Development and Characterization of Electrically Conductive Metal Matrix Composite Castings Through Microwave Processing

Abstract

The use of microwave vitality in heating of materials is not new; in any case, more current applications are rising in the field of material processing, which permitted microwave handling as novel processing strategies. The prior reported work depended on sintering of numerous ceramic materials, which are better absorbers of microwaves. The applications were further stretched out to metallic powders. As of late, scientists have created strategies to process bulk metallic materials. The advancements reported were in the field of joining of bulk metals and claddings on different steels. The melting and casting of bulk materials is a newer approach which has not been explored yet. The present work focuses on the development of metal matrix composite castings with copper as the matrix material and tungsten and molybdenum as the reinforcing materials in different weight % by melting of metallic powders through microwave processing routes. The compositions taken were pure copper, Cu-10 wt. % Mo, Cu-10 wt. % W, Cu-30 wt. % Mo, Cu-30 wt. % W, Cu- 50 wt. % Mo, and Cu-50 wt. % W. The fabricated composites were then characterized by SEM, EDS, Vicker’s micro-hardness, XRD, and four point probe resistivity measurement. Comparative analysis was carried out for the fabricated samples with the conventionally prepared sample. Results revealed that the matrix material and reinforcing materials were successfully fabricated as the metal matrix composite castings and the reinforcing materials were uniformly distributed all over the matrix. EDS reveals that the change in composition after the processing of metallic powders was approximately the same as the composition taken initially. Mechanical characterizations shows that the microwave processing enhances the mechanical strength due to better metallurgical bonding and diffusion, with lower processed defects. The vicker’s microhardness reveals that as the wt. % of reinforcing material increases in matrix, the vicker’s microhardness tends to increase. The maximum hardness achieved was 143 Hv for Cu-50 wt. % W. Electrical characterizations revealed that as the wt. % of reinforcing material increases, the electrical resistivity tends to increase and electrical conductivity tends to decrease. Further the thermal conductivity was also calculated for all the samples which reveals that it also shows the same trend as electrical conductivity.