| Summary: | 碩士 === 國立東華大學 === 材料科學與工程學系 === 99 === The low density of Al-Si alloy possesses good recycle property, corrosion resistance, high hardness, low thermal expansion and heat-resisting performance. Therefore, the applications of this alloy in the field of vehicle are increasing, for example engine liner of car or motorcycle, gear plate of bicycle. However, the improvement of wear resistance of Al-Si alloy in order to extend their applications, surface treatment is very important issue.
This research is focus on the near eutectic composition of Al-12wt%Si alloy. The direct chill casting method is used to cast the hypereutectic Al-Si alloy into 8’ billet. Then the billet is extruded into 5mm thick plate. The metallurgical bonded ceramic coating on this plate is fabricated by micro-arc oxidation (MAO) treatment. The effects of the electrolytic composition adding 4 different contents of Na2SiO3 and/or K2HPO3 will be investigated. To evaluate the microstructures, crystal structure, thickness of the coating layer, interface between the substrate and layer, optical microscope (OM), X-ray diffraction (XRD), scanning electron microscope (SEM) will be used. The wear resistance test is performed by using the pin-on disc method with different load and sliding length. Finally, from the results of microstructural evaluation and wear resistance test, this research will find out the optimal condition of MAO for Al-Si alloy, and transfer to industrial application.
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