Micro and nano ceramic-metal composite coatings by thermal spray process to control slurry erosion in hydroturbine steel: an overview

Abstract

The increasing rate of erosion due to the presence of excessive silt concentration in river water of the Himalayan region is adversely affecting the availability of most demanded hydropower in India. Many researchers investigated several methods to minimize the rate of erosion wear on hydro turbine blades, runners, pumps, guide vanes, valves, seats, etc. However, some of them are successful, some are not. The problem of silt erosion is encountered during the high flow monsoon period. Various techniques have been developed to rally suitable coatings like chemical vapor deposition technique, thermal spray technique, an electroplating technique, etc. Therefore, in this paper, an attempt has been made to provide an overview of suitable micro and nanocomposite coatings with the application of thermal spray high-velocity oxygen fuel deposition process to minimize the problem of erosion due to silt in hydropower plants.

Mechanical and microMechanical and microstructural characterization of yttria-stabilized zirconia (Y2O3/ZrO2; YSZ) nanopartstructural characterization of yttria stabilized zirconia (Y2O3/ZrO2; YSZ) nanoparticles reinforced WC-10Co-4Cr coated turbine steel

“…Nanoparticles of YSZ interlocked the WC-10Co-4Cr grains and filled the pores in the nanocomposite coating matrix, which resulted in a decrease in surface roughness and porosity. The decrease in porosity with the reinforcement of nanoparticles in the conventional coatings has also been observed by various researchers [47][48][49][50][51]. Reduction in the surface roughness and porosity resulted in the increase in the microhardness of the WC-10Co-4Cr nanocomposite coatings as compared to conventional coating.…”

Surface and bulk modification techniques to mitigate silt erosion in hydro turbines: a review of techniques and parameters

“…Apart from these parametric studies, many review papers have also addressed the issues related to the problem of slurry erosion. These addressed the slurry performance against various coatings [35], coated and uncoated materials [36], coatings by thermal spraying [37], laser cladding techniques [38], erosion models and CFD modelling to reduce the erosion in turbines [39], slurry and cavitation in a synergic way [40], and various materials and slurry erosion mechanisms [41].…”