International Journal of Materials Engineering 2012, 2(3): 23-31 DOI: 10. 5923/j.ijme.20120203.03 Synergistic Effects of Micro Size Flyash Particulate and Glass Fiber on Friction and Wear of Vinylester Hybrid Composites under Dry and Water Lubricated Sliding Condition S.R.Chauhan 1 , Bharti Gaur 2 , Kali Dass 1,* 1 Department of Mechanical Engineering National Institute of Technology Hamirpur (H.P.) 177005, India 2 Department of Chemistry National Institute of Technology Hamirpur (H.P.) 17700, India 3 Department of Mechanical Engineering National Institute of Technology Hamirpur (H.P.) 177005, India Abstract In this paper the tribological performance of vinylester and its composites under dry and water lubricated sliding conditions has been investigated. For investigating the friction and wear tests were carried out on a pin on rotating disc under ambient conditions at normal applied loads of 10, 30 and 50N and under sliding speed of 1.6, 2.8 and 4.0 m/s. The results showed that the coefficient of friction decreases with the increase in applied normal load under both dry and water lubricated condition. The specific wear rate of GFR vinylester composite reduces significantly with the addition of fly ash particulates. Keywords Specific Wear Rate, Glass Vinylester Composites, Scanning Electron Microscopy 1. Introduction In most of the thermosets, epoxy and vinyl ester resins exhibiting an attractive combination of mechanical, chemi- cal, thermal, and environmental stability. The fiber rein- forced polymeric composites have several potentially at- tractive properties including high specific stiffness and strength, good corrosion resistance and retention of these properties at high temperatures. The importance of tribo- logical properties convinced many researchers to study the friction and wear behaviour along with improving at the wear resistance of polymeric composites. For fiber rein- forced polymer matrix composites the process of material removal in dry sliding condition is dominated by four wear mechanisms, viz., matrix wear, fiber sliding wear, fiber fracture and interfacial debonding. Polymer composites are also increasingly used for a number of mechanical compo- nents such as gears, cams, wheels, brakes, clutches, bear- ings, bushes, etc., most of which are subjected to tribologi- cal loading conditions [1-6]. Researchers have shown that the friction and wear be- haviours of polymers in fluid environments differ to a great extent, from those in the dry friction conditions. The * Corresponding author: thakurkalidass999@gmail.com (Kali Dass) Published online at http://journal.sapub.org/ijme Copyright © 2012 Scientific & Academic Publishing. All Rights Reserved absorption of water and plasticization of polymer surfaces influence the friction and wear of the polymeric composites. It has been investigated that fluids such as water and other the solution inhibit the formation of transfer films of fiber/ polymer debris on the counterface and the wear rates are greater than those obtained in dry conditions. Absorption of water may cause reduction in strength, modulus of elasticity, increase in the elongation and swelling of the surface layer [7-10]. In the experimental findings of the tribological characterics of glass vinylester and SiC filled glass vinylester composites it has been reported that the water into the in- terface of polymer/metal sliding combination reduces the coefficient of friction, but increases the wear rate of the composites[11]. The investigation related to the tribological properties of polyether ether ketone (PEEK) has been reported in the studies[12-18]. The most of the investigations published were related to the friction and wear of polymers sliding against steels at dry sliding conditions. In addition, some investigations have been conducted on the friction and wear of polymers in water lubrication conditions[12-14]. The water into the interface of polymer/metal sliding combina- tion generally reduces the coefficient of friction, but may increase the wear rate of the polymer[19]. The investigation of water lubricated tribological performance of carbon re- inforced PEEK composite reported showed that the coeffi- cient of friction under water lubricated condition is lower than that the dry condition[20]. The friction and wear phe-