Nitrocarburized coating by plasma electrolytic saturation, PEN/C coatings, have been proposed to increase the corrosion and wear resistance of steel by using a process of low-temperature hydrostatic plasma. The objective of this work is to analyse the wear and corrosion resistance of PEN/C coatings on SAE 1045 steel, using the electrochemical slurry erosion wear test (ESEWT). This test allows the evaluation of the simultaneous effect of erosion wear and electrochemical behaviour on this coating. Thus, it was possible to evaluate the erosive and corrosive effect and the synergy of these phenomena on the PEN/C coated SAE 1045 mass loss rates. ESEWT tests were performed at different times and under different electrochemical conditions: under cathodic protection and open circuit potential (OCP). The PEN/C coating increased the corrosion resistance of SAE 1045. Synergy between the erosive wear and corrosion was the main factor in the mass loss rates of both analysed systems. The synergistic mechanism of the substrate occurred by removing the corrosion product and by activating the surface generated by the erosive process of the particles. The synergistic mechanism of the PEN/C coating occurred with the removal of inherent surface irregularities through the erosive process, combined with localized corrosion. saturation PENC PEN C lowtemperature low temperature 104 ESEWT. . (ESEWT) Thus conditions OCP. OCP (OCP) systems particles 10 (ESEWT (OCP 1

For the first time, the influence of gas mixture on first damage resistance of a plasma nitrided DIN 18MnCrSiMo6-4 bainitic steel was investigated. Samples were nitrided at 500 °C with three different N2-H2 gas mixtures, containing 5, 24, and 76 vol.% N2. Samples were characterized concerning the resulting roughness, microstructure, compound layer’s phase composition, residual stresses in the diffusion zone, and surface hardness. Tribological ball-on-flat tests were carried out in reciprocal mode using zirconia as ball material for friction coefficient and the compound layer resistance until the first damage. The test results were evaluated statistically by analysis of variance (ANOVA). As the amount of nitrogen in the gas mixture decreases, the ε-Fe2-3(C)N content in the compound layer decreases. A γ’-Fe4N monophasic compound layer was achieved at 5 vol.% N2 gas mixture. The diffusion zone as expected presented compressive residual stresses with the highest values near the surface. In the tribological tests, better results were obtained for 5 and 24 vol.% N2 in the gas mixture as higher amounts of γ’-Fe4N were formed. The 76 vol.% N2 gas mixture led to a brittle behavior, due to the biphasic compound layer (γ’-Fe4N and ε-Fe2-3(C)N) with a predominant content of ε-Fe2-3(C)N.

In this study, the sliding wear of a DIN 18MnCrSiMo6-4 continuous cooling bainitic steel plasma nitrided with a nitrogen rich gas composition was investigated. To evaluate the influence of processing time and temperature on mechanical and microstructural characteristics of nitrided layer, the samples were nitrided at 400, 450, 500 and 550 °C for 3, 6 and 9 h. The produced nitrided layers were characterized concerning the microstructure, phase composition, microhardness and surface roughness. The samples were tested by ball-on-flat reciprocating dry sliding for friction coefficient and wear analysis. The tests were stopped after a given damage criteria involving the rapid growth of the friction coefficients and wear. The correlation of the different treatment parameters and resulting case depths and surface hardness with sliding distance at the time of microcracks formation or delamination of the surface layer was evaluated statistically by the analysis of variance (ANOVA). The plasma nitrided samples at 550 °C showed better wear performances in the ball-on-flat tests than the other groups investigated, since these samples have a thicker compound layer and diffusion zone higher than the other conditions investigated. In general, the beginning wear is slower because of the hardest region of the compound layer.