A Study on Rust Removal and Inhibition on Surface of Wear Water Screw-thread Steel using Flame Hot Melting

摘要

Red rust develops on surface of screw-thread steel produced by controlled cooling with wear water. A combustion unit using flame hot melting with counterflow of combustible gas was designed to study rust removal and inhibition behaviors of a 20MnSi wear water screw-thread steel. Main composition of the red rust was identified to be Fe_2O_3 with SEM/EDS and XRD analysis. Two major reasons causing the red rust were analyzed. The Fe_2O_3 appears as a loose and porous microstructure with a shape of branches and leaves, which aggravates corrosion by absorbing water and gas. With the flame hot melting, a dense passive film of Fe_3O_4 and FeO is formed, which protects metal matrix from corrosion by isolating water and gas. The flame hot melting technique is superior to chemical-aeent coatine in terms of cost and environmental conservation.