Effect of ball milling and subsequent size reduction of graphite flakes on the surface mechanical properties of graphitized Al-1100 alloy

Abstract

Current study explains about ball milling and subsequent mechanical insertion of graphite particles into aluminium (Al-1100) surface for forming composites on surface through an electrical resistance heat supported pressing procedure. Ball milling of as-received 60 mesh graphite particles was carried out which successfully reduced the particle size. After that surface of the aluminium is coated with ball-milled graphite by solution casting. For impregnation, the interface of graphite/aluminium is locally heated by the assistance of an electrical resistance heating followed by mechanical pushing. Heat generation and thus level of aluminium surface softening can be structured by process factors like current and heating time. SEM, TEM, Raman spectroscopy and XRD were employed for microstructural characterization. Successful impregnation and agglomeration of graphite particles inside aluminium matrix is revealed from microstructural characterization. Impregnated graphite particles when characterized with Raman spectroscopy shows band shifting and increased intensity ratio (ID/IG). Presence of intermetallic compound (Al4C3) was not detected from the XRD and TEM study. Surface and subsurface mechanical characterization was carried out nanoindentation and microhardness respectively. The modified surface while shows an improvement of more than 120 % in mechanical properties, 130 % improvement is also observed in Young’s modulus. The projected method can be utilized as surface modification technique in solid-state by fabricating surface composites fabricated through mechanical insertion of particulate reinforcement at sub-melting temperatures of substrate and under open producing environment.