In this document, gaseous hydrogen dissociation and adsorption on metals, electrochemical hydrogen evolution and hydrogen diffusion are briefly described, with the main mechanism of hydrogen embrittlement. The work focuses on hydrogen diffusion and embrittlement on cast iron, copper and lead.
Existing literature generally suggests that these materials exhibit no significant effects when exposed to high-pressure gaseous hydrogen at room temperature. However, some detrimental effects can be observed during hydrogen electrochemical charging or exposure to high-temperature H2 environments. Hydrogen embrittlement (HE) effects were observed on cast iron under cathodic polarization. HE effects were related to size and distribution of graphite inside the alloy, owing to their traps effect for hydrogen. The solubility of hydrogen in copper and its alloys is very low at room temperature thus no detrimental effects were observed. Hydrogen molecule dissociation does not take place on lead at room temperature. If lead is polarized with very high cathodic current density in alkaline solution, lead can degrade through the formation of a volatile lead hydride.
