I. M. Goncharenko

Modification of the Near-Surface Layers of a Copper Foil under the Action of a Volume Gas Discharge in Air at Atmospheric Pressure

We have studied the modification of the near-surface layers of a copper foil under the action of a volume gas discharge, which was generated in air at atmospheric pressure by nanosecond high-voltage pulses of both negative and positive polarity applied between the foil and an electrode with a small radius of curvature. It is established that the surface layer of the discharge-treated copper foil in the central region is cleaned from carbon contaminations, while oxygen atoms penetrate in depth of the foil. The depth of a cleaned layer depends on the polarity of voltage pulses. For the positive voltage polarity on the foil, the cleaning takes place up to a depth exceeding 50 nm, while oxygen penetrates up to a depth of about 25 nm.

Surface modification of steels by complex diffusion saturation in low pressure arc discharge

A technique for surface hardening of type 4140 structural steel is proposed. The technique is based on the use of low pressure arc discharges. The complex treatment in one vacuum cycle involves a sequence of operations: ion cleaning of the surface and heating the sample, diffusion surface alloying with aluminum and nitriding. The sample temperature is not over 620 °C at all stages of the process. The structure, phase and element constitution, and microhardness of the surface layer have been investigated. It has been established that the significant increase in microhardness from 2.5 in the original state to 13 GPa in the modified layer after complex diffusion saturation in an arc discharge is due to the formation of iron nitride containing dispersed particles of aluminum nitride.

UV and IR laser radiation's interaction with metal film and teflon surfaces

The interaction of Xe (λ ∼ 1.73 μm) and XeCl (0.308 μm) laser radiation with surfaces of metal and TiN-ceramic coatings on glass and steel substrates has been studied. Correlation between parameters of surface erosion versus laser-specific energy was investigated. Monitoring of laser-induced erosion on smooth polished surfaces was performed using optical microscopy. The correlation has been revealed between characteristic zones of thin coatings damaged by irradiation and energy distribution over the laser beam cross section allowing evaluation of defects and adhesion of coatings. The interaction of pulsed periodical CO 2 (λ ∼ 10.6 μm), and Xe (λ ∼ 1.73 μm) laser radiation with surfaces of teflon (polytetrafluoroethylene—PTFE) has been studied. Monitoring of erosion track on surfaces was performed through optical microscopy. It has been shown that at pulsed periodical CO 2 -radiation interaction with teflon the sputtering of polymer with formation of submicron-size particles occurs. Dependencies of particle sizes, form, and sputtering velocity on laser pulse duration and target temperature have been obtained.

Nitriding of technical-purity titanium in hollow-cathode glow discharge

The process of nitriding at low pressures and temperatures (≤550°C) in hollow-cathode glow discharge plasma was studied for technical-purity titanium of the VT1-0 commercial grade. The diffusion saturation of titanium with nitrogen in plasma with a concentration of n = 1010–1011 cm−3 takes place at an ion current density on the cathode within 1.6–4.0 mA/cm2. It is established that a key role in the process of metal saturation is played by atomic nitrogen. The experiments revealed the formation of a layer of gradient structure with a high microhardness (∼14 GPa) on the surface of nitrided titanium.

IR- and UV-laser interaction with metal surfaces

The complex of experimental installations for studying of laser radiation interaction with surface of metals has been established. At titanium surface irradiating depending on the accumulated laser radiation energy, the surface color might be changed from bright yellow to red and deep-blue colors. The presented results testify to the possibility to use the change of titanium surface color at heating by laser irradiation in the open air to obtain dot raster images. Presently, form the world data available on interaction of laser radiation with metal and dielectric surfaces and development of experimental diagnostics techniques by itself it is allowed to raise a reverse question, i.e., restoration of laser radiation energy spatial distribution through surface imprint. Using imprints, it is also possible to make an express diagnostics of multi-layer surface coatings. With this in mind, we have made the detailed morphology of imprint of the pulsed HF-laser interaction with carbon steel surface through atomic force microscope.

Study of Fracture of Ti-Al-N Hard Coatings during Sliding Friction Using Acoustic Emission

This paper deals with the study of an interrelation between the parameters of acoustic emission signals and the mode of the friction and wear of Ti-Al-N hard nanocrystalline coatings deposited under various negative bias voltages applied to a specimen. A correlation between the parameters of acoustic signals, processes of coating fracture, and the friction coefficient is found.

Modification of thin metal and ceramic films by UV and IR laser radiation

Investigation of the modes of thin metal and ceramic films (0,3-1 μm) removal from the glass and stainless steel substrate by IR and UV laser radiation has been performed. It is presented that the efficient film destruction and removal occurs due to laser induced thermal strength under laser fluxes of ~0.5 J/cm2 not sufficient for phase transformation.

Study on the interaction of Xe and XeCl-laser radiation with metals and ceramics

The interaction of Xe- (λ~1.73 µm) and XeCl- (0.308 μm) lasers radiation with surfaces of metal and TiN-ceramic coatings on glass and steel substrates has been studied. Correlation between parameters of surface erosion (area of crater and amount of evaporated material versus laser focus position and number of pulses) was investigated. Monitoring of laser induced erosion on smooth polished surfaces was performed using optical microscopy. The correlation has been revealed between characteristic zones of thin coatings damaged by irradiation and energy distribution over laser beam cross section allowing evaluation of defects and adhesion of coatings.