Zirconium carbonitride

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... 

The formation of zirconium carbonitrides from carbon-deficient carbides has been studied.72... 

Zirconium carbonitride has been obtained by the low pressure CVD of Zr(NEt2)4 at... 

Production Zirconia is usually produced from zircon, ZrSi04. Zircon sands are first melted with sodium hydroxide and transferred to zirconium (IV) oxide. With addition of coal, the zirconium oxide is transferred to zirconium carbonitride in a plasma arc, which is converted again to zirconium (IV) chloride with chlorine. The chloride is reduced to zirconium with magnesium in a helium atmosphere at 800°C in the so-caUed Kroll-process ZrCLt -I- 2Mg —> Zr -1- 2 MgC. ... 

Mohun s experiments included chlorine treatment of silicon carbide, aluminum carbide, boron carbide, titanium carbide, zirconium carbide, and zirconium carbonitride, generally at temperatures... 

Nitrogen and carbon are the most potent solutes to obtain high strength in refractory metals (55). Particulady effective ate carbides and carbonitrides of hafnium in tungsten, niobium, and tantalum alloys, and carbides of titanium and zirconium in molybdenum alloys. 

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)... 

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 thermal conductivities of transition metal carbides increase with increasing temperature, an unexpected phenomenon that has been investigated extensively on titanium, zirconium, hafnium and carbides and carbonitrides. Previous studies have reported a linear increase of the thermal conductivity with temperature, but more recent investigations have revealed a nonlinear relationship. Carbon... 

Zirconium and niobium polymers were prepared by fairly similar routes, the ammonolysis of the tetrakis-dialkylamines [88] or the chlorides [89,90] in liquid ammonia. After pyrolysis, nitrides or carbonitrides were obtained in high ceramic yields. 

It is sometimes considered advantageous to allow atmospheric nitrogen to take part in the reaction and form a mixture of zirconium carbide with nitride, referred to as the cyanonitride or carbonitride . This gives a more exothermic reaction with chlorine than the carbide itself. 

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