Titanium compounds nitride

Next to Cr C2, TiC is the principal component for heat and oxidation-resistant cemented carbides. TiC-based boats, containing aluminum nitride, AIN, boron nitride, BN, and titanium boride, TiB2, have been found satisfactory for the evaporation of metals (see Boron compounds, refractory boron compounds Nitrides). 

Titan-s ure, /. titanic acid. -sMureonhydrid, n. titanic anhydride, titanium dioxide (TiOj). -schwefelsdure,/. titanosulfmic acid, -stahl, m. titanium steel, -stickstoff, m. titanium nitride, -verbindung, /. titanium compound, -weiss, n. titanium white. 

Titanium nitride films have usually been prepared by OMCVD from dialkylamido titanium compounds Ti(NR2)4 and ammonia, which plays a major role in the process as a reducing agent and source of nitrogen.12,13 Other authors have reported the use of azide compounds such as Cp2Ti(N3)2 or [Ti(NMe2)(N3)(p-NMe2)]3(p3-NH), with the former compound,14 contamination of the films by free carbon from the decomposition of the Cp group is mentioned, while with the latter,15 which occurs as a trimeric species, a lack of sufficient volatility rules out its use as a CVD precursor. 

With nitrogen zirconium unites directly, but less readily than does titanium. Several nitrides have been described, but the most definite, perhaps the only, compound formed is Zr3N2. This results also when zirconium is heated in an atmosphere of ammonia, or the compounds are reduced in the presence of air. It does not burn in oxygen or chlorine, hut evolves ammonia when fused with potash. 

Transition element carbides and nitrides are applied as cutting tools because of their extreme hardness and wear resistance. In some cases nitrides and carbides (e.g., of titanium) form solid solutions over the entire compositional range other transition metal nitrides and carbides exhibit fairly different structures and are not completely soluble. Carbon contents within the range of few percentage points usually do not influence the mechanical properties of transition metal nitrides, and vice versa. Hence, completely carbon-free nitrides or nitrogen-free carbides are not required, especially for the titanium compounds. 

When steel samples are reacted with U-Bi fuels containing zirconium and magnesium, the x-ray patterns of the surface are those for pure or very nearly pure nitrides or carbides. When graphite is contacted with the fuel, however, solid solutions of the carbide and nitride are often found. The unit cells vary from 4.567 Kx to 4.685 Kx for the zirconium compounds and from 4.237 Kx to 4.320 Kx for the titanium compounds. These parameters are low for complete carbon carbide structures. 

Other Binary Compounds.—Scandium nitride and zirconium and titanium carbide do not conform with the theoretical radii. It is possible that these crystals do not consist essentially of Sc+3, N 3, Ti+4, Zr+4 and C-4 ions, especially since zirconium and titanium nitride, ZrN and TiN, also form crystals with the sodium chloride structure but possibly also the discrepancy can be attributed to deformation of the anions, which have very high mole refraction values. 

The deposition of a binary compound can be achieved by a coreduction reaction. In this manner, ceramic materials such as oxides, carbides, nitrides, borides, and silicides can be produced readily and usually more readily than the parent metal. A common example is the deposition of titanium diboride ... 

CVD plays an increasingly important part in the design and processing of advanced electronic conductors and insulators as well as related structures, such as diffusion barriers and high thermal-conductivity substrates (heat-sinks). In these areas, materials such as titanium nitride, silicon nitride, silicon oxide, diamond, and aluminum nitride are of particular importance. These compounds are all produced by CVD. 1 1 PI... 

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 ... 

The first mechanism proposes that metal volatilisation causes rupture of molten droplets (as with magnesium), whereas the second considers the production of a volatile oxide such as CO inside materials such as steels that contain an excess of 0.1% carbon. The third mechanism involves the formation of oxy-nitride compounds which decompose at high temperatures, liberating nitrogen (as with titanium). 

In all these studies which were carried out over the five-year period, 1904-1909, the effects of catalysts on these fixations of nitrogen were investigated. For the barium compounds, iron oxide acted as a catalyst. For the titanium nitrides, various other metal oxides as well as a number of inorganic salts proved to be effective. For the silicium nitrides and aluminum nitrides, again metal oxides and salts had beneficial effects but in other proportions and to another extent than found for the titanium nitrides. Often, two or more catalysts were added to the reaction mixtures with beneficial effects, but no systematic quantitative comparisons were carried out at this time. Table I lists some of these experiments. 

Metals and ceramics (claylike materials) are also used as matrices in advanced composites. In most cases, metal matrix composites consist of aluminum, magnesium, copper, or titanium alloys of these metals or intermetallic compounds, such as TiAl and NiAl. The reinforcement is usually a ceramic material such as boron carbide (B4C), silicon carbide (SiC), aluminum oxide (A1203), aluminum nitride (AlN), or boron nitride (BN). Metals have also been used as reinforcements in metal matrices. For example, the physical characteristics of some types of steel have been improved by the addition of aluminum fibers. The reinforcement is usually added in the form of particles, whiskers, plates, or fibers. 

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