L. Kertész

On the formation of electroless amorphous layers. I. Phenomenological description of NiP deposited on Cu and Fe substrates

Abstract The formation of amorphous NiP coating by electroless deposition on to copper and iron substrates has been followed by soft X-ray emission spectroscopy (SXES), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Three different stages of formation can be distinguished. The first period is nucleation in an essentially two-dimensional layer where the formation of nuclei depends on the number and properties of the active sites on the underlying substrate layer. There is a three-dimensional spherical growth in the second stage. The concentration of phosphorus increased in the interspherical area. A relatively slow two-dimensional growth is characteristic of the third stage giving rise to a bright outer surface of the coating.

The process of formation of amorphous Ni-P layers made by electroless deposition☆

Abstract The composition, electronic states and structure of thin Ni-P layers deposited by the electroless method were studied by soft X-ray emission spectroscopy, differential thermal analysis, secondary ion emission, X-ray diffraction and auxiliary microscopic investigations. The first centres of the layer consisted of pure crystalline nickel nuclei. With increasing growth, the deviation from crystallinity increased, with continous changes in the composition. Also, diffusion processes take place transporting aluminium and silicon from the underlying substrate.

Study of morphology and composition of Pt-black catalysts: II. SXES investigations of Pt-black

Abstract Soft X-ray emission spectroscopy (SXES) of Pt-black samples has been studied. The shape, position and eventual shift of Pt, Si, O and C transitions has been followed. Fresh Pt samples show mainly the highest NVII platinum peak. The temperature of reduction influences the SXE spectrum only slightly. Upon sintering in hydrogen, OII–III and NVI transitions also appear and the same occurs when the sample is sintered in situ, under the electron beam. Si lines confirm the existence of oxidized silicon in the surface layers. The higher the temperature of sintering, the more graphitic the structure of surface carbon, although even at 750 K it does not correspond to pure graphite. Adsorbed and chemically bound oxygen to platinum and to its nonmetallic impurities has been found. Tentative suggestions have been put forward to explain the spectral characteristics observed partly by electronic interactions and partly by the chemical effects of impurities.

Correlation between the structural and electronic stability factors

Abstract A correlation between electronic density of states and heat of crystallization for FeSiB and FeWB amorphous metals was observed. The stabilization effect of electronic structure on the amorphous metastable state is demonstrated.

On the metastable states of amorphous Fe84-xWxB16 (0 ≤ x ≤5) alloys

Abstract A stability investigation of Fe 84− x W x B 16 alloys is given for the interdependence of thermal properties of crystallization and changes in the electronic structure. For the thermal analysis and for electronic structure, DTA and SXS methods were used, respectively. A systematic interaction of the electronic structure and the heat of crystallization was observed. Based on this data, the role of the electronic structure in the stability is determined. General remarks on stability are given from the trends of measured data.

The surface chemical bonding investigation of CVD coated tool-steel

Abstract The main task of the present paper is the investigation of special cutting tool-steel, coated with TiC and TiN compounds. The tools were tested in different states by soft X-ray emission spectroscopy (SXES) in the regions of the CKα NKα FeLa and OKa emission peaks of the compounds, and they were investigated at different depths of the coating layer. The emission lines of the steel holder and its surroundings appear at depths of more than 600 nm. Shifts of the OKa peak and the fine structure changes in it show clearly the corrosion steps and states of the used tools, corresponding to the degree of use. The measurements prove clearly that heat treatment is a sensitive step in the technology of preparation of the CVD coated tool-steel. Exposure to oxygen during heat treatment decreases the life of the tool drastically.

The SXES study of the amorphous Ni-P compounds

Abstract The aim of this work is the study of the electron states of Ni-P compound layers made by an electroless technique using soft X-ray emission sdpectroscopy (SXES). The information from SXES depends on the thickness and state (amorphous or crystalline) off the samples. There is a systematic change in the emission lines of nickel and phosphorus between the amorphous and crystalline states. In the amorphous state the main peaks are shifted and the fine structure has a blurred shape as compared to the crystalline state. The shift and the fine structure changes in spectra can be explained by the transformation of the chemical bonds and the symmetries within the compounds. The difference in fine structure of the Cu emission line caused by the chemical bonds due to the surface covering is also studied.

Changes in AlMgSi surface layers at different temperatures

Abstract It is possible to determine temperature ranges caused by electron beams under high voltage conditions. Combining the radiation power of the SXES equipment with the DTA curves we were able to make conclusions concerning the temperature range during the radiation time. Heat treatments under vacuum and continuous SXES measurements show a shift of the Fermi level and a change in the fine structure of the AlMgSi surface.

The interdependence of electronic and thermal stability factors of FeBSi metallic glasses

Abstract The effect of electronic structure on the stability of FeBSi amorphous alloys is compared with thermal effects as measured by soft X-ray fluorescent spectroscopy and differential thermal analysis. A linear dependence is found between the half band width (HBW), crystallization temperature ( T c ), and the amount of heat of crystallization ( ΔQ ) with electron concentrations. The results are explained in the light of recent theories. This explanation leads to the conclusion that the stability of the amorphous and intermediate states are stabilized by electronic structure.

The metastable states of some amorphous FeB alloys

Abstract The interdependence of the electronic and thermal properties and their effect on the stability of some Fe 86.5− x TM x B 13.5 (TM is transition metal, 0≦ x ≦5) alloys is investigated. Differential thermoanalysis and soft X-ray fluorescent spectroscopy were used to measure the thermodynamic phase changes and the partial electronic density of states, respectively. A general role of the electronic effects on the thermal stability is suggested from the trend of the measured data. It is concluded that the thermal stability is effectively controlled by the actual electronic structure of the alloy.