Original Article The effect of ceramic tribo-elements on friction and wear of smooth steel surfaces Andrzej Dzierwa 1 , Pawel Pawlus 1 and Rafal Reizer 2 Abstract The pin-on-disc dry sliding friction and wear experiments have been made on 42CrMo4 steel in contact with Si 3 N 4 , SiC, WC, Al 2 O 3 , and ZrO 2 ceramic balls. The tests were carried out at sliding speeds of 0.16 m/s, 0.24 m/s, and 0.32 m/s. During the tests, the friction force was monitored as a function of time. Discs and balls wear was measured after the tests using a white light interferometer Talysurf CCI Lite and Altisurf 520 optical profilometer with a CL1 confocal probe. To decrease variations in the experimental results, during the tests, wear debris was continuously removed from the disc surfaces. It was found out that with Al 2 O 3 counterpart the wear volume of the steel discs was the largest. However, the largest wear volume of the balls was observed for Si 3 N 4 ceramic balls. Keywords Friction, wear, ceramics, pin-on-disc tests Date received: 12 December 2017; accepted: 9 May 2018 Introduction Ceramics are used in a wide range of applications, both in lubricated and unlubricated contacts. The most common bulk ceramics in tribological use are based on alumina (Al 2 O 3 ), silicon carbide (SiC), sili- con nitride (Si 3 N 4 ), zirconia (ZrO 2 ), or boron carbide (B 4 C). Silicon nitride may be used in bearings and metal cutting tools, alumina in cutting tools and hip joints, silicon carbide in mechanical seals while zirco- nia in dies and hip joints. Boron carbide is mainly used in cutting and abrasive applications. 1–4 SiC, Si 3 N 4 , Al 2 O 3 , and ZrO 2 are useful ceramics as structural materials of tribo-elements. They are char- acterized by high hardness values in the range of 10–30 GPa, which are much higher than those of steels. High hardness and low ductility of ceramics limit the junction-growth at asperity contacts and keep friction coefficient below 0.8–0.9 even when interlocking of asperities takes large part of friction. 5 Silicon carbide is usually produced by mixing high purity silica (SiO 2 ) with carbon-rich powder and heat- ing them up to 2200–2500  C. The reaction between silica and carbon results in the formation of silicon carbide and carbon monoxide. Silicon carbide is a very hard material and difficult to make into a fine- grained dense ceramic. ZrO 2 of a high melting temperature (2700  C) has three kinds of crystal struc- tures. At room temperature, the crystal structure of zirconia is monoclinic while at about 1000  C, the crystal is transformed to tetragonal and at even higher temperatures, 2370  C, the tetragonal crystal is transformed to a cubic shape crystal. The trans- formation process is always accompanied by a great change in volume that is followed by the formation of cracks. Al 2 O 3 can be found in nature as bauxite, which contains hydrated alumina (Al 2 O 3 H 2 O). By chemical processing, high purity alumina (up to 99.5%) can be obtained. In addition, a dense product (99.9%) made of alumina can be achieved by a good sintering procedure and in combination with its chem- ical inertness. There are several tungsten ores that can be mined and refined into tungsten or made into tung- sten carbide. Wolframite is the best known ore. The ore is crushed, heated, and treated with chemicals in order to obtain tungsten oxide. Then, the fine particles of tungsten oxide are carburized, turning them into tungsten carbide. In one method, the tungsten oxide is mixed with graphite (carbon). This mixture is heated to over 1200  C and a chemical reaction occurs that removes the oxygen from the oxide and combines the 1 Faculty of Mechanical Engineering and Aeronautics, Rzeszow University of Technology, Rzeszow, Poland 2 Centre for Innovative Technology (CIT), University of Rzeszow, Rzeszow, Poland Corresponding author: Andrzej Dzierwa, Faculty of Mechanical Engineering and Aeronautics, Rzeszow University of Technology, Powstancow Warszawy 8 Street, Rzeszow 35-959, Poland. Email: adktmiop@prz.edu.pl Proc IMechE Part J: J Engineering Tribology 0(0) 1–10 ! IMechE 2018 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/1350650118780779 journals.sagepub.com/home/pij