Formation Mechanism and Control Methods of Oil Stains on Metal Surfaces Caused by Rust-Preventive Oil

To further understand the influencing factors of oil stains induced by rust-preventive oils on metal surfaces and their comprehensive prevention and control methods，rust-preventive oil stain tests were carried out to systematically evaluate the oil stain tendency of different types of rust-preventive oil additives on carbon steel surfaces.The results showed that formulations containing unsaturated fatty acid-type rust inhibitors are prone to oil stain formation，while calcium/barium sulfonates，saturated fatty acid derivatives，and film-forming agents with good stability have relatively low oil stain risk.The research further revealed that the formation mechanism of oil stains is the result of the synergistic effect between local microbattery effect and oxidative side reactions；an increase in moisture content will aggravate the severity of oil stains，and residues from metal pretreatment may also indirectly induce oil stains by damaging the integrity of the oil film.Based on the mechanism analysis，comprehensive methods including optimizing the selection of rust inhibitors，reducing the content of unsaturated components，introducing antioxidants and controlling environmental humidity are proposed to effectively reduce the oil stain risk during the application of rust-preventive oils.