Effects of erosion rate on the erosion-corrosion synergism of high velocity oxy-fuel sprayed Ni-based coatings

Two types of Ni-based coatings were deposited by high velocity oxy-fuel (HVOF) spraying process on ASTM 1020 low carbon steel substrate, and AISI 321 stainless steel was applied to the contrast test. The influences of erosion rate on the erosion-corrosion synergism and erosion-wear mechanism of the two coatings were investigated systematically in a liquid/solid two-phase flow (5% H₂SO₄ +15% silica sand). The volume loss rates stemming from the erosion-corrosion synergism of materials increased from 42-66% to 78-85% of the total volume loss rates when the erosion rate of the flow increased from 5 m/s to 10 m/s. It was indicated that the erosion-corrosion synergism was primary for the material removing during the erosion-corrosion process. Cutting, wear and plowing were the main features for Type-A coatings, while cutting, plowing and plastic deformation were the main characters for Type-B coatings and the two steels.