Spatial profile of Al-ZnO thin film on polycarbonate deposited by ring-shaped magnetized rf plasma sputtering with two facing cylindrical Al2O3 - ZnO targets

Radial profiles of the ion saturation current are measured in a ring-shaped magnetized radio-frequency plasma sputtering process with two facing cylindrical ZnO targets including Al2O3 (2% wt.). The profile has a non-uniform shape with a peak whose position corresponds to the target near the electrode due to the effect of the magnetic field distribution. It becomes uniform at large distances between the substrate and a target (d st ≥ 50 mm). The radial profile of the resistivity of the Al-ZnO (AZO) films deposited on a polycarbonate plate at Ar gas pressure of 0.27 Pa is uniform at about 10-3 Ω·cm for d st ≥ 50 mm. The films deposited at various positions and room-substrate-temperature also show a good crystallinity based on an X-ray diffraction peak of about 33.95 - 34.44°. The grains exhibit a preferential orientation along the [002] axis with its size ranging from 18.15 to 28.17 nm. A higher transmittance of 95.6 % in the visible region is also obtained.

Immunomodulatory Properties and Osteogenic Activity of Polyetheretherketone Coated with Titanate Nanonetwork Structures

Polyetheretherketone (PEEK) is a potential substitute for conventional metallic biomedical implants owing to its superior mechanical and chemical properties, as well as biocompatibility. However, its inherent bio-inertness and poor osseointegration limit its use in clinical applications. Herein, thin titanium films were deposited on the PEEK substrate by plasma sputtering, and porous nanonetwork structures were incorporated on the PEEK surface by alkali treatment (PEEK-TNS). Changes in the physical and chemical characteristics of the PEEK surface were analyzed to establish the interactions with cell behaviors. The osteoimmunomodulatory properties were evaluated using macrophage cells and osteoblast lineage cells. The functionalized nanostructured surface of PEEK-TNS effectively promoted initial cell adhesion and proliferation, suppressed inflammatory responses, and induced macrophages to anti-inflammatory M2 polarization. Compared with PEEK, PEEK-TNS provided a more beneficial osteoimmune environment, including increased levels of osteogenic, angiogenic, and fibrogenic gene expression, and balanced osteoclast activities. Furthermore, the crosstalk between macrophages and osteoblast cells showed that PEEK-TNS could provide favorable osteoimmunodulatory environment for bone regeneration. PEEK-TNS exhibited high osteogenic activity, as indicated by alkaline phosphatase activity, osteogenic factor production, and the osteogenesis/osteoclastogenesis-related gene expression of osteoblasts. The study establishes that the fabrication of titanate nanonetwork structures on PEEK surfaces could extract an adequate immune response and favorable osteogenesis for functional bone regeneration. Furthermore, it indicates the potential of PEEK-TNS in implant applications.

MODIFICATION OF HEAT-RESISTANT OXIDES AND CHLORIDES OF GRAIN SURFACES OF SYNTHETIC DIAMOND GRINDING POWDERS FOR APPLICATION IN GRINDING TOOLS

Further development of modern technologies of diamond processing is connected with application in the diamond tool of powders with new unique properties, special morphology of grains, with the increased chemical and thermal stability. To increase the heat resistance of diamonds, they are covered with a metal (metallization) or glass-ceramic layer, or introduced into the reaction mixture used in the synthesis of diamonds, alloying additives of certain elements. Recently, other methods of coating to increase the heat resistance of diamonds have been developed, such as: vacuum ion-plasma sputtering, epitaxial synthesis, magnetron sputtering, the method of liquid-phase deposition. The latter method is promising for modifying the grain surface of grinding powders of superhard materials by heat-resistant inorganic non-metallic coatings, as it is the most economically advantageous. Determining the features of the technology of modification by the method of liquid-phase application of heat-resistant inorganic coatings (oxides and chlorides of metals and nonmetals) on the surface of grains of grinding powders of synthetic diamond brand AC6, used for grinding tools in mechanical engineering. Modification was performed by the isothermal method of liquid-phase application of saturated solutions of both heat-resistant oxides (В2О3, Al2O3), chlorides (СаСl2, NaCl, MgCl2, FeCl3), and their mixtures (В2О3+СаСl2, В2О3+NaCl). Based on the analysis of the results of the research, it can be stated that the application of coatings of inorganic substances (some oxides and chlorides) increases the heat resistance of synthetic diamond grinding powders. Modification allows to reduce expenses of diamonds in wheels at grinding. Conditions for modification of heat-resistant oxides and chlorides, as well as their mixtures, grain surface of synthetic diamond grinding powders are determined. Modification of the surface of diamond grains with a combination of B2O3+Al2O3 is guaranteed to double the wear resistance of diamond wheels. It is established that in all cases of modification the roughness of the parameter Ra decreases. It is determined that by changing the surface modifier of diamond grains it is possible to affect the bearing capacity of the rough surface obtained by grinding. The development of effective ways to increase the heat resistance of grinding powders made of superhard materials, primarily abrasive grinding powders made of synthetic diamond powders, helps to improve the quality of the grinding tool.

In Situ Analyses of Surface-Layer Composition of CxNy Thin Films Using Methods Based on Penning Ionization Processes—Introductory Investigations

Carbon nitride materials have received much attention due to their excellent tribological, mechanical and optical properties. It was found that these qualities depend on the N/C ratio; therefore, the possibility to control it in situ in the sputtered film is of high importance. The plasma-electron spectroscopy method based on the Penning ionization process analysis is developed here to control this ratio in CNx films produced by plasma-sputtering in a pulsed-periodic regime of glow discharge. The electron energy distribution function is determined by the means of a single Langmuir probe placed in the center of the discharge tube. The mixture N2:CH4:He was used in the process of sputtering. The applied concentrations of CH4 varied in the range of 2–8%, and He concentration was 80–90%. The gas pressure in the discharge tube used for sputtering varied between 1 and 10 Torr, and the current was between 10 and 50 mA. It was shown that the proposed method enables the extraction of information on the composition of the surface layer of the investigated film and the development of an on-line inspection, without extracting the film from the sputtering chamber.

Influence of synthesis parameters and thermal annealing on grain size of polycrystalline aluminum thin film

The thin polycrystalline aluminium films were synthesized on monocrystalline silicon substrates by ion-plasma sputtering. The synthesis was carried out at temperatures of 80 and 160°C and deposition rate of 10 and 110 nm/min. As-deposited films were annealed for 15 h at 550°C. The morphology of aluminium films before and after annealing was obtained using SEM images. The surfaces of as-deposited Al thin films, synthesized at high temperature, were uneven, while for low temperature films they were smooth enough with Al hillocks on the top of the film. After thermal annealing, morphology of the films was changed slightly. XRD patterns were obtained to calculate the average Al grain size of as-deposited and annealed films. The XRD analysis showed that an increase in the synthesis temperature leads to an increase in the average grain size from 50 to 84 nm and that increase in the rate of Al film synthesis leads to an increase in the average grain size from 50 to 63 nm. As the result of annealing, the average grain size increased for all samples and the final meaning was from 78 to 140 nm.

INFLUENCE OF THE COMPOSITION OF THE RADIO-FREQUENCY SPUTTERING ATMOSPHERE ON THE DENSITY OF STATES AND INTERBAND LIGHT ABSORPTION IN THIN Y2O3 FILMS

The long-wavelength edge of the fundamental absorption band of thin Y2O3 films obtained by radiofrequency ion-plasma sputtering is investigated. The edge of interband absorption after annealing of the films in an atmosphere of argon, oxygen, or a mixture of these gases is shown to be approximated well by the Urbach empirical rule. Diffractograms of the obtained films were studied and a model of a heavily doped or defective semiconductor in the quasi-classical approximation was used to analyze the experimental results. This model allows determining the radius of the basic electronic state, the screening radius, and the rootmean-square potential depending on the sputtering atmosphere.