Process Crystal bar process

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an apparatus used crystal bar process. main body made of quartz glass. (1) vacuum pump, (2) 6 mm molybdenum electrode, (3) molybdenum net, (4) chamber raw metal, (5) tungsten wire



the crystal bar process. m refers metal


as seen in diagram below, impure titanium, zirconium, hafnium, vanadium, thorium or protactinium heated in evacuated vessel halogen @ 50–250 °c. patent involved intermediacy of tii4 , zri4, volatilized (leaving impurities solid). @ atmospheric pressure tii4 melts @ 150 °c , boils @ 377 °c, while zri4 melts @ 499 °c , boils @ 600 °c. boiling points lower @ reduced pressure. gaseous metal tetraiodide decomposed on white hot tungsten filament (1400 °c). more metal deposited filament conducts better , greater electric current required maintain temperature of filament. process can performed in span of several hours or several weeks, depending on particular setup.


generally, crystal bar process can performed using number of metals using whichever halogen or combination of halogens appropriate sort of transport mechanism, based on reactivities involved. metals has been used purify on industrial scale titanium, zirconium , hafnium, , in fact still in use today on smaller scale special purity needs.







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