Titanium, boride

Five phases of titanium boride have been reported. TiB2 [12405-65-35] Ti2B [12305-68-9] TiB [12007-08-8] [ 2447-59-5] and TiB 2 [51311-04-7]. 

This reaction, operated at pilot plant scale, has not as of this writing (ca 1997) been commercialized. The same reaction may be used for chemical vapor deposition of titanium boride. 

Table 3. Physical Properties of Titanium Borides, Carbides, and Nitrides ...

Borides are inert toward nonoxidizing acids however, a few, such as Be2B and MgB2, react with aqueous acids to form boron hydrides. Most borides dissolve in oxidizing acids such as nitric or hot sulfuric acid and they ate also readily attacked by hot alkaline salt melts or fused alkaU peroxides, forming the mote stable borates. In dry air, where a protective oxide film can be preserved, borides ate relatively resistant to oxidation. For example, the borides of vanadium, niobium, tantalum, molybdenum, and tungsten do not oxidize appreciably in air up to temperatures of 1000—1200°C. Zirconium and titanium borides ate fairly resistant up to 1400°C. Engineering and other properties of refractory metal borides have been summarized (1). 

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). 

Titanium Boride. TiB2 is extremely hard, corrosion resistant, and provides good protection against abrasion. 

High Strength Titanium Boride Whiskers, Japanese New Materials High Performance Ceramics (Jan. 1989)... 

Apart from the reactions described above for the formation of thin films of metals and compounds by the use of a solid source of the material, a very important industrial application of vapour phase transport involves the preparation of gas mixtures at room temperature which are then submitted to thermal decomposition in a high temperature furnace to produce a thin film at this temperature. Many of the molecular species and reactions which were considered earlier are used in this procedure, and so the conclusions which were drawn regarding choice and optimal performance apply again. For example, instead of using a solid source to prepare refractory compounds, as in the case of silicon carbide discussed above, a similar reaction has been used to prepare titanium boride coatings on silicon carbide and hafnium diboride coatings on carbon by means of a gaseous input to the deposition furnace (Choy and Derby, 1993) (Shinavski and Diefendorf, 1993). 

Titanium anodes, 15 591 Titanium aryloxides, 25 78 Titanium beach-sand mining, 24 847 Titanium borides, 25 5-6 physical properties of, 25 7 Titanium bromide... 

Square, M. Titanium Boride Cermet New Wear-Resistant Coating. Advanced Materials Processes, 117 (April 1990). 

Recent research has explored a wide variety of filler-matrix combinations for ceramic composites. For example, scientists at the Japan Atomic Energy Research Institute have been studying a composite made of silicon carbide fibers embedded in a silicon carbide matrix for use in high-temperature applications, such as spacecraft components and nuclear fusion facilities. Other composites that have been tested include silicon nitride reinforcements embedded in silicon carbide matrix, carbon fibers in boron nitride matrix, silicon nitride in boron nitride, and silicon nitride in titanium nitride. Researchers are also testing other, less common filler and matrix materials in the development of new composites. These include titanium carbide (TiC), titanium boride (TiB2), chromium boride (CrB), zirconium oxide (Zr02), and lanthanum phosphate (LaP04). 

Titanium borides have been reviewed66,67 and optimum conditions given for then-preparation from boron and titanium oxides.68 Electrolysis of a solution containing cryolite, NaOH, sodium borate, NaCl, and rutile at 1100°C results in the crystallization of TiB2 at the cathode.69 Mixtures of boride and nitride phases are formed during the interaction of BN with TiB2 at 1200—2000 °C.70... 

Thermal Evaporation The easiest way of evaporating metal is by means of resistance evaporators known commonly as boats . Boats, made of sintered ceramics, are positioned side by side at a distance of approximately 10 cm across the web width (Fig. 8.1). Titanium boride TiB2 is used as an electrically conductive material with boron nitride BN (two-component evaporator) or BN and aluminum nitride AIN (three-component evaporator) as an insulating material [2]. By combination of conductive and insulating materials, the electrical properties of evaporators are adjusted. 

Five phases of titanium boride have been reported. TiB2 [12405-65-35], TL,B [12505-68-9], TiB [12007-08-8], TL,B5 [12447-59-5], and TiB12 [51311-04-7]. The most important of these is the diboride, TiB2, which has a hexagonal structure and lattice parameters of a = 302.8 pm and c = 322.8 pm. Titanium diboride is a gray crystalline solid. It is not attacked by cold concentrated hydrochloric or sulfuric acids, but dissolves slowly at boiling temperatures. It dissolves more readily in nitric acid/hydrogen peroxide or nitric acid/sulfuric acid mixtures. It also decomposes upon fusion with alkali hydroxides, carbonates, or bisulfates. 

More than one boride phase can be formed with most metals, and in many cases a continuous series of solid solutions may be formed. Several methods have been used for the relatively large-scale preparation of metal borides. One that is commonly used is carbon reduction of boric oxide and the appropriate metal oxide at temperatures up to 2000 °C. Fused salt electrolysis of borax or boric oxide and a metal oxide at 700 1000 °C have also been used. Small-scale methods available include direct reaction of the elements at temperatures above 1000 °C and the reaction of elemental boron with metal oxides at temperatures approaching 2000 °C. One commercial use of borides is in titanium boride-aluminum nitride crucibles or boats for evaporation of aluminum by resistance heating in the aluminizing process, and for rare earth hexaborides as electronic cathodes. Borides have also been used in sliding electrical contacts and as cathodes in HaU cells for aluminum processing. 

Kecskes, L. J., Niiler, A., and Kottke, T., Precursor morphology effects in combustion-synthesized and dynamically consolidated titanium carbide and titanium boride. J. Am. Ceram. Soc., 76, 2961 (1993). 

Titanium boride (TlBg) B2Tl (cr) 274 Titaniun oxide (TiO) 0 Ti (cr,l) 1659... 

Titanium boride (TlBg) B2T1i(1) 275 Titaniun oxide (TiO) O Ti (g) 1660... 

Titanium boride (TlBg) B2Tlj(cr.l) 276 Titanium oxide (Ti02) 02Tii(l) 1682... 

BjTij(cr) Titanium boride (TiB) 256 1 Sodium borate (Na28g0j Q) 304... 

B./ii(cr) Titanium boride (TiB2) 274 BajBrj(g) Barium bromide (BaBr) 321... 

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