Processing and characterization of hybrid joints of polycarbonate (PC) and AA6061-T6 obtained by injection overmolding

Abstract

Polymer-metal hybrid joints have been increasingly used in several important industrial segments, specially in transports. What attracts this segment is the fact that these joints are able to combine the mechanical strength of metals and the processability, design flexibility, lightness and durability of polymers. In this context, this research project aims at the development of polycarbonate (PC) and AA6061-T6 joints, obtained by metal insert injection overmolding. This technique, even though widely used in the industry, still needs further scientific studies, specially when it comes to the effects of the processing conditions on the polymer-metal interface strength. Based on the discussed above, the PC/AA6061-T6 joints will be prepared with an automatic injection molding machine by varying the main parameters which influences the quality and strength of these joints. The static mechanical strength will be evaluated by lap shear testing under tensile loading and the mechanical durability by dynamic fatigue test. The static tests will be photographed and, using correlation of images, the dislocation fields of the joints will be determined. This will help to identify the most important areas of mechanical loading during the test, which will allow the understanding of the failure mechanisms and the comprehension of the global mechanic behavior of the joints. The microstructural features of the polymer-metal interface, in addition to the polymer filling and possible occurrence of defects and weld lines will be investigated via optical microscopy (OM) and scanning electron microscopy (SEM). Furthermore, the fracture surfaces of the samples submitted to the mechanical tests will be analyzed by OM and SEM, with the purpose of understanding the joining mechanism of the joints. The results will be analyzed by correlating processing, microstructure and properties. Thereby, it is hoped to comprehend the influence of the processing parameters, its interactions on the interface microstructural characteristics and the result of these interactions on the mechanical strength and durability of the joints, aiming at the improvement of the processing and maximizing the mechanical behavior of the hybrid PC/AA6061-T6 joints.