Oxidation state of individual alloying elements (Si, Al) and impurity element (Cu) upon segregation onto the surface of the sample FeSiAl alloys was investigated in an in situ study of segregation behavior in ultra-high vacuum. Chemical state of surface Si, Al and O as well as Cu was evaluated, by measuring the kinetic energy shifts that affect Si KLL, Al KLL, O KLL but also Cu LMM transitions, depending on chemical state of the element. It was found that Al oxidizes with temperature in all samples while Si behaves differently with maximum oxidation occurring around 300 °C, and oxidation not occurring at all in some samples. Segregated Cu stays predominantly in its elemental state which is consistent with relevant literature reports.
COBISS.SI-ID: 13283355
Homogeneous, 50-µm-thick, epoxy coatings and composite epoxy coatings containing 2 wt.% of 130-nm silica particles were successfully synthetized on austenitic stainless steel of the type AISI 316L. The surface morphology and mechanical properties of these coatings were compared and characterized using a profilometer, defining the average surface roughness and the Vickers hardness, respectively. The effects of incorporating the silica particles on the surface characteristics and the corrosion resistance of the epoxy-coated steel were additionally investigated with contact-angle measurements as well as by potentiodynamic polarization and electrochemical impedance spectroscopy in a 3.5 wt.% NaCl solution. The silica particles were found to significantly improve the microstructure of the coating matrix, which was reflected in an increased hardness, increased surface roughness and induced hydrophobicity. Finally, the silica/epoxy coating was proven to serve as a successful barrier in a chloride-ion-rich environment with an enhanced anticorrosive performance, which was confirmed by the reduced corrosion rate and the increased coating resistance due to zigzagging of the diffusion path available to the ionic species.
COBISS.SI-ID: 5394970
The deformation behavior and microstructure characteristics of 304L stainless steel during strip rolling and bar extrusion at different strains and temperatures, from room to liquid-nitrogen temperature, were investigated with Vickers hardness, light microscopy, and electron-backscatter-diffraction. The relative volume fractions of transformed martensite at different stages of the deformation process were assessed using Ferritescope MP-30. It was found that during rolling and extrusion the relative volume fraction of martensite increases with increasing strain and decreasing temperature. According to the enhancement of the mechanical and magnetic properties after isothermal treatment at 673 K (400 °C), it is assumed that both, epsilon-martensite and alpha prime-martensite, are present in the deformation microstructure, indicating the simultaneous stress-induced transformation and strain-induced transformation of austenite. The effects of the laser surface treatment and the local appearance of a non-magnetic phase due to the alpha prime --) gamma transformation after the laser surface treatment were also investigated.
COBISS.SI-ID: 13377307
Over the last decades considerable efforts are made to develop high performance spring steels, which would allow vehicles weight reduction. One way of improving steel properties is by refining its microstructure and reducing amount of inclusions. In the presented work the effect of cleaner and more uniform microstructure obtained through electroslag remelting (ESR) on the mechanical and dynamic properties of spring steel was investigated. Effect of the microstructure refinement was evaluated in terms of tensile strength, elongation, fracture and impact toughness, and fatigue resistance under bending and tensile loading.Results show that while ESR gives some improvement, especially in terms of better repeatability and reduced scattering, it has negative effect on fatigue properties of the spring steel.
COBISS.SI-ID: 1015210
The purpose of this work is to provide experimental evidence on the interactions of suspended nanoparticles with artificial or biological membranes and to assess the possibility of suspended nanoparticles interacting with the lipid component of biological membranes. Consistent with their smaller sized agglomerates, CA-adsorbed CoFe2O4 nanoparticles demonstrate more pronounced effects on artificial and biological membranes. Larger agglomerates of nanoparticles were confirmed to be reactive against lipid membranes and thus not acceptable for use with red blood cells. This finding is significant with respect to the efficient and safe application of nanoparticles as medicinal agents.
COBISS.SI-ID: 3091791