Experimental investigation on tribological behaviour of Al-TiCp composite under sliding wear conditions

Abstract

Cryogenic technology is used in various engineering and industrial applications such as aerospace, automotive, defence and medical fields due to its better cooling and /or lubrication action. Conventional materials used in cryo-techniques are substituted with metal matrix composites (MMCs) due to their high strength-to-weight ratio. Aluminium-reinforced titanium carbide particulate (Al-TiCp) composite has gained attention due to its superior thermomechanical and tribological characteristics, but the effect of cryogenic temperature technology on Al-TiCp MMC, have not been studied substantially. So an effort has been made in this current research work to bridge the gap. To determine the cryogenic tribological behaviour of Al-TiCp composite, sliding wear tests are conducted. A customised cryogenic-tribo setup has been developed by attaching cryogenic system to pin-on-disc configuration. Nozzle arrangement to the cryogenic-tribo setup feeds cryogenic fluid (liquid nitrogen: LN2) exactly into sliding contact with a restricted flow rate and constant pressure for better cooling and lubrication. Wear studies have been carried out under different applied loading and sliding velocities under LN2, cryogenic chilled air and dry environment. The present analysis reveals that the weight loss of composite sample increases linearly with increase in normal load and sliding distance whereas decreases with increase in sliding velocity. Auxiliary observations revels that presence of LN2 in sliding contact offers significant reduction in friction and wear values when compared to other environments. The performance improvement with LN2 could be due to the hydraulic pressure of trapped LN2 into the sliding contact which takes away a part of normal load resulting in reduced apparent friction coefficient and wear rate. Microscopic images of worn surfaces showed the cracks and fracture in the wear track over sliding surfaces is high in dry than compared to LN2 condition.