Fabrication of Al/Al₂O₃ composite by powder metallurgy method from aluminum and rice husk ash

บทคัดย่อ

Fabrication of Al-4wt.%Cu /Alumina composite was reported. The method of fabrication was powder metallurgy by in-situ reaction to form alumina during fabrication. Starting materials were mixture of aluminum, copper, and silica powders. Silica is in form of rice husk ash. The mixture was cold compacted, and sintered at 650°C for 1 h. Hot forging was carried out to further consolidate the sintered billet, followed by 10-h heat treatment at temperatures between 590 to 650°C. Phase analysis by XRD confirmed that in-situ reaction between silica and aluminum powders occurred during heat treatment at temperatures above 590°C. The products of reaction were silicon and gamma-alumina. Microstructure investigation showed that the reacted areas were the previous locations of silica powder. In some areas, remaining silica was found amid reaction products. Hardness of the fabricated composite made of Al-4wt.%Cu and 5, 10 and 15vol% silica are 16, 23, and 30 HRA, respectively.