Authors: R K Kumar M Kamaraj S Seetharamu T Pramod P Sampathkumaran
Publish Date: 2016/06/16
Volume: 25, Issue: 6, Pages: 1217-1230
Abstract
The hydro plants utilizing siltladen water for power generation suffer from severe metal wastage due to particleinduced erosion and cavitation Highvelocity oxyfuel process HVOFbased 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 highvelocity 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 86WC10Co4Crtype 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 resistanceThe authors thankfully acknowledge the management of CPRI for according permission to publish this paper The work carried out in the present study forms part of inhouse Research Contingency project RMTD02 supported by CPRI The support in the supply of HVAF coatings by Kermatico USA and HVOF coating by M/s Spraymet surface technologies Pvt Ltd Bangalore India is highly acknowledged
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