Quantitative Phase Analysis of Mixtures Containing α-, β-Tungsten and WO2

For incandescent lamp wire fabrication various powder metallurgical steps are necessary. The stepwise reduction of WO₃ to the tungsten metal powder is one of these. During reduction chemical reactions take place under participation of doping elements (K, Si and Al) causing the structure of non-sag wires. The origin of secondary β-W like an indicator for the activity of dopings has been attributed importance. Therefore it has been developed a method for quantitative phase analysis of α-W, β-W, WO₂ mixtures consisting of oxidation value determination to establish the WO₂ content and X-ray phase analysis for a quantitative separation of the α-W and β-W content. The influence of extinction effects caused by particle size has been investigated and it is proposed a correction method of the measured integral intensities as a function of half-width of the (110) α-W reflex. In regard of the obtained results the formation of the tungsten suboxide W₃O has been excluded.