23. - 25. 10. 2012, Brno, Czech Republic, EU

XRD AND SEM STUDY OF AL2O3/WS2 NANOSTRUCTURES Joanna KORZEKWA, Władysław SKONECZNY University of Silesia, Katowice, Poland, EU, [email protected]; [email protected]

Abstract In this paper the characteristics of Al2O3/WS2 nanocomposite layer will be presented. The Al2O3/WS2 oxide layers were obtained by hard anodizing process on an aluminum alloy. The main advantage of oxide layers prepared by hard anodizing is good adhesion to the base. Another benefit of anodizing oxide layers is the possibility to control tribological properties, mainly friction coefficient through the change in porosity, thickness or microhardness of the layer as a result of technological parameters (temperature, solution composition or current density change). During the process of growing of nanoceramic Al2O3 fibres, the dispersed particles of WS2 adsorb on nanofiber surfaces and subsequently are constructed with ternary electrolyte anions. The characteristics of matrix of Al 2O3 nanofibers with dispered WS2 phase were performed using scaning electron microscopy and X-ray structural studies. Keywords: Al2O3 oxide layer, tungsten disulfide 1. INTRODUCTION Aluminum alloys belong to a group of materials which are widely used in motorization, aircraft or food industry, where light weight or corrosion resistance is required. In recent years, considerable attention has been directed towards environmental requirements, as well as mechanical and endurance requirements. As a result, modern materials and advanced technologies are widely demanded [1,2]. Equally important in this topic are the methods of coating which improve existing products and materials, as well as new materials that meet specific requirements. The solid lubricants (e.g. soft metals: WS2, MoS2, graphite, dichalcogenides or polymers) are a part of parcel of predominant materials used for kinematics systems, where good tribological properties are required. They are applied as an inorganic fullerene like (IF), nanotubes or stable polytype (2H) [3,4,5]. The presented work has been devoted to modify the Al2O3 layer by 2H-WS2. As demonstrated in tribological studies, the addition of tungsten disulfide, molybdenum or graphite to the Al 2O3 layers causes the reduction of negative friction effects [5,6,7]. These results represent the characteristics of XRD and SEM studies of Al2O3/WS2 nanocomposite layers obtained on aluminum alloy substrate. 2. EXPERIMENTAL METHOD 2.1. Layers obtaining Hard anodizing process was performed on an aluminum alloy EN – AW – 5251 made by PN-87/H-92741/0103. Anodic oxidation was realized with GPR-25H30D feeder cable. Aluminium rectangular plates of the field -2 2 of 10 dm , underwent etching in 5% KOH and 10% HNO3, in order to remove soil on the surface prepared for anodizing. A lead plate of the same work surface was the cathode of the system. Oxidation was carried out in a water electrolyte consisting of sulfuric 18% (33 ml/l), oxalic (30g/l) and phthalic acids (76 g/l). The Al2O3/WS2 layers were formed through adding 10, 20 and 30 g of 2H-WS2 powder (Aldrich - Sigma, grain size