钛合金在不同滑动速度和介质下磨损行为和机制的研究

发布时间：2018-05-15 08:34

  本文选题：钛合金 + 磨损行为　； 参考：《江苏大学》2016年博士论文

【摘要】：钛合金通常被认为具有差的摩擦学特性,使其应用范围受到了很大的限制。随着钛合金的应用领域不断扩展,对其摩擦磨损性能的研究受到越来越多的关注。目前,国内外对钛合金摩擦磨损性能的研究尚不够全面和深入。本文系统研究了TC4和TC11两种典型钛合金在不同滑动速度和介质条件下的摩擦磨损行为和磨损机理,探讨了钛合金室温下磨损行为的影响因素以及不同滑动条件下钛合金的磨损机制及其转变,深入研究了钛合金摩擦层及摩擦氧化物在磨损过程中的作用及机理,并通过双滑动磨损试验验证了摩擦氧化物的作用。此项研究具有重要的理论意义和实际工业应用价值。结果表明:TC4和TC11两种钛合金的摩擦磨损行为和磨损机理随滑动速度的变化具有共性。钛合金的磨损率随滑动速度升高呈现出显著变化。随着滑动速度从0.5 m/s增加至4 m/s,磨损速率先降低,在0.75 m/s发生转折,然后快速升高,在2.68 m/s达到最大值,最后再次降低,在4 m/s达到最小值。在相同滑动条件下TC4合金的磨损率均略高于TC11合金。同样,磨损机理随着滑动速度升高也发生显著变化,0.75 m/s时主要为粘着磨损、磨粒磨损和氧化磨损;2.68 m/s时为金属剥层磨损;4 m/s时为轻微-氧化磨损。研究发现:钛合金并不总具有较差的耐磨性,而是随滑动条件变化呈现出两种磨损状态:轻微磨损和严重磨损。轻微磨损和严重磨损在滑动速度0.5-4 m/s范围内交替出现,并发生转变。在0.75-2.68 m/s速度范围内,随着载荷增加,发生轻微-严重磨损转变;而随滑动速度从2.68 m/s增加到4 m/s,发生严重-轻微磨损转变。后者表明钛合金“不符合Wilson和Apas的轻微-严重磨损转变的临界温度准则”,表现出与其它合金不同的特殊摩擦磨损特征。环境介质对钛合金磨损行为和机制有着显著影响,腐蚀和磨损之间存在明显的相互促进作用。在模拟海水中的磨损率始终最高,其次是纯水中磨损率,空气中磨损率最低。钛合金在空气条件下的磨损机理为粘着磨损和磨粒磨损,并伴有一定程度的氧化磨损;纯水介质中为磨粒磨损;模拟海水条件下为疲劳磨损和磨粒磨损。钛合金在室温条件下大气环境中形成的摩擦层通常可以分为两类:一般速度下的机械混合层和超高速度下的原位氧化物层。含摩擦氧化物的机械混合层被认为具有保护性。轻微磨损和严重磨损被认为与机械混合层中滑动诱发形成的摩擦氧化物的出现和消失相对应。这与传统观点认为的钛合金摩擦氧化物无保护性不同。采用双滑动磨损试验验证了室温条件下钛合金在4 m/s速度下滑动产生的摩擦氧化层具有显著的保护作用。通过对前人研究成果和本研究实验结果的分析,初步弄清了钛合金室温下磨损行为的影响因素,并随着滑动速度变化将其区分为三个主要影响区:(1)较低速度下的绝热剪切带(ASB)和机械混合层(MML)影响区;(2)中等速度下的塑性变形和MML影响区;(3)高速下的塑性变形和原位氧化层影响区。并给出了钛合金室温下随滑动速度和载荷变化的磨损机制图。随着滑动速度增加,磨损机制分别为粘着、磨粒和氧化磨损,剥层磨损,轻微-氧化磨损,严重-氧化磨损以及塑性挤出磨损。不同滑动速度下磨损影响区的转变导致了磨损机理发生改变,最终使得磨损行为发生变化。
[Abstract]:Titanium alloys are generally considered to have poor tribological properties, and the application scope of titanium alloys is greatly limited. With the continuous expansion of the application field of titanium alloys, more and more attention has been paid to the research on the friction and wear properties of titanium alloys. At present, the research on the friction and wear properties of titanium alloys at home and abroad is not comprehensive and deep. The friction and wear behavior and wear mechanism of two typical titanium alloys, TC4 and TC11 under different sliding speeds and medium conditions, are discussed. The influencing factors of wear behavior at room temperature and the wear mechanism and transformation of titanium alloys under different sliding conditions are discussed. The wear process of titanium alloy friction layer and friction oxide in the wear process is deeply studied. The effect and mechanism of the two sliding wear tests are verified by the double sliding wear test. This study has important theoretical significance and practical application value. The results show that the friction and wear behavior and wear mechanism of the two kinds of titanium alloys of TC4 and TC11 have common characteristics with the change of sliding velocity. The wear rate of titanium alloy varies with the sliding velocity. As the sliding speed increases from 0.5 m/s to 4 m/s, the wear rate decreases first, the wear rate decreases at 0.75 m/s, then increases rapidly, reaches the maximum at 2.68 m/s, and finally decreases again at 4 m/s. The wear rate of TC4 alloy is slightly higher than that of the TC11 alloy under the same sliding condition. The wear mechanism is also along with the wear mechanism. The increase of sliding speed also changed significantly. 0.75 m/s was mainly adhesive wear, abrasive wear and oxidation wear, metal peeling wear at 2.68 m/s and slight oxidation wear at 4 m/s. It was found that titanium alloy did not always have poor wear resistance, but showed two wear states with change of sliding conditions: slight wear and severity. Wear. Slight wear and severe wear occur alternately and change within the range of sliding speed 0.5-4 m/s. Within the speed range of 0.75-2.68 m/s, a slight severe wear transition occurs with the increase of load, while the sliding velocity increases from 2.68 m/s to 4 m/s, with a severe slight wear transition. The latter indicates that the titanium alloy "does not conform to Wilson and Ap." The critical temperature criterion for the slight severe wear transition of as shows the special friction and wear characteristics different from other alloys. The environmental medium has a significant influence on the wear behavior and mechanism of titanium alloy, and there is a significant mutual promotion between corrosion and wear. The wear rate in the simulated seawater is always the highest, followed by the wear in pure water. The wear rate of the air is the lowest. The wear mechanism of titanium alloy under air conditions is adhesion wear and abrasive wear, with a certain degree of oxidation wear, and abrasive wear in pure water medium, fatigue wear and abrasive wear under simulated seawater conditions. The friction layers formed in the atmosphere environment of titanium alloy at room temperature are usually divided. Two categories: mechanical mixing layer under general speed and in situ oxide layer under high velocity. The mechanical mixing layer containing friction oxides is considered to be protective. Slight wear and severe wear are considered to correspond to the occurrence and loss of the friction oxides formed in the mechanical mixing layer. The friction oxide of gold is not different. Double sliding wear test has been used to verify that the friction oxidation layer of titanium alloy at room temperature under 4 m/s velocity has significant protective effect. By analyzing the results of previous studies and the results of this study, the factors affecting the wear behavior at room temperature are clarified. With the change of the sliding velocity, it is divided into three main areas: (1) the adiabatic shear band (ASB) and the mechanical mixing layer (MML) in the lower velocity; (2) the plastic deformation and the MML influence zone at the medium speed; (3) the plastic deformation and the in situ oxidation layer under the high speed. Wear mechanism, with the increase of sliding speed, wear mechanisms are adhesive, abrasive and oxidation wear, peeling wear, slight oxidation wear, serious oxidation wear and plastic extrusion wear. The change of wear mechanism at different sliding speed leads to the change of wear mechanism, and finally the wear behavior changes.

【学位授予单位】：江苏大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TG146.23
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本文编号：1891741