铁基金属摩擦副表面自修复层分析

目的分析不同工况对表层自修复层的影响,探究羟基硅酸镁纳米管在摩擦磨损过程中的作用机理。方法以人工合成的羟基硅酸镁纳米管Mg3Si2O5(OH)4为自修复添加剂,在油润滑实验条件下进行铁基金属摩擦副摩擦磨损实验。利用SEM、EDS、激光拉曼光谱仪及显微维氏硬度计分别对自修复层厚度、自修复层元素组成、自修复层表面结构及自修复层表面显微硬度进行表征。结果在转速为1000、2000 r/min时,载荷为200、300、400 N的实验条件下,表层均有自修复层的生成。在转速为2000 r/min、载荷为400 N时,表层自修复层的厚度最大。实验过程中,摩擦副得到修复,出现负磨损,自修复层的主要元素为C、O、Fe等。高转速载荷工况下,其摩擦系数相比基础油下降0.008。自修复层为类金刚石结构,其平均硬度值在673HV左右,为基体的1.87倍。结论羟基硅酸镁、基础油及磨屑三者共同作用,在高能摩擦作用下合金化,形成高硬度的类金刚石结构修复层,能有效保护摩擦副工作面,并延长寿命。加大实验载荷与实验转速,能加速自修复层的形成,实现摩擦副负磨损,并降低摩擦系数。

Self-reparing Layers Analysis on the Surface of Iron-based Metal Friction Pairs

The work aims to analyze the effects of different working conditions on superficial self-repairing layers, and study the mechanism of action of magnesium silicate hydroxide nanotube in the process of friction and wear. With artificially synthesized magnesium silicate hydroxide nanotube Mg3Si2O5(OH)4 as a self-repairing additive, friction and wear test was applied to an iron-based metal friction pair under the condition of oil lubrication. Thickness, elemental composition, surface structure and surface microhardness of the self-repairing layer was characterized by SEM, EDS, laser Raman spectrometer and micro Vickers, respectively. The self-repairing layers were detected at the revolving speed of 1000 r/min and 2000 r/min, and the load of 200 N, 300 N and 400 N. The thickest self-repairing layer was obtained at the revolving speed of 2000 r/min and load of 400 N. Negative wear happened to repaired friction pairs during the experiment, and the self-repairing layers were mainly composed of such elements as C, O, Fe. Compared with base oil experiment, friction coefficient at high speed and load decreased by 0.008. The self-repairing layers were diamond-like structures, and average hardness of the self-repairing layers was about 673HV, which was 1.87 times that of substrate. Alloyed repair layers of high hardness diamond-like structure take shape under the combined action of magnesium silicate hydroxide, base oil and ablation as well as the effect of high energy friction, which can effectively protect working face of friction pair and prolong its service life. By increasing experimental load and revolving speed, the formation of self-repairing layer can be accelerated, negative wear of friction pair can be realized and friction coefficient can be reduced.