表面纳米化及离子氮化钛合金的三体磨料磨损性能研究

发布时间：2018-02-27 07:57

  本文关键词： TA2钛合金 超声表面滚压 等离子渗氮 三体摩擦　出处：《中国地质大学(北京)》2017年硕士论文　论文类型：学位论文

【摘要】：TA2钛合金作为一种轻质结构材料被广泛应用于航天器件、特殊地质钻探等领域,但其合金含量少、硬度低、不耐磨,易产生粘着磨损,因此必须对其进行表面强化。本研究旨在探究模拟月壤颗粒对TA2钛合金表面第三体形成的影响及TA2钛合金的表面强化及抗磨机制,对钛合金在月壤取样工程中的应用具有重要意义。本研究运用超声表面滚压(USRP)+离子渗氮的复合强化技术,选用750℃氮化,USRP+750℃氮化,850℃氮化,USRP+850℃氮化对TA2进行表面强化,运用显微硬度、光学显微、XRD、SEM、EDS等微观分析表征了所制备的钛合金样品;并创造性地添加模拟月壤颗粒作为外源第三体,研究了钛合金的三体摩擦学性能。研究结果为:(1)“USRP+离子渗氮”的复合强化处理能有效提高TA2的力学及摩擦学性能。USRP预处理能够促进离子渗氮,提高强化层厚度和表面硬度,USRP+850℃离子氮化处理后TA2钛合金的性能改善最明显且硬度提升最大,至1097HV0.05。同时USRP处理能够减小样品氮化后的表面粗糙度,使氮化钛合金的表面性能有所改善,摩擦系数减小。(2)在干摩擦条件下,模拟月壤颗粒在钛合金表面可形成连续分布的第三体,对摩擦学性能有决定性影响。第三体起到隔离摩擦副的作用,颗粒的微滚动减小了摩擦阻力,同时使摩擦过程更稳定,使钛合金的摩擦系数减小。(3)在三体摩擦学体系中,硬质第三体磨粒会对低硬度钛合金产生明显犁削作用,颗粒的“钉扎作用”会造成二次磨损,增大了钛合金材料的磨损率。750℃氮化钛合金的主要磨损机制为犁削磨损;第三体磨粒在磨痕处的聚集会加剧表面的应力集中,使850℃氮化钛合金萌生更多疲劳裂纹从而产生疲劳磨损。(4)不同粒径的模拟月壤颗粒对氮化钛合金的摩擦学性能有重要影响。大粒径(200-991μm)模拟月壤颗粒容易形成强力链,增大了摩擦阻力、加剧了载荷分布的不均匀性,使摩擦系数及波动增大,也更容易产生显微切削形成严重磨粒磨损。小粒径颗粒在摩擦过程中使应力分布更均匀,摩擦系数减小,但此时加剧了高硬度氮化钛合金的疲劳破坏,造成表面疲劳磨损。
[Abstract]:As a light structure material, TA2 titanium alloy is widely used in spacecrafts, special geological drilling and other fields, but its alloy content is low, hardness is low, wear resistance is not good, and adhesive wear is easy to occur. The purpose of this study was to investigate the effects of simulated lunar soil particles on the formation of the third body on the surface of TA2 titanium alloy and the mechanism of surface strengthening and antiwear of TA2 titanium alloy. It is of great significance for the application of titanium alloy in lunar soil sampling engineering. In this study, the surface strengthening of TA2 was carried out by using the composite strengthening technology of ultrasonic surface rolling pressing (USRP) ion nitriding. The titanium alloy samples were characterized by microhardness and optical microanalysis, and the simulated lunar soil particles were creatively added as the external third body. The tribological properties of titanium alloy were studied. The results show that the compound strengthening treatment of "USRP ion nitriding" can effectively improve the mechanical and tribological properties of TA2. The properties and hardness of TA2 titanium alloy were improved most obviously by increasing the thickness of strengthening layer and surface hardness after ion nitridation at 850 鈩，

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