Russian Physics Journal最新文献

A variant describing the structure of the material synthesized using the structurization parameter is suggested. This process is presented as a reversible reaction the rate of stages of which depends on the temperature. The model of coating synthesis on a substrate under laser control conditions is supplemented with structurization stages. It is shown that the synthesis product is always heterogeneous and contains both the initial reagents and reaction product in structured and unstructured states.

A method of reducing the roughness and improving the hardness and tribological properties of the surface of metal materials and products manufactured using additive technologies that consists in the creation of a metal film on the surface of the layer alloyed by the method of electron-ion-plasma processing that combines vacuum arc deposition of a thin (up to several microns) film and subsequent pulsed electron-beam irradiation of a film/substrate system is presented. On the example of Zr (film)/stainless steel 308LSi (substrate) specimens, it is shown that the proposed method of combined processing allows not only reducing considerably the roughness of the surface layer, but also improving its hardness and tribological properties compared to the initial material by a factor of 2.5 and up to 15 times, respectively.

The energy thresholds and the kinetics of explosive degradation of PETN and its composites is studied experientially under ignition by a laser pulse (λ₀ = 1064 nm, τ_p = 12 ns) depending on the concentration of absorbing additives and the pressure changing in the range from 40 to 600 MPa. A complex dependence of the initiation thresholds on the pressure and additive concentration has been demonstrated. Results are explained by the authors within the framework of the thermal micro-spot model of initiating the transparent explosive components (the hot spot model).

The paper deals with digital holography that provides non-destructive flaw detection in objects produced by fused deposition modeling printing and suitable for application in the terahertz range. The 200 GHz holographic image recording system is based on the quasi-optical lens transmission line. Holographic images are obtained for the phase-contrast object in the form of two ribbons of conducting acrylonitrile butadiene styrene (ABS) separated in thickness and Y coordinate. These bands locate inside another ABS dielectric material. The angular spectrum method is used to determine the position of artificial inhomogeneities in the sample with a 3 mm accuracy.

The temperature of the surface of A7 aluminum alloy specimens with TiCuN coatings 1–6 μm thick has been measured during irradiation with intense pulsed electron beams having different energy densities and pulse durations using a high-speed infrared pyrometer. Numerical simulation of the thermal fields for the same conditions shows good similarity to the experimental data and allows temperature dependences to be determined at different depths from the specimen surface and different distances from the beam symmetry axis for coatings of various thicknesses with different melting depths of the aluminum base to be determined together with the lifetime of the liquid phase.

An axisymmetric stationary problem of elastic deformation of a circular cylinder is considered in the case of an impact on the lateral surface of an absolutely rigid ring with angular lines. Equilibrium equations in displacements are used. In this case, the stress and strain tensors have four nonzero components. All stresses are found by calculations, and zones of possible destruction of the material are determined by their maximum values.

Sequential excitation of two nonlinear transmission lines with saturated ferrite by one high-voltage pulse has been implemented. The central frequencies of the high-frequency pulses of each line were approximately 3 and 4 GHz. It is shown that this method of excitation of oscillations allows implementing a sequence of radio pulses with a repetition frequency of tens of MHz as well as increasing the energy efficiency of high-frequency pulse generation in the specified frequency ranges.

The paper presents testing results and certification of VMM3a integrated circuits, which are planned to be used in the data acquisition system in the spin physics detector experiment on the NICA collider. The key parameters of the circuits evaluated during testing, include the power consumption, amplitude and time measurement accuracy, response correctness in various operating modes. The obtained results are used to identify circuits matching the experimental conditions and units with defects.

The results of the study of corrosion properties of a bioresorbable Mg-Zn-Zr-Ce magnesium alloy in coarse-grained (CG) and ultrafine-grained (UFG) states are presented. A solution of 0.9 wt.% NaCl (NaCl) and phosphate-buffered saline (PBS) is used as the corrosion medium. An ambiguous corrosion behavior of the alloy depending on its structural state and type of corrosion medium is revealed. The most favorable corrosion performance is observed for the UFG state of the Mg-Zn-Zr-Ce alloy held in the PBS solution for a period of 14 days. The mass gain of UFG alloy samples in this solution is 0.2%, while the mass loss of CG alloy samples is 0.5%. In the NaCl solution, the mass loss of UFG and CG alloy samples is comparable, being 0.3%. A distinctive feature of the corrosion behavior of the Mg-Zn-Zr-Ce alloy in both CG and UFG states in NaCl is the uneven dissolution of the samples compared to their dissolution in PBS. It is shown that the corrosion layer of the UFG alloy after tests in both PBS and NaCl twice as thin as the corrosion layer of the CG alloy, which is attributed to the formation of a passivation layer on the surface of the UFG samples due to the defect structure.

The thermogravimetric method is used to study the degradation of polypropylene (PP), mixed polyamide PA6/66 (PA), and their mixtures with PA contents of 10 and 40 wt.% in the temperature range from 30 to 700 °C in air. A significant inhibitory effect of PA on PP degradation is discovered. The maximum decomposition temperatures of mixtures in the presence of polyamide increase by more than 50 °C. This effect is comparable to the inhibitory effect of known antioxidants. A mechanism of inhibitory action is proposed as a result of the reaction of the PA phase with the oxidation products and the PP radicals.