(昆明理工大學(xué) 材料科學(xué)與工程學(xué)院，昆明 650093)
摘 要: 為提高鋁合金的摩擦磨損和耐蝕性能，在A390鋁合金基體上通過激光熔覆制備NiCrAl/TiC復(fù)合涂層。采用XRD和EDS分析了涂層的物相組成，結(jié)合SEM觀察了涂層的微觀組織，運用摩擦磨損試驗機(jī)和電化學(xué)工作站測試了涂層的摩擦磨損和耐腐蝕性能。結(jié)果表明：復(fù)合涂層主要物相為AlNi、Al3Ni2、TiC，同時含有少量的Cr13Ni5Si2、Cu9Al4和α(Al)。涂層自下至上分別為短棒狀樹枝晶、胞狀晶、柱狀樹枝晶和等軸晶。相同磨損條件下，A390基體發(fā)生了嚴(yán)重的磨粒磨損和剝層磨損，而激光熔覆涂層只產(chǎn)生了輕微的磨粒磨損，熔覆層的相對耐磨性為3.16。在3.5% NaCl溶液中的極化曲線和電化學(xué)阻抗譜(EIS)顯示：熔覆層自腐蝕電位較A390基體的正移，腐蝕電流密度減小；熔覆層呈單容抗特性，而A390基體在高頻區(qū)表現(xiàn)為容抗特性，在中低頻區(qū)則為感抗特性。在Bote圖中，低頻區(qū)熔覆層對應(yīng)的相位角和中低頻段熔覆層的阻抗模值均大于A390基體的，表明熔覆層的耐蝕性遠(yuǎn)高于A390基體的。熔覆層的腐蝕形貌為局部點蝕，A390基體的腐蝕形貌為晶間腐蝕和剝蝕。
關(guān)鍵字: 鋁合金；復(fù)合涂層；激光熔覆；磨損行為；耐蝕性能
（Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, China）
Abstract:In order to improve the frictional wear behavior and corrosion resistance of aluminum alloy, NiCrAl/TiC composite coating was fabricated on A390 aluminum alloy by laser cladding. The phase constitution, microstructure, frictional wear behavior and corrosion resistance of the composite coating were analyzed using X-ray diffraction (XRD), energy dispersive spectrum (EDS), scanning electron microscope (SEM), friction and wear testing machine and electrochemical workstation. The results show that the coating is mainly composed of AlNi, Al3Ni2 and TiC phases, and a small amount of Cr13Ni5Si2, Cu9Al4 and α(Al) phases. The microstructures of the coating from the bottom to top are dendrite crystal, cellular crystal, columnar dendrite crystal and equiaxed crystal, respectively. Under the same wear condition, A390 substrate exhibits serious abrasive wear and peeling characteristics, while the cladding coating exhibits slight abrasive wear behavior. The relative wear resistance of cladding coating is 3.16. The polarization curves and electrochemical impedance spectroscopy (EIS) in 3.5% NaCl solution indicate that the corrosion potential of the coating is more positive than that of the matrix, and the corrosion current density decreases significantly. The coating exhibits capacitive reactance behavior, but A390 substrate exhibits capacitive reactance in high frequency area and impedance in medium low frequency area. In Bote diagram, the phase angle of composite coating in low frequency area and the impedance modulus value of coating in low-middle frequency are larger than those in the matrix. This proves that the composite coating has better corrosion resistance compared to that of A390 aluminum alloy. The corrosion morphology of the cladding coating is localized pitting, but the corrosion morphology of A390 matrix is intergranular corrosion and erosion.
Key words: aluminum alloy; composite coating; laser cladding; wear behavior; corrosion resistance
