Processing and characterisation of new nanocrystalline Al_2O_3-fly ash composites

摘要

In this study, new nanocrystalline Al_2O_3-fly ash Ceramic Matrix Composites (CMCs) were developed through the powder metallurgy route. It was found that wet milling of the mixture for 18 h improved mixing, decreased the Al_2O_3 crystallite size to around 10 nm, and reduced the fly ash particle size. For samples sintered at 1350℃ for 16 h, the addition of 5 wt% fly ash to alumina increased the micohardness from 525 to 1325 HV while the addition of 10 and 20 wt% decreased it to 508 and 444 HV respectively. Composites containing 5 and 10 wt% fly ash had higher density than Al_2O_3, while samples containing 20 wt% fly ash had lower density. Increasing the sintering time led to the increase in the density of all the samples sintered at 1350℃.