Tribology International 40 (2007) 98–104 Tribology at high-velocity impact $ M. Baki Karamıs - Ã Erciyes University, Mechanical Engineering Department, 38039 Kayseri, Turkey Received 7 September 2005; received in revised form 20 February 2006; accepted 21 February 2006 Available online 17 April 2006 Abstract The tribological events taking place when a high-velocity projectile hits a SiC particulate reinforced AA 5083 composite material was examined under real conditions. The samples were cast in a disc shape by squeeze casting method. Different volume fractions of SiC particles were used. They were solidified under 180 MPa in a steel mould with a 650–700 1C temperature range. SiC particles with the size of 250–500 mm, and 30% and 45% in volume fraction were incorporated into the matrix material. The composites were machined to ensure a smooth surface and to obtain samples without burrs. The samples had a diameter and thickness of 140 and 20 mm, respectively. The terminal ballistic tests were carried out in an army zone under standard test conditions. An AP 7.62 mm armour piercing projectile with a speed of 710 m/s was used for testing the composite. The frictional characteristics and wear mechanisms caused by high-velocity impacts to the composite were determined by SE microscopy studies. The evaluations of the tribological events on both the hole and projectile tip surfaces resulting from high-velocity friction were carried on. As the projectile moved thorough the composite, some material broke from the matrix body and conglomerated along the path followed by the missile. Then these conglomerated blocks yielded and slided along the hole surface. There were also scratching and local melting on the hole surface. Similarly, some ploughing took place on the hole, some SiC particles were removed from the matrix body by the friction effect of projectile and these particles were conglomareted on the tip surface of the projectile. Thus, the nature of wear mechanism on the projectile surface was predominantly abrasive while those of the friction surfaces of the composites were predominantly abrasion and melt wear. r 2006 Elsevier Ltd. All rights reserved. Keywords: Metal matrix composites; Ballistic impact; Penetration; High-velocity impact 1. Introduction Particle reinforced MMCs have the cumulative good properties of both ceramics and matrix materials. Although many studies have been carried out concerning the quasi- static properties of the composites, their tribological behaviour at higher velocities have not been investigated sufficiently. On the other hand, they are widely used in military, automobile, aerospace and defence industries due to their attractive properties. On military side, MMCs are used in jet fighters as structural and high-temperature engine components. The recognition of MMCs as maturing materials technology stimulated exploratory research related to the armour potential of this material [1]. Under dynamic loading conditions, such as penetration of projectile into MMCs armours, particulate-reinforced MMCs often sustain high strain rate deformations. The hypothesis that MMCs exhibit excellent work hardening under dynamic loading supports the observed ballistic performance [1–3]. Projectiles are in competition with armours. While the armour materials have been improved against primitive projectiles in recent years, the aimed effect of new projectiles are to pierce the armour. Therefore it is desirable that armour should be able to withstand the latest projectile type. This is a measure on the performance of the armour whether it is strong or not [4]. The mechanical properties gained with reinforcement of metals improve their piercing resisting properties. The penetration behaviour of the high-velocity projectiles is affected by the strength of MMC. ARTICLE IN PRESS www.elsevier.com/locate/triboint 0301-679X/$ - see front matter r 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.triboint.2006.02.063 $ This manuscript was presented at the International Tribology Conference (ITC), May 30–June 2, 2005, Kobe, Japan. Ã Tel.: +90 352 4375755; fax: +90 352 4375784. E-mail address: karamisb@erciyes.edu.tr.