The behavior corrosion inhibition of aluminum alloy (Al6061) in acidic (0.1 M HCl) and saline (3.5% NaCl) solutions was investigated in the absence and the presence of expired diclofenac sodium drug (DSD) as a corrosion inhibitor. The influence of temperature and was studied using electrochemical techniques. In addition, scanning electron microscopy (SEM) was used to study the surface morphology. The results showed that DSD acted as a powerful inhibitor in acidic solutions, while a moderate influence was observed with saline one. Maximum inhibition efficiency was 99.99 and 83.32% in acidic and saline solutions at 150 ppm of DSD, respectively. Corrosion current density that obtained using electrochemical technique was increased with temperature and decreased with the addition of DSD in both, acidic and saline solutions. DSD acted as a mixed-type corrosion inhibitor in acidic solution, while it affected the cathodic reaction in saline solution. Scanning electron microscopy (SEM) showed a significant surface damages in the absence of DSD. Quantum chemical theoretical studies were also addressed. Three states of DSD were considered in understanding the mechanism of inhibition. Normal, dissociated, and protonated states were optimized using Density Function Theory (DFT). Highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO), energy gap (ΔE), dipole moment (µ), and other parameters were used to compare the performance of DSD states. Theoretical studies showed that the protonated state gave higher protection efficiency.

在不存在和存在过期双氯芬酸钠药物的情况下，研究了铝合金 (Al6061) 在酸性 (0.1 M HCl) 和盐水 (3.5% NaCl) 溶液中的腐蚀抑制行为(DSD) 作为缓蚀剂。使用电化学技术研究了温度的影响。此外，使用扫描电子显微镜（SEM）来研究表面形貌。结果表明 DSD 在酸性溶液中是一种强大的抑制剂，而在盐水中观察到中等影响。在 150 ppm DSD 的酸性和盐水溶液中，最大抑制效率分别为 99.99% 和 83.32%。使用电化学技术获得的腐蚀电流密度随温度升高而增加，并随 DSD 在酸性和盐水溶液中的加入而降低。DSD在酸性溶液中起混合型缓蚀剂作用，而在盐溶液中则影响阴极反应。扫描电子显微镜 (SEM) 显示在没有 DSD 的情况下有显着的表面损伤。还讨论了量子化学理论研究。在理解抑制机制时考虑了 DSD 的三种状态。使用密度函数理论 (DFT) 优化正常、解离和质子化状态。最高占据分子轨道 (HOMO)、最低未占据分子轨道 (LUMO)、能隙 (ΔE)、偶极矩 (μ) 和其他参数用于比较 DSD 状态的性能。理论研究表明，质子化状态提供了更高的保护效率。偶极矩 (μ) 和其他参数用于比较 DSD 状态的性能。理论研究表明，质子化状态提供了更高的保护效率。偶极矩 (μ) 和其他参数用于比较 DSD 状态的性能。理论研究表明，质子化状态提供了更高的保护效率。