Irregular Electrodeposition of Cu-Sn Alloy Coatings in [EMIM]Cl Outside the Glove Box with Large Layer Thickness

Thick Cu−Sn alloy layers were produced in an [EMIM]Cl ionic-liquid solution from CuCl2 and SnCl2 in different ratios. All work, including the electrodeposition, took place outside the glovebox with a continuous argon stream over the electrolyte at 95 °C. The layer composition and layer thickness can be adjusted by the variation of the metal-salts content in the electrolyte. A layer with a thickness of up to 15 µm and a copper content of up to ωCu = 0.86 was obtained. The phase composition was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray fluorescence (XRF). Furthermore, it was found that the relationship between the alloy composition and the concentration of the ions in the electrolyte is described as an irregular alloy system as according to Brenner. Brenner described such systems only for aqueous electrolytes containing complexing agents such as cyanide. In this work, it was confirmed that irregular alloy depositions also occur in [EMIM]Cl.

The Morphology, Structure, Mechanical Properties and Biocompatibility of Nanotubular Titania Coatings before and after Autoclaving Process

The autoclaving process is one of the sterilization procedures of implantable devices. Therefore, it is important to assess the impact of hot steam at high pressure on the morphology, structure, and properties of implants modified by nanocomposite coatings. In our works, we focused on studies on amorphous titania nanotubes produced by titanium alloy (Ti6Al4V) electrochemical oxidation in the potential range 5–60 V. Half of the samples were drying in argon stream at room temperature, and the second ones were drying additionally with the use of immersion in acetone and drying at 396 K. Samples were subjected to autoclaving and after sterilization they were structurally and morphologically characterized using Raman spectroscopy, diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) and scanning electron microscopy (SEM). They were characterized in terms of wettability, mechanical properties, and biocompatibility. Obtained results proved that the autoclaving of amorphous titania nanotube coatings produced at lower potentials (5–15 V) does not affect their morphology and structure regardless of the drying method before autoclaving. Nanotubular coatings produced using higher potentials (20–60 V) require removal of adsorbed water particles from their surface. Otherwise, autoclaving leads to the destruction of the architecture of nanotubular coatings, which is associated with the changing of their mechanical and biointegration properties.

Production of Al-Si Alloys by the Direct Silicon Reduction from the Amorphous Microsilica

The survey of modern methods of silumins obtaining has been conducted. The prospects of silumins obtaining using amorphous silica caused by, firstly, with a high yield of silicon production waste; secondly, with the lost profit from their industrial use and, thirdly, with the increasing of efficiency of silumins production process by omitting partially the energy-consuming stage of metallurgical silicon production. Thermodynamic possibility of silicon dioxide reduction in aluminum melt has been determined. The method of aluminum-silicon alloys production by introducing preheated amorphous silica into the aluminum melt together with argon stream (with subsequent intensive mixing and casting into the electromagnetic crystallizer) has been studied. It has been determined that this method can allow to produce pre-eutectic aluminum-silicon alloys with more than 5 wt.% of silicon.

Combined Method for the Synthesis of Ultrafine Powder Carbides of W, Ti, V

In this work we propose a new method for synthesis of ultrafine powders of tungsten, titanium and vanadium carbides combining two methods – liquid-phase precipitation on carbon substrate and low-temperature microwave heat treatment in argon stream. An entire spectrum of intermediates obtained by thermolysis, reduction and carbonization of precursors, as well as the final products has been presented. As a result of sample assessment, the phase composition, structure, morphology and particle size, as well as the size of specific surface areas have been determined.

Polyol-mediated preparation of disklike (ZnSe)2·EN precursor and its conversion to ZnSe crystals with quasi-network structure

In this paper, we reported the rapid synthesis of disklike (ZnSe)2·EN precursor via a simple and convenient polyol method. Annealing the precursor in argon stream at 500 °C resulted in the formation of ZnSe crystals with unique quasi-network structure. The obtained samples were characterized by powder x-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, infrared absorbance spectra, and thermogravimetric analysis. The influence of PEG200 on the final products in the system was also discussed.

New Dinuclear Mn(II) Phenanthroline Adipato Complex: Synthesis and Structural and Thermal Characterization of Mn2(phen)2(H2O)2(C6H8O4)2

Reaction of freshly precipitated Mn(OH)2−2x(CO3)x · yH2O, adipic acid and phenanthroline in CH3OH/H2O afforded a new dinuclear Mn(II) complex, Mn2(phen)2(H2O)2(C6H8O4)2 1, aside the known [Mn(phen)2(H2O)(C6H8O4)]·7H2O 2. Single crystal X-ray analyses showed that complex 1 consists of the centrosymmetric dinuclear molecules resulting from two [Mn(phen)(H2O)]2+ moities bridged by two twisted tridentate adipato ligands. The Mn atoms are each in severely distorted octahedral geometry defined by two N atoms of one phen ligand, three carboxyl O atoms of two adipato ligands and one H2O molecule with d(Mn-N) = 2.246 and 2.296 Å and d(Mn-O) = 2.066 - 2.339 Å . The complex molecules are assembled via π-π stacking interactions into 2D layers, which are held together by both strong O-H ··· O and weak C- H ··· O hydrogen bonds. The thermal behavior of 1 and 2 upon heating in argon stream is discussed.

Some problems connected with boron determination by atomic absorption spectroscopy and the sensitivity improvement

Two atomizers were compared: an N2O-C2H2 flame and a stabilized U-shaped DC arc with aerosol supply. Both the high plasma temperature and the reducing atmosphere obtained by acetylene addition to the argon stream substantially increase the sensitivity of boron determination by atomic absorption spectroscopy (AAS) when the arc atomizer is used. The results were compared with those for silicon as a control element. The experimental characteristic concentrations for both elements were compared with the computed values. The experimentally obtained characteristic concentration for boron when using the arc atomizer was in better agreement with the calculated value. It was estimated that the influence of stable monoxide formation on the sensitivity for both elements was about the same, but reduction of analyte and formation of non-volatile carbide particles was more important for boron, which is the main reason for the low sensitivity of boron determination using a flame atomizer. The use of an arc atomizer suppresses this interference and significantly improves the sensitivity of the determination.

Wear-Induced Changes in the Raman, Infrared, and Fluorescence Spectra of Silicon Nitride Surfaces

Commercial α-silicon nitride plates and balls used in simulated sliding bearing tests were found to fluoresce under 514.5-nm argon-ion laser excitation after heating to above 350 °C in a stream of argon. Wear track areas fluoresced much more intensely than their surroundings. When small concentrations of ethylene or other carbonaceous gas were added to the argon stream, carbonaceous deposits formed primarily in the wear track in amounts roughly paralleling the fluorescence intensity. Some of the deposits were lubricating carbon and some nonlubricating silicon oxycarbide. Continuous high-temperature lubrication was possible by balancing deposit removal by wear with surface-chemical deposit formation rates. Raman, infrared, fluorescence, and other spectroscopies helped explain the process. Defect energy states within the large silicon nitride energy gap and dangling bonds appear to play a role.