V. S. Sypchenko

Study of coatings based on titanium oxides and oxynitrides using a set of methods

A set of methods has been applied to study the properties of titanium oxide and oxynitride coatings on steel. It is established that the coatings consist of two phases with a nanocrystalline and an amorphous structure with a high proportion (∼50 %) of grain boundaries; anatase is the dominant crystalline phase. The obtained results can be applied in the development of coatings for stents as well as for manufacturing hydrogen accumulators.

Influence of the plasma-immersion ion implantation of titanium on the structure, morphology, and composition of the surface layer of Zr–1Nb alloy

The results of investigating the plasma-immersion ion implantation of titanium into Zr–1Nb alloy from arc-discharge plasma are presented. The investigations are performed using 1.5-kV bias voltage applied to the sample by means of a coaxial plasma filter for 5, 15, and 30 min. Scanning electron and atomic-force microscopy data demonstrate that, after implantation, grains with sizes of ~50–100 nm and craters with lateral sizes varying from ~1 μm to vanishingly small values are detected on the surface. Energy-dispersive X-ray spectroscopy data indicate the formation of an oxide film under titanium implantation. It follows from X-ray diffraction analysis that implanted titanium is in the dissolved state and the crystal-lattice-parameter ratio c/a increases after ion implantation. The layer-by-layer elemental analysis of the implanted layer performed via optical emission spectroscopy is evidence that the titanium-concentration maximum is shifted to larger depths with incresing implantation duration.

Features of the plasma saturation of nanocrystalline and coarse-crystalline titanium samples with hydrogen and deuterium

We investigate the laws governing the saturation of nano- and coarse-crystalline Ti-6Al-4V alloy samples with hydrogen from high-frequency and glow discharge plasmas with a view to finding materials suitable for making hydrogen accumulators. We conclude that nanocrystalline Ti-6Al-4V alloy holds promise for creating hydrogen accumulators, and hydrogen plasma of high-frequency discharge origin is a cleaner hydrogen saturation medium than that of non-self-sustained discharge origin.

Research of Hydrogenation and Dehydrogenation Effect on the Structural and Phase State of the Titanium Alloy

Effect of hydrogen on the structural and phase state of the fine-grained and submicrocrystallinestructure of two-phase (alpha + beta) titanium Ti-6Al-4V alloy was investigated by the methods of electron microscopy and X-ray diffraction analysis. Hydrogenation is found to result in minor structural and phase changes both in fine-grained and submicrocrystalline samples.The use of electron beam exposure combined with heating for hydrogen release in the Ti-6Al-4V alloy is shown to reduce degassing time and decrease the hydrogen concentration to the values closed to the engineering standards for the Ti-6Al-4V alloys.

Investigation of the structure, elemental and phase composition of coatings on the basis of oxynitride titanium deposited by reactive magnetron sputtering

The structure, morphology and properties of titanium-oxynitride coatings deposited by pulsed reactive magnetron sputtering were investigated. The methods of X-ray diffractometry, Raman spectroscopy, secondary ion mass-spectrometry and scanning electron microscopy are used. It is established that the structure, and the elemental and phase composition of coatings depend on the size of the ratio of oxygen/nitrogen in the composition of the reactive gas, and also on the magnitude of the negative bias applied to the substrate. The increase in the fraction of nitrogen leads to a reduction in the speed of sputtering, to a reduction in the contact angle of wetting, an increase in hardness and a reduction in Young’s modulus when a negative offset was used.

On the heterogeneous chemiluminescence of Y2O2S crystal phosphors activated by europium

The results of studying the kinetic and spectral characteristics of the heterogeneous chemiluminescence excited by the products of sulfur-dioxide dissociation (SO + O) are presented. It is shown that heterogeneous SO + O chemiluminescence emerges not only upon the adsorption, oxidation, and desorption of reagents, but also during atom-molecule exchange O + SO2-L → SO-L + O.

Study of Hydrogen Accumulation in Palladium and Silver- Palladium Alloy

This work presents the results of investigation of the hydrogen accumulation characteristics in palladium, silver and palladium-silver alloy (Pd60Ag40) at their saturation with hydrogen from different aggregate states of the ambient medium (plasma, liquid, hydrogen atmosphere).The presence of silver in the alloy of palladium-silver leads to the following features: the capture of hydrogen by Pd and Pd60Ag40 samples depends on the method of saturation. In the case, while plasma and electrolytic hydrogen saturation in both samples is being trapped in the same type of traps (not significantly different in binding energy). While the saturation by Sieverts method takes place, traps formed are characteristic for each type of the samples. In case of electrolytic and plasma saturation in palladium and palladium-silver alloy, the main type of trap is the binding of hydrogen in palladium hydride. Alloying palladium with silver does not lead to decreasing the sorption capacity of the alloy Pd60Ag40 compared to Pd.

Features of hydrogen accumulation in metals during saturation in plasma, electrolyte, and hydrogen under pressure

Features of the temperature spectra of thermally stimulated gas evolution are investigated to determine features of the incorporation of hydrogen into titanium, palladium, and steel of 12Kh12M1BFR grade (metals substantially different with regard to hydrogen solubility) from media of various aggregate states. The conclusions are drawn with regard to the order of filling of high-temperature and low-temperature traps in dependence on the metal and method of saturation.

Hydrogen-Permeability of Titanium-Nitride (TiN) Coatings Obtained via the Plasma-Immersion Ion Implantation of Titanium and TiN Vacuum-Arc Deposition on Zr−1%Nb Alloy

The surface of Zr‒1%Nb zirconium-alloy samples is treated with titanium via plasma-immersion ion implantation (PIII). Afterward, TiN coatings are deposited onto the implanted and initial samples by means of vacuum-arc deposition (VAD). Before and after each of the treatments mentioned above, changes in the hydrogen sorption rate, depth distribution of elements, and surface topography are investigated. It is found that separately performed VAD and PIII reduce the hydrogen sorption rate by a factor of 2‒15. At the same time, a combination of operations so that PIII is carried out before VAD decreases the sorption rate by one‒two orders of magnitude. It is revealed that the key parameter of the aforementioned methods affecting hydrogen permeability, the depth distribution of elements, and the surface topography is the bias value applied to the sample (substrate). In the case of our setup, the optimum biases of PIII and VAD are‒1500 and‒150 V, respectively.

Electron-Stimulated Hydrogen Desorption from Nickel and Palladium

New experimental data are presented on the radiation-stimulated diffusion of hydrogen in metals, in particular, nickel and palladium, under the action of a 30-keV accelerated electron beam. Hydrogen desorption rates from nickel and palladium are determined for thermal and electron beam heating; a substantial shift of the thermal gas-desorption peaks to the low-temperature range is detected upon radiationinduced heating. The presence of an internal hydrogen atmosphere is shown to create favorable conditions for the vibrational-translational exchange (V–T exchange), non-equilibrium redistribution, and desorption of hydrogen from a solid upon irradiation. Accelerated hydrogen migration stimulated by electrons with an energy below the defect-formation threshold is explained at a qualitative level. First-principles calculations of the electronic structure of the metal–hydrogen system reveal that plasmons are also an efficient mechanism for radiation-energy dissipation over the whole crystal.