Erosion–corrosion of thermal-sprayed nylon coatings

Abstract

Thermal-sprayed coatings nylon1010, SiCw-nylon1010 and Al 2O 3 p-nylon1010 were deposited on 16Mn steel. Erosion–corrosion tests were conducted using an erosion–corrosion tester in pH 1–12 sand slurry with impact velocities from 2.1 m/s to 5.6 m/s. The effects of pH value and impact velocity on the coatings were discussed. The results showed that the coatings presented good erosion–corrosion resistance except both in strong acid and in alkaline slurries. It was found that both SiC whisker and Al 2O 3 particles added into nylon increased the erosion–corrosion resistance of the nylon coating because they resisted the impact of sand particles. The Al 2O 3p-nylon1010 coating had the lowest erosion–corrosion loss rate at low velocity. However, at higher velocity its erosion–corrosion loss rate increased due to the spalling of Al 2O 3 particles. At all test conditions, the plastic deformation, tearing and the dissolve swelling and hydrolysis of nylon matrix were dominant mechanisms. At higher velocities the partial spalling of Al 2O 3 particles occurred so that they could not play a reinforcement role. In strong acid or alkaline slurry, the erosion–corrosion resistance of the coatings depended not only on the properties of nylon and reinforcements as well as their bonding but also on the synergetic effects between erosion and corrosion.