A study on solid state recycling of copper alloy chips

Full text: Machining processes of metals results in the formation of large quantities of chips. The large amount of the starting material loss requires economical ways to recycle the chips. During the waste recycling by re-melting, a considerable of metal amount is lost as a result of oxidation [1]. In addition, the labor and energy cost as well as the expenditures on environment protection raise the overall manufacturing processes cost. In recent years, solid state recycling processes have been suggested to recycle metallic scraps [1]. One solid phase recycling method of metal chips is by pulverization, to produce metal powders to make sintered components. In many of the cases, ball milling has been the main method used to convert machining chips into metal powders. Therefore, this work aims to study leaded copper alloy UNS C98840 chips reuse by the solid-state reaction. The chips comminution was performed by grinding in a ball mill using ceramic balls. The obtained powder morphology was analyzed by scanning electron microscopy (SEM) and the chemical and structural characterization were performed by energy dispersive microscopy (EDS) and X-ray diffraction (XRD). The powder (<150 μm) was compacted by uniaxial pressing in a hydraulic press under a load of 150 MPa. The green compacts were sintered in an argon atmosphere furnace at 800ºC for 40 min. Thus, the sintered samples were analyzed by diametrical compression, microhardness and XRD. These sintered samples have demonstrated good properties for applications within the engineering industry. References: [1] Afshari, E.; Ghambari, M. Characterization of pre-alloyed tin bronze powder prepared by recycling machining chips using jet milling. Materials and Design, v. 103, p. 201–208, 2016. (author)