In this article, the depositions and functional characterizations of Ta-N and Ta-Al-N coatings for protection purposes, grown by reactive high-power impulse magnetron sputtering onto silicon substrates, are described. Nitride films were grown while changing the substrate polarization voltage (i.e., the applied bias voltage) during the process. Moreover, the effects of adding Al to form a ternary system and the resulting variation of the coatings’ mechanical and tribological properties have been widely investigated by nanoindentation, scratch, and wear tests. Micro-Raman characterization has been applied to the wear tracks to explore the comprehensive tribo-environment and wear mechanism. Interestingly, Ta-Al-N films, despite significantly improved mechanical properties, show a premature failure with respect to Ta-N coatings. The wear mechanisms of Ta-N and Ta-Al-N systems were revealed to be very different. Indeed, Ta-Al-N films suffer higher oxidation phenomena during wear, with the formation of an oxidized surface tribofilm and a reduced wear resistance, while Ta-N coatings undergo plastic deformation at the wear surface, with a slightly adhesive effect.

The sustainable production of energy without environmental footprints is a challenge of paramount importance to satisfy the ever-increasing global demand and to promote economic and social growth through a greener perspective. Such awareness has significantly stimulated worldwide efforts aimed at exploring various energy paths and sources, in compliance with the ever more stringent environmental regulations. Research advancements in these fields are directly dependent on the design, fabrication, and implementation of tailored multi-materials for efficient energy production and harvesting and storage devices. Herein, we aim at providing a survey on the ongoing research activities related to various aspects of functional materials for energy production, conversion, and storage. In particular, we present the opportunities and the main open challenges related to multifunctional materials spanning from carbon-based nanostructures for chemical energy conversion, ferroelectric ceramics for energy harvesting, and phase change materials for thermal energy storage to metallic materials for hydrogen technologies, heat exchangers for wind energy, and amphiphobic coatings for the protection of solar panels. The relevance of designing tailored materials for power generation is also presented. Finally, the importance of applying life cycle assessment to materials is emphasized through the case study of AlTiN thin films.

This scientific work aims to optimize the preparation of titanium nitride coatings for selective H₂ separation using the Reactive High Power Impulse Magnetron Sputtering technology (RHiPIMS). Currently, nitride-based thin films are considered promising membranes for hydrogen. The first series of TiN_x/Si test samples were developed while changing the reactive gas percentage (N₂%) during the process. Obtained coatings were extensively characterized in terms of morphology, composition, and microstructure. A 500 nm thick, dense TiN_x coating was then deposited on a porous alumina substrate and widely investigated. Moreover, the as-prepared TiN_x films were heat-treated in an atmosphere containing hydrogen in order to prove their chemical and structural stability; which revealed to be promising. This study highlighted how the RHiPIMS method permits fine control of the grown layer’s stoichiometry and microstructure. Moreover, it pointed out the need for a protective layer to prevent surface oxidation of the nitride membrane by air and the necessity to deepen the study of TiN_x/alumina interface in order to improve film/substrate adhesion.

The Divertor Tokamak Test (DTT) vacuum vessel (VV) is a toroidal chamber that ensures an enclosed vacuum environment for the plasma, a confinement barrier, and temperature control. Water flows in the double-shell D-shaped VV cross-sectional structure made from stainless steel to operate at a set temperature. Beyond temperature control, the water cooling circuit needs to act as a neutron shielding media to protect the structures installed outside of the VV, namely, the superconducting coils. The shielding function is achieved due to the addition of boric acid in the water. The requirement on the borated water for the DTT VV is to have 8000-ppm B solution highly enriched in ¹⁰B (95% ¹⁰B). Given the lack of water chemistry guidelines for fusion power plants, the water chemistry requirements from fission power plants were investigated. In this work, general corrosion of stainless steel, 316L type family, in concentrated borated water solutions was investigated experimentally using metal release test. Samples were exposed to ultrapure water (UPW) and 8000-ppm B borated water at 80 °C for one week to quantify the amount of ions released in solution. 316L general corrosion was studied considering the different water chemistries, UPW versus borated water, and steels microstructures. DTT VV presents many welded joints, so general corrosion of welding-induced microstructure was here investigated compared to 316L base microstructure. The release of ions from general corrosion was found to be more influenced by water chemistry than microstructure.

CoCrMo alloys are interesting materials for implantable devices due to their favorable mechanical properties, high wear resistance, and good biocompatibility with the human body. Recent studies have demonstrated the possibility to further increase their wear resistance with an innovative approach consisting of nitriding treatments by the High-Power Impulse Magnetron Sputtering (HiPIMS) technique. Given the novelty of this treatment, it is relevant to develop a preliminary sustainability analysis of the processes to highlight the total environmental impact and to evaluate possible strategies to decrease it. Here, a Life Cycle Assessment (LCA) of HiPIMS nitriding treatments of CoCrMo alloys using a tantalum or molybdenum target is presented. The main impact driver in all impact categories was the electrical consumption of the vacuum apparatus and cooling system of HiPIMS instrumentation with a 45–47% and 37–39% contribution for Ta-based, and 39–40% and 41–42% for Mo-based treatments, respectively. Climate Change was found to be the most impacted category, followed by Resource Use both for Mo and Ta nitriding targets. Therefore, some perspectives to enhance the environmental sustainability of the synthesis process have been considered by means of a sensitivity analysis. Moreover, a Critical Raw Material (CRM) assessment is discussed, providing a complete sustainability evaluation of the proposed HiPIMS treatments.