Mechanical and electrical properties of CNT/Cu composites fabricated by spark plasma sintering
Spark plasma sintering was used to fabricate CNT/Cu MMCs, with increasing CNT content (0.05, 0.25, 0.5 and 1 wt%) in each sample. A novel dispersion method was utilised to coat milled Cu particles with SiO2 nanoparticles and CNTs ready for sintering. SiO2 nanoparticles increased surface area for enhanced CNT dispersion and attachment. CNT clustering was evident with increased CNT content amongst Cu particles. Sintered samples showed larger CNT filled pores with increasing CNT concentrations. Microhardness peaked at 0.5 wt% CNTs (61.19 HV), increasing 12% in contrast to pure Cu. The peak electrical conductivity was measured at pure Cu (49.8 MS/m) and drops significantly with the addition of increasing CNT content (41.2, 39.8, 33, 30.2 MS/m), respectively. The drop in electrical conductivity is mostly attributed to increased CNT agglomeration and enlarged pore size which cause electron and phonon scattering. Relative densities greater than 90% were measured, indicating less than 10% porosity was achieved. Successful dispersion of CNTs was possible up to 0.5 wt% CNT through the novel dispersion technique. Pure Cu is best chosen for maximum electrical conductivity while 0.5 wt% CNT is best for increased surface hardness.