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1 – 2 of 2Qiang Sun, Quantong Jiang, Siwei Wu, Chang Liu, Heng Tang, L. Song, Hao Shi, Jizhou Duan and BaoRong Hou
The purpose of this paper is to explore the effect of ZnO on the structure and properties of micro-arc oxidation (MAO) coating on rare earth magnesium alloy under large…
Abstract
Purpose
The purpose of this paper is to explore the effect of ZnO on the structure and properties of micro-arc oxidation (MAO) coating on rare earth magnesium alloy under large concentration gradient.
Design/methodology/approach
The macroscopic and microscopic morphology, thickness, surface roughness, chemical composition and structure of the coating were characterized by different characterization methods. The corrosion resistance of the film was studied by electrochemical and scanning Kelvin probe force microscopy. The results show that the addition of ZnO can significantly improve the compactness and corrosion resistance of the MAO coating, but the high concentration of ZnO will cause microcracks, which will reduce the corrosion resistance to a certain extent.
Findings
When the concentration of zinc oxide is 8 g/L, the compactness and corrosion resistance of the coating are the best, and the thickness of the coating is positively correlated with the concentration of ZnO.
Research limitations/implications
Too high concentration of ZnO reduces the performance of MAO coating.
Practical implications
The MAO coating prepared by adding ZnO has good corrosion resistance. Combined with organic coatings, it can be applied in corrosive marine environments, such as ship parts and hulls. To a certain extent, it can reduce the economic loss caused by corrosion.
Originality/value
The effect of ZnO on the corrosion resistance of MAO coating in electrolyte solution was studied systematically, and the conclusion was new to the common knowledge.
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Keywords
Powder lubrication is widely used in industrial production, but most of the research that analyze the wear process and speculate on the wear mechanism of the tested specimens…
Abstract
Purpose
Powder lubrication is widely used in industrial production, but most of the research that analyze the wear process and speculate on the wear mechanism of the tested specimens lacks reliability, and it is difficult to reveal the essence of the friction and wear process. The purpose of this paper is using the optical in situ observation method to observe the condition of the powder lubrication layer in real time and dynamically, and directly obtain the morphology change of the specimen during the whole wear process, which is helpful to the establishment of new tribological basic theories such as friction and wear mechanism and lubrication theory.
Design/methodology/approach
Mechanical model of powder lubrication is established considering asperity and powder layer, and the influence of adhesion effect on load and friction force is analyzed. The finite difference method is used to solve the above physical model, and the influence of the adhesion effect on load and friction force is analyzed. The total load and friction of the friction pair are composed of two parts: fluid and asperity. Based on the optical in situ observation method to build a test platform. The interface of the adhesion stage was observed by SEM.
Findings
When the film thickness ratio is less than 1, the local damage and diffusion of the powder layer are basically completed and the adhesion stage is entered. At this time, the asperity is not fully loaded, the powder layer is loaded by 50%, the asperity is less loaded, the deformation is small and the possibility of plastic flow is reduced. However, in the adhesion stage, the friction force is basically generated between asperity, and the friction force ratio of the asperity is 80%. Heavy load and surface roughness of the specimen are the necessary conditions for the powder adhesion period.
Practical implications
In this paper, the failure process of the powder layer at the friction interface with different roughness and load is studied based on the optical in situ observation method. Second, the contact surface with the micro-convex body and powder layer is simulated, and the influence of adhesion effect on the mechanical properties of the real contact surface in the process of powder lubrication is analyzed, thus providing theoretical guidance for mechanical processing, workpiece operation and lubrication design.
Originality/value
Mechanical model considering asperities and powder layer powder lubrication was established to analyze the influence of the adhesion effect on load and friction. Based on the optical in situ observation method to build a test platform. The tests found that the failure process of the powder lubricating layer includes five stages: powder complete stage, local failure stage, local failure diffusion stage, powder adhesion stage and complete failure stage.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-11-2022-0322/
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