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Temperature-programmed desorption (TPD) has been applied for the first time to a study of time-dependent outgassing process from a metal surface. The TPD area which corresponds to the adsorbate coverage, decreased with the pumping time t, whose temporal dependence t -β/(1-β ) quantitatively agreed well with what was predicted by the Freundlich adsorption isotherm...
Ti-Al and Ti-Si alloys were prepared by RF sputtering in a low-pressure argon atmosphere. The microhardness and thermal stability of these alloys were investigated in relation to the structure of alloys. In Al-Ti system, an amorphous phase and AlTi 3 were formed in the composition range of 35-60at%Ti and 60-80.5at%Ti, respectively. In Al-Si system, an amorphous phase was formed for Si content...
CO adsorption properties of the bimetallic Pd/Al systems have been studied using thermally programmed desorption (TPD) and X-ray photoelectron spectroscopy (XPS) under UHV conditions. The samples were prepared by vacuum evaporation of Pd onto pure Al substrates. Measured TPD and XPS spectra of CO from bimetallic surfaces were compared to the ones of clean bulk metals. The deposited Pd ad-layers exhibited...
Recent extensive studies of triboemission of electrons revealed a key role of insulating capabilities of solids forming sliding contact on the intensity and behavior of emission processes. Also, it was found that the dominating emission mechanisms differ for insulators and conductors. In consideration of these substantially different natures of electron triboemission from solids of different insulating...
The rate of removal of a thin film of organic impurities during discharge cleaning in pure oxygen plasma was studied. Aluminum discs with a thickness of 2mm and a diameter of 18mm were first cleaned and then covered with a thin film of a polymer. The thickness of the film was estimated by AES depth profiling and was found to be about 36nm. The samples were exposed to oxygen plasma. The plasma density...
An analytical theory of size-dependent energetic characteristics of a metal film is developed in a free-electron model and a finite square potential well. A regular expansion of energetic characteristics in terms of 1/L is performed. The errors occurring at each step of the expansion are analyzed. This simple model allows to calculate size oscillations of the Fermi energy and the work function.
The paper describes the development of methods for hardening of pieces of aluminum alloys by ion-induced deposition of Cr–N films. We investigated the nitrogen distribution in the films and in the aluminum substrate. The method of secondary ion mass-spectrometry (SIMS) and a nuclear reaction method (NRM) were used in the study described. A computer model was developed that allowed us to describe the...
A Pd–Al bimetallic system was prepared on a MgO (001) single-crystalline substrate surface by vacuum deposition. The early stages of the growth in dependence of Pd and/or Al deposition sequence were studied. The reflection high-energy electron diffraction method was used for structural investigation during the deposition. The results can be interpreted in terms of formation of stable Pd–Al alloy covered...
The results of the surface treatment of commercial aluminum by nitrogen ion implantation at 120keV and implanted fluences ranging from 3×l0 17 to 1.1×10 18 ions/cm 2 are reported. The treatment was found to lead to the formation of the hexagonal phase AIN, a decrease in strain and an increase of crystallite sizes. The modification of the surface layer so produced was thought...
Angular distributions for grazing scattering of C60+ fullerenes with energies of up to some 10keV from an atomically clean and flat Al(001) surface are studied. Scattering proceeds in the regime of surface channeling where the motions of projectiles parallel and normal to the surface are widely decoupled. At low energies for the motion with respect to the surface normal, the clusters are scattered...
Small amounts of metallurgical grade silicon were melted in an electron beam furnace in different experimental conditions in order to investigate the aluminum (Al) evaporation behavior during the electron beam melting (EBM) process. Impurity was significantly decreased in the early periods of melting at 9, 15, and 21 kW. These changes slowed down with the extension of the melting time. Moreover, the...
The chlorination process in aluminum production by carbothermic-chlorination reduction of Al 2 O 3 under vacuum has been investigated by XRD, SEM and thermodynamic analysis. The results of thermodynamic calculations indicated that the chlorination of Al 4 C 3 or Al 4 O 4 C possibly proceeded at temperature 1300 °C under 5–50 Pa. The experiment results...
Thin films of metal for electronics, nano/microelectromechanical systems and optical coatings are often prepared by various vacuum deposition techniques. Modeling such metal vapor flows using methods such as the direct simulation Monte Carlo (DSMC) can aid in the design and analysis of deposition systems and accelerate development of films with desired properties. The determination of suitable variable...
The purification of metallurgical grade silicon, especially the removal of aluminum, was investigated by electron beam melting and solidification. Small amounts of silicon raw materials were melted in an electron beam furnace with same melting time and different solidification time to obtain the distribution of Al in silicon ingot. The removal mechanisms in different stages were also discussed. The...
Success of third and fourth generation light sources is highly dependent upon the smoothness of internal surfaces in small aperture undulators. The ratio of the undulator length to the chamber aperture is very large, making mechanical polishing difficult to implement. Chemical polishing is a viable alternative option. This study investigates the effectiveness of a chemical polishing step as a finishing...
We propose a simple numerical model for distribution of Aluminum (Al) in silicon ingot during vacuum directional solidification, including segregation from silicon crystal to silicon melt as well as evaporation from silicon melt to vacuum atmosphere. According to the model, the effective segregation K eff and the total evaporation coefficient k T(Al) of Al under the experimental conditions...
Few investigations have been carried out on the influence of the variation of pulse current parameters on the anodized aluminum. The present paper deals with some experimental results regarding the influence of pulse current parameters on the nanostructure and color absorption ability of colored anodized aluminum. Under these conditions, the nanostructure and the color were found to be dependent on...
The use of a short coaxial plasma line termed the “plasma bulb” has been investigated for enhancement of the wettability of aluminum (Al) and polymethylmethacrylate (PMMA) surfaces. In comparison with other plasma lines, the plasma bulb uses a single magnetron for microwave generation that could produce plasma for surface treatment. For the treatments of Al and PMMA surfaces, various plasma parameters...
The vacuum volatilization of aluminum from silicon melt is studied by the molecular interaction volume model (MIVM) in this paper. The activities and activity coefficients of components in the Si–Al binary melt were investigated based on the MIVM and the results show that the predicted values of activities are in good agreement with the experimental data. The infinite dilution activity coefficients...
The Taiwan Photon Source (TPS) is a 3 GeV third generation accelerator light source. The vacuum systems contain an electron storage ring (SR) of 518.4 m in circumference and a concentric booster (BR) of 496.8 m in circumference, linked with the transport lines one from the booster to storage ring (BTS) and the other from the linear accelerator to the booster (LTB). To ensure the highest stability...
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