Electropositive titanium metal

The reduction of a transition-metal oxide and boron oxide by an electropositive metal such as Al, Mg or an alkali metal has been used as a pathway to titanium, iron, chromium, tungsten and alkali-earth borides . ... 

It is used for the production (thermal reduction) of other metals, such as zinc, iron, titanium, zirconium, and nickel. For instance, because of its strong electropositive nature, magnesium can desulfurize molten iron when it combines with the sulfur impurities in the iron to produce high-grade metallic iron plus MgS. 

Hydrogen reacts at elevated temperatures with many transition metals and their alloys to form hydrides. The electropositive elements are the most reactive, that is, scandium, yttrium, the lanthanides, the actinides and members of the titanium and vanadium groups (Figure 5.20). 

Reactive metals are of interest for two primary reasons (1) reaction with the uppermost part of the SAM which can drive uniform nucleation with no penetration and (2) for electropositive metals, injection of electrons into the SAM to create a favorable dipole at the metal/SAM interface for device operation. With respect to the first, as opposed to the results with non-reactive metal deposition, some reports of reactive metal deposition appear to show prevention of metal penetration with the avoidance of short-circuits across the M junction. In general, serious concerns remain that some of metal atoms react destructively with the SAM backbone to produce inorganic species, e.g., carbides and oxides in the case of aggressive metals such as titanium. 

Schrock carbene complexes may be identified by their alkyl substituents on the carbene carbon and an electropositive, early-transition metal. As shown in Figure 2, the Schrock complexes are considered a result of spin-coupling between the carbene triplet state and the two electrons on the metal [8]. The reactivity of the Schrock carbene carbon is nucleophilic [4]. The reaction involving bis(cyclopentadienyl)carbene titanium(IV) and the electrophile acyl chloride in Eq. (3) [9], for example, illustrates the nucleophilicity of... 

Properties Dense, silvery solid. D 19.0, mp 1132C, bp3818C, heat of fusion 4.7 kcal/mole, heat capacity 6.6 cal/mole/C. Strongly electropositive, ductile and malleable, poor conductor of electricity. Forms solid solutions (for nuclear reactors) with molybdenum, niobium, titanium, and zirconium. The metal reacts with nearly all nonmetals. It is attacked by water, acids, and peroxides, but is inert toward alkalies. Green tetravalent uranium and yellow uranyl ion (U()2") are the only species that are stable in solution. 

In addition to stabilization contributed by these covalent bonding interactions, the surface of the metal becomes slightly oxidized upon interaction with the polymer and the polymer is similarly reduced. Therefore there is an electrostatic interaction that further stabilizes the polymer-metal interface. The most extreme case of this is seen with aluminum. The covalent interactions that stabilize the iron and titanium surfaces are limited for aluminum however, the charge transfer between polymer and metal surface is at a maximum for aluminum and therefore it is suspected that electrostatic interaction may be a more dominant factor in the adhesion of the polymeric materials to electropositive main group metal surfaces. Figure 4 shows representative interactions between the polymer states and the metal d-states of the surfaces. It can be seen that orbital interactions for pemigraniline are not favored as there are fewer states of appropriate energy for interaction. 

Finally, in this model, the electronic character of the metal will clearly determine the level of adhesion and interaction between the substrate and the coating. For electropositive metals such as titanium, aniline-based coatings may be less effective, as redox-active states of the polymer will be critically affected by interfacial bonding. 

Some metais, including titanium, zirconium, hafnium, lanthanum, and the lanthanons, are most conveniently obtained by reaction of their oxides or halides with a more electropositive metal. Sodium, potassium, calcium, and aluminum are often used for this purpose. Thus titanium may be made by reduction of titanium tetrachloride by calcium ... 

More recently, attention has been directed to the "ninth form of corrosion, biologically influenced corrosion, which includes studies on an area referred to as "ennoblement. The presence of biofilms on metals and alloys immersed in natural seawater produces a complex, heterogeneous chemistry along the metallic surface. It has usually been observed that passive alloys such as aluminum, stainless steels, nickel-base alloys, or titanium show an increase to more noble (electropositive) potentials or ennoblement of several hundred millivolts with exposure time in natural seawater, thus magnifying the potential differences that may exist between dissimilar alloys [26,55-64]. Ennoblement is likely caused by the formation of microbiological films, which increase the kinetics of the cathodic reaction [55-63],... 

For the synthesis of metalloid (B, Si) alkoxides, the method generally employed consists of the reaction of their covalent halides (usually chlorides) with an appropriate alcohol. However, the replacement of chloride by the alkoxo group(s) does not appear to proceed to completion, when the central element is comparatively more electropositive. In such cases (e.g. titanium, niobium, iron, lanthanides, thorium) excluding the strongly electropositive s-block metals, the replacement of halide could in general be pushed... 

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