State of the art of particle emissions in thermal spraying and other high energy processes based on metal powders

Abstract : Thermal spray is a high energy-based process, like additive manufacturing and powder atomization, leading to fine particle emission. But there is little information about these nanoparticles and their characteristics: workers’ exposure, filtration efficiency, dustiness. This paper aims to update the knowledge of the thermal spray community, to focus on thermal spraying and to a lesser degree on powder atomization and additive manufacturing technology, regarding emissions due to the high energy-based process. The three processes are presented before introducing an updated survey of thermal spray activities in France. The main thermal spray equipment is wire arc and plasma spraying. The main metal used is Al and Ni. The paper also highlights the lack of knowledge among workers on thermal spray emissions. Most workers are not made aware of collective protection (emission filtration equipment used) and personal protection (PPE). A complete bibliographical review is presented on the problem of ultrafine particle emissions mainly for the thermal spray process. Ultrafine particles are always characterized inside a working environment. The objective of this article is to list all publications related to ultrafine particle emissions around the working environment of a thermal spray process to raise awareness of the academic and industrial communities about the actual risks associated with this exposure. Finally, the authors are looking at the list of dust filtration equipment by presenting their advantages and disadvantages for particle filtration.