Silt erosion performance of high velocity oxy fuel- (HVOF) sprayed Al2O3–Cr2O3 composite coatings on turbine steel

Abstract

Purpose The purpose of this paper is to investigate the erosion performance of high velocity oxy fuel- (HVOF) sprayed Al2O3–Cr2O3 composite coatings under silt slurry conditions. Design/methodology/approach The requisite HVOF composite coatings has been deposited on the stainless steel substrate (SS-304). The slurry erosion pot tester of make Ducom was used for conducting the silt slurry erosion tests on the required substrates. The comprehensive experiments were conducted at different particle size of silt in the range 212–250, 150–212, 53–106 µm, and the concentration of the silt ranged from 10%–40% by weight. The rotational speed of the pot tester has been varied between 500 and 1,500 revolutions per minute, and the test duration has been kept to 4 h. Findings The erosion wear resistance of the uncoated SS-304 has been greatly enhanced by the application of HVOF-sprayed Al2O3–Cr2O3 composite coatings. The addition of CeO2 has a significant impact in reducing the erosive wear caused by silt slurry. The composite coating powder composition of 65%Cr2O3 + 34.5%Al2O3 + 0.5%CeO2 has shown the highest erosion resistance. Practical implications The developed coatings have the potential to be used for hydro turbines as subjected to silt slurry conditions. Originality/value The erosion wear experiments are conducted comprehensively for coated and uncoated samples and the scanning electron micrographs supports the findings.