Effect of Mill Type on Morphology of AA6013 Aluminium Powder
In conventional recycling method, metal chips are cast after pressing and melting in electric arc furnace. Material loss occurs during the recycling from liquid metal due to the several reasons. Direct recycling method which produces the aluminium powder from aluminium chips using mechanical mill can be an alternative to conventional recycling method. Thus material and energy losses, and labour cost will be reduced by direct recycling method without melting. In this study, the particle morphology of powder direct recycled from AA6013 aluminium alloy chips with cryogenic, disc and ball type grinders is investigated. Mechanical milling resulted flaky and irregular shaped AA6013 particles. It was ascertained that the chips did not break sufficiently in despite of the long duration milling mechanisms by ball mill. Cryogenic mill provides the energy required for milling mechanisms to act. Disc mill has the highest impact energy was determined. Consequently, efficiency of ball mill is lower than the efficiency of cryogenic and disc type mills. Shape factors of powders produced with ball and cryogenic mills were found greater than that of the powder produced by disc mill. Disc mill has the most efficient and effective impact energy which produces the smaller particles per minute, was determined.
Mechanical milling of Al and synthesis of in-situ Al2O3 particles by mechanical alloying of Al-CuO system
Abstract Initially, pure Al was milled for upto 20 h in order to find out the milling characteristics of Al. The effect of milling on the crystallite size, lattice strain, lattice parameter and the melting characteristics of Al was determined. Later Al-5 vol. % CuO was milled to investigate the possibility of synthesis of in-situ Al2O3 by mechanical alloying (MA) and subsequent annealing of the milled powder. The DSC plot of the 25 h milled Al ponder shows an exothermic peak of crystallization instead of an endothermic peak due to melting. In-situ α-Al2O3 reinforcing particles have been successfully synthesized by annealing of the 25 h milled Al-5 vol. % CuO powder mixture. Al-5 vol. % CuO powder mixture was initially milled for 25 h and later annealed at 650 °C and 1100 °C for a period of 2 h. Various techniques like differential scanning calorimetry (DSC), differential thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM) have been used to investigate the formation of phases during MA and subsequent annealing of the milled product. The formation of in-situ nanostructured α-Al2O3 particles was confirmed by annealing of the 25 h milled Al-5 vol. % CuO powder mixture at 650 °C and 1100 °C for 2 h. The exothermic reaction between Al and CuO represented as 2Al + 3CuO→ Al2O3 + 3Cu was induced by MA and was later completed during annealing.
Wear characteristics of Al-Si alloys
Abstract The wear characteristics of Al-Si alloys containing 2–20 wt.% have been studied using a pin-on-disc type wear testing machine at room temperature. The effects of alloy composition, sliding distance, sliding speed and load on wear rate of Al-Si alloys have been investigated. It has been found that the wear rate is strongly dependent on alloy composition, applied load and sliding speed. The wear rate decreases and the load-bearing capacity of the alloy increases with increasing silicon content. The nature of the wear process changes with alloy composition and experimental conditions.