Nanocrystalline Coatings in Copper Pipes for Cold Water Plumbing Systems

Abstract

Copper is the most important raw material for cold-water plumbing systems in private and public buildings. One disadvantage of copper pipes is that small amounts of copper dissolve into the drinking water. Protective layers of cuprite (anodic coatings industrially applied) typically have lattice imperfections that can facilitate general corrosion. In this study, cuprite coatings were applied cathodically using electrolysis. The galvanic deposition at fixed voltage resulted in a coarse crystalline coating; the crystallites had a [111] fibre texture. Pulsed electrodeposition (PED) resulted in a variety of layers with different semiconducting characteristics. With this procedure, nanocrystalline arrangements could also be produced. In this case however, it was only possible to coat short sections of piping, which led to increased disorder at the edges. All coated pipes, together with untreated control pipes, were connected for a period of one to three years to the public drinking water system. During this time, nearly all of the coated pipes demonstrated a lower level of copper solubility than the control pipes.