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5363 |
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Thursday, June 08, 2017, Hall 26 10:00 AM Wear Protection II |
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Understanding the influence of micro- and sub-micro structural features on the mechanical properties of HVO/AF sprayed WC-CoCr cermets |
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Maria Parco* / TECNALIA, Spain Ignacio Fagoaga/ Fundación Tecnalia Research & Innovation, Spain Georgy Barykin/ Fundación Tecnalia Research & Innovation, Spain Andrey Chuvilin/ CIC Nanogune, San Sebastian / IKERBASQUE, Bilbao., Spain Carlos Vaquero/ Fundación Tecnalia Research & Innovation, Spain |
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HVOF processes represent the state of art for the spray deposition of wear and corrosion resistant coatings since their supersonic gas velocities in combination with moderate flame temperatures allow the deposition of optimal coatings with very high bond strengths, fine surface finishes and low oxide levels. However, new generation coating materials (fine powders), stringent quality requirements and the high productivity demanded by the industry, push the HVOF technologies to their limits. Recently, a novel air-oxygen controlled high velocity combustion process has been development by Tecnalia. The system operates within the supersonic regime using a broad range of fuel/oxidant ratios thanks to the use of air-oxygen mixtures and a carefully designed gun. Extremely low flame temperatures can be achieved while keeping a supersonic flow of combustion products, thus allowing the solid state deposition of almost all industrially relevant metal alloys with superior deposit qualities. In previous reports, the potential of the system for the development of super hard cermet coatings using different types of conventional and fine WC-Co(Cr) powders was showed. In this work, a systematic investigation of the influence of the powder structure and process parameters on the resulting coating structural features at the sub-micron and nano-scale has been performed. For comparison, different fine structured commercially available WC10Co4Cr powders have been investigated. The coating structure has been characterized with by high resolution SEM cross-section imaging (dual beam SEM-FIB system) and X-ray diffraction analysis. The resulting coating quality has been further compared in terms of ascertained mechanical properties like the microhardness, nanohardness, Young's modulus and the cross sectional fracture toughness. |