Alloys technetium

Group 7 (Mn, Tc, Re). No binary compounds are formed with manganese, and no homogeneous product could be prepared. Technetium reacts with W, forming a solid solution and a a-phase (WTcs). Timgsten-technetium alloys are of practical interest as superconductors. 

The atomic absorption characteristics of technetium have been investigated with a technetium hollow-cathode lamp as a spectral line source. The sensitivity for technetium in aqueous solution is 3.0 /ig/ml in a fuel-rich acetylene-air flame for the unresolved 2614.23-2615.87 A doublet under the optimum operating conditions. Only calcium, strontium, and barium cause severe technetium absorption suppression. Cationic interferences are eliminated by adding aluminum to the test solutions. The atomic absorption spectroscopy can be applied to the determination of technetium in uranium and its alloys and also successfully to the analysis of multicomponent samples. 

Technetium metal is grayish-silver and looks much like platinum. As with most transition elements, technetium in pure form is a noncorrosive metal. It requires only 55 ppm of technetium added to iron to transform the iron into a noncorroding alloy. Because of technetiums radioactivity, its use as an alloy metal for iron is limited so as to not expose humans to unnecessary radiation. 

Technetium is one of the few artificially produced elements that has practical industrial applications. One is that a very small amount (55-ppm) added to iron creates a corrosion-resistant alloy metal. This property is shared with many of the other transition metallic elements, but not with other artificially produced elements that have higher atomic numbers and are radioactive. 

Technetium is also used as an alloy metal to produce super-strong magnets that are supercooled to near absolute zero to improve their efficiency. Powerful magnets are used in imaging equipment and possibly in future magnetic driven trains. Its radioactivity makes it useful as a tracer in the production of metals and tracing flowing fluids in pipelines. 

Superconductivity has been observed in technetium metal and in alloys based on technetium with additions of Pd, Os, Rh, Ru, Sn, V. Ti, Re, W,... 

Some other applications of technetium are the following [283] use of some of its alloys as superconductors with high critical temperature, use of 99Tc in high-temperature thermocouples, construction of basic anticorrosive covers for nuclear reactors, etc. 

Phillips and Timms [599] described a less general method. They converted germanium and silicon in alloys into hydrides and further into chlorides by contact with gold trichloride. They performed GC on a column packed with 13% of silicone 702 on Celite with the use of a gas-density balance for detection. Juvet and Fischer [600] developed a special reactor coupled directly to the chromatographic column, in which they fluorinated metals in alloys, carbides, oxides, sulphides and salts. In these samples, they determined quantitatively uranium, sulphur, selenium, technetium, tungsten, molybdenum, rhenium, silicon, boron, osmium, vanadium, iridium and platinum as fluorides. They performed the analysis on a PTFE column packed with 15% of Kel-F oil No. 10 on Chromosorb T. Prior to analysis the column was conditioned with fluorine and chlorine trifluoride in order to remove moisture and reactive organic compounds. The thermal conductivity detector was equipped with nickel-coated filaments resistant to corrosion with metal fluorides. Fig. 5.34 illustrates the analysis of tungsten, rhenium and osmium fluorides by this method. 

Technetium is used in steel alloys. An alloy is made by melting and mixing two or more metals. The mixture has properties different from those of the individual metals. Technetium-steel alloys are very resistant to corrosion or reaction with oxygen and other materials. No more than 50 parts per million of technetium to steel produces this property. Technetium-steel has limited uses, however, because technetium is radioactive. People cannot be exposed to technetium-steel directly. Thus far, technetium-steel has no commercial uses. 

FP-4 (zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, silver, cadmium, indium, tin, antimony)—are only slightly soluble (<1 wt %) in the process alloy, thus will partition between both product streams. The process, as presented, offers no method of FP-4 removal and possibly an unwanted increase in these products would occur if the fuel were to be recycled. However, it would be possible to separate the FP-4 from the plutonium/thorium stream by recovering the plutonium/thorium by hydriding. The FP-4 do not form stable hydrides and would remain in solution. 

Microgram amounts of TcOj can be ascertained by measuring the absorbance of the colored complex, formed with toluene-3,4-dithiol in 2.1 M HCl, after extraction into carbon tetrachloride. One hour must be allowed for the development of the color. ITie molar absorbance index at 410 nm is 1.1-10" mole -1-cm. Beer s law is followed over the range of 1.1 to 16.1 pg Tc/ml. Because many cations interfere, an initial separation of technetium is necessary [73]. The same complex was used for the determination of technetium in uranium fission element alloys after separation of Tc by distillation from sulphuric acid [74j. I hc complex formation of technetium, rhenium, and molybdenum with toluene-3,4-dithiol and its analytical application have been studied in detail [71]. 

The TcAl6 phase was shown to be isoslructural with MnAlf, and ReAle- TcAli2 exhibits the same structure as M0AI12 and ReAli2 [51]. No new intermediate phases were found to exist in alloys of technetium with rhodium, palladium or platinum. The solubility of technetium in these metals increases in the given sequence ]71]. The group Vlll transition elements Co, Ni, Rh, Pd, Ir. and Pt show extensive solid solubility in technetium metal at 1050 "C [72]. The solid solubility of technetium in nickel is... 

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