The effect of caffeine and theophylline concentrations as corrosion inhibitors for grey cast iron, in combination with a coating (Paraloid B-72) in a saline medium was evaluated through electrochemical impedance spectroscopy. Both compounds showed good results regarding to the inhibiting capability efficiency. Caffeine showed inhibition against corrosion in high concentrations and theophylline did so in low concentrations, thus exerting a synergic effect with the Paraloid B-72. The immersion time effect was also studied in both compounds. Results showed that 50 mg/m² of theophylline + paraloid B-72, presented the most stable coating in the metal surface. By means of SEM-EDS, it was confirmed that the presence of the inhibitors on the metallic surface diminished the corrosive process as a result of the absence of chloride ions. Finally, Fourier transformed infrared spectroscopy (FT-IR) was employed to demonstrate the chemical interactions between the theophylline or caffeine and Paraloid B-72 functional groups.

通过电化学阻抗谱评估了咖啡因和茶碱浓度作为灰铸铁腐蚀抑制剂的作用，并与盐介质中的涂层（Paraloid B-72）结合使用。两种化合物在抑制能力效率方面均显示出良好的结果。咖啡因在高浓度下显示出对腐蚀的抑制作用，而茶碱在低浓度下显示出对腐蚀的抑制作用，因此与Paraloid B-72发挥协同作用。还研究了两种化合物的浸入时间效应。结果表明50 mg / m ²茶碱+抛物面B-72的涂层在金属表面呈现出最稳定的涂层。通过SEM-EDS，证实了在金属表面上抑制剂的存在减少了由于不存在氯离子的腐蚀过程。最后，使用傅立叶变换红外光谱（FT-IR）来证明茶碱或咖啡因与Paraloid B-72官能团之间的化学相互作用。