Abstract
The powder metallurgy process and field emission properties of copper/carbon nanotube composites were studied in this work. Pure copper powder and multi-wall carbon nanotubes were mixed by ball milling, compacted and sintered in vacuum at 1000 ℃ for two hours. The sintered 5 mm thick specimens were plane-strain extruded 50% followed by rolling and process annealing to get a final thickness of 0.5 mm. The hardness of the specimens was measured to determine the appropriate annealing condition. It is found that by adding less than 4 vol% CNTs, there were little effects on the hardness of the specimens. The process annealing temperature of 700℃was chosen. The as-sintered specimens and thin sheet specimens were then polished and etched. Optical microscope and scanning electron microscope were used to study the morphology of the specimens. It was found that in the as sintered specimens the CNTs were covered on the grains. In contrast, in the worked and annealed specimens the CNTs were more randomly distributed both at grain boundaries and in grains. Different etching condition was adopted to get different appearance of CNTs on the exposed surface of the specimens for the field emission properties measurement. The lowest turn-on voltage of the thin sheet sample was found to be 0.875 V/um.