Effect of the C/N ratio modification on the corrosion behavior and performance of carbonitride coatings prepared by cathodic arc deposition

This study focuses on investigating carbonitride coatings, specifically CNTi-(Zr, ZrNb, and ZrSi), as promising candidates for enhancing the durability and efficiency of Ti6Al4V materials used in nuclear fusion technology. X-ray diffraction analysis identified distinct phases, including TiN, ZrN, ZrC, and TiC. The corrosion studies showed complete degradation of the TiN, ZrC, and ZrN phases in the TiZrCN coating after tests, while the TiC phase exhibited relative stability. The surface morphologies and elemental mapping analysis demonstrated the loss of homogeneity in element distribution after corrosion process. The addition of Si and Nb elements into TiZrCN significantly influenced the coatings' corrosion behavior, with breakaway corrosion observed in CNTi- (Zr and ZrSi) coatings and localized corrosion in CNTi-(ZrNb) coatings. Notably, the CNTi-(ZrSi) coating formed an oxide phase in the presence of NaCl, whereas the CNTi-(ZrNb) coating exhibited continuous resistance and a low corrosion rate. Irradiation was carried out for the generation of active isotopes, showing that no radioactive isotopes were formed in any of the investigated samples

Development of methods for the preparation of radiopure ⁸²Se sources for the SuperNEMO neutrinoless double-beta decay experiment

A radiochemical method for producing 82Se sources with an ultra-low level of contamination of natural radionuclides (40K, decay products of 232Th and 238U) has been developed based on cation-exchange chromatographic purification with reverse removal of impurities. It includes chromatographic separation (purification), reduction, conditioning (which includes decantation, centrifugation, washing, grinding, and drying), and 82Se foil production. The conditioning stage, during which highly dispersed elemental selenium is obtained by the reduction of purified selenious acid (H2SeO3) with sulfur dioxide (SO2) represents the crucial step in the preparation of radiopure 82Se samples. The natural selenium (600 g) was first produced in this procedure in order to refine the method. The technique developed was then used to produce 2.5 kg of radiopure enriched selenium (82Se). The produced 82Se samples were wrapped in polyethylene (12 μm thick) and radionuclides present in the sample were analyzed with the BiPo-3 detector. The radiopurity of the plastic materials (chromatographic column material and polypropylene chemical vessels), which were used at all stages, was determined by instrumental neutron activation analysis. The radiopurity of the 82Se foils was checked by measurements with the BiPo-3 spectrometer, which confirmed the high purity of the final product. The measured contamination level for 208Tl was 8-54 μBq/kg, and for 214Bi the detection limit of 600 μBq/kg has been reached.</p

PHYSICAL AND CHEMICAL RESEARCHES OF THE RELAXOL SERIES OF CEMENT COMPOSITION WITH COMPLEX CHEMICAL ADDITIVE KDJ-3

To study the process of structure formation of the cement composition, the method of infrared spectroscopy, X-ray phase analysis and electron microscopy were used. With the help of mechanical mixing it is difficult to provide the binder with the right amount of water. This task is performed by a complex additive, improving the wettability of cement particles. By reducing the content of calcium hydroxide, the possibility of the formation and existence of polybasic calcium hydroaluminates decreases. This circumstance prevents the formation of calcium hydrosulfonate (GSAC) in the later periods of hardening. On electron micrographs of cement stone samples with the addition of the obtained complex additive KDj-3, the pores are filled with both gypsum and calcium hydrosulfonic aluminum. The compaction and hardening of the structure of portland cement compositions in the initial stages of hardening is a consequence of the fact that both gypsum and calcium hydrosulfonic aluminate, with the addition of a complex additive, crystallize with an increase in volume

Structure and thermal analysis of Ba<inf>0.5</inf> La<inf>0.5</inf> MnO<inf>3</inf> polycrystalline powder

© 2019 World Scientific Publishing Company. The structure and thermal properties of Ba0.5La0.5MnO3 polycrystalline powder have been investigated using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) techniques. The structural studies have shown that Ba0.5La0.5MnO3 compound crystallizes in perovskite structure with Pm-3m cubic symmetry group. The lattice parameters were obtained to be a = b = c = 3.9073 Å. Mass changes have been observed from thermogravimetric (TG) and differential thermogravimetric (DTG) curves obtained in a wide temperature interval of 30-950°C. Free energy and enthalpy changes for all observed transformations were determined. Observed endo and exo effects