| Summary: | 碩士 === 國立臺灣科技大學 === 機械工程系 === 94 === The purpose of this study was to investigate the phase morphology, thickness, and anti-oxidation behavior of the Al-Si layer of the different content of Si.
The results showed that the aluminide coating layers of the three specimens consisted of three phases: Al (Al-Si), FeAl3, and Fe2Al5 were detected from the top coating to the steel substrate. According as the increase of the Si content, the thickness of the aluminide layer gradually decreased and the aluminized layer became flatter and smoother. Thus, it inhibited the growth of the aluminized layer. The data from isothermal and thermal cycle in 850℃static air, we found that the FeAl changed from the FeAl2 and Fe2Al5 in the interior parts of the pure Al, Al-1wt％Si, Al-7wt％Si specimens. The final thickness of the aluminized layer of the three specimens was approximately the same. According as the increase of the Si content, the distribution of Cr3Si was more densely. In addition, as for the weight gain of oxidation, it was little effect on the increase of the weight gain without the addition of Si in aluminized coating samples at isothermal and thermal cycle in 850℃static air. These results indicated that the property of high temperature and oxidation did not improve by the addition of Si content. Moreover, the values of increasing mass were significantly changed in the Al-7wt％Si specimens, compared to the pure Al and Al-1wt％Si specimens. Also, the crack and destroy of oxide scale was more obvious in the Al-7wt％Si specimens than others at the process of thermal cycle.
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