Focus on self-repairing performance and mechanism of Cu-DDP additive in base lubricating oil

Purpose - The purpose of this paper is to prove the self-repairing Cu film of Cu-DDP additive in base lubricating oil. Design/methodology/approach - Cu nanoparticles coated with dialkydithiophosphate (Coded as Cu-DDP) were synthesized in situ by redox method. The size and structure of Cu-DDP were characterized using transmission electronic microscopy (TEM) and electronic diffraction (ED) analysis. The self-repairing performance of Cu-DDP as additive in base lubricating oil was evaluated by MRH-3 stock-on-ring testing machine. Scanning electronic microscopy (SEM), UMT-2 tribometer, X-ray photoelectron spectroscopy (XPS), and energy-dispersive spectrum (EDS) were used to study the self-repairing Cu film on the stock. Findings - The test results showed that the modified Cu-DDP additive in base lubricating oil exhibited excellent anti-wear and friction-reducing properties, as well as good self-repairing performance. Research limitations/implications - The thickness of the self-repairing Cu film was unknown, and the relationship between thickness of the Cu film and load, time, rotation velocity was still necessary to investigate. Practical implications - The Cu-DDP additive was involved P and S elements, therefore, it is still promising to seek environment friendly additive without P and S elements. Originality/value - For the first time, MRH-3 stock-on-ring testing machine, Scanning electronic microscopy (SEM), UMT-2 tribometer, X-ray photoelectron spectroscopy (XPS), and energy-dispersive spectrum (EDS) were widely used to study the self-repairing Cu film on the stock.