Preparation and Properties of Silane Coupling Agent Modified Basalt Flake Polyurethane Anti-Corrosion Coatings

Abstract

Strong corrosive atmospheric environments of level C4–C5 have a serious safety impact on steel structures and industrial production. The use of anti-corrosion coatings is the most economical and efficient way of all means of anti-corrosion. To further improve the anticorrosion performance of polyurethane anticorrosion coatings, this paper adopts KH-560 silane coupling agent to modify basalt flake and add it as filler into one-component polyurethane resin with wet curing characteristics. Anti-corrosion coatings were prepared by combining pre-dispersion and high-speed dispersion. The prepared coating specimens were sprayed onto Q235 plates and tinplate plates by simple spraying. Test results show that the addition of modified basalt flakes (MBFs) helps to improve the mechanical and corrosion resistance of the coating. When 30% MBFs were added, the mechanical properties, acid and alkali resistance, and corrosion resistance of the coating reached the best, and the aging resistance was good. Among them, the adhesion of the coating could reach 15.36 MPa, and the coating surface did not show obvious flaring and peeling phenomenon after 1000 h of neutral salt spray test. The water contact angle of the coating increased from 77.77° to 81.31°. Meanwhile, the anti-corrosion performance of the base coating in 3.5 wt% NaCl solution was investigated using electrochemical impedance spectroscopy (EIS). The corrosion current density of the added modified basalt scale coating was in the order of 10−6, which was enhanced by one order of magnitude compared to that of the unmodified basalt scale. The annual corrosion rate of the MBFs coating was only 0.076588 mm·a−1. The superior anticorrosive properties of silane coupling agent-modified basalt flake composite coatings provide a new meaning for the development of anti-corrosive coatings.