The hydro plants utilizing silt-laden water for power generation suffer from severe metal wastage due to particle-induced erosion and cavitation. High-velocity oxy-fuel process (HVOF)-based coatings is widely applied to improve the erosion life. The process parameters such as particle velocity, size, powder feed rate, temperature, affect their mechanical properties. The high-velocity air fuel (HVAF) technology, with higher particle velocities and lower spray temperatures, gives dense and substantially nonoxidized coating. In the present study, the cavitation resistance of 86WC-10Co4Cr-type HVOF coating processed at 680 m/s spray particle velocity was compared with HVAF coatings made at 895, 960, and 1010 m/s. The properties such as porosity, hardness, indentation toughness, and cavitation resistance were investigated. The surface damage morphology has been analyzed in SEM. The cohesion between different layers has been examined qualitatively through scratch depth measurements across the cross section. The HVAF coatings have shown a lower porosity, higher hardness, and superior cavitation resistance. Delamination, extensive cracking of the matrix interface, and detachment of the WC grains were observed in HVOF coating. The rate of metal loss is low in HVAF coatings implying that process parameters play a vital role in achieving improved cavitation resistance.

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In this study, the composites with incorporation betel nut powder at three levels (10, 18 and 25%) in Polycarbonate (PC) and Acrylonitrile Butadiene Styrene (ABS) matrices having Kevlar Fibres (KF) and Molybdenum Disulphide (MoS2) nano particles in fixed amounts are looked into for their tribological characteristics. The effect of hardness, surface roughness and density was evaluated. FTIR and X-ray diffraction (XRD) studies have been carried out to identify the phases. The effects of load on the slide wear loss and coefficient of friction of the composites were determined using Pin on Disc set up. The wear test pertaining to the betel nut bearing (BNP) composites were compared with those of betel nut free ones i.e. PC/ABS/KF/MoS2. The results revealed that with increase in load, the wear loss increases. Further with increase in betel nut powder concentration from 10% to 25% there is a decrease in wear loss as well as coefficient of friction. The surface morphology of the worn surface were examined using Scanning Electron Microscopy (SEM) which revealed higher plastic deformation, debris formation and furrowing in BNP free systems compared to betel nut bearing ones.

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