Russian Physics Journal最新文献

Oxide coatings formed on the surface of medical instruments made of titanium-based alloys help physicians to protect patients from toxic titanium alloying elements and increase the resistance of the instruments to scratching and wearing. As a rule, the formation of a coating/substrate system is accompanied by an analysis of the adhesive properties of the applied coating. This paper presents an analysis of the results obtained by studying the structure and adhesive properties of titanium oxide and zirconium oxide films formed on the surface of titanium alloy samples of Grade 5 by vacuum arc plasma-assisted method with varying discharge current values of the plasma source operating on the basis of an independent arc discharge with glow and hollow cathodes. The studies showed that the oxide films contain droplet fraction particles the characteristics of which are determined by the film deposition mode. It has been established that the critical load force at which destruction of (peeling off) the film from the substrate (titanium alloy Grade 5) is observed in the ZrO₂ film/Grade 5 substrate system is maximum at the “PINK” discharge current I_p = 0 A and minimum at I_p = 90 A. It was found that in the TiO₂ film/Grade 5 substrate system, the maximum value of the critical load force is realized at the “PINK” discharge current I_p = 130 A and minimum at I_p = 0 A.

Non-destructive testing (NDT) techniques, including thermal electromotive force (ThermoEMF) and four-probe resistivity (FPP) measurements, offer an innovative approach to assessing chromium coatings on zirconium alloy E110, which are utilized in the manufacturing of core components resistant to emergencies in nuclear reactors. These methods quantify their critical properties, such as electrical conductivity, thermoelectric stability, and coating uniformity, providing insights into the coating structural quality and adhesion.

The paper focuses on the structure and properties of welding joints of the high-strength 1370 aluminum alloy obtained by electron-beam welding (EBW). This issue is relevant to the housing assembly technique of space vehicle gyroscope sensors. The heat-affected zone geometry produced by the electron beam, is studied herein as well as the welding joint structure, depending on welding parameters. EBW of the 1370 aluminum alloy has a positive effect on the strength properties of the welding joint. The energy dose per unit length of the joint must be correct. Insufficient energy dose leads to lack of welding penetration and low joint strength, whereas its excess provides the liquid metal evaporation and the formation of pores and cracks. Feasibility is demonstrated for welding the aluminum alloy at a higher speed.

A physical concept of thermodynamic structural-phase states of a physical system is proposed in application to ultrahigh diluted aqueous solutions low-stable to external impacts. The physical analogy between the states of these solutions and the condensed physical systems helps to understand physics of various effects observed in ultrahigh diluted aqueous solutions. In particular, this approach allows the role of shaking of the chemical solutions in the Epstein effect to be evaluated by mechanochemical methods. An analysis of the thermodynamic and structural-phase low-stable states of the physical system makes it possible to propose a possible mechanism for the system transition to a new phase state under a low-stable external impact on the example of an ordering alloy system. In this case, the small external impact (for example, shaking) can lead to significant phase changes of the system state in which the structural units are close thermodynamically, but can differ significantly in symmetry. It is discussed how the effect of the state of the suitable symmetric liquid solution of a substance under a small external impact (for example, in the form of shaking) can be experimentally realized.

The increasing electron density in the ionosphere at the D layer resulting from solar flare X‑rays, is likely to affect the propagation of very low frequency in both magnitudes and variations. The present study analyzes the observed events recorded by the Iraqi Ionospheric Observation Station IISO conducted on the 31st August, 2024 at Thi Qar University. The results show a match coincident with other observatories such as HWU and DHO and a high match with the X‑ray data detected by the GOES-16 satellite. The analysis focuses on three isolated incidents resulting from solar flares of class M and C, where sudden ionospheric disturbances appearing in the amplitude spike belong to classes M1.2, C9 and M1.8. The study and observation using the IISO, are compared with the French station, were signals are received from transmitters HWU, DHO and TTB, as well as GOES satellite data and appear to match these stations. It is found that the TBB signal shows no events well, despite its proximity to the receiver. In general, the obtained results indicate to a noise in the signal coming from several reasons including electromagnetic interference, weather, atmospheric conditions, problems with equipment, transmitter malfunctions at the TBB station, incompatibility, the need to reset transmitters, or solar disturbances such as solar storms and different reception angles, as well as physical obstacles and repeated reflections, which induce noise.

The paper reports on the synthesis and characterisation of Ce³⁺ activated Mg₃WO₆ phosphor, with variable (0.5 to 2.5 mol%) concentration of doping Ce³⁺. The sample is synthesised via the combustion method. The crystal structure is determined by the X‑ray diffraction analysis, which shows the monoclinic structure with a P 1 2/c1 space group. The phosphor surface morphology is analysed by scanning electron microscopy, which shows the non-uniform particle distribution. The EDX analysis confirms the proper formation of phosphor. Photoluminescence study shows that prepared phosphor exhibits both the down- and up-conversion phenomenon. The notable peak at 275 nm is mainly due to the effective transitions from 4f ground state of Ce³⁺ to the field-splitting levels of 5d state. The emission peak at 475 nm is mainly due to the transitions of 5d excited state to ²F_7/2 and ²F_5/2 ground states.

This study investigates the impact of incorporating copper and nickel micropowders on the fatigue life of polyetheretherketone (PEEK) carbon fiber reinforced composites. Powders are sprayed on the surface of PEEK/carbon fiber prepregs thus leading to modification of interlayers. The fatigue behavior of these hybrid composites is analyzed under two stress levels (0.77 and 0.8 of tensile strength). The research demonstrates that addition of copper and nickel micropowders to interlayers of the PEEK composites significantly enhances their fatigue resistance.

The paper investigates the influence of the ultrafine-grained (UFG) structure of Ti–42Nb–7Zr and Mg–2.9Y–1.3Nd alloys on their substructure and strain behavior induced by quasi-static tension. It is shown that the ultrafine grain (UFG) structure provides changes in stress-strain curves. Structural transformations due to quasi-static tension are described for both ultrafine- and coarse-grained structures of these alloys. The alloys with the coarse-grained structure demonstrate the formation of localized deformation bands with misoriented network substructure. The UFG Ti–42Nb–7Zr alloy structure is characterized by the formation of larger equiaxial grains with a lower dislocation density that indicates to a localized alloy softening before fracture. The fracture of the UFG Mg–2.9Y–1.3Nd alloy demonstrates the cellular-network substructure.

The physical and mechanical principles governing aeroacoustic vibrations within a cylindrical channel have been established through a series of numerical experiments aimed at investigating the impact of multidirectional turbulent gas flow on the propagation of these vibrations. The developed physical and mathematical model has demonstrated its efficacy, as verification processes confirmed a strong correspondence between the results of numerical simulations, experimental findings, and existing literature data. This validation allows us to assert the reliability of the model and its potential for further research endeavors. The outcomes of the numerical experiments distinctly reveal that the amplitude of waves propagating upstream surpassed that of downstream and non-flow waves at equal distances from the acoustic source within the cylindrical channel. The results obtained were corroborated through comparison with experimental and relevant literature data. The identified influence of flow can be practically applied in cross-correlation analyses of the amplitude of aeroacoustic vibrations resulting from leaks in gas pipelines, thereby enhancing the accuracy of leak detection systems.

Petrov homogeneous null spaces are considered. Using vector fields of the canonical reper, the vacuum Maxwell equations and the nonholonomic components of the momentum energy tensor of the electromagnetic field are derived. Examples of integration of these equations for spaces with motion groups of the first and second type according to the Bianchi classification are given.