Abstract:
In recent time, nanoparticles have been known to offer better properties than the bulk form in composite development. This informed the basis for this research to study the effects of rice husk ash-graphite-copper nanoparticles admixture on selected properties of aluminium 6063 hybrid reinforced composites. The Rice Husk Ash (RHA) was obtained by burning the rice husk inside drum and condition the RHA in a muffle furnace at a temperature of 650 ℃ for 2 hours. The copper nanoparticles (CuNP) were synthesized by chemical reduction using copper (II) sulphate pentahydrate as precursor salt and ascorbic acid as reducing and capping agent and the process was accelerated by microwave irradiation. The prepared RHA and CuNP were characterized by X - Ray Fluorencence (XRF), Scanning Electron Microscope (SEM), Energy Dispersive X - Ray Spectrometer (EDX), Fourier Transform Infra-Red (FTIR) and particle size analyzer and Ultraviolet – visible Spectrophotometer. The results revealed that RHA contain 84.35 % of silicon oxide, as well as porous and multifaceted particle size and shape. Particle size distribution was 2 μm. CuNP stabilized in between wavelength of 550 and 600 nm, peaks correspond to alcohol OH, alkyne, carboxylic acid and amide which suggested that CuNP was surrounded by organic molecules, 95.49 wt % Cu and 4.51 wt % O2 as well as crystallized particles with cube – like morphology and agglomeration. The XRD revealed Cu and Cu2O with crystallite size 40.42 and 45.24 nm, respectively. Rice husk ash and graphite were mixed in fixed weight ratios of 3: 1 while copper nanoparticles were varied from 1 to 4 weight ratio to prepare hybrid reinforced Al6063 based composites using two-step stir casting and spin casting technique. Composite samples were prepared for hardness, impact, tensile and wear tests which were evaluated following standard testing procedures. It was observed that the developed composites had enhanced mechanical properties with composite sample denoted as Al3R1G4Cu having superior hardness, tensile and impact energy values of 134 MPa, 77 VHN and 33.9 J, respectively. The wear volume, wear rate and friction coefficient were reduced by the incorporation of the copper nanoparticles. As the copper nanoparticles increases from 1 wt% to 4 wt%, the wear rate reduces from 1.69768 x 107 to 1.17118 x 107 mm3/m and 2.81104 x 107 to 1.54606 x 107 mm3/m under the loads of 5 and 10 N respectively. The friction coefficient reduces from 0.496 to 0.262 and 0.513 to 0.406 under the loads of 5 and 10 N respectively. With the addition of 4 wt% CuNP, the wear rate and friction coefficient were at the optimum. The friction coefficient decreased due to the lubricating effects of graphite and CuNP as compared to the Al6063 alloy. In conclusion, the rice husk ash-graphite-copper nanoparticles admixture caused enhanced mechanical properties for Al 6063 hybrid reinforced composites.
