The corrosion–wear coupling damage failure of 8Cr4Mo4V bearing steel under marine atmospheric conditions significantly limits aeroengine bearing applications. The present work aims to investigate the evolution of the corrosion–wear properties of 8Cr4Mo4V bearing steel at varied corrosion intervals and estimate the corrosion–wear interaction (CWI) effect. Neutral salt spray tests combined with tribological experiments were employed to explore the effect of corrosion on wear and the influence of wear on corrosion, and a quantitative characterization method of corrosion–wear interactions was proposed by establishing the component relationships of material losses in the corrosion–wear process. The results indicate that the corrosion rates initially increase and then decrease, ultimately resulting in a pattern characterized by predominant total corrosion and nested localized corrosion. The corroded surfaces tremendously influence the friction coefficient curves at the third stage, and a synergistic acceleration effect exists in the CWI behavior of 8Cr4Mo4V bearing steel under the action of corrosion and wear. A sample corroded for 6 h displayed the significant facilitative effect of corrosion on wear, exhibiting the highest CWI ratio and a greater total mass loss primarily attributed to corrosion. This study offers a significant reference for the quantitative assessment of the tribo-corrosion properties of bearings in a marine atmospheric environment.

Purpose: The purpose of this paper is to improve binding force between the coating and the steel substrate by using chemical modification on the steel surface; at the same time, it can also increase the corrosion resistance of the coating. Design/methodology/approach: The main components of the conversion film include tannic acid, sodium molybdate and silane coupling agent KH560. After the preparation was completed, the samples were tested and analyzed, including surface morphology, conversion film components, bonding force with organic resins and corrosion resistance. Finally, it drew a conclusion that the conversion film can greatly improve the bonding strength of the steel substrate and epoxy resin. Findings: When the content of tannic acid is 4 g/L meanwhile the content of KH560 is 20 g/L, the conversion film has the strongest binding force with epoxy resin, from 2.15 Mpa of untreated steel to 4.60 Mpa, growth of 140 per cent. At the same time, the resulting conversion film also improves the corrosion resistance of the steel surface by a small margin. Originality/value: A method of enhancing the bond between an epoxy coating and steel is provided. Verify the mechanism of this method.

In this research, high-performance ZnAl-layered double hydroxides (ZnAl-LDHs) with different Zn²⁺ concentrations were prepared on the surface of an anodized 1060 aluminum alloy using the in situ growth method, and the influence of Zn²⁺ concentration on corrosion resistance and tribological behavior was further explored. The surface morphology, element distribution, phase composition, and mechanical performance of ZnAl-LDHs/anodic aluminum oxide (AAO) composite coatings were tested and analyzed. Subsequently, the investigation of the anti-corrosion properties and tribological behavior of as-prepared composite coatings and AAO were conducted experimentally. The results show that with the increase in Zn²⁺ concentration, the thickness and bonding strength of the coatings gradually increase, and the hardness progressively decreases. The ZnAl-LDHs/AAO composite coating with a Zn²⁺ concentration of 0.3 mol/L exhibits the best anti-corrosion ability, which has the minimum corrosion current density of 2.435 × 10⁻⁹ A/cm². This can be attributed to the uniform and compact ZnAl-LDH films where the porous structure of the AAO is well sealed. Moreover, the excellent friction-reduction and anti-wear properties of ZnAl-LDHs/AAO composite coatings with larger Zn²⁺ concentrations are verified using a ball-on-disc rotating wear tester under dry wear. A reasonable mechanism for improving tribological properties of resulting ZnAl-LDHs/AAO composite coatings is proposed.

The present work aims to explore corrosion damage evolution characteristics of 8Cr4Mo4V bearing steels in marine contaminated atmospheric conditions, considering effects of corrosion temperature, corrosion medium, medium concentration and rust layer. Salt spray tests and electrochemical techniques were conducted to evaluate the corrosion resistance and electrochemical corrosion property of 8Cr4Mo4V bearing steels, respectively. The corrosion kinetics, corrosion morphology, corrosion product composition, corrosion voltage, corrosion current density, impedance mode and polarisation resistance of samples were characterised by weight gain method, SEM, XRD and electrochemical tests. Results show that the corrosion damage degree of bearing steel in a simulated marine-industrial atmosphere is more serious compared with a marine atmosphere; the multi-layer composite rust layer is mainly iron oxides and hydroxyl oxides, accompanied by the formation of micro-cracks. The increased corrosion temperature, NaCl concentration, HSO ₃ ⁻ concentration and NH ₄ ⁺ concentration cause obvious fluctuations of electrochemical parameters and polarisation resistance of bearing steels, while the electrochemical impedance behaviour of corroded bearing steels changes in reverse due to the generation of rust layers, acting as a protector of the substrate material. These investigation findings prominently contribute to evaluating the accelerated corrosion behaviour and describing corrosion defect evolution of 8Cr4Mo4V bearing steels in a marine-contaminated atmosphere.