Effectiveness of Process Parameters on Uniformity of Fly Ash inside Aluminum-Fly Ash Composites

摘要

In fabricating Aluminum-Fly Ash (ALFA) composites by stir casting, the stirring conditions directly influence the distribution of fly ash particles in the melt, thereby affecting the reaction ability between fly ash particles and aluminum melt. In this study, the seized fly ash particles after being pickled by acid were preheated to 400℃, 600℃ and 800℃ for 2 hrs, respectively. 1.5 kgs of ADC6 aluminum alloy were heated to 700℃ and then 5 wt% of fly ash were added into the melt, while the dosing flow rate of fly ash flow were 0.10 g/sec, 0.15 g/sec and 0.20 g/sec, respectively. Stirring speed of 300rpm, 400rpm and 500rpm were used till 20 sec after the fly ash being added completely. Finally, the casting was molded by the mold immersed rapid solidification process (MIRSP). The distribution of fly ash in the aluminum substrate was observed using the formed casting. The results showed that the higher the preheating temperature of fly ash and the smaller dosing flow rate help improve the uniformity of the distribution of fly ash in the melt. As preheating temperature at 800℃, dosing flow rate of 0.10 g/sec and stirring speed of 300rpm, the optimal distribution uniformity for enhanced fly ash in the melt was obtained. In addition, the higher the stirring speed, although getting a better mixing efficiency, but compared to the other two process conditions, its influence on the distribution was less obvious.