TC4钛合金热氧化层微米压痕/划痕试验研究
Study on Micro-indentation and Micro-scratch Experiment of Thermal Oxidation Coating on TC4 Alloy
张春艳, 王振林, 田中青, 杨 惠
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作者单位：重庆理工大学 材料科学与工程学院, 重庆 400050
中文关键字：TC4； 热氧化层； 微米压痕； 微米划痕； 力学性能
英文关键字：TC4; thermal oxidation coating; micro-indentation; micro-scratch; mechanical properties
中文摘要：采用微米压痕实验测试了氧化层的硬度、弹性模量，研究了热氧化工艺对TC4钛合金表面热氧化层力学性能的影响；通过微米划痕实验考察了氧化层的临界荷载以及划擦行为。结果表明：热氧化处理后TC4表面生成由金红石TiO2和少量Al2O3所组成的氧化层，钛合金表面硬度和弹性模量显著增加，弹性模量与硬度的比值降低, 表明热氧化工艺可改善钛合金的耐磨性。长时间的高温氧化可以增加氧化层的厚度，但在划擦过程中氧化层发生两次脱落，表明氧化层由外表层和次外层组成，外层结合力差，易发生一次脆性剥落，内层与基体的结合强度较高，但在较大载荷作用下会产生微裂纹，导致氧化层的二次剥落。
英文摘要：An oxide layer was produced on the surface of TC4 alloy by thermal oxidation process to improve the tribological properties of titanium alloy. The Young's modulus(E) and hardness of oxide layer were measured by micro-indentation. The effects of thermal oxidation on the mechanical properties of thermal oxidation coating were studied. The scratch resistance and damage behaviours of the oxide layer were evaluated using micro-scratch techniques. The results show that the oxide layer on TC4 alloy surface is multi-layered oxide consisting of predominant TiO2 and Al2O3. Thermal oxidation treatment can increase the surface hardness and elastic modulus significantly and reduce the E /H ratio of the TC4, which indicate the treatment can enhance the wear resistance of TC4 alloy. Long time treatment can increase the thickness of the oxide layer, but the outside layer is apt to desquamate during the scratching. The oxide layer closing to substrate has better bonding properties, but microcrack forms as a result of high stress loading, which lead the layer to flake off completely.