Metallurgical coatings and thin films have been developed in the field of high performance metallurgy since a long time ago. This surface functionalization, more and more integrated from the beginning in the steps of design of efficient architectures having to work in environments sometimes extreme and often complex, is the result of the implementation of surface treatment processes sometimes quite old, sometimes much more emerging. Very often, it is the increase of the service life of the components that is the main driver for the development of surface engineering in the metallurgy field. The coatings must often operate under combined stresses such as: mechanical and corrosion, oxidation and irradiation, corrosion and irradiation.

In general, the design of a coating must be done on the basis of precise specifications and the choice of the method of elaboration must be made taking into account a certain number of scientific, technological, economical and environmental criteria. Material efficiency, especially when it comes to using for example critical metals as well as the recyclability of scarce resources can also, in some cases, become one of the criteria of choice. Surface engineering is one of the key technologies for the development of low carbon energies, along with 3D printing and safe nanomanufacturing. We are more and more witnessing a convergence of these three families of processes which leads either to an incremental innovation, or to a breakthrough innovation. Surface engineering, both in the field of thin films, but also for thermal spray technologies, has made many advances in the past two decades, making possible applications that were not in the past. This is particularly the case with developments in extreme environments, particularly for the nuclear energy sector, but also for the aerospace sector. In the PVD field, the development of HiPIMS technology is now very close to the production of protective coatings for EATF (Enhanced Accident Tolerant Fuels) but is also under development in the field of nuclear fuel reprocessing. This very generic technology is also developed in the energy efficiency sector. In the field of CVD, the great diversity of organometallic chemistry offers real opportunities for the development of DLI-MOCVD (or ALD), and recent advances concerning the upscaling of technology will be presented, in particular for applications in the nuclear energy field. The great versatility of the process will also be presented. We will also illustrate the convergence between nanotechnologies and surface engineering technologies using two examples from thermal projection / nanotechnologies hybridization and PVD / nanoparticles generation coupling. Finally, as for all development and implementation processes, surface engineering benefits greatly from digital technologies progresses, in particular Artificial Intelligence, that makes the optimization of complex processes faster.