Effect of ball-milling process parameters on mechanical properties of Al/Al2O3/collagen powder composite using statistical approach

Chrome containing leather-wastes (CCLW) is a waste obtained from leather industries. These wastes always produced environmental pollution. However, CCLW can be utilized in the production of various materials. In this research, chromium in the form of collagen powder after extracting from CCLW has been utilized to fabricate the composite material. Extracted collagen was mechanically alloyed with alumina ceramic fragments to acquire in a separate unified facility. Response surface methodology (RSM) was employed to obtain the optimum combination of solid-state synthesis processing variables. Optimum mechanical-alloying parameters were found to be ball-to-powder weight-ratio (BPR) of about 5, ball milling speed of about 178 rotation per minute and ball-milling time of about 93 h. The microstructure of ball processed reinforced composite material demonstrated a uniform distribution and proper wettability in aluminum-based matrix material. Tensile strength and hardness of Al/5% Collagen/5% Al2O3 composite material were enhanced by about 38.25% and 45% respectively. However, the density, toughness and ductility of composite material were reduced by 0.16%, 25% and 24.24% respectively. Surface roughness of Al/5 wt.% Collagen/5 wt.% Al2O3 composite was found to be 3.10  μm at a speed of 190 m/min, feed of 0.14 mm/rev and depth of cut of 0.20 mm.