The behavior of tungsten oxides in the presence of copper during hydrogen reduction

The behavior of tungsten oxides during hydrogen reduction in the presence of copper was investigated by measuring the changes in humidity and electrical resistance during the reduction process. A non-isothermal analysis of the humidity changes could manifest an effect of copper on the reduction of tungsten dioxide during the hydrogen reduction process of ball-milled WO3-CuO powder mixtures. To investigate the detailed effect of copper on tungsten oxide reduction, raw tungsten oxide powder was reduced under a coiled copper wire, while changes in the electrical resistance change were simultaneously measured by the dc four-point probe method. The results of this analysis showed a deviation from a tungsten oxide-free reference over the reduction temperature of tungsten dioxide. These results were confirmed by observing the microstructure of the copper surface. Deposited tungsten was observed on the copper surface after the hydrogen reduction of tungsten oxide beneath the copper wire. (c) 2005 Elsevier B.V. All rights reserved.