Infrared Studies of Protective Films Formed by Acetylenic Corrosion Inhibitors

Infrared spectra of surface films formed on iron and steel mirrors by propargyl alcohol, acetylene, and ethynyl‐cyclohexanol acid corrosion inhibitors were recorded using a multiple reflectance technique. These spectra showed that the acetylenic molecules reacted at the metal surfaces in solutions to produce protective polymer film coatings. Corrosion protection increased markedly as the polymer coatings grew from nearly two‐dimensional, adsorbed layers to films 20°–200A° thick. Saturated hydrocarbon material composed the majority of these films. Hydrogen evolved by the acid corrosion reaction probably participated in hydrogenating adsorbed acetylenic species. The polymer also contained several polar species including hydroxyl and carbonyl groups. Increased carbonyl content appeared to decrease the protectiveness of these films.