Dry Sliding Wear And Friction Behavior Of Silicon Carbide And Multi Wall Carbon Nanotubes Reinforced Magnesium Matrix Hybrid Composites

• Main Author: Tee, Zhen Wei
• Format: Thesis
• Language: English; English
• Published: UTeM 2016
• Subjects: T Technology (General); TA Engineering (General). Civil engineering (General)
• Online Access: http://eprints.utem.edu.my/id/eprint/18608/1/Dry%20Sliding%20Wear%20And%20Friction%20Behavior%20Of%20Silicon%20Carbide%20And%20Multi%20Wall%20Carbon%20Nanotubes%20Reinforced%20Magnesium%20Matrix%20Hybrid%20Composites%2024%20Pages.pdf; http://eprints.utem.edu.my/id/eprint/18608/2/Dry%20Sliding%20Wear%20And%20Friction%20Behavior%20Of%20Silicon%20Carbide%20And%20Multi%20Wall%20Carbon%20Nanotubes%20Reinforced%20Magnesium%20Matrix%20Hybrid%20Composites.pdf; http://eprints.utem.edu.my/id/eprint/18608/; https://plh.utem.edu.my/cgi-bin/koha/opac-detail.pl?biblionumber=100901
• Institution: Universiti Teknikal Malaysia Melaka

In order to optimize the functionality of magnesium, a modest attempt has been made to develop magnesium hybrid composites incorporating of synthesis micro and nano size fillers. Commercially pure magnesium (Mg) reinforced with (i) 10 wt.% micro-sized silicon carbide (SiC) particles (ii) combination of 10 wt.% micro-sized silicon carbide (SiC) particles and 1 wt.% multi-walled carbon nanotubes (MWCNTs), respectively, were synthesized via powder metallurgy route followed by hot extrusion. After the specimen preparation, microstructural characterization studies were conducted to determine the distribution of reinforcement, grain morphology, and presence of porosity by using Optical Microscope, Scanning Electron Microscope and Field Emission Scanning Electron Microscopy. Density and porosity measurements were carried out accordance with Archimedes’ principle. Micro-Vickers Test was also carried out to investigate the hardness of material. The dry sliding tests were performed using a pin-on-disc tester against a grey cast iron counterbody under two applied normal loads (5, 10, 20, 40 N) with four sliding speeds (0.5, 1.5, 3.5, 4.5 m/s) corresponding to a constant sliding distance of 5000 m to identify the wear rate and coefficient of friction of magnesium composite. The morphology of the worn pin surfaces and collected wear debris were examined using Scanning Electron Microscope. Throughout this work, reasonably uniform distribution of SiC particulates and MWCNTs in magnesium matrix were observed. Low porosity (below 2.0 %) was obtained which indicated the suitability of the processing parameters. The Vickers hardness of all the hierarchical magnesium composite configurations are significantly higher than the pure magnesium. Wear rate for both unreinforced magnesium and its composite increased with increasing load but the incorporation of micro and nano size fillers reduced the wear rate of magnesium particularly at loads of 5, 10, 20 N. The sliding speed increment induced higher wear on magnesium composites. However, at the highest load of 40 N, a crossover in wear rate was observed with the increased in sliding speeds, i.e., at sliding speed of 1.5 m/s the wear rate of the composite higher than unreinforced magnesium, but the incorporation of SiC and MWCNTs shifts to minimize the wear rate at sliding speeds of 3.5 and 4.5 m/s respectively. There is a small reduction in the coefficient of friction for Mg/SiC/MWCNTs composite as compared to Mg/SiC particularly at low loads of 5, 10, 20 N as the sliding speed increased but the change of coefficient of friction among different materials become insignificant at high load of 40 N. Five wear mechanisms mostly operated in combination namely abrasion, adhesion, oxidation, delamination and plastic deformation have been observed in various sliding conditions. Such modify hybrid approach may bring significant implications on application particularly in automotive and aviation sectors. These would become as another material option to further improve the fuel efficiency as well as service life of components.