Titanium melting techniques

The carbides and nitrides of vanadium and titanium crystallize in the same face centered cubic (fee) system, and because of the closeness of their cell parameters (Table 15.1) form solid solutions. These ceramic materials exhibit interesting mechanical, thermal, chemical and conductive properties.1,2 Their high melting point, hardness and wide range of composition have therefore attracted considerable attention in the last decade. Moreover, their good abrasion resistance and low friction also make these ceramics attractive for protective coating applications.3-5 Chemical vapor deposition (CVD) is a commonly used technique for the production of such materials. In the conventional thermally activated process, a mixture of gases is used.6-9 In the case of TiC, TiN, VC and VN, this mixture is... 

Herrmann and co-workers synthesized [Os(0)(Me)4] from 0s04 and dimethylzinc or methyltris(isopropoxy)titanium (180). An alternative route is by methylation of the glycolate osmium(VI) complex [0=0s(0CH2CH26)2] with dimethylzinc (180). The thermally labile ethyl derivative [Os(0)(Et)4] has also been prepared (180). [Os(0)(Me)4] is an orange, air-stable, volatile, crystalline compound that melts at 74°C without decomposition. The gas-phase average molecular structure of [Os(0)(Me)4], determined by electron diffraction techniques, is consistent with a theoretical model of C4 symmetry with d(Os—C) = 2.096(3) A, d(0s=0) = 1.681(4) A, and ZO—Os—C = 112.2(5)° (180). Cyclic voltammetric studies showed that [Os(0)(Me)4] undergoes reversible reduction at - 1.58 V and an irreversible oxidation at -f 2.2 V vs Ag/AgCl in MeCN. 

Depending on the chosen production technique, the preparation of raw stock entails either the production of bricks from titanium raw stock and coke or the grinding of these components to make up the furnace charge. Chlorination is carried out with evaporated or diluted chlorine (e.g., gaseous chlorine obtained in the production of electrolytic magnesium) in shaft electric furnaces, salt melt furnaces or in apparatuses with a fluidised layer. 

The choice of the chlorination technique and equipment for the process greatly depends on the compositon of raw stock for chlorination. For shaft furnaces and fluidised layer apparatuses, it is advisable to chlorinate titanium raw stock with relatively small amounts of oxides of calcium, magnesium, manganese and other metals which form low-melting chlorides in chlorination. On the other hand, in chlorination in salt melt these oxides do not have any significant effect on the process. 

Most metals can be electrolytically deposited from water-free melts of the corresponding metal salts. It is well known that aluminum, lithium, sodium, magnesium, and potassium are mass produced by electrolytic deposition from melts. Industrial processes for the melt-electrolytic production of beryllium, rare earth metals, titanium, zirconium, and thorium are also already in use. Pertinent publications [74, 137, 163] describe the electrolytic deposition of chromium, silicon, and titanium from melts. Cyanidic melts are used for the deposition of thick layers of platinum group metals. It is with this technique that, for instance, adhesion of platinum layers on titanium materials is obtained. Reports concerning the deposition of electrolytic aluminum layers [17, 71-73, 94, 96, 102, 164, 179] and aluminum refinement from fused salts [161] have been published. For these processes, fused salt... 

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