TECHNICAL PAPER Characterization, Tribological and Mechanical Properties of Plasma Paste Borided AISI 316 Steel M. Keddam 1 • R. Chegroune 1 • M. Kulka 2 • N. Makuch 2 • D. Panfil 2 • P. Siwak 3 • S. Taktak 4 Received: 16 December 2016 / Accepted: 26 April 2017 Ó The Indian Institute of Metals - IIM 2017 Abstract The AISI 316 steel was treated by the plasma paste boriding by using a gas mixture of 70%H 2 –30%Ar with a boron source of 100% B 2 O 3 in the temperature range of 700–800 °C for 3, 5 and 7 h. The boride layers formed on the samples were observed by scanning electron microscope. The iron borides were also identified by the use of an X-ray microanalyzer, equipped with energy dis- persive X-ray spectroscopy. The XRD analysis was carried out to identify the iron and metallic borides present inside the boride layer. Based on the kinetic data, the value of boron activation energy for the AISI 316 steel was esti- mated as 118.12 kJ mol -1 and compared with the data available in the literature. A regression model based on ANOVA analysis was used to predict the boride layers’ thicknesses depending on the boriding parameters: the treatment time and the boriding temperature. A good cor- respondence was obtained between the experimental values and those predicted by the regression model. Furthermore, the wear behavior of the sample borided at 750 °C for 5 h was investigated. The significant increase in wear resis- tance of plasma borided layer was observed in comparison with the untreated AISI 316 steel. The nanomechanical properties of the sample, plasma paste borided at 700 °C for 7 h, were examined using the nanoindenter with a Vickers diamond tip. The load–displacement curves, as well as, Young’s moduli and hardness were shown for the selected measurements. The obtained results depended on the phase composition of the tested area. Keywords Plasma paste boriding  Kinetics  Borides  Activation energy  Wear  Nanoindentation 1 Introduction Boriding is an effective surface treatment to improve the tribological and corrosion properties of ferrous alloys [1]. It is widely employed in many industrial sectors such as manufacturing, transport, machinery and energy [2]. This thermochemical treatment is carried out by heating the material to be treated at a temperature of 700–1050 °C for a specific time duration. The boriding treatment can be realized in solid, liquid, gaseous or plasma media [3–6]. The formation of boride layer follows as a consequence of boron diffusion at atomic scale into the substrate to produce the boron compounds. In case of ferrous alloys, the boride layer may contain either a single Fe 2 B phase or two phases (FeB and Fe 2 B) [1]. The formation of metallic borides with alloying elements such as Cr, V, Ni and Mo is possible in the alloyed steel because of their chemical affinity for boron [7, 8]. It is possible to diminish the boriding temperature and the process time by using ion implantation boriding [9], and plasma-assisted boriding [10]. Although the plasma boriding process is very advantageous in comparison to the & M. Keddam keddam@yahoo.fr; mkeddam@usthb.dz 1 Laboratoire de Technologie des Mate ´riaux, Faculte ´ G.M. et G.P, USTHB, B.P. No. 32, El-Alia, 16111 Bab-Ezzouar, Algiers, Algeria 2 Institute of Materials Science and Engineering, Poznan University of Technology, Pl. M.Sklodowskiej-Curie 5, 60-965 Poznan, Poland 3 Institute of Mechanical Technology, Poznan University of Technology, 3 Piotrowo Street, 60-965 Poznan, Poland 4 Department of Metallurgical and Materials Engineering, Faculty of Technology, Afyon Kocatepe University, 03200 Afyonkarahisar, Turkey 123 Trans Indian Inst Met DOI 10.1007/s12666-017-1142-6