The Effect of Surface Siloxane Layers on the Penetration of Hydrogen into Iron

In acid and weakly alkaline media, including those containing hydrogenation promoters, mono- and polymolecular siloxanes layers applied to iron inhibit both the summary cathodic process and the penetration of hydrogen into the metal, provided the structure and thickness of the layers have been controlled by properly chosen adsorption conditions and the chemical nature of the starting silane. In varying the length of organic radical the deceleration of hydrogenation correlates with the hydrophobization of the surface. The charge of the siloxane layer additionally strengthens or weakens the antihydrogenating action of the layer, attracting or repelling the promoter, respectively.