Development of Microwave Assisted Erosion Resistant Claddings For Fluid Machines

Abstract

Slurry and cavitation erosion often limit the durability of many fluid machines such as hydro turbines, pumps, and propellers resulting in significant economic losses. Conventional materials and existing surface modification techniques are unable to encounter both slurry and cavitation erosion simultaneously. The main objective of this work was to synthesize composite claddings/coatings with different reinforcement size fractions (micro, nano, and bimodal) using microwave irradiation and thermal spraying to counter both slurry and cavitation-induced damages. Further, the role of different post-processing techniques (nitriding, annealing, and deep cryogenic treatment (DCT)) was also explored. Detailed microstructural and mechanical characterization techniques were utilized to understand and establish structure-property relations. Results showed that the bimodal reinforcement provides the highest resilience to both slurry and cavitation erosion among different composite claddings, owing to the synergy between nano and microparticles. A detailed comparison with the conventionally used stainless steels and coatings prepared through different routes was also made. The DCT helped enhance the erosion resistance among different post-processing routes due to increased high hardness and fracture toughness due to reduced porosity. The present work provides a potential solution for improving the durability of hydro-machinery components exposed to harsh working conditions. newline