THE ANNALS OF UNIVERSITY “DUNĂREA DE JOS“ OF GALAŢI FASCICLE VIII, TRIBOLOGY 2003 ISSN 1221-4590 168 TRIBOLOGICAL FEATURES OF PM IRON-COPPER BASED MATERIALS Cristina Tei ş anu 1 , Andrei Tudor 2 , Ş tefan Gheorghe 1 , Ion Ciupitu 1 1 University of Craiova, 2 “Politehnica” University of Bucharest, România cteisanu@mecanica.ucv.ro ABSTRACT New antifriction materials based on iron-copper powders with several addition elements such as tin, lead and molybdenum disulphide have been developed by PM techniques in order to improve antifriction and mechanical properties. The powder mixtures have been uniaxially cold compacted at 500 MPa obtaining cylindrical specimens and sintered in dry hydrogen atmosphere at 900°C for 50 minutes. The tribological behaviour of the selected iron-copper based alloys has been analysed by pin on disc tests without lubrication and the coefficient of friction and wear rate have been studied in order to identify the effect of the base material composition. Also, the wear surface scars and the microstructure of the wear surfaces have been investigated. KEYWORDS: Iron-Copper based alloys, friction coefficient, wear rate. 1. INTRODUCTION Technical and economical advantages of the P/M technique lead to performing a wide type of new materials and products with special characteristics required by modern technique [1]. In the recent years the iron base sintered bearings production was considerable increased at the expense of the copper based ones, due to the low cost and availability of the iron powders as well as the higher strength. The mechanical properties of a part are strongly related to the composition of the materials. For tribological applications, the properties of the surface are related to the different metallic and intermetallic phases formed in the material. In order to meet the requirements of future possible applications, it is important to improve the existing and develop new methods of enhancing the applied properties. This may be achieved by efficient alloying, using efficient combinations of alloying elements [2]. Sintered iron base antifriction materials were not developed until the last decade because of poor corrosion resistance and antifriction properties. Considering the low cost and availability of iron, additions such as copper, graphite, manganese, lead and tin to iron have been attempted, but improvement in one property was offset by a decrease in other properties [3, 4, 5, 6]. In order to improve antifriction and mechanical properties, the present paper focused on the development of Fe-Cu-Sn-Pb-MoS 2 antifriction alloy [7, 8, 9, 10]. The reasons for non-uniformity density distribu- tion are friction between powder particles and die, and internal friction between powder particles. Because of its lamellar structure, MoS 2 is one of the most popular and usable solid lubricants [11, 12]. MoS 2 might be used for the reduction of powder particles – die wall friction as well as interparticle friction during conventional cold die compaction [13]. Most of the machine tools parts having functional role are removed due to the wear of the contact surfaces being in relative movement [14]. Friction and wear does not represent material properties, but show a response of the system. Dry friction or Coulomb friction refers to the tangential component of the contact force between two dry surfaces being in relative movement one to another or when only one surface is moving. Wear can be produced by removing the material from the contact surface, so the solid body properties at the surface or on a small depth are damaged without material loss. Wear can also be produced by detachment the material from the surface and its transfer to the counterpart surface or by loosing the material as wear particles [15, 16]. 2. EXPERIMENTAL PROCEDURE As experimental materials iron powder produced by DUCTIL S.A. BUZAU (DP 200 – HD), electrolytic copper powder, tin powder, lead powder and molybdenum disulphide powder, which was added as solid lubricant, were used. Elemental