Optimization of microstructure and properties of composite coatings by laser cladding on titanium alloy
Optimization of microstructure and properties of composite coatings by laser cladding on titanium alloy
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DOI：
10.1016/j.ceramint.2020.09.063
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发表时间：
2021-01
影响因子：
5.2
通讯作者：
Yanan Liu;Li-jun Yang;Xuejiao Yang;T. Zhang;R. Sun
中科院分区：
文献类型：
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作者：
Yanan Liu;Li-jun Yang;Xuejiao Yang;T. Zhang;R. Sun
近年来，激光熔覆技术的发展为钛合金表面改性带来了新的途径。采用同轴送粉激光熔覆技术在Ti 811合金表面制备了复合涂层。研究了激光能量密度（Led）和CeO 2含量对涂层组织分布、显微硬度和摩擦学性能的影响。此外，基于Bramfitt二维晶格失配理论对TiC-TiB 2结构的生长机制进行了研究。结果表明，涂层的相组成主要为TiC、TiB 2、Ti 2Ni和α-Ti。当激光能量为45 J/mm 2，CeO 2含量为2wt%时，优化后的涂层组织分布均匀，晶粒细小，是获得最佳成形质量和性能的重要因素。此外，TiC（111）与TiB 2（0001）界面的高度匹配有助于TiC-TiB 2复合结构的形成，并对TiC的晶粒尺寸和分布产生积极影响。由于CeO 2的细晶强化和弥散强化作用，2Ce涂层的显微硬度和耐磨性显著提高，直接导致涂层的平均硬度高达811.67 HV0.5，同时摩擦系数较低。
Recently, the current technological progress in developing laser cladding technology has brought new approaches in surface modification of titanium alloys. Herein, composite coatings were fabricated by the laser cladding process on Ti811 alloys using a coaxial powder feeding method. A comprehensive study was performed on the laser energy density (Led) and CeO2content on the structure distribution, microhardness and tribological properties of the coatings. In addition, the growth mechanism of the TiC–TiB2structure was studied based on the Bramfitt two-dimensional lattice mismatch theory. The results indicated that the phase composition of the coating mainly contained TiC, TiB2, Ti2Ni, and α-Ti. The optimized coating contributed to uniform microstructure distribution and fine grain size when Ledwas 45 J/mm2and the CeO2content was 2 wt%, playing an important role in the best forming quality and properties. Besides, the high matching degree of an interface between TiC (111) and TiB2(0001) contributed to the TiC–TiB2composite structure, which positively influenced the grain size and distribution of TiC. The microhardness and wear resistance of the 2Ce coating was dramatically enhanced due to the fine grain strengthening and dispersion strengthening effects of CeO2, contributing directly to generate a high average hardness of 811.67 HV0.5with a lower friction coefficient.