Preprint Article Version 1 This version is not peer-reviewed

Structure and Properties of High-Hardness Silicide Coatings on Cemented Carbides for High Temperature Applications

Version 1 : Received: 29 April 2018 / Approved: 1 May 2018 / Online: 1 May 2018 (11:04:54 CEST)

A peer-reviewed article of this Preprint also exists.

Humphry-Baker, S.; Marshall, J. Structure and Properties of High-Hardness Silicide Coatings on Cemented Carbides for High Temperature Applications. Coatings 2018, 8, 247. Humphry-Baker, S.; Marshall, J. Structure and Properties of High-Hardness Silicide Coatings on Cemented Carbides for High Temperature Applications. Coatings 2018, 8, 247.

Journal reference: Coatings 2018, 8, 247
DOI: 10.3390/coatings8070247

Abstract

An oxidation resistant coating on cemented tungsten carbides is characterised in this work. Cemented tungsten carbides (cWCs) are routinely used in mining and manufacturing but are also candidate materials for compact radiation shielding in fusion power generation. In both environments, cWCs will suffer significant degradation due to oxidation at relatively low temperatures. In a recent study, a Si-deposition coating method was demonstrated to improve the oxidation resistance of cWCs by up to a factor of 1,000. This work focusses on the growth kinetics, phase composition, and mechanical properties of these coatings. By combining quantitative X-ray diffraction, electron microscopy and nanoindentation, we show that the coating layer has a 20 % higher hardness than the substrate, which was explained on the basis of a previously-unknown presence of a fine distribution of very hard SiC laths. To interpret the coating stability, a coating growth map is developed. The map shows the structure is stable under a broad range of processing temperatures and composite compositions, demonstrating the potential application of these coatings in a variety of nuclear shielding cWCs.

Subject Areas

Cemented carbides, cermets, iron binders, oxide coating, radiation shielding, nanoindentation, passivation, silicides.

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