Microwave and spark plasma sintering of carbon nanotube and graphene reinforced aluminum matrix composite

Graphene and carbon nanotube due to their outstanding mechanical performance were used as reinforcement in aluminum (Al) based composite through spark plasma sintering (SPS), microwave (MW) and conventional techniques. The initial compositions of Al-1 wt% CNT, Al-1 wt% GNP and Al-1 wt% CNT-1 wt% GNP were mixed by a high energy ultrasonic device and mixer mill to achieve homogenous dispersion. The SPS, MW and conventional processes were conducted at almost 450, 600 and 700 °C, respectively. The maximum relative density (99.7 ± 0.2% of theoretical density) and bending strength (337 ± 11 MPa) obtained by SPS, while maximum microhardness of 221 ± 11 Vickers achieved by microwave for Al-1 wt% CNT-1 wt% GNP hybrid composite. X-ray diffraction (XRD) examinations identified Al as the only dominant phase accompanied by very low intensity peaks of Al4C3. Field emission scanning electron microscopy (FESEM) micrographs demonstrated uniform distribution of GNP as well as CNT reinforcement in spark plasma sintered samples.