Optimization of friction, wear and sealing performance of valve plate pair in seawater axial piston pump using composite biomimetic multistage texture

Abstract The friction, wear, and leakage of the valve plate pair in seawater axial piston pumps represent a critical performance bottleneck. Although surface texturing is an effective solution, existing research predominantly focuses on single-level, uniformly distributed textures under mineral oil lubrication, failing to address the region-specific balance between friction reduction and leakage control in seawater-lubricated valve plate pair, where the suction and discharge zones require stronger leakage suppression, and the transition zone demands maintaining a stable, gradually improving frictional state. To overcome this limitation, this study designed a composite biomimetic multistage texture incorporating triangular and elliptical secondary groove (ESG) structures. A CFD-based water film model was developed to evaluate friction, wear and leakage performance, and an orthogonal design was applied to identify the optimal texture parameters and distribution strategy. The composite biomimetic multistage texture achieved simultaneous optimization of leakage rate and friction coefficient. A valve plate pair was manufactured using CF/PEEK and 431 stainless steel, and tribological tests were conducted in a seawater environment. The effects of texture dimensions on friction and wear behavior were systematically examined. The experimental results validated the simulation findings and elucidated the underlying friction and wear mechanisms. The composite biomimetic multistage textured samples exhibited a maximum reduction of 62.8% in the friction coefficient compared with the smooth samples demonstrating the effectiveness of the design in reducing friction while maintaining favorable sealing performance under seawater lubrication.