XPS Studies of the Initial Oxidation of Polycrystalline Rh Surface

Increased interest in the oxidation process of polycrystalline rhodium, observed in recent years, is the result of its application in exhaust catalytic converters. However, most studies have involved sample surfaces with low Miller indices. In our research, we investigated polycrystalline rhodium foil containing crystallographically different, highly stepped, µm-sized crystallites. These crystallites were exposed to identical oxidizing conditions. To determine crystallographic orientation, the electron backscattering diffraction (EBSD) method was used. To investigate the initial stages of oxidation on the individual crystallites of Rh, X-ray photoelectron spectroscopy (XPS) studies were performed. The results obtained for the individual crystallites were compared and analyzed using chemical state quantification of XPS data and multivariate statistical analysis (MVA).

Phenomena of Adiabatic Shear Bands Forming of Structural Steels Under Impact Load Conditions

The paper presents the results of an experimental study on adiabatic shear bands (ASB) in two grades of steel with three different microstructures. Samples were subjected to impact forces in order to obtain a targeted shear band. The process of deforming the samples was carried out with a bar impact rod moving at high speeds in the range of 1.4 m/s to 16.5 m/s was carried out. Microstructural studies of deformed samples were performed using the Electron Backscatter Diffraction (EBSD) method. The results of the experiments show that the ASB type depends on the initial microstructure of the material and the deformation speed. It has been shown that, depending on the type of microstructure, ASBs are characterized by a different mechanism of formation and show different character.

The Problem of Copper Softening During Cold Gas Dynamic Spraying

The effect of the gas-dynamic (cold) spraying of the Cu-Al2O3-Zn powder mixture on the microstructure and strength of the copper substrate is investigated. A copper cold drawn contact wire was used as a substrate. We propose using gas-dynamic cold spraying to restore the local wear of the contact wire. The study of the microstructure using the electron backscattered diffraction (EBSD) method showed the presence of grain orientation characteristics of the cold drawing of copper. Recrystallization of the surface layers of the contact wire during spraying does not occur. Using the microhardness measurement, the absence of softening of the layers of the contact wire with a depth of up to 2 mm is shown. The results of mechanical tests show that spraying does not lead to a decrease in the tensile strength of the contact wire. The results of creep tests show that spraying does not lead to a decrease in the heat resistance of the contact wire.

THE CHARACTERISTICS OF Al-Si COATING ON STEEL 22MnB5 DEPENDING ON THE HEAT TREATMENT

The coating on the 22MnB5 steel is intended to protect it against oxidation during the forming process. This steel is hot-pressed. A preheating before the pressing and subsequent hardening in the tool affects the properties of the AlSi coating. This study summarizes the results of investigating the effect of heat treatment parameters on the formation of intermetallics in the AlSi coating. The chemical analysis of the coating was performed by the EDX and EBSD method and the mechanical properties were determined by the Hysitron TI 950 TriboIndenter™ system. The result of this study is that, due to a diffusion during the heat treatment, the brittle coating was transformed into a tougher phase.