K Srinivasa Rao

Friction surfacing : novel technique for metal matrix composite coating on aluminium-silicon alloy

Abstract The present work pertains to the study of wear and corrosion resistance of surface coating of SiCp reinforced AA 2124 aluminium alloy composite onto the surface of aluminium alloy A356. In order to improve wear and corrosion resistance of A356 Al–Si alloy, SiCp reinforced composite was coated on A356 Al–Si alloy substrate by friction surfacing technique. The coating was characterised by metallography, dry sliding wear and potentiodynamic polarisation testing. The present study revealed that aluminium alloys could be friction surfaced with metal matrix composites. The coating exhibited excellent wear resistance, which is attributed to the formation of strong metallurgical bond with the substrate. The coating was also found to have adequate corrosion resistance. The study assumes special significance as deposition of metal matrix composites utilising friction surfacing is reported for the first time.

Enhancement of wear and corrosion resistance of cast A356 aluminium alloy using friction stir processing

The present work pertains to investigation carried out on the feasibility of locally modifying the surface properties of cast aluminium alloy A356 using friction stir processing (FSP). The friction stir processed zone was characterized by metallography, electron micro probe analysis, hardness, dry sliding wear and potentio dynamic polarization testing. Hardness mapping showed that stir zones experienced increase of 40% compared to the as-cast metal. Further uniform micro-hardness was observed in the friction stir processed zone, which was not the case with as-cast A356 aluminum alloy. The FSP of cast A356 alloy exhibited excellent wear resistance, which is attributed to break-up of the coarse silicon rich eutectic particles, dendrite structure and homogenous distribution of fine Si particulates throughout the α-Al matrix due to intense plastic deformation and mixing during friction stir processing. The friction stir processed zone was also found to have adequate corrosion resistance. This work demonstrates that friction stir processing is an effective strategy for enhancement of wear and pitting corrosion resistance of as cast aluminum alloys