The determination of oxygen in powdered tungsten carbide by reducing fusion: Suppression of primary carbon dioxide, selection of working conditions and adsorbed-moisture effects.
A method for the reducing fusion determination of oxygen in powdered tungsten carbide is described. It is shown that, as theory predicts, tungsten carbide may evolve its oxygen content not only as carbon monoxide but also as perceptible quantities of carbon dioxide. An easy suppression of this primary carbon dioxide, and thus of any error associated with it made when computing the sample oxygen content, is obtained by the simple expedient of dropping the samples into the crucible a few seconds after having started the instrument analytical cycle, i.e. when the crucible is already at very high temperature. Criteria followed in the selection of the sample fusion conditions and their possible application to the analysis of massive tungsten carbide samples are discussed. The very large effect of the adsorbed moisture content on the results is made evident, and practical means (preliminary water desorption from samples kept at 200 degrees under high vacuum) to overcome it are suggested.
Colombo
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Commission of the European Communities, Joint Research Centre, Ispra Establishment, Chemistry Division, 21020 Ispra, Italy.
Vivian
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