目的 研究钛金属材料干摩擦磨损失效机制.方法 选用TA2工业纯钛和TC4钛合金材料,采用CETR UMT-3多功能摩擦磨损测试仪进行往复摩擦磨损试验,采集摩擦系数曲线,计算摩擦系数均值,从动态和静态分析钛金属材料的摩擦特性.采用Micromet-6030型自动显微硬度计测量样品材料表面硬度值,通过表面硬度分析耐磨损性能.采用Nova Nano SEM 650场发射扫描电镜并配置能谱仪对磨损表面和磨屑进行微观形貌观察和元素成分计量分析,从微观角度分析钛金属材料的磨损机理.采用Olympus Lext OLS3000-R型激光共聚焦显微镜测量磨损体积和轮廓,并观察磨损表面的三维形貌.结果 频率对钛金属材料的摩擦系数和耐磨损性能影响较大,随着频率的加快,摩擦系数增大,数据跃变幅度增大,磨损体积随之增大.载荷对摩擦系数影响相对较小,随着载荷增大,在摩擦初期,摩擦系数有下降交汇趋势;摩擦后期,摩擦系数才明显上升,载荷与磨损体积之间基本呈线性增长关系.钛金属材料的磨痕呈现为"擦后型,随着载荷的增大和频率的加快,磨损体积轮廓呈现出加深变宽的趋势.TC4的表面硬度约为359.2 HV,TA2的表面硬度约为247.8 HV,前者比后者高出约111.4 HV.在相同试验条件下进行干摩擦磨损试验,TA2的磨损体积约为TC4的2.5倍,TA2的耐磨损性能相对较差.TA2的磨屑为细小的颗粒状磨屑,磨损表面存在严重的剥层脱落特征;TC4的磨屑粒径大小不一,在低频低载状态下,磨损表面有犁沟痕迹,不存在明显的剥落坑.随着载荷和频率的增大,摩擦表面层出现裂纹和碎化剥落现象.结论 TA2的磨损机制主要是剥层磨损和磨粒磨损.在低频低载状态下,TC4的磨损机制主要为磨粒磨损和氧化磨损,随着载荷和频率的升高,在瞬时闪现温度和载荷的作用下,其磨损机制主要为粘着磨损和剥层磨损.%Objective To research the failure mechanism of dry friction and wear on titanium materials. Methods TA2 in-dustrial titanium and TC4 titanium alloy materials were used. The reciprocating friction and wear testing was performed with CETR UMT-3 multi-purpose friction and wear tester, which collected the friction coefficient curve, calculated the mean value of the friction coefficient and analyzed the dynamic and static friction characteristics of titanium materials. The surface hardness of sample material was measured with Micromet-6030 automatic microhardness tester, and the wear resistance was analyzed ac-cording to surface hardness. Microstructure of the wearing surface and abrasive dust was observed with Nova Nano SEM 650 field emission scanning electron microscopy and energy disperse spectroscopy to measure and analyze components of element. The wear mechanism of titanium materials was analyzed from the micro perspective. Wear volume and profile were measured with Olympus Lext OLS3000-R laser confocal microscope, while the three-dimensional topography of the worn surface was measured. Results The frequency had a significant influence on the friction coefficient and wear resistance of titanium materi-als. As the frequency increased, the friction coefficient, the data jump and the wear volume all increased. The influence of load on the friction coefficient was relatively small. As the load increased, the friction coefficient showed a downward and intersec-tion trend at the beginning of the friction, and the coefficient of friction increased significantly in the later, the load and wear volume grew with substantially in a linear relationship. Wear trace of titanium showed a "U" shape. With the increase of load and frequency, the wear volume profile had a tendency of being deeper and wider. The surface hardness of TC4 was about 359.2 HV and that of TA2 was about 247.8 HV, which was about 111.4 HV lower than the former. The dry friction and wear tests under the same test conditions showed that the wear volume of TA2 was about 2.5 times the TC4, which indicated a rela-tively poor wear resistance of TA2. TA2 had fine granular wear debris, with serious peel off characteristics of its wear surface. By contrast, TC4 wear debris had varies particle size in the low frequency and low load conditions, with no obvious peeling pit on the wear surface furrow traces. With the increase of load and frequency, the phenomenon of crack and fragmentation ap-peared on the surface layer of friction. Conclusions The wear mechanism of TA2 is mainly peeling layer wear and abrasive wear. Under low frequency and low load conditions, the wear mechanism of TC4 mainly abrasive wear and oxidation wear. With the increase load and frequency, it becomes adhesive wear and delamination wear under the effect of the instantaneous flash temperature and load.
展开▼
