Capillary porous systems (CPSs) containing liquid lithium are typically fabricated from tungsten fibers. These CPS units are often attached to a steel base using spot welding or simple clamps, methods that are inefficient for transferring high heat flux. In this work, the CPS was integrated into a base structure made of steel (AISI 316LN and AISI 420) and a nickel alloy (Ni34Fe). This study investigated the composite structures under static and cyclic thermal loads, measured their thermal diffusivity, and examined the effects of lithium corrosion. The composite with the Ni34Fe matrix demonstrated the highest resistance to static and cyclic thermal loading and exhibited thermal diffusivity values of up to 8.5 mm2/s. In contrast, composites with steel-based matrices failed after 100 cycles at 500 degrees C/50 degrees C, primarily due to the formation of brittle intermetallic phases. However, the main drawback of the Ni34Fe alloy was its susceptibility to grain boundary corrosion in liquid lithium at 500 degrees C.

The results of mechanical testing and fractography of the ring samples, made of the model Zr–Nb–Sn–Fe alloy, are presented. The most reliable macro- and micro- parameters to quantify the fracture surface are defined. The correlations of some hydride microstructure metrics with fracture parameters are investigated. The advantages and disadvantages of individual metrics are revealed. Threshold stress for the near-surface radial hydride fracture at room temperature is obtained.

Chromium coatings can significantly improve the corrosion resistance of fuel rod cladding made from EP823-Sh steel in liquid lead environments at temperatures up to 650°C. To ensure the long-term effectiveness of the coating, it is crucial to prevent the diffusion interaction between the chromium layer and the underlying steel throughout the operational lifespan of the fuel rod. High-temperature tests on samples reveal a coating-steel interaction layer. At 420°C, with a holding time of 1000 h, the coating retains its adhesion to the steel, and no interaction is observed between the two materials. However, at 540°C and 650°C with a holding time of 1000 h, a diffusion layer with uneven thickness (ranging from 150 to 600 nm) forms at the coating-steel interface. This layer, which has a complex composition, effectively blocks further diffusion of elements from both the coating and the steel. The EP823-Sh steel contains approximately 1 wt

Lithium-based capillary porous systems (CPS) made of tungsten mesh are a part of the most prospective approach to plasma facing components. Currently, tungsten mesh as a part of the CPS is mounted directly on the experimental assembly without a proper joining with a substrate. Tungsten mesh filled with steel could be used as a base structure for the CPS. The experiment considers the wetting of tungsten by steel melt and the features of short- and long-term interaction between the two materials. Wetting was studied by improved sessile drop experiment. The results show that an average contact angle is 69° for SS316LN and 83.2° for SS420 melt on tungsten substrate with a temperature of 500–650 °C. Tungsten-steel composite was manufactured by infiltration of tungsten mesh with a steel melt. As a result of an active dissolution of tungsten in steel melt, (Fe,Cr)7W6 interaction layer with a thickness up to 10 µm forms around tungsten. Optimal structure with the thinnest intermetallic layer is obtained in the zones with the lowest temperature and the highest cooling speed.

The development of filler metals for producing biocompatible metal-ceramic brazed joints is a subject of great interest. The basis for such filler metals can be a titanium-zirconium system, additionally alloyed with copper and nickel to reduce the melting point. However, attention must also be paid to the pre-treatment of ceramics to improve the performance properties of the brazed joint. In this work, the ceramic surface was modified using a laser and titanium hydride powder. ZTA-Ti brazed joints were manufactured with various combinations of ceramic surface pre-treatments. It was found that the filler metal contact angle was 115° at 980 °C on the ZTA ceramic surface treated with a laser. In the case of hydride application, the wetting angle dropped significantly to 15° at 980 °C. A study of the microstructure showed that the brazed joint consists of α-(Ti, Zr) grains and an intermetallic Ti2Cu compound. Corrosion tests in accordance with the ASTM F2129 standard demonstrated that brazed joints where titanium hydride treatment was not used for the ceramic surface did not meet the biocompatibility criteria due to corrosion of the intermetallic layer. The metal ion content in the Ringer’s Locke solution after testing exceeded the safe limit by several tens of times. Shear strength tests revealed that the fracture of the joints was brittle and occurred through the reaction layer and the ceramics itself. The strength ranged from 28.8 to 121 MPa, depending on the treatment of the ceramic surface.

A 1350-00 nickel alloy powder coating has been deposited on thin-walled 12Kh18N10T stainless steel tubes by high-speed laser cladding. Cladding has been performed using cw radiation from a 10-kW ytterbium fiber laser on a robotic complex. The shapes of the gas–powder jet for Fraunhofer nozzles have been determined. The influence of the laser radiation power and the amount of supplied powder on the structure of the coatings obtained has been evaluated. Metallographic studies of the obtained samples have been carried out. It has been shown that laser cladding under optimal conditions provides an almost nonporous coating with minimal penetration of the base material, ensuring metallurgical fusion. According to the X-ray spectral microanalysis, the chemical composition of the deposited coating hardly differs from the chemical composition of the used powder. The thickness of the deposited layer is adjusted within 100–300 µm in one pass, depending on the deposition modes. The fusion line is identical in structure, which shows a high uniformity of heat input during cladding. The size of the region of thermal influence in the substrate material varies within 50–200 µm, depending on the deposition modes.

The purpose of this work was to determine the wetting angles on ZTA ceramic and titanium by new Zr-30Ti-20Co filler metal, identify the mechanism of crystallization during brazing and conduct further corrosion tests of Ti-ZTA brazed joints in Ringer Locke solution. With electronic microscopy, XRD and EDS study it was found that the structure of the joint was represented by eutectic and eutectoid structural components, consisting of α-(Ti,Zr) and (Ti, Zr)2Co phases. With a cyclic potentiodynamic test the pitting corrosion of intermetallic compounds (Ti, Zr)2Co in the brazed joint was revealed. The analysis of ions concentration in Ringer Locke solution shows that cobalt ions are mainly released into the solution during electrochemical tests.

This paper describes a fast and flexible microfabrication method for thermal conductivity gas sensors useful in high-temperature applications. The key parts of the sensor, the microheater and the package, were fabricated from glass-coated platinum wire and the combination of laser micromilling (ablation) of already-sintered monolithic ceramic materials and thick-film screen-printing technologies. The final thermal conductivity gas sensor was fabricated in the form of a complete MEMS device in a metal ceramic package, which could be used as a compact miniaturized surface-mounted device for soldering to standard PCB. Functional test results of the manufactured sensor are presented, demonstrating their full suitability for gas sensing applications and indicating that the obtained parameters are at a level comparable to those of standard industrially produced sensors. The results of the design and optimization principles of applied methods are discussed with regard to possible wider applications in thermal gas sensor prototyping in the future. The advantage of the developed sensors is their ability to operate in air environments under high temperatures of 900 °C and above. The sensor element material and package metallization were insensitive to oxidation compared with classical sensor-solution-based metal–glass packages and silicone MEMS membranes, which exhibit mechanical stress at temperatures above 700 °C.

Experimental results for hydrides reorientation in unirradiated E635 guide tubes are presented. The key parameter for reorientation–the threshold stress was found. Some features of microstructure of hydrides with different orientation are discussed. For cooling rates, which are specific for active zones of pressurized water reactors, δ-hydride is shown to be the only phase that occurs.

The processes of corrosion damage of the inner surface of the cladding are determined by corrosive reagents aggressive with respect to the cladding and the type of fuel used. Reactor irradiation of cladding made of EP823-Sh steel with mixed nitride fuel planned for use in the BREST-OD-300 reactor revealed non-uniform corrosion of the inner surface of the cladding. In this paper, the use of the chromium coating is proposed to prevent the corrosion of the inner surface of the steel fuel cladding. The results of corrosion tests of chromium coating applied to the inner surface of cladding made of EP823-Sh steel by electrolytic deposition are presented. Electron-microscopic studies of the chromium coating on EP823-Sh steel showed no significant signs of corrosion damage when tested in the environment of simulant fission products (CsI+Te) and in liquid lead at 650 °C.

Brazed joints between tungsten and steel are the essential part of the divertor armor block. Meanwhile, liquid Li is considered as a prospective coolant and plasma facing material. Therefore, it is important to estimate the corrosion rate of the brazed seam. Corrosion mechanism in liquid Li at 600 °C after 100 h exposure investigated on two types of brazed joints: with Cu and with TiZrBe filler metals. Severe corrosion damage and corrosion failure occur on the brazed seam with Cu filler. Corrosion primarily affects Cu phases in brazed seam. The brazed joint with TiZrBe filler metal shows high corrosion resistance. Results of chemical analysis indicates that corrosion products deposited on specimen surface contain high Fe and Cr content. The corrosion mechanism is similar to corrosion of steel. Corrosion in liquid Li causes preliminary dissolution of Cr-containing phases.

The results of the analysis of physical and chemical interaction in the Zr-Refractory metal-Cr systems are presented. Refractory metals (RM) are chosen as the material of a diffusion barrier layer between the zirconium alloy and the chromium coating. It is assumed that the refractory metal will suppress the interaction between the chromium coating and zirconium alloys providing increased resistance in high-temperature oxidation conditions at temperatures up to 1500 degrees C. Analysis of physical and chemical interaction in the system Zr-RM-Cr showed the prospects of using niobium and tungsten as a barrier layer material. Analysis of the literature data led to the conclusion that it is necessary to look for an alternative for the single-element refractory metal diffusion barrier. High-entropy alloys based on refractory metals can be an alternative. These alloys are characterized by high heat resistance and stable thermal properties.

The paper presents a detailed analysis of helium (He) bubble development in ODS-EUROFER steel caused by helium ion implantation in different regimes, with a particular attention to the role of the oxide nanoparticles in promoting the growth of He bubbles, helium accumulation and gas-driven swelling. The Transmission Electron Microscopy (TEM) characterization of steel samples implanted applying systematic variation of experimental parameters has allowed clarifying the trends of the bubble microstructure evolution depending on the implantation dose, flux, and sample temperature. It was found that in all investigated implantation regimes He bubbles formed both in the grain bulk and on various structural defects (dislocations, grain boundaries, oxide particles and carbide precipitates), but the sizes and densities of bubbles in different bubble populations were sensitive to particular irradiation conditions. In the majority of cases the main traps for implanted helium and the main contributors to the estimated swelling were bubbles associated with grain boundaries, though in some cases (high implantation dose or lower temperature) the bubbles in the grain bulk were competitive with the grain boundary bubble population. Oxide particles in ODS-EUROFER were found to be excellent nucleation sites for He bubbles and practically each observed particle hosted a single relatively large bubble, sometimes as large as the particle itself. However, the contribution of oxide-associated bubbles to the estimated swelling and He inventory was found to be minor as compared to other bubble populations because of a relatively low number density of nano-oxides. Comparison of ODS-EUROFER and EUROFER 97 samples implanted with He ions in identical regimes has demonstrated lower efficiency of ODS-EUROFER for accumulating implanted helium in bubbles and noticeably higher share of helium atoms trapped in the vacancy defects invisible by TEM.

The technological approach for the low-scale production of field-effect gas sensors as electronic components for use in non-lab ambient environments is described. In this work, in addition to the mechanical protection of a gas-sensitive structure, an emphasis was also placed on the very topical issue of thermal stabilization around the one temperature point, even if it is several degrees higher than the surrounding one, which will probably also be useful for any type of application for many types of field-effect sensors. Considerable attention was paid to the characterization of the results obtained by various invasive and non-invasive methods for diagnosing the manufactured construction. The technology described in this article occupies an intermediate position between laboratory samples tested in clean rooms with stable ambient atmospheres, and experimental and small-scale production sensors designed for real operating conditions to solve the narrow application of measuring low concentrations of hydrogen.

The crystallographic texture determines the anisotropy of zirconium alloys and is a sensitive indicator of all processes occurring in materials during plastic deformation, heat treatment, and operation. At present, the development of methods of scanning electron microscopy (SEM), as well as synchrotron radiation diffraction (SRD), makes it possible to significantly simplify the laborious procedure of texture analysis using the traditional X-ray diffraction method based on the results of the "reflection" survey. This work is devoted to the development of methods for quantitative X-ray texture analysis of deformed and annealed zirconium tubes using synchrotron radiation and the comparison of this data with the results obtained by the traditional X-ray texture analysis method. The results of texture analysis performed by different methods are compared. It is shown that when using the SEM and narrow beams of synchrotron radiation, the texture analysis is not very representative. Regularities are established for the improvement of the phase structure in deformed E110 and E635 alloys during annealing in the temperature range 480 - 640 degrees C, as well as some features of the SEM and SRD data. Regularities of recrystallization of the alpha-Zr-phase in the case of the presence of up to 1.6 wt.% of the beta-phase are revealed.