Effect of High-Energy Ball Milling in Toluene on the Morphology, Phase Evolution, and Contamination for Some Elemental Powders

This study reports the effect of milling time on the carbon content, morphology, crystallite size, and phase evolution of pure elemental Al, Fe, Ni, Cu, Cr, Mo, Si, Co, W, V, Ta, and Ti powders during high-energy ball milling (HEBM) in toluene. The XRD results show that the HEBM of Ti resulted in the formation of TiCx, which was confirmed by Raman Spectroscopy, while milling of Ta resulted in the formation of TaCx and TaHx. In comparison, there was no carbide or hydride phase formation up to 20 hours of milling for all other elemental powders. The weight percentage of carbon in the milled powder was observed to increase progressively with milling time. Ti powder showed the highest wt pct of C followed by Ta, W, Si, Al, Cr, Fe, Mo, V, Co, Ni, and Cu, respectively. The presence of carbon could be attributed to the dissociation of toluene and erosion of tungsten carbide balls and vials. The results show that carbon pickup significantly depends on the element being milled. The D50 particle size reduced appreciably after 20 hours of milling. The crystallite size for all the powders reduced progressively with milling time and was found to be in the range of 20 to 36 nm after 20 hours of milling.