Effect of Chromium on Mechanical Properties of Carbon Nanotube Reinforced Copper-Chromium Composite

Abstract

In the present work, Cu-0.5wt.%CNT and Cu-0.5wt.%CNT-1wt.%Cr composites were prepared via the conventional powder metallurgical route. For Cu-0.5wt.%CNT composite, the CNTs were sonicated in 10 mL ethanol first for better dispersion and later for 5 hours wet ball milling was performed. For Cu-0.5wt.%CNT-1wt.%Cr composite, first Cu and Cr powders were dry milled for 20 hours and later wet milling was done for 5 hours by adding sonicated CNTs. The powders obtained were dried in a vacuum oven at 40 °C for 2 hours. After drying, the pellets of 6.5mm diameter were obtained via uniaxial pressing and cold isostatic pressing. The samples were sintered at 950 °C in a tube furnace (under an inert environment) for 5 hours. The densification of pure copper and composites were measured by using a densitometer. The density of Cu, Cu-0.5wt.%CNT and Cu-0.5wt.%CNT-1wt.%Cr was found to be 90%, 90.56% and 86.81%, respectively. Scanning electron microscopy was used to study the topography of the prepared pallets, which shows the denser microstructure of sintered pallets as compared to non-sintered pallets. A micro-Vickers hardness tester was used to measure the hardness of the pure copper and the composite samples. The hardness of Cu, Cu-0.5wt.%CNT and Cu-0.5wt.%CNT-1wt.%Cr was calculated to be 54 HV, 84 HV and 74 HV, respectively. A Universal Testing Machine was used for finding the young modulus and yield point of the pure copper and composites. For Cu-0.5wt.%CNT composite, the young modulus and yield point were found to be higher as compared to both pure copper and Cu-0.5wt.%CNT-1wt.%Cr composite.

In the present work, Cu-0.5wt.%CNT and Cu-0.5wt.%CNT-1wt.%Cr composites were prepared via the conventional powder metallurgical route. For Cu-0.5wt.%CNT composite, the CNTs were sonicated in 10 mL ethanol first for better dispersion and later for 5 hours wet ball milling was performed. For Cu-0.5wt.%CNT-1wt.%Cr composite, first Cu and Cr powders were dry milled for 20 hours and later wet milling was done for 5 hours by adding sonicated CNTs. The powders obtained were dried in a vacuum oven at 40 °C for 2 hours. After drying, the pellets of 6.5mm diameter were obtained via uniaxial pressing and cold isostatic pressing. The samples were sintered at 950 °C in a tube furnace (under an inert environment) for 5 hours. The densification of pure copper and composites were measured by using a densitometer. The density of Cu, Cu-0.5wt.%CNT and Cu-0.5wt.%CNT-1wt.%Cr was found to be 90%, 90.56% and 86.81%, respectively. Scanning electron microscopy was used to study the topography of the prepared pallets, which shows the denser microstructure of sintered pallets as compared to non-sintered pallets. A micro-Vickers hardness tester was used to measure the hardness of the pure copper and the composite samples. The hardness of Cu, Cu-0.5wt.%CNT and Cu-0.5wt.%CNT-1wt.%Cr was calculated to be 54 HV, 84 HV and 74 HV, respectively. A Universal Testing Machine was used for finding the young modulus and yield point of the pure copper and composites. For Cu-0.5wt.%CNT composite, the young modulus and yield point were found to be higher as compared to both pure copper and Cu-0.5wt.%CNT-1wt.%Cr composite.