چكيده به لاتين
In the present study, a Functionally graded Al-based composite reinforced whit Multi-wall Carbon Nanotubes (MWCNTs) and Aluminum oxide nanoparticles (nAl2O3) is produced by using a conventional flake-powder metallurgy method, including an ultrasonic bath and high-energy Ball milling followed by a Spark Plasma Sintering(SPS). The carbon nanotubes were dispersed in the Al particles by nano-alumina particles as a solid mixing agent. Two different amounts of MWCNT were added with a ratio of 2 and 5 vol% to the aluminum matrix. Al-CNT composite powders were mixed for 1 hour under ultrasonic process and magnetic stirrers. The dispersion of CNTs in the Al matrix was done by mechanical milling at 2 and 4 hours. The Al-CNT-nAl2O3 powder mixtures were condensed in the form of Layered Graded Functional Changes of 0 to 5 vol% carbon nanotubes. Morphology of FGM structure by Field Emission Scanning Electron Microscopy (FESEM), Sintering Behavior of Composite Powders by differential thermal analysis (DTA), Structural changes of carbon nanotubes by Raman spectroscopy , The final Functional graded Composite phase analysis by X-ray diffraction (XRD), density and porosity, electrical resistance, hardness and Wear resistance were investigated.
In this research, dispersion of carbon nanotubes with a ratio of 2 and 5 vol% with Al-flake particles was performed after 2 and 4 hours of high energy planetary ball milling. By increasing the milling time, the ratio of ID/IG calculated from the Raman spectrum of carbon nanotubes decreased. Differential thermal analysis showed that the Al4C3 phase was not formed prior to the temperature of 600 °C. FGM sintering is performed according to DT analysis at 600 °C. Phase analysis showed that any phase has not been formed after SPS process. The density of compressed FGM at 2 and 4 hours milling time was 2.635 and 2.589, and Porosity percentage was 0.75 and 1.38, respectively. The highest hardness was equal to 122 HV for a layer containing 2 vol% CNT and ball milled for 4 hours. The electrical resistivity had the highest increase for the sample containing 2 vol% CNT and 4 hours of ball milled and the electrical resistance decreased with increasing CNT volume fraction in the aluminum matrix. The friction coefficient for the 5 vol% CNT layer and 4 hours of ball milled was about 0.04. The layer containing 5 vol% CNT and ball milled for 2 hours was fractured during wear test due to the Agglomeration of carbon nanotubes and the prevention of complete Al sintering.
Keywords: functionally graded materials, carbon nanotubes, Al-CNT nanocomposites
