Project Details
Projekt
Contribution to clarify the adhesion mechanisms of cold gas dynamic sprayed coatings
Subject Area
Coating and Surface Technology
Term
from 2012 to 2016
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 211746431
The aim of the proposed project prosecution still is the clarification of the adhesion mecha-nisms of cold gas dynamic sprayed metallic coatings using aluminium coatings on ceramic substrates. This aim is backed by the increasing significance of cold gas dynamic sprayed metal/ceramic laminates and composites e.g. in energy and automotive applications. By ana-lysing the chemico-physical mechanisms on the interface between ceramic substrate and metallic coating, the basic model on adhesion mechanisms which results from the first project period will be extended. Hence, the formerly focused single- and polycrystalline Al2O3 substrates are complemented by Si3N4, SiC, MgF2 and AlN. This selection covers both technological relevance and signifi-cant differences concerning the chemical bonding conditions referred to the share of ionic bonding. The planned investigations now focus on the resulting influences of these different bonding conditions on the consequential mechanisms of the coating adhesion. To complete the parameter matrix, substrate temperature during coating, feedstock powder fraction and subsequent heat treatments are also varied, and their influence on the coating/substrate in-terface formation and the coating adhesion strength are evaluated. The adhesion and bonding conditions within the metal/ceramic interface are analysed and described using the methods of REM and TEM as well as XRD and EELS. An important tool to develop the exact coating adhesion model is the similar investigation of aluminium PVD coatings on the same substrate ceramics. The typical atom-by-atom PVD coating formation allows the formation of metal/ceramic interfaces without macro- and meso-type defects, like those that occur from spraying processes. Hence, the investigations of PVD coatings allow the description of interface defects resulting from lattice misfits between the substrate and the coating material. The gained results both add new insights to the PVD coating formation of metals on ceramics and help to correctly interpret findings from the CGS interface investigations.
DFG Programme
Research Grants
Participating Person
Dr.-Ing. Thomas Grund
