Elemental Powder

ZrSe [12166-53-9] and ZrTe [39294-10-5] (138). Zirconium disulfide [12039-15-5] is made from the elemental powders and by the action of carbon disulfide on zirconium oxide above 1200°C (139) some ZrOS [12164-95-3] is usually also obtained. The higher sulfides disproportionate at ca 700°C synthesis reactions at 900—1000°C with S Zr ratios between 0.2 and 2.3 produced crystals that were identified as Zr S2 [12595-12-9] ... 

Mechanical alloying (MA) of elemental powders followed by hydrogenation... 

Deposition by sputtering and laser ablation (vapor-phase transfer from a target bombarded by inert gas ions or laser beam) or ion beam mixing of nanoscale multilayers, all of which similarly can produce nonequilibrium species Mechanical alloying, a process in which elemental powders are blended and alloyed by ball milling, can produce ultrafine grain sizes and nonequilibrium phases that store the mechanical energy imported in the process. ... 

Many borides can be synthesized by novel synthetic methods, inclnding shock-induced chemical reactions, mechanical alloying by ball milling, and self-propagating high-temperature synthesis. In these methods, intimately mixed elemental powders are brought to react by a rapid pressure increase, mechanical deformation including local... 

A promising method for densification of combustion-synthesized products is a combination of SHS with hot isostatic pressing (HIP). This idea was first applied to the synthesis of TiB2 ceramics under a pressure of 3 GPa, which was provided by a cubic anvil press, resulting in 95% dense material (Miyamoto et al, 1984 Yamada et al., 1987). The relatively low exothermic reaction of SiC from elemental powders was also carried out under these conditions (Yamada et al, 1985), and 96% conversion to 8-SiC was achieved as compared to 36% conversion when the reaction was initiated locally. 

In Japan, several commercial projects have been reported in the literature. For example, at the National Research Institute for Metals, the NiTi shape-memory alloy is produced by combustion synthesis from elemental powder for use as wires, tubes, and sheets. The mechanical properties and the shape-memory effect of the wires are similar to those produced conventionally (Kaieda et ai, 1990b). Also, the production of metal-ceramic composite pipes from the centrifugal-thermite process has been reported (Odawara, 1990 see also Section III,C,1). 

Maupin, H. E., and Rawers, J. C., Metal-intermetallic composites formed by reaction-sintering elemental powders. J. Mater. Sci. Lett., 12,540 (1993). 

Rabin, B. H., and Wright, R. N., Synthesis of iron aluminides from elemental powders reaction mechanisms and densification behavior. Metall. Trans. A, 22A, 277 (1991). 

Resolution of racemic allyl alcohols (general procedure).Elemental powdered Te (2.0-2.5 equiv) andNaBH (4.0-5.0 equiv) in DMF (0.5-1.0 M in Te) are mixed nnder an inert atmosphere and heated to 70-80°C for 0.5 h. The grey suspension turns a deep purple colour. The reaction is cooled to room temperature and the glycidyl sulphonate (1.0 equiv based on Te) in DMF is added. The reaction is monitored by NMR analysis of reaction aliquots and is... 

Fabrication [6.26,6.27]. Heavy metals are produced by conventional P/M techniques. A flow chart of the fabrication process is shown in Fig. 6.14. Elemental powders (W,... 

XRF Fluorescence of X-rays Elements Powder/natural Elemental abundance ppm 10s Stone, pottery, soils... 

NAA Gamma radiation Elements Powder Elemental abundance ppm 10- Stone, pottery... 

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