电解质浓度对TiB2基刀具表面MAO涂层组织和摩擦性能的影响

研究了以高浓度Na₅P₃O₁₀作为电解液对钛合金实施微弧氧化,并对其表面结构和各成分组成情况进行了分析,之后测试了氧化层的表面硬度及其耐磨特性。研究结果表明:提高Na₅P₃O₁₀浓度后,发生了电导率明显增大现象,反应时间显著缩短。加入50 g/L的Na₅P₃O₁₀涂层的表面形成了尺寸差异较大的微孔,这些微孔的尺寸都在1μm以内,表面较平滑。所有微弧氧化涂层内都存在B、Ti、O。各膜层中主要存在B₂TiO₅,同时形成了B₂O₃与金红石TiO₂衍射峰。逐渐提高Na₅P₃O₁₀含量后,加入50 g/L的Na₅P₃O₁₀涂层试样获得了更高硬度,但硬度变化速率发生了降低。加入50 g/L的Na₅P₃O₁₀涂层具备很高极限载荷,迅速达到了稳定的摩擦状态,因此摩擦系数快速减小到稳定的程度。基体的表面受到了较大破坏,产生了许多磨屑颗粒与犁沟;涂层表现为粘着磨损的特征,可以显著降低粘着磨损的程度。

Impact of Electrolyte Concentration on Microstructures and Tribological Behavior of Micro Arc Oxidized TiB2-Alloy Surfaces

The surfaces of TiB₂-alloy were modified with micro-arc oxidized(MAO)coatings.The influence of the concentration of Na₅P₃O₁₀ electrolyte on the MAO reaction and tribological properties of MAO coatings was investigated with X-ray diffraction,scanning electron microscopy and conventional mechanical probes.The results show that the Na₅P₃O₁₀-concentration had a major impact.For example,as the concentration increased from 10 to 50 g/L,the conductivity and oxidation rate of electrolyte increased,resulting in a shortened MAO reaction time.When it comes to tribological properties of the highly porous MAO coatings,comprising B₂TiO₅,B₂O₃ and rutile-phased TiO₂ grains,an increase of Na₅P₃O₁₀-concentration significantly enhanced the surface hardness,decreased the friction-coefficient,and reduced the wear-rate.Adhesive wear was found to be responsible for the wear mechanism of MAO coatings.