On the use of auxiliary systems during thermal spraying

Whatever the degree of knowledge and control which can be obtained on each critical parameter of a thermal spray process, it seems now understood that it will ever be extremely difficult to obtain the desired properties of a coating only by controlling the spray parameters. In fact, a number of desired properties require contradictory settings of parameters, which rends necessary the choice of compromises. Therefore, it appears more and more necessary to introduce in the system new degrees of freedom in order to cut the Gordiosʹ knot of the interrelated parameters. new degrees of freedom can be brought by auxiliary systems such as those enabling to control the surface state or the energy level in the system. Auxiliary systems could be defined in a number of ways, incorporating pre-treatments and post-treatments as well as control systems. In this paper, we shall only consider the systems, which are or could be implemented simultaneously to the deposition stage apart from the controlling devices. The purpose is to help and realise the usefulness of considering the possibility of using such devices in order to be able to design and produce more efficient thermal spray coatings.