Servicio de Información Comunitario sobre Investigación y Desarrollo - CORDIS

Plasma sprayed silicon carbide for critical tribological components

A cost effective processing route has been developed for the deposition of silicon carbide layers on system components for critical tribological applications requiring wear and corrosion resistance. The initial stage of the project involved the production of powders suitable for vacuum plasma spraying, the production of coatings from the precursor powders and the evaluation of the basic coating properties in order to optimize the spraying process. Plasma spraying silicon carbide in isolation was confirmed not be effective due to the material subliming in the plasma flame. The development of a method of transport the silicon carbide through the flame was investigated, the principle aim being to encapsulate the silicon carbide during spraying. The coatings produced were tested for hardness, density, and particle melting characteristics to identify potential parameter ranges for corrosion and wear. The most promising coatings produced were used on test pump components. Corrosion performance was assessed along with hydroabrasive erosion and the results used to identify optimum deposition conditions. Sliding wear behaviour was assessed. Suitable coating systems were characterized. Corrosion fatigue, mechanical and thermal properties were assessed and adequate coating thickness and the required degree of thermal shock resistance achieved. The later powders were comparable, and under certain test conditions, better than current commercial materials. Components which could benefit from a wear and corrosion resistant coating have been identified. These included shafts, wear rings, bearings and pump bodies. These were redesigned to accept the thick plasma sprayed layers and evaluated under service type conditions. The performance of coated pump components was found to be particularly impressive in trials pumping water with a high sand content, and indeed the coating of a relatively cheap pump component was shown to be a feasible alternative to producing pump parts from more complex and expensive substrate materials. The project has shown that a silicon carbide containing powder can effectively coat pump parts, enhancing their performance. Consortium members are therefore seeking a powder manufacturer with the aim of further development and assessment of this opportunity.

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AEA Technology
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