Effect of Velocity on Erosion Performance of 13Cr4Ni and H.V.O.F. Coatings

ABSTRACT: The slurry erosion of two coatings applied by high velocity oxy fuel ( H.V.O.F.) processes onto shot-blasted 13Cr4Ni steel was studied, and the results were compared to those obtained with 13Cr4Ni, which are commonly used for hydraulic turbines and accessories., while the microstructure and worn surfaces were characterized by optical and scanning electron microscopy. Slurry erosion tests were carried out in a modified impact test rig, in which the samples were placed conveniently to ensure grazing incidence of the particles. the slurry was compose of distilled water and quartz sand particles with an average diameter between 165 µm (AFS 50/70) and the slurry concentration content was 20000 ppm in all the tests. the three different ranges of velocity is taken i.e. 25m/s, 60m/s and 80m/s. at normal impact angle and comparison regarding the erosion resistance was determined from the mass loss results. Higher erosion will be seen at medium range of velocity i.e. at 60m/s. the coated surfaces showed higher erosion resistance than the uncoated stainless steels, with the lower volume losses measured for the Cr2O3 deposit. SEM analysis of the worn surfaces revealed intense plastic deformation in both coated and bare stainless steels, with little evidence of brittle fracture in the microstructure. The measured adhesive strength of the coatings was considered acceptable for the processes employed