Analysis and development of a brazing method to weld carbon fiber reinforced poly ether ketone ketone (CF/PEKK) with amorphous PEKK

Abstract

In this study a brazing method for carbon fiber reinforced poly ether ketone ketone (CF/PEKK) is developed that allows welding below the melting temperature of the single components. Prior to manufacturing of CF/PEKK laminates an amorphous PEKK film is co-moulded to its surface. The CF/PEKK laminates are welded using of an amorphous PEKK foil that acts as filler material. The temperatures for five different brazing processes were defined based on the results of thermal analysis. The welding properties for each process temperature are characterized mechanically and analytically. The crystal morphology of PEKK, which primarily depends on the process temperature, is known for its influence on the mechanical properties. Microanalytical SEM investigations focus on the morphology of the weld zone in order to evaluate diffusion processes at the interfaces. Compared to DSC measurements, the SEM investigations offer a basic understanding of the welded process and its influence on the welding properties. When applying a welding temperature of 60 ◦C below the processing temperature of CF/PPS laminates, a welding factor of 0.93 could be obtained. Furthermore, based on the SEM investigation it is possible to derive more promising improvement measures for the brazing method.