Innovative Polymer Coating Systems – Applied by Laser Sintering Technique
The most important business and economic reason for coating metals is to protect them from corrosion and wear. The polymer coating technology is a promising candidate to fulfill these issues and, thus, can be used for various purposes and for performance requirements.
Current developments in mechanical engineering and in the automotive industry are concerned with increasing the energy efficiency and sustainability of components. Therefore, a possible approach is function integration, which enables the application of different functions on one component. A further aspect of energy saving by mass reduction can be taken into account by substituting steel by lightweight metals. But in most of the application cases the requirements exceed the properties of the base materials. To overcome this mismatch, multifunctional, application-adapted coatings are required.
In this study the development of a multilayer approach is presented, where PEEK (poly-ether-ether-ketone) is used as a base coating material for Aluminum substrates. The coating is applied by using laser radiation to increase the energy efficiency of the coating process on the one hand and to reduce thermal stress on the component on the other hand.
The aim of this study is to create a polymer coating system, which is composed of a first layer against corrosion, followed by a tribological layer for wear protection and final running-in top layer with solid lubricant behavior, whereas every layer is applied by using laser radiation.
To reach the target, a comparative study was carried out to evaluate the performance of some additives in PEEK dispersions and their variable concentrations that led to different process parameters resulting in different behavior of the coating under dry sliding conditions. Hereby, an extensive evaluation, taking into account measured parameters like maximum lifetime, the coefficient of wear and friction, porosity and roughness values and correlating them with parameters of the laser coating process, led to a deep understanding of the tribological mechanisms. Thus, by combination of the different achieved properties a multilayer system was established, which combines high corrosion and wear protection accompanied by a tribofilm formation on the counter body resulting in low friction and a manifold increasing of the lifetime of the coating system.