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Nondestructive testing is an integral part of quality assurance for critical products. The complex structure of metal-polymer hydrogen cylinders complicates the reliable detection of defects using a single type of flaw detection. In this regard, the application of combined nondestructive testing is of interest. This study examines the joint use of ultrasonic and thermal flaw detection with the synthesis of their results. Experimental verification demonstrated that the developed methodology for synthesizing ultrasonic and thermal testing data improved defect detectability compared to the separate use of these nondestructive testing methods. [ABSTRACT FROM AUTHOR]

New metal–ceramic laminated composites Ta/Ti3Al(Si)C2–TiC were obtained by spark plasma sintering. The samples were synthesized at a temperature of 1250°C and a pressure of 50 MPa for 5 min. For formation of the composites, preceramic paper with a powder filler based on the MAX phase of Ti3Al(Si)C2, as well as metal foils made of tantalum, were used. The phase composition, microstructure, and elemental composition were analyzed by X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy, respectively. It was found that as a result of sintering, dense multilayer composites were formed, consisting of tantalum metal layers, ceramic layers containing Ti3Al(Si)C2, TiC, and Al2O3 phases, as well as reaction layers ~13 μm thick at the metal–ceramic interface enriched with Ta, Al, and Si. Based on the mechanical test data, the ultimate bending strength of the obtained composites was determined (σbs = ~430 MPa). Metal–ceramic laminated composites with a refractory tantalum layer were shown to exhibit a ductile fracture mechanism accompanied by a more than fourfold increase in absolute deformation compared to a Ti3Al(Si)C2-based ceramic composite. This is achieved due to deflection, branching of cracks at the metal–ceramic interface, and plastic deformation of tantalum layers. [ABSTRACT FROM AUTHOR]

Structural and phase stability of the Pd-plated Ti3(Al, Si)C2–TiC composite at elevated temperatures was analyzed by the in situ X-ray diffraction method using synchrotron radiation. Porous Ti3(Al, Si)C2–TiC composite was prepared by spark plasma sintering of preceramic paper with 90 wt % of a Ti3(Al, Si)C2 powder filler at 1000°C and 20 MPa. The sintered composite was covered with a Pd film via electroless plating. During in situ investigation, the Pd-plated composite was linearly heated from 25 to 1000°C and annealed for 1 h at a maximum temperature. Structural and phase analysis reveals a formation of new Pd2Si, PdAl, and PdCx phases. It was noted that the newly formed phases began to be formed during heating at ~750°C. Scanning electron microscopy showed that the obtained Ti3AlSiC2–TiC composite had a well-developed porous structure where some pores were filled with Pd. After high-temperature treatment, Pd could be detected at depths up to 5 μm into the Ti3AlSiC2–TiC composite. [ABSTRACT FROM AUTHOR]

The paper is devoted to the formation of SiC-ceramics from preceramic paper. Preceramic paper is a comparatively novel material consisting of a cellulose matrix and a powder filler. It is flexible and amenable to mechanical processing. This makes it possible to form multi-layer paper composites for sintering, where the composition, shape, and properties of each individual layer can be controlled. SiC-ceramic samples have been obtained by spark plasma sintering of preceramic paper based on a SiC powder (90 wt %) as a feedstock. The surface microphotographs of the obtained SiC-ceramics were analyzed. The values of density, porosity, and water absorption were determined. The phase composition and pore size distribution over the material structure were established. Based on the results, the effect of spark plasma sintering parameters (holding temperature and pressing pressure) in the ranges of 5–100 MPa and 2100–2200°C, respectively, on the structure-phase state formation of the SiC-ceramics was investigated. [ABSTRACT FROM AUTHOR]

The effect of the crystal structure of the Mo sublayer on the resistance of the zirconium alloy Zr–1Nb with a Cr/Mo coating to high-temperature oxidation in air is studied. Three types of coatings are deposited by magnetron sputtering: single-layer Cr coating with a thickness of 8 µm and two-layer coatings with a sublayer of Mo (3 µm) of various textures and an outer protective layer of Cr (8 µm). Different textures of molybdenum films are formed by changing the configuration of the magnetron-sputtering system. Coated samples are oxidized in an atmospheric oven at 1100°C for 15, 30, 45, and 60 min. The results of X-ray-diffraction- and scanning-electron microscopy show that the use of a Mo sublayer limits the mutual diffusion of the Cr–Zr system. The diffusion of Mo leads to the formation of interdiffusion layers of Cr–Mo and Mo–Zr. Faster diffusion is observed at the Cr–Mo interface. The thickness of the residual Cr layer in two-layer coatings is greater than that in a single-layer coating under similar oxidation conditions. [ABSTRACT FROM AUTHOR]

The paper proposes a new approach to gradient porous composites based on the Ti3Al(Si)C2 MAX phase. This approach is based on the production of preceramic paper with the different content of the powder filler based on MAX phases and their spark plasma sintering. The analysis of the microstructure and phase composition is conducted for these composites. It is shown that the obtained composites have a clear interface between layers with different porosity. It is found that the content of organic components in preceramic paper affects the phase composition of the fabricated composites. The MAX phase content in dense and porous layers is 86 and 56 vol.%, respectively. Microhardness measurements performed in the composite cross-section show the hardness of 600 to 800 HV, depending on the layer porosity and phase composition. [ABSTRACT FROM AUTHOR]

This review focuses on the comparison of the spark plasma sintering (SPS) with other fabrication methods of MAX-phase materials. In the view of optimizing properties for prospective applications, we summarized different routes to synthesize and sinter bulk/powder MAX-phases with various microstructures, discussed the phase composition of MAX-phases obtained by SPS and other methods. In the article, we introduced the experimental features of various sintering methods and carried out the comparative analysis of "competition phenomenon" between the SPSed MAX-phases and MAX-phases prepared by other technologies. We referred to relevant reports and reviews in which one can acquire a comprehensive understanding of sintering kinetics, sintering thermodynamics, grain growth kinetics, and densification mechanisms. Furthermore, the influence of the sintering routes on the properties of the MAX-phases was discussed paying emphasis on the mechanical properties. [ABSTRACT FROM AUTHOR]

Thin films of TiN are deposited onto Zr–1% Nb alloys using vacuum-arc plasma in two steps. First, the plasma-immersion ion implantation (PIII) of titanium is implemented; then, without interrupting the experiment, the vacuum-arc deposition (VAD) of TiN is carried out. The VAD and PIII modes for obtaining the most effective coating (from the viewpoint of protecting the substrate from corrosion and hydrogen embrittlement) have been previously determined. Within studies of the mechanical properties of the obtained coatings, a study of changes in the adhesion of coatings under Arctic conditions (at a temperature of –20°C, seawater ice) and hydrogenation of the samples is carried out. It is established that coatings that are frozen in seawater ice for 24 hours without preliminary saturation with hydrogen have the best adhesive strength. The mechanism of the established effect is briefly discussed. [ABSTRACT FROM AUTHOR]

In this study, a noncommercial 3D printing machine was used to fabricate Ti-6Al-4V alloy by electron-beam melting (EBM). The influence of beam current on the microstructure, phase composition and mechanical properties of electron-beam-melted Ti-6Al-4V alloy was investigated. Numerical simulation is implemented to evaluate thermal fields during electron-beam melting of Ti-6Al-4V powder. The decrease in beam current from 3.5 to 2.5 mA leads to refinement of microstructure: The average width of α plates decreases from 10 down to 6 μm. The formation of finer microstructure is attributed to higher cooling rate at lower beam current confirmed by simulation. The phase composition of EBM Ti-6Al-4V indirectly depends on the beam current. High content of β phase (7%) was achieved at the beam current of 3 mA. The produced Ti-6Al-4V samples are characterized by high microhardness (470-520 HV). [ABSTRACT FROM AUTHOR]

The method of Rutherford backscattering (RBS) of 4He ions is used to detect impurities in the surface region of natural diamond crystals. In order to decrease the influence of luminescence from the surface of diamond, the recording of scattered ions is performed by an annular detector, which decreases the statistical error and improves the measurement accuracy. The limit of impurity detection is 1014 at/cm2 for light impurities and 1012 at/cm2 for heavy impurities. [ABSTRACT FROM AUTHOR]

The structure of the titanium alloy Ti–6Al–4V manufactured by electron-beam melting is shown to be represented by initial β-phase grains more than 40 μm in size; the internal volume of the grains is filled with α-phase precipitates in the form of plates. The average size of the α plates is 1.6, 2, and 5 μm at beam currents of 2, 2.5, and 3 mA, respectively. In situ X-ray diffractometry using synchrotron radiation shows that the phase transitions in the titanium alloy are divided into three main stages during hydrogenation to a concentration of 0.6 wt % at a temperature of 650°C and a pressure of 1 atm. An increase in the beam current from 2 to 3 mA does not significantly affect the phase composition of the alloy. During hydrogenation, the growth rate of the volume concentration of the β phase is lower at a higher beam current. This indicates a decrease in the rate of hydrogen absorption with increasing beam current, which is associated with an increase in the size of α plates. [ABSTRACT FROM AUTHOR]

The surface of Zr‒1%Nb zirconium-alloy samples is treated with titanium via plasma-immersion ion implantation (PIII). Afterward, TiN coatings are deposited onto the implanted and initial samples by means of vacuum-arc deposition (VAD). Before and after each of the treatments mentioned above, changes in the hydrogen sorption rate, depth distribution of elements, and surface topography are investigated. It is found that separately performed VAD and PIII reduce the hydrogen sorption rate by a factor of 2‒15. At the same time, a combination of operations so that PIII is carried out before VAD decreases the sorption rate by one‒two orders of magnitude. It is revealed that the key parameter of the aforementioned methods affecting hydrogen permeability, the depth distribution of elements, and the surface topography is the bias value applied to the sample (substrate). In the case of our setup, the optimum biases of PIII and VAD are‒1500 and‒150 V, respectively. [ABSTRACT FROM AUTHOR]

The features of obtaining track membranes (TMs) with the help of a classical cyclotron situated at Tomsk Polytechnic University are discussed. It is demonstrated that TMs can be employed as templates. The results of research into columnar nanostructures formed with the help of a TM template are presented. The creation of regular microstructures is investigated using deep X-ray lithography with synchrotron radiation and templates made of track membranes. [ABSTRACT FROM AUTHOR]

The influence of plasma-immersion titanium-ion implantation on the hydrogen saturation of E110 zirconium alloy is described. Titanium ions are implanted from the metal plasma of an arc discharge at an accelerating-pulse bias potential of 1.5 kV (the pulse-repetition frequency is 100 kHz, and the pulse length is 5 μs) for 30 min. The phase composition, morphology, and valence state of the alloy surface layer are studied. Comparative analysis of changes in the hardness and wear resistance of the alloy subjected to implantation is performed. It is demonstrated that the rate of hydrogen penetration into the surface-doped alloy decreases substantially at a gas-phase hydrogenation temperature of 400°C. [ABSTRACT FROM AUTHOR]