Processing and Sintering of Yttrium-Doped Tungsten Oxide Nano-powders

• Innovative chemical methods are capable of fabricating nanoscale tungsten oxide compoundsd oped with various rare-earth elements with high purity and homogeneity, which can be processed under hydrogen into nanostructured oxide-dispersed tungsten composite powders having several potential applications. However, hydrogen reduction of doped-tungsten oxide compounds is rather complex, affecting the morphology and composition of the final powder. In this study we have investigated the reduction of tungstic acid in the presence of Y and weprovide the experimental evidence that Y2O3 can be separated from Y-doped tungstic acid via hydrogen reduction to produce Y2O3-W powders. The processed powders were further consolidated by spark plasma sintering at different temperatures and holding times at 75 MPa pressure and characterized. The optimized SPS conditions suggest sintering at 1400 °C for 3 min holding time to achieve higher density composites with an optimum finer grain size (3 μm) and a hardness value up to 420 HV. Major grain growth takes place at temperatures above 1300 °C during sintering. From the density values obtained, it is recommend to apply higher pressure before 900 °C to obtain maximum density. Oxides inclusions present in the matrix were identified as Y2O3•3WO3 and Y2O3•WO3 during high resolution microscopici nvestigations.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Elektroteknik och elektronik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Electrical Engineering, Electronic Engineering, Information Engineering (hsv//eng)

Nyckelord

nanostructured W

ODS-tungsten

Nano W-Y2O3

tungsten oxide reduction

Tungstic acid

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vet (ämneskategori)

art (ämneskategori)