Proceedings of SerbiaTrib '13

of the composite coatings 20g/l of micro- or nanopowderswere added into the electroplating bath,dispersed using ultrasounds (200W, 24kHz) for30min and then maintained in suspension undercontinuous mechanical stirring during theelectrodeposition. The micro-particles have a meandimension of 2μm and a very irregular and sharpshape, while the nano-particles have a meandiameter of 45 nm [19].2.2 Samples characterizationThe specimens characterization includesmicrostructure, chemical composition,microhardness, wear resistance at both roomtemperature and 300°C and corrosion resistance intwo different environments.The microstructure of the specimens have beenanalysed by SEM (Zeiss Evo-40) + EDXS (Oxfordinstruments INCA) in cross section. Both the SiCcontent and the coatings’ porosity were calculatedusing an image analysis software [13]. For nanocomposite coating The SiC content was measuredthrough the measurements of RF GDOES (HR-Profile, Horiba Jobin Yvon), calibrated using 28CRM (Certified Reference Material) samples. Thesystem was set up using an Ar pressure of 650Paand a applied power of 50W. The micro-compositecoating were not analysed by the GDOES becauseof some issues related to the plasma erosion of thereinforcing particles [21].Micro-hardness measurements (HV 0,3 ) havebeen performed on cross section of the specimens.Wear tests have been performed using a CETRUMT tribometer in a ball-on-disc configuration atboth room temperature and at 300 °C. The testingparameters are summarized in Table 2. The volumeloss has been evaluated using a stylus profilometer(DEKTAK 150 Veeco). The wear rate K [10 −6mm 3 /Nm] has been calculated using the equationdescribed in [22].Table 2: Wear test parameters.Counter materialApplied loadTest radiusRotation speedSliding speedTest durationWC sphere (d 9.5mm)70N18mm300rpm0.565 m/s60 minFig.1: Microstructure of gr. 22 steel.The Gr 22 steel presents a ferritic microstructurewith some carbides precipitated in the metal matrix,that leads to the high creep strength of material.The carbides are mainly produced by Cr and Mo.The hardness of the material is about 180±20 HV 0,3and the ferritic grain size is about 45±15 µm.In Fig.2 are shown the SEM micrographsobtained for Thermal spray coatings and therelative data acquired by mechanicalcharacterization and image analysis. In Tab. 3 thethermal spray coatings’ properties are listed.a)b)3. EXPERIMENTAL RESULTS3.1 Microstructural characterizationIn Fig. 1 is shown the microstructure of the steelsubstrate.48 13 th International Conference on Tribology – Serbiatrib’13