人造摩擦层对H13钢和TC4合金摩擦磨损行为的影响

发布时间：2018-07-09 21:19

本文选题：H13钢 + TC4合金　；参考：《江苏大学》2017年硕士论文

【摘要】：磨损是金属构件的主要失效形式之一,对金属材料的摩擦磨损性能展开研究并提高其耐磨性能具有重要的理论意义和工程应用价值。研究表明,当磨面出现稳定存在且以氧化物为主要成分的摩擦层时,磨损率可以得到不同程度的降低。但氧化物需要在高温或高速条件下才能形成,因此限制了摩擦层在减磨方面的应用。本文采用销盘式摩擦磨损试验机,室温条件下分别在H13/GCr15钢和TC4/GCr15钢磨面添加固态颗粒,促使形成人造摩擦层以减少基体磨损量。分别研究了Fe_2O_3、MoS_2和其不同比例的混合物对两种合金材料摩擦磨损行为的影响。通过XRD、EDS和SEM等微观手段对摩擦表面和剖面的物相、成分、形貌和结构进行表征,并探讨不同实验条件下的磨损机理。实验结果表明,在磨损表面添加Fe_2O_3、MoS_2或其不同比例的混合物可以形成人造摩擦层,而人造摩擦层的形成对H13钢和TC4合金磨损率和磨损机制具有显著的影响。对于H13钢和TC4合金,在不添加任何颗粒时,磨损机制为典型的磨粒磨损和粘着磨损,磨损率随载荷的升高快速增加。此时,磨面并未出现氧化物,即未形成覆盖整个磨面的摩擦层,且H13钢亚表面出现明显的塑性变形并伴有明显孔洞。在磨面添加固态颗粒时,磨损率得到不同程度的降低,发生严重-轻微磨损转变。当添加Fe_2O_3固态颗粒时,Fe_2O_3颗粒可以在H13钢和TC4合金的磨面上快速团聚并烧结,形成覆盖整个磨面的人造摩擦层,对基体起到显著的保护作用,但此时摩擦系数达到最大值。此外,较差的热传导性和较高的承载性能可以一定程度的降低由于热软化所导致的亚表面塑性变形。当添加MoS_2颗粒时,由于MoS_2与H13钢之间具有较强的吸附作用,因此,在滑动初始阶段即可在H13钢的磨面快速形成MoS_2摩擦层并稳定存在。MoS_2摩擦层的存在不仅对磨面起到保护作用以降低磨损率,同时由于其优异的润滑性能,显著的降低了摩擦系数,同时也降低了亚表面的塑性变形区。但对于TC4合金,MoS_2的添加并未显著降低其磨损率,仅能降低摩擦系数,这可能是由于MoS_2颗粒与TC4基体亲和力相对较差,在滑动过程中被挤出磨面所致。当添加Fe_2O_3和MoS_2的混合物时,在所有测试载荷范围内两种基体的磨损率均在较小范围内波动,趋近于零(TC4合金80%MoS_2除外),且同时获得较低的摩擦系数。
[Abstract]:Wear is one of the main failure forms of metal members. It is of great theoretical significance and engineering application value to study the friction and wear properties of metal materials and to improve their wear resistance. The results show that the wear rate can be reduced in varying degrees when there is a stable friction layer with oxide as the main component. However, oxides need to be formed at high temperature or at high speed, so the application of friction layer in reducing wear is limited. In this paper, solid particles were added to the wear surfaces of H13 / GCr15 steel and TC4 / GCr15 steel at room temperature by using a pin-disc friction and wear tester, which promoted the formation of an artificial friction layer to reduce the wear rate of the matrix. The effects of Fe _ 2O _ 3M _ S _ 2 and its mixture on the friction and wear behaviors of the two alloys were studied. The phase, composition, morphology and structure of friction surfaces and profiles were characterized by means of XRDX EDS and SEM, and the wear mechanism under different experimental conditions was discussed. The experimental results show that the artificial friction layer can be formed by adding Fe _ S _ 2O _ 3Mo _ S _ 2 or its mixture to the worn surface, and the formation of artificial friction layer has a significant effect on the wear rate and wear mechanism of H13 steel and TC4 alloy. For H13 steel and TC4 alloy, the wear mechanism is typical abrasive wear and adhesive wear without adding any particles, and the wear rate increases rapidly with the increase of load. At this time, there is no oxide on the surface, that is, there is no friction layer covering the whole surface, and there is obvious plastic deformation and obvious hole on the subsurface of H13 steel. When solid particles are added to the grinding surface, the wear rate decreases to some extent, and a serious to slight wear transition occurs. When Fe _ 2O _ 3 solid particles are added, Fe _ 2O _ 3 particles can be rapidly agglomerated and sintered on the wear surfaces of H13 steel and TC4 alloy, forming an artificial friction layer covering the whole wear surface, which plays a significant protective role on the matrix, but the friction coefficient reaches the maximum at this time. In addition, poor thermal conductivity and high bearing capacity can reduce the subsurface plastic deformation caused by thermal softening to some extent. When MoS2 particles were added, because of the strong adsorption between MoS2 and H13 steel, At the initial stage of sliding, MoSII friction layer can be formed quickly on the wear surface of H13 steel and the existence of the friction layer. MoS2 friction layer not only protects the wear surface to reduce the wear rate, but also reduces the friction coefficient because of its excellent lubricity. At the same time, the plastic deformation zone of the subsurface is reduced. However, the addition of TC4 alloy MoS _ 2 does not decrease the wear rate, but can only decrease the friction coefficient, which may be due to the relatively poor affinity between MoS _ 2 particles and TC4 matrix and the extrusion wear surface during sliding. When Fe _ 2O _ 3 and MoS _ S _ 2 mixtures were added, the wear rates of the two substrates fluctuated in a smaller range in all test load ranges, reaching zero (except for TC4 alloy 80 and MoSflesh _ 2), and a lower friction coefficient was obtained at the same time.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG174.4

【参考文献】