激光熔覆Ni基纳米复合涂层的冲蚀性能研究

目的 对动态腐蚀条件下涂层的耐蚀性进行分析评估。方法 采用激光熔覆技术，在40Cr钢表面沉积Ni基纳米复合涂层。模拟真实的海洋环境，对Ni基涂层进行冲蚀实验，分析了海水冲击、颗粒磨损等外力作用与腐蚀之间的耦合作用对涂层性能的影响。选用自制的360°旋转冲刷机，研究含沙量、旋转速度对涂层耐蚀性的影响，并对冲蚀后的样品进行显微观察、质量损失分析和电化学性能的测试。结果 当含沙量为0.3%，腐蚀时间为48 h时，不同转速下耐蚀性由强到弱依次为300 r/min >600 r/min >900 r/min；腐蚀时间为96 h时，不同转速下耐蚀性由强到弱依次为300 r/min >900 r/min >600 r/min；腐蚀时间为144 h时，不同转速下耐蚀性由强到弱依次为300 r/min >900 r/min >600 r/min。当转速为600 r/min时，腐蚀时间由48 h进行到144 h，在无沙条件下，质量几乎没有变化，甚至有微小的增量；当含沙量为0.3%时，涂层的质量损失较为明显，冲蚀144 h后，质量损失达73.71 g/m2。结论 当含沙量一定，且冲刷速度较低时，腐蚀主要以电化学作用为主，提高转速，腐蚀速率加快。当转速一定时，腐蚀速率增大。在含沙量很高的情况下，腐蚀情况稍有减缓。

Seawater Erosion-Corrosion Resistance of Ni-based Composite Coatings by Laser Cladding

Objective To analyze corrosion resistance of coating under dynamic corrosion conditions. Methods The Ni- based composite coating was deposited on 40 Cr steels by laser cladding. The real marine environment was simulated to have washout test on the Ni-based coating and analyze the coupling effect of the external force, for instance the seawater impact, particle wear on the corrosion resistance of coating. The self-made 360° rotary scouring machine was selected to study the influences of erosion velocity and sediment concentration on the corrosion resistance of coating. The microstructure after erosion corrosion was observed by optical microscope, the weight loss and electrochemical property were also discussed. Results When the sediment concentration was 3%, the corrosion time was 48 h, the corrosion resistance sequence at different rotational speeds was 300 r/min > 600 r/min > 900 r/min. The corrosion resistance sequence at different rotational speeds was 300 r/min > 900 r/min > 600 r/min after 96-hour corrosion. It became 300 r/min > 900 r/min > 600 r/min after 144-hour of corrosion. At the circumstance of 600 r/min rotational speed and absence of sand, the weight was almost unchanged, and even increased slightly as the corrosion time varied from 48 h to 144 h; Whereas significant weight loss occurred at 3% sediment concentration, particularly, the weight loss increased to 73.71 g/m2 when the erosion time reached 144 h. Conclusion When the sediment concentration must be, and the erosion rate is low, mainly by the electrochemical corrosion effect is given priority to, improve the speed, the corrosion rate was accelerated. When the rotation speed must be corrosion rate increased. In the case of high sediment concentration, the corrosion situation slow down a bit.