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Tensile and fracture behavior of single and dual matrix aluminum-carbon nanotube composites
Research on Al-CNT composites is in strong demand due to their high specific properties, and their potential applications in many advanced areas like in automotive and aerospace industries. In the current study, tensile and fracture properties of aluminum-multiwall carbon nanotube composites (Al-CN...
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AUC Knowledge Fountain
2013
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| Summary: | Research on Al-CNT composites is in strong demand due to their high specific properties, and their potential applications in many advanced areas like in automotive and aerospace industries. In the current study, tensile and fracture properties of aluminum-multiwall carbon nanotube composites (Al-CNT) were investigated. A 99.7% pure AlPOCO® aluminum powder having an average particle size of 75 microns, in addition to 70-90% pure Elicarb® multi-walled carbon nanotubes having 10-12 nm average diameter were utilized in the synthesis of single and dual matrix multiwall carbon nanotube reinforced aluminum composites. Single matrix Al-CNT composite powders with 1, 2, 2.5, 5 wt.% CNT fraction were synthesized using the high energy ball milling (HEBM) of Al and CNT powders for 1 hour at 400 rpm. Dual matrix Al-CNT composites of 1, and 2.5 wt.% CNT loadings were synthesized from 1:1 mixtures of single matrix Al-2 and 5 wt.% CNT composite powders, respectively, and unmilled aluminum powders using HEBM for 1 hour at 400 rpm. Composite powders of different compositions were consolidated using conventional powder metallurgy processes; this included cold compaction, hot compaction, sintering, and hot extrusion processes in order to obtain high density compacts of the Al-CNT composites that are appropriate for different mechanical testing procedures. Several mechanical testing and characterization methods were applied to closely explore the mechanical properties and structural features of the Al-CNT composites. This included mechanical tension, and Elastic plane-strain fracture toughness tests as well as scanning electron microscopy, x-ray diffraction, Nanoindentation, and Raman spectroscopy. Improvements in composite properties by tailoring the synthesis parameters as well as structural related information revealed by different testing and characterization methods are reported later in this study. It was concluded that the addition of CNT to the Aluminum matrix had a positive impact on the material strength with a corresponding loss in ductility. The study also showed that the dual matrix principle could positively retain some of the material ductility when employing the right milling conditions and mixing ratios. On the other hand, no significant influences of CNT on the elastic plane strain fracture toughness of aluminum was observed. Instead, transition of the material fracture behavior to a less ductile manner was observed. |
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