated engineering property data in Reference 133 (see also Carbides). 

Zirconium tetraiodide [13986-26-0], Zrl, is prepared directly from the elements, by the reaction of iodine on zirconium carbide, or by halogen exchange with aluminum triiodide. The reaction of iodine with zirconium oxide and carbon does not proceed. The physical properties are given in Table 7. 

The first carbonitride alloys based on Ti(C,N)—Ni—Mo were iatroduced ia 1970 foUowed by (Ti, Mo)(C,N)-based compositions having fine microstmctures that provided a balance of wear resistance and toughness (4). Continued research on the titanium carbonitride alloys, often called TiC—TiN cermets, ia the 1980s led to the developmeat of complex cermets having a variety of additives such as molybdeaum carbide(2 l) [12069-89-5] M02C, TaC, NbC, zirconium carbide [12020-14-3], ZrC, hafnium carbide [12069-85-1], HfC, WC, vanadium carbide [12070-10-9], VC, chromium carbide (3 2)... 

The physical properties of ZrC are Hsted in Table 2. Zirconium carbide is much less important than TiC for cemented carbides. 

Other compounds have been deposited by fluidized-bed CVD including zirconium carbide (from ZrCl4 and a hydrocarbon), hafnium carbide (from HfC and methane or propylene), and titanium carbide (from TiCl3 and propylene). 

Zirconium carbide (ZrC) is a refractory interstitial carbide with a high melting point. It is produced by CVD mostly on an experimental basis although it has some nuclear applications. Like TiC, cubic ZrC has a variable composition and forms solid solutions with oxygen and nitrogen over a wide range of composition. Its characteristics and properties are summarized in Table 9.10. 

Zirconium carbide has also been deposited from the tetrachloride with methane or cyclopropane as the carbon source,... 

Zirconium carbide is a highly refractory compound with excellent properties but, unlike titanium carbide, it has found only limited industrial importance except as coating for atomic-fuel particles (thoria and urania) for nuclear-fission power plants.l " ] This lack of applications may be due to its high price and difficulty in obtaining it free of impurities. 

An extension of the reduction-chlorination technique described so far, wherein reduction and chlorination occur simultaneously, is a process in which the oxide is first reduced and then chlorinated. This technique is particularly useful for chlorinating minerals which contain silica. The chlorination of silica (Si02) by chlorine, in the presence of carbon, occurs above about 1200 °C. However, the silica present in the silicate minerals readily undergoes chlorination at 800 °C. This reaction is undesirable because large amounts of chlorine are wasted to remove silica as silicon tetrachloride. Silica is, therefore, removed by other methods, as described below, before chlorination. Zircon, a typical silicate mineral, is heated with carbon in an electric furnace to form crude zirconium carbide or carbonitride. During this treatment, the silicon in the mineral escapes as the volatile oxide, silicon monoxide. This vapor, on contact with air, oxidizes to silica, which collects as a fine powder in the furnace off-gas handling system ... 

The mono- and di-alkali metal acetylides, copper acetylides, iron, uranium and zirconium carbides all ignite in chlorine, the former often at ambient temperature. See Caesium acetylide Halogens Dicopper(I) acetylide Halogens Iron carbide Halogens... 

Zirconium carbide, 4 649t, 686 cemented carbides, 4 656 as industrial hard carbide, 4 674 physical properties of, 4 684t preparation, 4 675, 676 stoichiometry, 4 651 Zirconium carbide nitride, 26 627 Zirconium carbonitride... 

Of a series of powdered refractory compounds examined, only lanthanum hexa-boride, hafnium carbide, titanium carbide, zirconium carbide, magnesium nitride, zirconium nitride and tin(II) sulfide were dust explosion hazardous, the 2 latter being comparable with metal dusts. Individual entries are ... 

Hafnium carbide, 0521 Lanthanum hexaboride, 0193 Magnesium nitride, 4698 Tin(II) sulfide, 4900 Titanium carbide, 0561 Zirconium carbide, 0565 Zirconium nitride, 4733... 

Zirconium carbide (ZrC) is used for light bulb filaments, for cladding metals to protect them from corrosion, in making adhesives, and as a high-temperature lining for refractory furnaces. 

The metal is most often recovered from its principal ore, zircon. The ore is mined, crushed and preliminary segregation is by gravity, electrostatic, and magnetic separation. Separated ore mixed with carbon is charged into an arc furnace and heated to about 3,500°C. This forms zirconium carbide and silicon monoxide, and the monoxide is driven off as vapor. Zirconium carbide is then placed in a chlorinator and heated with chlorine gas at high temperatures. The carbide is converted to zirconium tetrachloride, ZrCfl. Also, small amounts of hafnium that is always associated with zirconium converts to its tetrachloride, HfCfl. 

The metal reacts rapidly with carbon dioxide above 1,000°C forming zirconium oxide and zirconium carbide ... 

Zirconium carbide is a refractory material. It is used in making incandescent filaments, high temperature electrical conductors, and cutting tool components. 

Zirconium carbide is prepared by heating a mixture of zirconium oxide and coke in an arc furnace. 

Zirconium oxide is reduced by carbon when heated in a arc furnace, forming zirconium carbide... 

Zirconium Carbide Zirconium Hydride Zirconium Hydroxide Zirconium Nitrate Zirconium Oxide Zirconium Silicate Zirconium Sulfate Zirconium Tetrachloride Zirconyl Chloride Chemical Substances Index CAS Registry Number Index... 

Dash RK, Yushin G, Gogotsi Y et al (2005) Synthesis, structure and porosity analysis of microporous and mesoporous carbon derived from zirconium carbide. Micropor Mesopor Mater 86(l-3) 50-57... 

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