Alexander Berner

Study of the wear behavior and adhesion of diamond films deposited on steel substrates by use of a Cr–N interlayer

Abstract In the present work, we report on the wear behavior and adhesion of diamond films deposited on steel coated by a Cr–N interlayer. The wear behavior of the diamond films was studied under fretting conditions. Fretting was used as a typical wear process occurring during vibration and friction. Wear grooves obtained after the fretting test under different loads and for different numbers of cycles were studied by profilometry, high-resolution scanning electron microscopy and electron probe microbeam analysis. The adhesion of the deposited diamond films was measured by using scratch and indentation tests. The fracture behavior of the diamond film/nitrided chromium interlayer complex under different conditions was studied and correlated to the interlayer nitridation conditions.

Influence of CrN interlayer properties on the initial stages of CVD diamond growth on steel substrates

Abstract In our previous works, CrN interlayers have been reported to be a successful solution for the deposition of good adhered diamond films on steel substrates. The properties of the CrN interlayer have been found to have a strong effect on the initial stages of CVD diamond formation. In the present work, the effect of different nitridation temperatures on the initial stages of CVD diamond growth are reported. Surface morphology, incubation time and diamond particle density at the initial stages of deposition were studied by High Resolution Field Emission Gun Scanning Electron Microscopy (HR FEG SEM). Raman Spectroscopy was used to determined the quality of the deposited films, the presence of sp2-bonded carbon and residual stress in the diamond films. Phase composition and element profiles across the interlayer were investigated after different pretreatments and as a function of deposition time using X-ray Diffraction (XRD) and quantitative Electron Probe Microbeam Analysis (EPMA). Adhesion of the deposited diamond films to substrates nitrided at different temperatures was evaluated by the indentation technique, and was correlated with substrate surface morphology.

Microstructure of reaction zone at the Ti–AlN interface

Abstract The phase composition of the reaction zone between Ti matrix and AlN particles was investigated employing electron probe X-ray microanalysis (EPMA) and electron backscatter diffraction techniques (EBSD) in scanning electron microscopy (SEM). The TiN (cubic, NaCl type), Ti3AlN (cubic, perovskite type) and Ti-rich Ti3Al (hexagonal, Ni3Sn type) phases were identified in the reaction zone after anneals at 900, 1000 and 1100°C. The binary nitride TiN and the ternary nitride Ti3AlN exhibit a complex interpenetrating morphology. A two-phase, Ti3AlN/Ti3Al, lamellar region was observed between the Ti3AlN and Ti3Al layers after annealing at 1000 and 1100°C.

Electron Energy-Loss Near-Edge Structure of Alumina Polymorphs

In the present work the electron energy-loss near-edge structures (ELNES) of γ- and δ-Al2O3, both based on f.c.c. packing of oxygen anions, was investigated. The spectra were interpreted in terms of the relative occupancy of tetra- and octahedrally coordinated sites within the oxygen sublattice. This relative occupancy was found to be similar for both structures.

Effect of impurities on initial stages of phase formation for the system of Ti deposited on (001) Si–Ge layers

Effect of impurities (oxygen, carbon) on initial stages of phase formation for the system of Ti overlayer deposited in a 2×10−7 Torr vacuum on Si0.82Ge0.18 layers epitaxially grown on (001) Si has been studied by Auger electron spectroscopy, X-ray powder diffractometry, conventional and high resolution transmission electron microscopy and energy dispersive spectroscopy. The change in impurity contents at the Ti/SiGe interface was realized by changing the thickness of the Ti overlayer. Two sets of Ti/SiGe/Si samples with 10 and 60 nm thick Ti were investigated. It was shown that for the samples with 60 nm thick Ti the content of the oxygen and carbon at the Ti/SiGe interface was one order of magnitude lower than that in the samples with 10 nm thick Ti overlayer. The first crystalline phase formed as a result of annealing at a vacuum better than 2×10−7 Torr was Ti5(Si,Ge)3 for samples with a high level of the impurities and C49-Ti(Si,Ge)2 for samples with a low level of the impurities. An amorphous phase was revealed for both sets of specimens during the initial stages of phase formation. The results obtained were interpreted within the framework of a recently developed model of phase formation.

Quantitative EPMA of element depth distribution

A new model for the ionization depth distribution function has been proposed. Within the framework of this model full electron flux is considered to be divided into two fluxes propagating in forward and backward directions through a sample. The intensities of these fluxes can be derived on the basis of simple assumptions of electron-solid interactions. The approach can be effectively applied to a system with an arbitrary form of depth concentration profile. The obtained results are in reasonable agreement with Monte Carlo simulations and experimental results. Some mathematical techniques have been presented for quantitative analysis of thin films on substrates and element depth distribution.

Novel sample preparation technique for the study of multicomponent phase diagrams

Abstract A technique for alloy sample preparation, based on thin film deposition, has been developed for a study of binary and ternary compositions. Thin elemental wedge-shaped layers of the components were gradually sputtered in an alternating manner to form multilayered structure. The samples obtained had compositions which depended upon their location on the substrate. Such samples, containing differently composed AuAgCu alloys were heat treated to promote formation of stable phases. The alloys thus formed were studied by X-ray diffraction and various microscopic techniques. This article demonstrates the advantages of this method over conventional bulk-based methods.

Quantitative Analysis of Ti-Si-Ge/Si-Ge/Si Structures by EDS and AES

Abstract. A method for quantitative analysis of Ti-Si-Ge/Si-Ge/Si structures with submicron thick layers by energy dispersive spectroscopy (EDS) in transmission electron microscopy (TEM) and Auger electron spectroscopy (AES) was developed. Quantitation of the results of both AES and EDS techniques was performed on the basis of a single reference specimen for the Ti-Si-Ge system comprising a uniform layer of the Ti(Si0.85Ge0.15)2 phase on a silicon substrate. The reference sample was prepared by the same procedure as the samples used in the study, and was thoroughly characterized by X-ray diffractometry, transmission electron microscopy and energy dispersive spectroscopy in scanning electron microscopy. Using this reference sample the elemental sensitivity factors relative to Si were found for both techniques, which enable us to obtain the elemental depth distributions for the studied samples. Good agreement between the results obtained by EDS/TEM, AES and supplementary techniques was found.

Effect of Chromium Substrate Pretreatment on Diamond Growth by the Chemical Vapour Deposition Method

The effects of nitriding and carburizing chromium substrates on the nucleation of CVD diamond were studied. Surface morphology, incubation time and diamond particle density at the initial stages of deposition were examined using high resolution scanning electron microscopy (HRSEM) as a function of the substrate pretreatment. The presence of amorphous carbon, as well as residual stress in the deposited films were determined by Raman spectroscopy.

Computer Simulations of the X-Ray Intensity Distribution from Submicron Particles Embedded in a Matrix

Computer simulations of the X-ray intensity distribution from submicron particles embedded in a matrix were performed. The results of simulations confirmed the possibility of approximation of the real X-ray distribution by a finite distribution with the same integral and mean value. It was shown that the mean particle size can be calculated from the coefficient of variation of the measured mass concentration with a reasonable degree of accuracy. In addition, the possibility to determine the coefficient of variation of the particle size from the skewness of the concentration distribution was shown.