Slurry Erosion Behaviour of Plasma Thermal Sprayed (50%) WC-Co-Cr and Ni-Cr-B-Si Coatings of Different Thickness on CA6NM Turbine Steel Material

Harpreet Singh,Deepak Kumar Goyal,Khushdeep Goyal

doi:10.13189/mst.2014.020403

Abstract

Erosive wear behaviour of hydraulic turbine material i.e. CA6NM is investigated. The samples of CA6NM steel were coated by (50%) WC-Co-Cr and (50%) Ni-Cr-B-Si powder with plasma thermal spray technique. Erosion tests have been conducted on self-made erosion test rig which has varying factors. The comparison has been done for mass loss for coated and uncoated materials at different conditions. The study reveals that the impact velocity, slurry concentration and impact angle are most significant among various factors influencing the wear rate of these coatings. After a fix time weight loss on samples are compared. This technique helps in saving time and resources for a large number of experimental trials and successfully predicts the wear rate of the coatings both within and beyond the experimental domain. The coated samples show better results as compared to uncoated. SEM analysis gives the information about the surface topography of samples.

Highlights

Silt erosion of hydro turbines is a very acute problem and leads to huge losses to the hydropower industry
It was observed that these factors increases the wear rate,which results decrease in Slurry Erosion Behaviour of Plasma Thermal Sprayed (50%) WC-Co-Cr and Ni-Cr-B-Si
Otsubo et al [12] had investigated the structure, hardness, and shear adhesion strength for Cr3C2-NiCr cermet coatings sprayed onto a mild steel substrate by 200 kW high power plasma spraying (HPS) and high velocity oxy-fuel (HVOF) processes

Summary

Introduction

Silt erosion of hydro turbines is a very acute problem and leads to huge losses to the hydropower industry. It was observed that these factors increases the wear rate ,which results decrease in Slurry Erosion Behaviour of Plasma Thermal Sprayed (50%) WC-Co-Cr and Ni-Cr-B-Si. Coatings of Different Thickness on CA6NM Turbine Steel Material competence of turbines and collapse of hydraulic turbines takes place. Otsubo et al [12] had investigated the structure, hardness, and shear adhesion strength for Cr3C2-NiCr cermet coatings sprayed onto a mild steel substrate by 200 kW high power plasma spraying (HPS) and high velocity oxy-fuel (HVOF) processes. They studied that amorphous and supersaturated nickel phases occurred in both as-sprayed coatings. These investigations could help to improve the performance of this steel in real working environments

Experimentation

Results and Discussion

Effect of Various Parameters

SEM Analysis

Conclusions