Abstract
The use of Physical Vapor Deposition (PVD) and Chemical Vapor Deposition (CVD) thin coatings has become a widespread practice in the design of components subject to an aggressive environment. Corrosion in an aggressive environment can be critical for the design of structural components under constant and fatigue loads, due to the presence of Stress Corrosion Cracking (SCC) and fatigue corrosion. The protection from aggressive environments granted by the use of thin coatings is desired also in nonstructural, electrochemically active components, such as medical implants and fuel cells. In the present work, a review of the most recent industrial patents related to the application of PVD and CVD coatings developed in the last decade for the reduction of the detrimental effects of corrosion is presented. The article illustrates some selected patents which deal with the corrosion protection of components subject to fatigue loads and to static corrosion. Regarding dynamically loaded parts the reviewed papers describe thin coatings adopted to screen out turbine blades and disks from pitting corrosion, erosion and oxidation. A method to protect sliding parts of compressors using Hydrofluoroolefin refrigerant is also reported. In the latter part of the work, technical solutions for components under static corrosion are investigated, by presenting patents related to the coating of Implanted Medical Devices (IMD) and fuel cells, thus providing shielding from the external aggressive environment. Finally, a patent which proposes a multilayer finishing to improve the corrosion protection of common PVD treatments is presented.
Keywords: Corrosion fatigue, erosion, fuel cells, implanted medical devices, oxidation, pitting corrosion, thin coatings, turbines.
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