Mechanical and structural impacts of fly-ash reinforcement on graphite-aluminum composites

Materials with light-weight, optimum thermo-mechanical properties are in great demand for thermal management systems. Graphite-Aluminum (Gr-Al) composites are being reinforced to achieve the above objectives. This paper reports the effects of fly-ash powder on the mechanical and structural characteristics of spark plasma-sintered Gr-Al composites. Graphite powder (53 ?m) and 20%wt aluminum powder (1-2 ?m), were reinforced with 0, 10, 20, and 30 %wt fly-ash powder (53 ?m), designated as GA, GAF-1, GAF-2, and GAF-3, respectively. Sintering was conducted at a heating rate of 50 oC/min, temperature of 550 oC, pressure of 5x10-2 mbar, and 10-minute holding time. Characterization was based on morphology, microhardness, displacement, relative density, peak intensity ratios, and tensile strength. The fly-ash particles had a cup-like shape, with dominance clearly noticeable in GAF-3. GAF-1 had the highest increase in peak intensity of 12.67%. GA showed the highest displacement rate (0.983 mm/min within the first 4 minutes of heating) and instantaneous relative density (0.97). However, an increase in fly-ash led to a 11.22% increase in porosity and a 35.85% increase in the micro-hardness while GAF-3 gave the highest ultimate tensile strength of 388.92 MPa. Reinforcing the Gr-Al matrix with Fly-ash makes it suitable for industrial applications.