Redox viscometry of some Fe-bearing silicate melts
b'The dependence of shear viscosity on the oxidation state of six ferrosilicate melts has been measured using the concentric cylinder method and a gas mixing furnace. The measurements were performed under air, COr, and COr-CO mixtures at I atm and in a temperature range of 1345 to 1470"C. The experimental procedure involved a continuous\\nmeasurement of viscosity during stepwise reduction of the melts. Melt chemistry was controlled by dip sampling the tiquids at each oxidation state. The resulting glassesw ere\\nanalyzed by electron microprobe, a volumetric FeO itration, and 57Fe Mdssbauer spectroscopy.\\nThe electron microprobe data indicate Fe loss for some of the most reduced samples.T he wet chemical (+ microprobe) and spectroscopicd eterminations of theseF erich\\nsamples yield oxidation states that are in excellent agreement. The viscosity of all melts investigated herein decreasesw ith melt reduction. The viscosity\\ndecrease is, in general, a nonlinear function of oxidation state expressed as Fe2*/F\\u20ac,o,.'