机械研磨处理对医用Zn-Li-Er合金表面组织演化规律及磨损行为研究OA

Improving the wear resistance of medical zinc alloys is crucial for ensuring the long-term safety,functionality,efficacy,and cost-effectiveness of biodegradable implants during in vivo service.However,how to balance the mechanical properties,biocompatibility and degradation behavior remains a key challenge for medical zinc-based materials.The work aims to propose and systematically implement an innovative surface strengthening strategy that combines bulk thermal deformation with surface nanostructures,which is a combined process of surface mechanical grinding treatment(SMAT)after hot rolling and apply this method to a novel Zn-Li-Er medical alloy to improve its corrosion and wear resistance while elucidating the potential microstructural evolution mechanisms under different surface treatment conditions.Firstly,the Zn-Li-Er alloy was hot-rolled at 320℃ with a 70%thickness reduction to refine the bulk grains and induce strain hardening.After this,high-energy ball milling under different diameters(3,5,7 and 9 mm)was used as the surface mechanical wear treatment,causing severe plastic deformation.The originality of this method lied in the customized selection of impact ball sizes,which could be targeted at manipulating deformation energy input and surface strain gradient thickness.Moreover,it could also control the evolution of the gradient nanostructures throughout the entire processing area.Sectional morphology of samples revealed a clearly defined gradient structure,with the most intense grain refinement localized near the surface.Micro-indentation hardness results further demonstrated a pronounced hardness gradient induced by this structural transformation.The surface roughness was quantitatively characterized with a 3D laser confocal microscopy.Key roughness parameters(Ra,Sa,Sq)showed a size-dependent increase with ball diameter,and Ra increased from 5.997 μm(3 mm)to 9.033 μm(9 mm).Sa and Sq also exhibited similar trends,increasing from 4.977 μm/2.098 μm to 7.036 μm/2.929 μm,respectively.The results showed that the increase in impact energy of larger steel balls led to intensified surface deformation and more prominent brittle fracture characteristics.The wear resistance of the treated surfaces was evaluated in Hank's simulated body fluid with a multi-functional material surface performance tester.Among all ball sizes,the alloy subjected to 5 mm grinding balls exhibited the optimal corrosion-wear resistance,with a significantly reduced wear rate of only 0.28×10-3 g/(N·m).This improvement is due to the formation of a highly refined nanocrystalline layer on the surface,which has higher hardness and the ability to resist plastic indentations or abrasive wear.The accumulation of deformation-induced energy provides the driving force for continuous dynamic recrystallization,thereby forming nanoscale grain structures and enhancing mechanical integrity.Nevertheless,the work also demonstrates a trade-off between hardness and surface morphology.Larger-sizes balls enhance hardness through more extensive grain refinement,but this will cause the surface morphology of the alloy to deteriorate.The higher roughness diminishes the effective contact area during friction,increases local contact stress,and elevates the friction coefficient,ultimately accelerating wear.This mechanistic insight highlights the importance of optimizing impact parameters to achieve a desirable balance between hardness and topographical smoothness.Overall,this work not only introduces a novel integrated approach for enhancing the corrosion-wear performance of biodegradable Zn-based alloys but also reveals the synergy roles of ball sizes,gradient nanostructure,and the wear-corrosion in physiological environments.It is expected that this research work will provide reference and theoretical support for the subsequent optimization of the wear performance of medical Zn-based alloys.