Lightweight metallic matrix composites: Development of new composites material reinforced with carbon structures

Abstract

Carbon nano/micro-structures used as fillers in metallic lightweight alloy matrix composites are receiving considerable attention in scientific research and industrial applications. Aluminum and magnesium are the most studied light metals used as matrices in metal composites materials, principally for their low density (respectively 2.7 g/cm3 and 1.7 g/cm3) and low melting temperature (around 660 °C for both metals). A good interaction between matrix and fillers is the first step to obtain an increase in bulk properties; furthermore, the manufacturing procedure of the composite is fundamental in terms of quality of fillers dispersion. In this work the influence of surface modifications for three classes of carbon fillers for aluminum and magnesium alloy (AZ63) as matrices is studied. In particular, the selected fillers are short carbon micro fibers (SCMFs), carbon woven fabrics (CWF), and unidirectional yarn carbon fibers (UYFs). The surface modification was carried out by a direct coating of pure nickel on fibers. The electroless pure nickel plating was chosen as the coating technique and the use of hydrazine as reducing agent has prevented the co-deposition of other elements (such as P or B). Scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS) analyses were performed to study the effect of surface modifications. The mechanical properties of manufactured composites were evaluated by 4-point flexural tests according to ASTM C1161 (room temperature). Results confirm improved interactions between matrix and fillers, and the specific interaction was studied for any chosen reinforcement.