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分别以高纯N2和高纯Ar为保护气体,在TC4钛合金基材表面激光原位合成了TiN/钛基复合涂层。运用X射线衍射仪、扫描电子显微镜和显微硬度计对复合涂层的微观结构和力学性能进行了分析,通过空气电阻炉初步测试了复合涂层的相对高温耐氧化性。结果表明,Ar气氛下原位合成的复合涂层含有较多未完全反应的Ti相,组织均匀性较差,涂层截面显微硬度分布不均;而N2气氛下的原位合成反应比较充分,原位合成复合涂层主要由TiN和Ti3Al两相组成,涂层组织均匀致密,含较多高硬度TiN相,显微硬度自基体至涂层过渡平缓,且平均显微硬度较Ar气氛下复合涂层高约40.7%,600℃和800℃的相对耐氧化性值分别是TC4基体钛合金的6.83倍和1.94倍,较Ar气氛下的复合涂层提高约17.96%和19.75%。
TiN / Ti-based composite coatings were synthesized by laser in-situ on the surface of TC4 titanium alloy with high purity N2 and high purity Ar as shielding gas respectively. The microstructure and mechanical properties of the composite coating were analyzed by X-ray diffraction, scanning electron microscopy and microhardness tester. The relative high temperature oxidation resistance of the composite coating was tested by air resistance furnace. The results show that the composite coating synthesized in-situ contains more incompletely reacted Ti phases in the Ar atmosphere, the microstructure homogeneity is poor, and the microhardness of the coating cross-section is unevenly distributed. However, the in-situ synthesis reaction in the N2 atmosphere is quite adequate , In-situ composite coating is mainly composed of two phases of TiN and Ti3Al, the coating is uniform and dense, contains more high hardness TiN phase, the microhardness transition from the matrix to the coating is gentle, and the average microhardness than Ar atmosphere The composite coating is about 40.7% higher and the relative oxidation resistance at 600 ℃ and 800 ℃ is 6.83 and 1.94 times higher than that of the TC4 matrix titanium alloy, respectively, which is 17.96% and 19.75% higher than that of the composite coating under the Ar atmosphere.