Hydride titanium

Titanium hydride is used as a source for Ti powder, alloys, and coatings as a getter in vacuum systems and electronic tubes as a sealer of metals and as a hydrogen source. 

Zirconium i dride. Zirconium hydride [7704-99-6] ZrH2, is a britde, metaUic-gray soHd that is stable in air and water, and has a density of 5.6 g/cm. The chemical properties of ZrH2 closely resemble those of titanium hydride. Thermal decomposition in vacuum (1 mPa (7.5 x 10 //mHg)) begins at 300°C and is nearly complete at 500—700°C. It is prepared in the same manner as T1H2. 

Fig. 2. Iron—titanium hydride vessel (508 kg hydride, 6.4 kg hydrogen) performance of the Provo-Orem (Utah) bus at 3.4 MPa (493 psi) charge pressure, having 22 cylinders, each with a 75 mm dia and 1750 mm length, where (-) indicates tank pressure. To convert MPa to psi, multiply by 145. See text.

Titanium trifluoride may be prepared ia 90% yield by the reaction of gaseous hydrogen fluoride, ia practice ia a 1 4 ratio of hydrogen HF, with either titanium metal or titanium hydride at 900°C. 

Titanium Silicides. The titanium—silicon system includes Ti Si, Ti Si, TiSi, and TiSi (154). Physical properties are summarized in Table 18. Direct synthesis by heating the elements in vacuo or in a protective atmosphere is possible. In the latter case, it is convenient to use titanium hydride instead of titanium metal. Other preparative methods include high temperature electrolysis of molten salt baths containing titanium dioxide and alkalifluorosiUcate (155) reaction of TiCl, SiCl, and H2 at ca 1150°C, using appropriate reactant quantities for both TiSi and TiSi2 (156) and, for Ti Si, reaction between titanium dioxide and calcium siUcide at ca 1200°C, followed by dissolution of excess lime and calcium siUcate in acetic acid. 

Also the titanium hydride can react with PhSiH3 to form 63, followed by the extrusion of silylene again with formation of the hydride. 

Stability of the Pyrotechnic Mixture Titanium Hydride TiHx/KC104 Report SAND-75-5889... 

Carlson, The Effect of Particle Size-Surface Area and Oxygen on the Hydrogen Content of Titanium Hydrides , Ref 160, p 616. See also related paper on p 50 of Ref 160 124) F.W. 

The theoretical hmit of 5.4% (NaAlH4+2 mol% TiN) for the two subsequent decomposition reactions is in both cases only observed in the first cycle. The reason for the decrease in capacity is stiU unknown and litde is known about the mechanism of alanate activation via titanium dopants in the sohd state. Certainly, the ease of titanium hydride formation and decomposition plays a key role in this process, but whether titanium substitution in the alanate or the formation of a titanium aluminum alloys, i.e., finely dispersed titanium species in the decomposition products is crucial, is stiU under debate [41]. 

When it was heated to 700 C in a mixture of water vapour and air, titanium caused a violent detonation due to the hydrogen formed. Titanium hydride might have formed, which also detonates in air. When it is in contact with hydrogen peroxide, it gives rise to an immediate detonation at ambient temperature. 

See Metal powders, above Titanium hydride, below... 

Pyrophoricity and detonation behaviour of titanium hydride powders of various particle sizes were studied in comparison with those of titanium metal powders [1]. Maximum dust explosion pressures of 8.2 bar, with a maximum rate of rise of 816 bar/s have been recorded [2]. 

Titanium disulfide, 25 57, 58 Titanium disulfide electrodes sloping discharge curve, 3 414 Titanium esters, 25 1 Titanium fluorides, 25 47-49 Titanium halides, 25 47-55 Titanium hydride, 13 626 Titanium hydrides, 25 5 Titanium-hydrogen system, 25 3-5 phase diagram for, 25 5 Titanium iodides, 25 54-55 Titanium/isopropoxy/nitrilotriethoxy ratio, 25 93... 

Cathodic currents causing titanium hydride formation and embrittlement. 

D. Reduction of Imines with Hydrogen in the Presence of a Chiral Titanium Hydride Complex... 

FIGURE 1. Scheme showing the reduction of the imine RsRlC=N—R with hydrogen using the chiral catalyst (R,R)-ethylene-l,2-bis( j5-4,5,6,7-tetrahydro-l-indenyl)titanium hydride [(R,R)- (EBTHI)Ti—H, (R,R)-44], prepared from the precatalyst (R,R)-ethylene-l,2-bis(()5-4,5,6,7-tetrahydro-l-indenyl)titanium (R)-l,l -binaphthyl-2,2 -diolate [(7A/. A )-45. Reprinted with permission from Reference 52. Copyright (1994) American Chemical Society... 

Norbomadiene and ethene can be codimerised to give vinylnorbomene, which is isomerised to ethylidenenorbornene with the same nickel or titanium hydride catalyst (Figure 9.14). 

Industrially this diene is made the same way as ethylidenenorbomene from butadiene and ethene, but now isomerisation to 2,4-hexadiene should be prevented as the polymerisation should concern the terminal alkene only. In both systems nickel or titanium hydride species react with the more reactive diene first, then undergo ethene insertion followed by (3-hydride elimination. Both diene products are useful as the diene component in EPDM rubbers (ethene, propene, diene). The nickel hydride chemistry with butadiene represents one of the early examples of organometallic reactions studied in great detail [22] (Figure 9.14). 

Analogous to the DSA manufacture, a pure htanium dioxide coating can be prepared, which shows a high activity and stabihty (also against titanium hydride formation), for electroorganic cathodic reductions (e.g. [40], see Chapter 7). 

---