钛合金固相渗硼-稀土渗硼机理研究

The Mechanism Study of Titanium Alloy Packing Boronizing-Rare-Earth Boronizing

表面强化处理可以大幅提升钛合金的耐磨性,也有利于钛合金在高温环境中应用。钛合金高温固相渗硼是重要的表面强化方式,添加稀土提高渗硼效率是重要技术手段。为深入研究稀土的渗硼催化机制,本文开展了900~1050℃渗硼试验,重点分析了渗硼剂在试验后的相组成变化。结果表明,稀土可通过与硼源、氧发生化学反应,生成熔点较低的稀土硼酸盐。本文对该硼酸盐发挥的作用进行了解释,论述了稀土在渗硼反应过程中的作用。经过渗硼的钛合金表面形成了TiB/TiB2双相渗层,显微组织分析表明该渗层与基材结合紧密、无孔洞缺陷。本文还对渗硼钛合金的拉伸性能、表面摩擦系数、维氏硬度、高温洛氏硬度、结合力等基础力学性能进行了测试,结果表明,渗硼钛合金具有优良的综合力学性能。

Surface strengthening can highly improve the wear resistance of titanium alloys, which is also good for their applications at higher temperature. High-temperature pack boronizing is one of the most important strengthening methods for titanium alloys. Adding rare earth(RE) is a key way to increase the boronizing efficiency. To deeply undertand the RE boronizing mechanism, boronizing tests at 900~1050 ℃ were carried out and the chemical composition changes of the boronizing agents during the boronizing was particularly investigated. The results showed that the RE oxides reacted with boron and oxygen, forming low-melting point borates. After the boronizing, dense TiB/TiB2 dual phase layer was formed showing a strong bonding with the titanium alloy. Basic mechanical properties of the boronized titanium alloys, such as tensile property, surface wear coefficient, Vickers hardness, high-temperature Rockwell hardness, and bonding force were tested. The results showed that the boronized titanium had excellent mechanical properties.