| Summary: | 碩士 === 國立臺灣海洋大學 === 機械與機電工程學系 === 103 === Aluminum-Fly ash composites have characteristics of low density, good performance of resistance, high damping and rigidity etc. The sir casting is the most common way to produce the composites with the combination of liquid aluminum and solid fly ash. Aluminum-Fly ash composites mainly produce the Al2O3 as the strengthening phase by chemical reaction, but Magnesium in the aluminum alloy would react with melt to produce MgAl2O4, which do affect the materials characteristic. Thus, in this study, the Taguchi method and ANOVA analysis is used to analyze hardness and porosity of the composites by the three factors, such as Magnesium content (3 wt%, 5 wt, 7 wt), fly ash content (3 wt%, 6wt, 9 wt), and reaction temperature (700℃, 750℃, 800℃), which carrying the chemical reaction for 30 hours. Then the studied results are compared with those of Magnesium content of 0wt%, 2wt%, respectively, added fly ash 3wt%, 6wt%, 9wt% reacting for 0 hour and 30hours.
The results show that the reaction temperature has greater influence as compared to other two factors for the hardness. As fly ash contents less than 9wt%, the hardness of the composite improves insignificant. Thus, the Magnesium content in the composite is less than 3wt% for better improvement. Furthermore, adding 2wt% Magnesium in ALFA composites cannot increase the wettability between fly ash particle and the base material, but cause the fly ash particles unbreakable after 30 hours reaction. The hardness of composites increases nearly 8% as compared to the base material (ADC10+Mg 2 wt%). The density of composites also increases with respect to the base material, which contents no Magnesium and reacting for 30 hours. Therefore, adding Magnesium in ALFA composites produced by stir casting can achieve lightweight material and increase the material hardness.
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