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Results of studies of the morphology, elemental and phase compositions of coatings prepared by pulsed magnetron sputtering of the AlN-TiB2-TiSi2 composite ceramic target have been reported. The used technology allows us to prepare a protective amorphous-like layer with ordering areas with sizes up to 1 nm. The heat treatment of samples at 900 and 1300°C leads to the depletion of the coating surface of boride phases and the formation of α-Al2O3- and β]-TiO2-based protective films on the surface. The growth of crystallites of the nanostructured coating to 11–25 nm is observed. The annealing at 1300°C allows us to obtain the thermally stable crystalline state of substance, the nanohardness of which is 11 GPa.

Samples of steel St3 with Ni-Cr-B-Si-Fe coatings deposited using a plasma jet with subsequent partial melting of the coatings by a plasma jet have been investigated for the first time using the methods of Rutherford backscattering spectroscopy, scanning electron microscopy, X-ray fluorescence analysis, X-ray photoelectron spectroscopy, and nanoindentation. The structure and the phase and elemental compositions of these coatings have been studied. Ni-based nanocrystalline phases and CrNi3-based microcrystalline phases with crystals from 50 to 150 nm in size, extended defects of the microstructure, and nanoregions with different orientations of the crystal lattice and grain sizes on the order of 2–3 nm have been found.

New findings of studies of the structural, tribological, and physicomechanical characteristics of structural steel 40Kh treated by plasma flow under melting accompanied by either tungsten or molybdenum alloying are presented. Rutherford back-scattering of ions, scanning electron microscopy (with microanalysis), X-ray fluorescent spectral analysis, X-ray phase analysis, wear-resistance tests, measurement of the coefficient of friction, and transmitting electron microscopy with diffraction are the basic research methods. It is found experimentally that a thin layer 5 μm thick saturated with nitrogen and an alloying element (Mo or W) with regularly arranged crystallites arises on the steel 40Kh surface. The crystallites in this layer have a needle- and ribbon-shaped structure. A deeper layer located about 40 μm thick consists of micro- and nanosized grains. Friction and wear studies of the plasma-flow treated (melt) samples show the steel wear resistance to increase 2–2.5 times and the coefficient of friction to decrease from 0.4–0.5 to 0.10–0.15 compared to the untreated samples.

A new type of coating is developed, which is a mechanical mixture of two different powders, namely, Ni-Cr-B-Si-Fe (PG-19N-01) and WC-Co (hard alloy). After the coatings from this mixture are deposited, their surface layer is fused with a plasma jet using an eroding electrode made of W. The additional treatment of the coatings with the plasma jet yields new phases and causes the redistribution of elements in the layer 45–60 μm deep; the percentage ratio of the phases WC, α-CoCr, Co, and Ni, as well as Cr3Ni2 + γ-(Fe, Ni) appearing during coating deposition also changes. The redistribution of elements occurs in the upper coating layer owing to fusion with the plasma jet. These processes yield variations in the physical-mechanical properties of the coatings, such as the hardness and elastic modulus; the coating wear rate decreases severalfold. It is found that with increasing load applied to the Berkovich pyramid the elastic modulus of the coating drops from 240 (at an indentation depth of 50 nm) to 175 GPa (at 150 nm). The elastic modulus of the substrate rises from 25 to 42 GPa. The coating hardness calculated from the loading-unloading curves is 15.3 to 10.6 GPa under increased load applied to the indentor. Specimens covered with the coating fused with the plasma jet in three passes demonstrate the lowest material wear.

Results of studies of the morphology, elemental and phase compositions of coatings prepared by pulsed magnetron sputtering of the AlN–TiB2–TiSi2 composite ceramic target have been reported. The used technology allows us to prepare a protective amorphouslike layer with ordering areas with sizes up to 1 nm. The heat treatment of samples at 900 and 1300°C leads to the depletion of the coating surface of boride phases and the formation of αAl2O3 and β]TiO2based protective films on the surface. The growth of crystallites of the nanostructured coating to 11–25 nm is observed. The annealing at 1300°C allows us to obtain the ther mally stable crystalline state of substance, the nanohardness of which is 11 GPa.

The coating of the AlN-TiB2-TiSi2 system has been produced by the magnetron sputtering of a target. At the high-temperature (900 and 1300°C) actions the coating crystallization to form crystallites of sizes 11–25 nm has been observed. It has been defined that the amorphous-like structure is promising for the use of these coatings as diffusion barriers both as the independent elements and a contacting layer in multilayer wear-resistant coatings. It has been shown that the use of the resultant composite as an effective protective coating for cutting tools will make it possible to increase the tools wear resistance by more than 30% at the temperature up to 1300°C in the cutting zone.

The oil system of a high-pressure centrifugal compressor for transportation of natural and petroleum gas is one of the important systems in the design of gas-pumping units of gas and petroleum and gas industry compressor stations. The basic plan of a high-pressure centrifugal compressor oil system is shown in Fig. 1. The basic functions of the oil system are delivery of oil to the annular and thrust bearings and the toothed coupling, sealing of the centrifugal compressor by delivery of oil to the end seals with a pressure somewhat higher than the gas pressure in the sealed cavities, removal of oil from the gas cavities of the centrifugal compressor under pressure with subsequent degassing of it, cooling and filtration of the oil, and elimination of leaks into the tank. To a significant degree the oil system of a centrifugal compressor determines the operating reliability of the unit as a whole. Design decisions made in the stage of development of the centrifugal compressor to a significant degree depend on the operating costs, which are influenced not only by the unplanned shutdowns of the unit but also by the irreversible losses of oil. Both the end seals and the system for removal of oil, the basic elements of which are the oil-water separators (Fig. 1) designed for removal of oil, condensate, and other liquids from the gas cavities under pressure in the whole range of operating pressures of compressors, have a substantial influence on the oil losses and operating reliability of the off system. As is known, in centrifugal compressors, oil-water separators in which the relief valve is made in the form of a needle, a ball, or a gate and connected by a system of levers with a float providing opening of it are most frequently used [1]. With an increase in operating pressure there is an increase in the force clamping the relief valve to the seat of the overflow valve, which in turn requires an increase in the lifting force of the float. The force of action of the float on the relief valve may be increased by increasing the float diameter or the amplification factor of the lever system. In this case there is an increase in the dimensions of the off-water separator and, consequently, in its metal content and also in its cost and, most importantly, a decrease in its reliability. The M. V. Frunze Sumy Machine Construction Scientific-Production Association (SMNPO) Joint-Stock Company (AO) has developed an off-water separator design (Fig. 2) providing high throughput and distinguished by simple and reliable operation at high operating pressures [2]. The oil-water separator consists of the welded housing 2 with the fittings 5 and 6, respectively, for supply of the liquid-gas mixture and removal of the gas and also the base 1, in which a channel is made for draining of the oil and a two-stage drain mechanism connected by the level system 3 to the float 4 is located. The two-stage drain mechanism (Fig. 3) includes a supplementary valve and the main slide valve located in the housing 5, in the bottom of which is the drain channel 6. The supports of the lever system 4 and 13 are fastened to plate 12, which in turn is fastened to the housing of the drain mechanism. To compensate the weight of the float and the lever system the relief device with spring 11 is located on the plate. The supplementary valve is located with a sliding fit i~ the guide sleeve 1, which is rigidly fastened to the housing 5. The main valve operating the internal cavity of the housing into the above-the-valve A and the drain B chambers is located in the holes of this housing with a sliding fit. The drain chamber is connected by holes with the inner cavity of the oil-water separator and the above-the-valve chamber by the guaranteed gaps 9 and 10, respectively, with the drain chamber and the internal cavity of the oil separator. The main valve is tightened by spring 7 and has an axial channel 8 shut off by the supplementary valve. In the general condition, that is, in the absence of oil and pressure in the cavity of the oil -water separator, under the action of the float and the lever system, spring 11 of the relief device is compressed and the supplementary valve covers the axial channel and, simultaneously compressing the spring under it, presses it to the seat of the drain channel. With an increase