Surface treatments using matter or energy beams

Treatments using material or energy beams are playing an increasingly important role in the very wide range of surface treatment techniques. This is due to the various advantages offered by this type of treatment. In fact, the use of beams, whether particle or energy beams, makes it easy to carry out localized treatments, an undeniable advantage over liquid baths or gaseous atmospheres. As it is rare for a part to be subjected to uniform stress over its entire surface, it makes sense to provide the optimum solution for each zone, in order to achieve the right properties in the right places. But other advantages also justify their development, such as the ease with which parts can be handled, as they remain dry and most of the time at near-ambient temperature, the speed of execution linked to the ability to carry out localized treatments with powerful tools, and above all the limitation of waste and pollution in the absence of baths or degreasing phases, a point that is becoming increasingly important as environmental regulations become stricter.

Of course, there are limitations, mainly concerning the shape of the surfaces to be treated and the processing time. By definition, a beam, whether of material or energy, is directional and therefore works in line of sight. Complex surfaces and bores are therefore difficult to treat using this method. What's more, the equipment is often expensive, and consequently its occupancy rate needs to be high to ensure an acceptable return on investment.

The diversity of material and energy beams is enormous, and their physical principles, as well as their effects, are at first sight very varied: how can we compare a photon, a particle accelerated and melted at high temperature, and steel shot? In fact, analogies do exist, particularly in terms of the energies involved on impact with the substrates to be treated. What's more, the material can sometimes serve only as an energy carrier, as in the case of shot blasting, or participate directly in the construction of the coating, as in the case of Cold Spray. The aim of this article is therefore to provide an initial joint overview of material and energy bundles in terms of their production methods, implementation technologies and typical applications, using interactions with the substrate as a guiding principle.