The goal of this work was to reveal the influence of the diamond particle size on the wear resistance of silver/diamond electroplated dispersion coatings. For this purpose, a series of samples was realized by the use of a silver cyanide electrolyte containing different sized micro diamond particles. For all galvanic deposition processes, the authors applied identical plating parameters (plating voltage, current, temperature and particle concentration in the plating bath), in order to obtain coatings having a thickness between 9 and 15 #m. Diamond micro particles with different grain size (1, 0.25 and 0.1 #m) were co’deposited together with the silver matrix on copper substrates. The characterization of the coatings structure was carried out by scanning electron microscopy (SEM) and the sliding wear resistance of the silver base composite layers was determined using a pin’on’ disk wear tester. The results of the above mentioned investigations showed that the layer containing the smallest diamond particles provided the highest wear resistance. Electrodeposition, silver based dispersion coatings, sliding wear, diamond particles. I. INTRODUCTION HE basic concept of tribology is that friction and wear are best controlled with a thin layer or intervening film of material separating sliding, rolling and impacting bodies. There is almost no restriction on the type of material that can form such a film and some solids, liquids and gases are equally effective [1]. Abrasive wear, adhesive wear and fretting are often reduced by wear resistant coatings. Wear resistant coatings consist of carefully applied layers of usually hard materials which are intended to give prolonged protection against wear. There are The work has been funded by the Sectorial Operational Programme Human Resources Development 2007’2013 of the Romanian Ministry of Labour, Family and Social Protection through the Financial Agreement POSDRU/6/1.5/S/19. I. V. Rigou is Ph.D Student at University “Eftimie Murgu” of Resita, Romania at the Department of Mechanics (tel: +40727371290; e’mail: i.rigou@uem.ro). G. Mărginean is Dr. Eng. at the Department of Materials Science, University of Applied Sciences Gelsenkirchen, Germany (gabriela.marginean@fh’gelsenkirchen.de). D. Frunzăverde is Prof. Univ. Dr. Eng. at the University “Eftimie Murgu” Resita, Romania (dfrunzaverde@yahoo.com). C. V. Câmpian is Prof. Univ. Dr. Eng. at the University “Eftimie Murgu” Resita, Romania (v.campian@uem.ro). numerous methods of applying hard materials. The benefit of hard’coating technology is that a cheap substrate material can be improved by a coating of an exotic, high’performance material [1]. Contacts are made of elemental metals, composites or alloys that are obtained by the melt’cast method or manufactured by powder metallurgy (P/M) processes [2]. The benefits exhibited by metal matrix composites, such as lower density, increased specific strength and stiffness, increased high’temperature performance limits and improved wear’abrasion resistance, are dependent on the properties of the matrix alloy and of the reinforcing phase [3]. Coatings are today widely used to control friction and wear in all kinds of sliding contacts. Dispersion coatings consist of gently dispersed nonmetal particles in a metal matrix. They are used in a very large industrial field, especially when good tribological properties of the material surface are required [4]. A majority of contact applications in the electrical industry utilize silver’type contacts, which include the pure metal, alloys and powder metal combinations. Silver, which has the highest electrical and thermal conductivity of all metals, is also used as a plated, brazed or mechanically bonded overlay on other contact materials’notably, copper and copper’base materials [2]. Electrical contact materials are used in diverse service conditions and no metal has all the desired properties required to accomplish the objectives of different contact applications. The usefulness of an electrical contact material also depends on a variety of electrical and mechanical properties, service life, load and economic conditions [2]. Silver’diamond is a microcomposite produced by co’ deposition of diamond particles during electroplating of silver. Because of the excellent electrical and thermal conductivities, silver can carry high currents without excessive heating, even when dimensions of the contacts are only moderate [2]. II. EXPERIMENTAL    The silver/diamond dispersion coatings were obtained using a silver and potassium cyanide bath, containing 10vol.% diamond micro particles as dispersed phase. In order to observe the effect of diamond particles size on the wear The effect of diamond particle size on the wear resistance of silver/diamond electroplated dispersion coatings I.V. Rigou, G. Mărginean, D. Frunzăverde, C.V. Câmpian T Recent Researches in Mechanics ISBN: 978-1-61804-020-6 219