Jing Zhang, Dejun Kong
School of Mechanical Engineering, Changzhou University, Changzhou 213164, China.
Materials (Basel). 2018 Feb 11;11(2):283. doi: 10.3390/ma11020283.
A cold sprayed Al coating on S355 structural steel was processed using a laser remelting (LR). The surface and cross-section morphologies, chemical compositions, and phases of as-obtained Al coating before and after LR were analyzed using a scanning electronic microscope (SEM), energy dispersive spectrometer (EDS), and X-ray diffractometer (XRD), respectively, and their hardness was measured using a micro-hardness tester. The friction-wear behaviors of Al coating before and after LR in 3.5% NaCl solution were conducted to simulate the sand and gravel scouring on its surface in seawater, the effects of wear loads and speeds on the tribological properties of Al coating were analyzed, and the wear mechanisms under different wear loads and speeds were also discussed. The results show that the Al coating after LR is primarily composed of an Al phase and its hardness is 104.66 HV, increasing 54.70 HV than the cold sprayed Al coating. The average coefficient of friction (COF) of cold sprayed Al coating at the wear load of 0.5, 1.0 and 1.5 N is 0.285, 0.239, and 0.435, respectively, while that after LR is 0.243, 0.227, and 0.327, respectively, decreased by 14.73%, 5.02% and 24.83% compared to the cold sprayed Al coating. The wear rate of cold sprayed Al coating at the wear load of 0.5, 1.0 and 1.5 N is 1.60 × 10, 2.36 × 10, and 2.40 × 10 mm³/m·N, respectively, while that after LR is 1.59 × 10, 1.70 × 10, and 1.94 × 10 mm³/m·N, respectively, decreased by 1%, 32%, and 23%, respectively, indicating that LR has high anti-friction performance. Under the wear load action of 1.0 N, the average COF of laser remelted Al coating at the wear speeds of 300, 400 and 500 times/min is 0.294, 0.279, and 0.239, respectively, and the corresponding wear rate is 1.06 × 10, 1.24 × 10, and 1.70 × 10 mm³/m·N, respectively. The wear mechanism of cold sprayed Al coating is primarily corrosion wear at the loads of 0.5 and 1.0 N, and that at the load of 1.5 N is abrasive wear and fatigue wear; while that after LR is abrasive wear and fatigue wear, with no corrosion wear, showing that LR improves its corrosion and wear resistance.
采用激光重熔（LR）工艺对S355结构钢上的冷喷涂铝涂层进行处理。分别使用扫描电子显微镜（SEM）、能谱仪（EDS）和X射线衍射仪（XRD）分析了LR处理前后所得铝涂层的表面和横截面形貌、化学成分及相组成，并使用显微硬度计测量了其硬度。对LR处理前后的铝涂层在3.5%氯化钠溶液中的摩擦磨损行为进行了研究，以模拟海水对其表面的砂石冲刷，分析了磨损载荷和速度对铝涂层摩擦学性能的影响，并探讨了不同磨损载荷和速度下的磨损机制。结果表明，LR处理后的铝涂层主要由铝相组成，其硬度为104.66 HV，比冷喷涂铝涂层提高了54.70 HV。冷喷涂铝涂层在0.5 N、1.0 N和1.5 N磨损载荷下的平均摩擦系数（COF）分别为0.285、0.239和0.435，而LR处理后的分别为0.243、0.227和0.327，与冷喷涂铝涂层相比分别降低了14.73%、5.02%和24.83%。冷喷涂铝涂层在0.5 N、1.0 N和1.5 N磨损载荷下的磨损率分别为1.60×10、2.36×10和2.40×10 mm³/m·N，而LR处理后的分别为1.59×10、1.70×10和1.94×10 mm³/m·N，分别降低了1%、32%和23%，表明LR具有较高的减摩性能。在1.0 N磨损载荷作用下，激光重熔铝涂层在300、400和500次/分钟磨损速度下的平均COF分别为0.294、0.279和0.239，相应的磨损率分别为1.06×10、1.24×10和1.70×10 mm³/m·N。冷喷涂铝涂层在0.5 N和1.0 N载荷下的磨损机制主要为腐蚀磨损，在1.5 N载荷下为磨粒磨损和疲劳磨损；而LR处理后的为磨粒磨损和疲劳磨损，无腐蚀磨损，表明LR提高了其耐腐蚀和耐磨性能。
