In the present research work, microstructural evolution and corrosion behaviour of the high-velocity oxy-fuel (HVOF) sprayed Alloy718-nano Al₂O₃ composite coatings were examined. These coatings were deposited on the grey cast iron (C.I) substrate. The agglomerated nano-Al₂O₃ reinforcement particles in three different proportions (10, 20 & 30 wt.%) were varied in the Alloy718 based matrix to develop the composite coatings. Corrosion testing of bare and coated samples was carried out at an ambient temperature in the NaCl solution (3.5 wt.%) using the potentiodynamic polarization technique. The polarization resistance (Rp), the corrosion efficiency and the corrosion rate (CR) were measured for the developed coatings and substrate. The surface morphology of as-sprayed and corroded coatings was studied using scanning electron microscopy coupled with energy-dispersive spectroscopy. X-ray diffraction analysis was conducted to determine the different phases present in the feedstock powders and as-sprayed coatings. The as-sprayed coatings were seen with nano-Al₂O₃ particles uniformly embedded in the melted Alloy718 matrix. The coating with 30 wt.% nano-Al₂O₃ particles revealed the maximum microhardness of about 129621 HV_0.2 compared to other coatings. The results showed that the corrosion resistance of the composite coatings increases with the increase in alumina particles in the Alloy718 matrix. The 30 wt.% alumina coating showed maximum resistance to corrosion due to the maximum decrease in the electrochemically active area associated with this coating.

在目前的研究工作中，研究了高速氧燃料 (HVOF) 喷涂的 Alloy718-纳米 Al ₂ O ₃复合涂层的微观结构演变和腐蚀行为。这些涂层沉积在灰口铸铁 (CI) 基材上。团聚的纳米Al ₂ O ₃三种不同比例（10、20 和 30 重量％）的增强颗粒在基于合金 718 的基体中变化以开发复合涂层。在环境温度下，使用动电位极化技术在 NaCl 溶液 (3.5 wt.%) 中对裸露和涂层样品进行腐蚀测试。对开发的涂层和基材测量极化电阻 (Rp)、腐蚀效率和腐蚀速率 (CR)。使用扫描电子显微镜结合能量色散光谱研究喷涂和腐蚀涂层的表面形貌。进行 X 射线衍射分析以确定原料粉末和喷涂涂层中存在的不同相。喷涂后的涂层与纳米 Al ₂ O ₃颗粒均匀地嵌入熔化的 Alloy718 基体中。与其他涂层相比，具有 30 wt.% 纳米 Al ₂ O ₃颗粒的涂层显示出约 129621 HV _0.2的最大显微硬度。结果表明，随着Alloy718基体中氧化铝颗粒的增加，复合涂层的耐腐蚀性能提高。由于与该涂层相关的电化学活性区域的最大减少，30 wt.% 氧化铝涂层显示出最大的耐腐蚀性。