Flow induced fiber orientation in short carbon fiber reinforced copper matrix composites

Abstract

This study investigated the effect of a distinctive design of mold to align short carbon fiber in copper matrix composite produced via metal injection molding. The mold was designed to improve the fiber orientation during flow in the core region of test samples. The composite feedstocks comprising polymeric binder and Cu powder reinforced with 0, 5 and 10 vol. % carbon fiber, prepared in Z-blade mixer, were injection molded to fabricate green samples. Green samples were debound to remove the binder and sintered in sintering furnace at 1050 °C in Argon atmosphere. Dispersion of carbon fibers was examined in composite feedstocks and TGA was used to determine the degradation temperature of binder. Uniform dispersion of carbon fibers was observed in compounded feedstocks, green and sintered samples. Fiber orientation was quantified at various locations of skin and core of the green and sintered samples. Quantification of fiber orientation showed the best value of more than 90% of short fibers aligned in green test samples whereas sintered samples demonstrated just above 70% of fiber alignment in the flow direction in Cu-10%CF at section N. Overall, the results showed fiber alignment within ±22.5° in both green and sintered samples without significant skin-core effect. Moreover, the calculated mechanical properties increased with an increase in alignment of carbon fiber in the Cu matrix. Conclusively, fiber alignment can be improved by controlling flow of molten feedstock during molding with potentially high mechanical properties of composite.