AZ91D 镁合金 Ni-P-TiN 复合涂层的电沉积制备及其耐蚀性能

摘要

In order to improve the corrosion resistance and microhardness of AZ91D magnesium alloy, TiN nanoparticles were added to fabricate Ni−P−TiN composite coating by electrodeposition. The surface, cross-section morphology and composition were examined using SEM, EDS and XRD, and the corrosion resistance was checked by electrochemical technology. The results indicate that TiN nanoparticles were doped successfully in the Ni−P matrix after a series of complex pretreatments including activation, zinc immersion and pre-electroplating, which enhances the stability of magnesium alloy in electrolyte and the adhesion between magnesium alloy and composite coating. The microhardness of the Ni−P coating increases dramatically by adding TiN nanoparticles and subsequent heat treatment. The corrosion experimental results indicate that the corrosion resistance of Ni−P−TiN composite coating is much higher than that of uncoated AZ91D magnesium alloy and similar with Ni−P coating in short immersion time. However, TiN nanoparticles play a significant role in long-term corrosion resistance of composite coatings.%为了提高 AZ91D 镁合金的耐蚀性能和显微硬度，通过电沉积方法制备 TiN 纳米粒子掺杂的 Ni−P−TiN复合涂层。应用扫描电镜、能谱和 XRD 等手段研究涂层的表面、界面形貌和显微组成，并结合电化学方法研究涂层的耐蚀性能。研究结果表明，经过活化、浸锌和预镀层等系列复杂前处理，可有效提高镁合金在电镀液中的稳定性和涂层结合力，TiN 纳米粒子可以通过电沉积方式掺杂至 Ni−P 基体中。TiN 纳米颗粒和后续热处理可以有效提高 Ni−P 涂层的显微硬度。腐蚀结果表明 Ni−P−TiN 复合涂层的耐蚀性能比裸 AZ91D 镁合金大幅增加。在短期浸泡内，Ni−P−TiN 的耐蚀性能与没有 TiN 纳米粒子掺杂的 Ni−P 涂层相当，但 TiN 纳米粒子对于提高复合涂层长期耐蚀性能具有重要影响。