Four plasma cermet coatings with similar compositions based on TiC carbide and NiCrMo matrices with additional Cr3C2, WC carbides, and carbon were studied. The average oxygen content for four cermets increases from 0.51 % for powders to 0.86 % for coatings with a minimum plasma power and does not increase with its increase. The maximum average nitrogen content in the coatings, 0.34 %, is determined by the nitrogen content in the plasma. When spraying coatings, the loss of carbon, relative to the initial powder composition, is 2.79 – 3.76 %, less than in the manufacture of powders for spraying 4.3 – 6.6 %. Carbides Cr3C2, WC, matrix elements and the content of additional carbon determine the formation of the annular zone around TiC carbide, increase the total carbide content in the coating from 60 to 74 – 83% and the microhardness of the coating is 18 GPa with an indenter load of 200 gf.

— Relatively thin (~30 μm) and thick (100 μm) plasma-sprayed hydroxyapatite (HA) coatings grown on unheated and preheated (550°C) titanium substrates have been characterized by X-ray diffraction and scanning electron microscopy. The microstructure of the coatings grown on unheated substrates contains a considerable density of defects and is fragmented. The coatings grown on preheated substrates have a denser, perfect microstructure. The presence of the CaO and tetracalcium phosphate phases in the thick coatings grown on preheated substrates suggests that the temperature in the spraying zone approaches the partial decomposition temperature of HA. The formation of a well-defined basal texture ( I (002)/ I (211) = 2.72) is favored by the high temperature maintained during the growth of these coatings. We discuss the effect of specific structural features on the strength of coating–substrate bonding and analyze the correlation between the texture factor and coating adhesion/cohesion.

Five cermet coatings based on carbides 45TiC – 10Cr3C2 – 5WC with different contents of additional carbon were formed by plasma spraying with local protection: 0; 1.4; 2 and 2.8 %. In four cermets, the matrix was based on Ni – 20Cr. In one cermet, the alloy used was 38.5Co – 32Ni – 21Cr – 8Al – 0.5Y. All matrices were additionally introduced Mo. Powders for spraying were obtained by crushing cakes. In the particles of the obtained powders, carbides are distributed relatively uniformly; in coatings, this is noticeable to a lesser extent. After liquid-phase sintering, WC and Mo are not fixed in cermets; part of the Cr3C2 carbide passes to another structural state. The initial carbides in the cake and coating partially dissolve and, upon solidification and together with matrix elements and additional carbon, form an annular zone around the initial TiC carbide, decreasing its lattice period, X-ray fixes TiMoC2 carbide, the content of which is higher than the content of TiC carbide in the initial mixture. The content of the initial carbides in the coatings, measured by optical microscopy, decreases from 71 vol.% In the powder to 48 vol.% At the minimum plasma power and up to 36 vol.% At the maximum power. The average total TiMoC2 content of carbides in coatings according to x-ray data for four cermets is 76 %, higher than their content in spraying powders, 72 %, due to higher spray hardening rates. The average microhardness for all coatings is 22.01 GPa with an indenter load of 20 gf, which is lower than the average microhardness for all powders, 23.51 GPa. With an indenter load of 200 gf, the average microhardness for all coatings of 15.88 GPa corresponds to the average microhardness for all powders, 15.17 GPa.

Phosphate coatings have been produced by plasma-spraying hydroxyapatite (HA) and tricalcium phosphate (TCP) powders onto Ti substrates at initial temperatures of 20, 300, and 550°C, followed by hydrothermal treatment (HTT) at 650°C, and the variation in the phase composition of the coatings has been examined in relation to the phase composition of the plasma-sprayed powders: 100 wt % HA, 100 wt % α‑TCP, and 100 wt % β-TCP. The as-prepared coatings produced by plasma-spraying the HA powder consisted of 87–91 wt % HA and 9–13 wt % CaO, and after HTT their phase composition was 89–93 wt % HA and 7–11 wt % CaO. The coatings produced by plasma-spraying the α-TCP powder at initial substrate temperatures from 20 to 550°C consisted entirely of a crystalline α-TCP phase. The coatings produced by plasma-spraying the β-TCP powder consisted of both β-TCP and α-TCP, and the content of the latter phase decreased from 100 to 80% as the substrate temperature was raised from 20 to 550°C. After HTT, the coatings contained 26–28% HA, independent of the phase composition of the starting TCP powders.

Samples of a solid solution aluminum oxonitride (γ-AlON) of spinel structure with different ratios of components (Al2O3 and AlN) were prepared by the sol–gel technique combined with high-temperature solid-state synthesis at 1750°C in a nitrogen atmosphere. The X-ray diffraction study of polycrystalline samples was performed by the Rietveld method. It was shown that the crystal structure of γ-AlON can be described by the model of permanent anions. The occupancies of tetrahedral and octahedral positions by aluminum atoms in the cationic sublattice of spinel are less than one, and the vacancies are predominantly located in octahedral positions. The lattice constant of the spinel phase (7.9499 Å) in the sample with 67 mol % of Al2O3 and the near-stoichiometric composition Al23O27N5, almost coincides with early published data. The spinel parameter u slightly depends on the concentration and is equal to ∼0.3810.

The distribution of copper, carbon, and oxygen in the surface layers of steel 30KhGSN2A plates after the implantation of copper ions from a pulsed ion source with an accelerating voltage of 30 kV in a vacuum chamber with a residual gas pressure of 8 × 10 –4 Pa is studied by Auger spectroscopy. The depth profile of copper in the surface layer has a maximum at a distance of ~90 nm from the plate surface. This profile is close to the depth distribution of implanted copper atoms in 30KhGSN2A steel under the same conditions that was simulated by the Monte Carlo method. The difference between the experimental and calculated profiles is caused by the fact that a 50-nm-thick carbon layer forms on the steel surface during implantation. In the revealed intermediate layer (50–120 nm), iron is partly in the oxidized state. Possible mechanisms of the influence of the structure of the surface layers that form during copper implantation into steel 30KhGSN2A plates on their tribological properties are considered.

Using the Rietveld X-ray method, the powders of tricalcium phosphate (α-TCP) were analyzed after their treatment in a planetary mill in various liquids (butanol, isobutyl alcohol, acetone, and ethanol). No features of the decomposition of α-TCP were detected and the parameters of its atomic-crystal structure did not change significantly. The reduction of the coherent scattering domains (DS) ( d ~ 800 Å) was a major contribution to X-ray line broadening, while its value did not depend on physical properties of liquids. Particles dispersed during their processing in the mill owing to their brittle destruction by chipping. After 60 min of powder processing in butanol, mean particle size decreased by a factor of five (from 9.7 to 2 μm). After annealing at 1300°C, the fluorohydroxyapatite phase was detected in powders, whose formation was assisted by the impurities from fluorine-containing structural elements of the mill.

We have studied the structure of hydroxyapatite (HA) powders prepared by hydrolyzing dicalcium phosphate dihydrate (DCPD) in an aqueous sodium acetate solution at a temperature of 60°C for 16 h or a longer time. The results demonstrate that the HA in the powders has a distorted structure. The Baur’s distortion index for the PO4 tetrahedra is DI(TO) ≃ 0.03, whereas hydroxyapatite single crystals have DI(TO) ≃ 0.005. The powders are similar in structural parameters to calcium-deficient HAs: they have Ca/P ≃ 1.6 and an imperfect substructure (crystallite size of ≃30 nm) and contain sodium impurities. The structural features of the HA powders are analyzed in the context of their ability to biodegrade (dissolve).

WinFit software is used to determine using the profile of a single diffraction peak the sizes of coherent scattering domains and microstrains for tungsten powders obtained through plasma chemical synthesis and hydrogen reduction from tungstic acid. It is shown that the use of the (110), (200) or (211) diffraction peaks is the most expedient for the calculations. At the same time, it should be noted that, in the case of significant microstrains, the sizes of coherent scattering domains calculated using the second and the third peaks are underestimated.

The change in the phase composition of a cold-worked austenitic–martensitic VNS9-III TRIP steel after static tension at a strain rate of 0.1, 5, 7, and 10 mm/min is studied by X-ray diffraction. The steel in the initial state has the following three phases: fcc γ phase and two bcc phases (α1, α2). A high degree of preferred (211) crystallite orientation is observed for the α1 phase, and a preferred (100) orientation is observed for the α2 phase. Deformation under static tension leads to a decrease in the content of austenite (γ phase) in the steel structure at the expense of formation of deformation martensite. The lower the strain rate, the lower the volume fraction of the γ-phase: it is 46% in the initial state, 36% at a tension rate of 10 mm/min, and 18% at a tension rate of 0.1 mm/min. The γ-phase content decreases mainly due to an increase in the α1 phase content.

The structure and properties of alloy V1469 sheets, which are characterized by a developed crystallographic texture, are studied. The texture of the central part of the sheets is usually represented by the predominant brass-type {110}〈112〉 component, whereas the texture in the sheets under study should be described by nine orientations, among which {112}〈110〉 and {111}〈110〉 shear orientations are most intense. The improved fracture toughness characteristics of these sheets are likely to be related to an increase in the fraction of strongly misoriented grain boundaries and the scattering of cracks by them.

Powders prepared through dicalcium phosphate dihydrate (DCPD) hydrolysis to octacalcium phosphate (OCP) and hydroxyapatite (HA) in an aqueous sodium acetate solution have been characterized by X-ray diffraction. The lattice parameters of the synthesized OCP and HA phases have been determined as functions of holding time at synthesis temperatures of 37 and 60°C. The structure of the HA obtained through hydrolysis at 60°C has been refined, and the distortion of the elements of the crystal lattice of this compound has been assessed in terms of Baur indices. A model has been proposed for the heterogeneous nucleation and growth of the OCP phase on DCPD crystals, in which the structure of these compounds is represented as made up of groups similar in structure to Posner regions.

The structure of hydroxyapatite plasma coatings on a titanium substrate has been investigated by the X-ray Rietveld method. The hydroxyapatite crystal structure in plasma-deposited samples is characterized by strong distortions of its main element (tetrahedral PO 4 cluster) and coordination calcium polyhedra, as well as calcium deficit in the Ca2 site; however, these features do not change the main motif of the hydroxyapatite structure. The bond distortions in PO 4 clusters are estimated by the Bauer method. It is shown that hydrothermal treatment leads to the almost complete recovery of the hydroxyapatite structure.

The article presents the results of the investigation of the influence of shock-wave effects on the structure and the critical currents of multilayer high-temperature superconductors—HTS tapes produced by the EAS-E HTS (VAC). Shock-wave exposure was carried out using an installation of a plasma focus (PF) type. It was experimentally found that an increase in the critical current by 20% or more was achieved in its own magnetic field and in external magnetic fields in the range of 0.5–2.5 T. The increase depended on the conditions of the shock-wave treatment (the distance from the plasma source (PF anode) and the number of shock wave pulses). In magnetic fields of more than 3 T, the effect of an increase in the critical current was not observed. Microstructural studies revealed both a compression and destruction of the individual layers of HTS in the strike zone depending on the conditions of the impact. The most severe degradation of the structure and the critical current was shown on the tape samples treated at distances of 25–30 mm from the PF anode. The critical current increased and exceeded the initial values of untreated tapes (75–85 A) at distances of 35–65 mm. The phase composition of HTS layers by XRD changed little after shock-wave treatment. Depending on the number of shock pulses and distance from the anode in the area of treatment, the tape’s thickness was reduced owing to compression or was increased owing to swelling of the tape.

We have studied a process for the preparation of apatite precursors through calcium carbonate conversion into dicalcium phosphate dihydrate, which is then hydrolyzed to octacalcium phosphate. The process enables the preparation of both phase-pure octacalcium phosphate and calcium phosphate mixtures with variable dicalcium phosphate dihydrate : octacalcium phosphate and hydroxyapatite : octacalcium phosphate ratios.