Co800基激光熔覆/重熔增强多物相复合层组织及耐磨性能

目的 增强钛合金表面耐磨损性能。方法 采用激光熔覆与激光重熔技术在TC4钛合金表面制备Co800–Si₃N₄–YPSZ(Y₂O₃部分稳定ZrO₂)与Co800–Si₃N₄–YPSZ–MGOSs(单层氧化石墨烯薄片)复合层，并对熔覆层及重熔层微观组织结构、元素分布及耐磨损性能进行分析。结果 细晶强化作用改善了Co800–Si₃N₄–YPSZ–MGOSs熔覆层的耐磨性。激光重熔后，在熔池快速冷却过程中产生了非晶–纳米晶相，促进了多物相重熔层形成。MGOSs受热分解释放了C，在熔池中原位生成了Ti(CN)。结论 含有Ti₅Si₃、TiN及TiC等多种硬质增强相的Co800–Si₃N₄–YPSZ–MGOSs熔覆层的摩擦因数较TC4的摩擦因数降低，其磨损体积约为TC4磨损体积的1/7。

Microstructure and Wear Resistance of Co800 Based Clad/Re-melt Multi-phase Composite Layer

The work aims to strengthen the wear resistance of titanium alloy surface. Co800-Si3N4-YPSZ (yttria partially stabilized zirconia) and Co800-Si3N4-YPSZ-MGOSs (monolayer graphene oxide sheet) composite layers were prepared on the TC4 titanium alloy by laser cladding/re-melting technology and the microstructure, element distribution and wear resistance of the clad/re-melt layers were analyzed. The wear resistance of Co800-Si3N4-YPSZ-MGOSs clad layer was enhanced by the fine grain strengthening. The amorphous and nanocrystalline phases were produced under an action of the rapid cooling rate of a laser induced pool after laser re-melting process, promoting the formation of multi-phase re-melt layer. MGOSs released C due to thermal decomposition in the laser induced pool, forming Ti(CN) by in-situ reaction. The friction coefficient of Co800-Si3N4-YPSZ-MGOSs clad layer is lower than that of TC4 due to the formation of the reinforcement phases such as Ti5Si3, TiN, TiC, etc., so the wear volume loss is about 1/7 of that of TC4.