Influence of Thermal Treatment on the Structure, Physical and Mechanical Properties of Nanostructured Coatings (Ti, Hf, Nb, Si)N Deposited by C-PVD Method

The paper describes the nanostructured coatings produced by C-PVD method at various deposition conditions. Samples with thickness of 2, 3 mm and diameter 10, 42 mm were constructed of steel 0.55 % Fe, 0.45 % C with polished surface. The samples were tested by XRD (small angle X-Ray diffraction), SEM with EDX, AFM, scratch – tester REVETEST, tests of wear resistance and acoustic emission, nanoindenter before annealing. It was discovered that the size of nanograins varied from 3,3 nm to 8 nm by annealing at 500°, 800° and 1000°C. By dint of μ- PIXE were discovered the segregation process of impurities at the junctions of interfaces and at nanograin boundaries. Moreover as a result of the thermal annealing hardness of coatings increased on 18- 20 %. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3523

Preparation, Structural and Optical Characterization of ZnO/Ag Thin Film by CVD

Zinc Oxide thin films doped with Ag have been synthesized by CVD technique. By increasing the dopant from 0 to 10 % Ag in ZnO thin films were found to lead to pronounced changes in their morphology. From optical properties the band gap energy of pure ZnO thin film was 3.25 eV, with the increasing of Ag doping from 1 to 10% it is not affected. X-ray diffraction has shown that the maximum intensity peak corresponds to the (101) predominant orientation for ZnO and ZnO:Ag. SEM images show that more crystalline behavior by increasing the doping. EDXA analysis showed that the structure of ZnO film contains Zn and O elements and Ag, Cu, Si for doping at 10 % Ag

Analysis of the Influence of Deposition Conditions on the Structure of the Coating Nb-Al-N

Nanocomposite Nb-Al-N films prepared by magnetron sputtering have been studied. It has been found that, in the films, there are two stable crystalline structural states, namely, NbNz and B1-Nb1 – xAlxNyO1 – y, and an amorphous like component related to aluminum oxynitride upon reactive magnetron sputtering. The substructure characteristics are sensitive to the current supplied to an Al target and related to the Knoop nanohardness and hardness, which change within in the ranges of 29-33.5 and 46-48 GPa, respectively. Ab initio calculations for the NbNz and Nb2AlN phases and NbN / AlN heterostructures have been performed to interpret the obtained results for the first time

The effect of Al target current on the structure and properties of (Nb2Al)N films with an amorphous AlN phase

Nanocomposite films based on (Nb2Al)N intermetallic nitride have been obtained by the method of magnetron sputtering. Xray diffraction analysis revealed two stable states of the crystalline structure: (i) NbN with low amount (within 5 at %) of dissolved Al in a composition close to (Nb2Al)N and (ii) an amor phous component related to aluminum nitride formed by reactive magnetron sputtering. The substructural characteristics (grain size and microdeformation level) are sensitive to the current via Al target and exhibit correlation with nanohardness and Knoop hardness of the film, which vary within 29–33.5 and 46–48 GPa, respectively

Structure and properties of nanostructured NbN and Nb-Si-N films depending on the conditions of deposition: Experiment and theory

The first results of studying the phase–structural state, properties, sizes of nanograins, hardness, and microstresses in nanocomposite NbN and Nb–Si–N films are given. The investigated films were obtained by the method of the magnetron sputtering of Nb and Si targets onto silicon substrates at different negative potentials at the substrate (from 0 to –70 V), nitrogen pressures PN, and discharge powers at the targets. To determine the thermal stability of the films, they were annealed at 600, 800, and 1000°C in a vacuum.It was revealed for the first time that the NbN films have a twophase nanocomposite structure, which consists of δNbN (NaCl structure type) and α'NbN. The δNbN phase is also formed in Nb–Si–N films, where it is enveloped by an amorphous Si3N4 phase The hardness of the Nb–Si–N films reaches 46 GPa, which cor responds to the level of superhardness, while the hardness of the NbN nanocomposites is somewhat lower, but also very high (34 GPa). The experimental results for the Nb–Si–N films were explained based on the data obtained from the firstprinciples calculations of the NbN/SixNy heterostructures by the molecular dynamics method

Structure and properties of nanocomposite Nb-Al-N films

Nanocomposite Nb–Al–N films prepared by magnetron sputtering have been studied. It has been found that, in the films, there are two stable crystalline structural states, namely, NbNz and B1–Nb1 ⎯ xAlxNyO1 – y, and an amorphouslike component related to aluminum oxynitride upon reactive magnetron sputtering. It has been established that the substructure characteristics are sensitive to the current supplied to an Al target and are related to the Knoop nanohardness and hardness, which change in the ranges of 29–33.5 and 46–48 GPa, respectively. Ab initio calculations for the NbNz and Nb2AlN phases and NbN/AlN heterostructures have been performed to interpret the obtained results for the first time.

Phase composition and physical properties of Co-Cr base coating

Coating structure was mainly composed of α-fcp- and β-fcc-cobalt. Selected temperature interval for coating formation, according to XRD analysis, allowed us to form inter-metalloid compounds of CoxCry-type cobalt with chromium. Subsequent melting of a surface layer by a plasma jet resulted to doping of the coating surface by Mo atoms (compounds) from doping electrodes. It was demonstrated that essential improvement of servicing characteristics was due phase transformations induced by high-temperature plasma jet, Mo doping, redistribution of elements in the coating, and appearance of micro- and nano-grained structure, as well as decreasing porosity due to repeated melting. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2065

UnibucLLM: Harnessing LLMs for Automated Prediction of Item Difficulty and Response Time for Multiple-Choice Questions

This work explores a novel data augmentation method based on Large Language Models (LLMs) for predicting item difficulty and response time of retired USMLE Multiple-Choice Questions (MCQs) in the BEA 2024 Shared Task. Our approach is based on augmenting the dataset with answers from zero-shot LLMs (Falcon, Meditron, Mistral) and employing transformer-based models based on six alternative feature combinations. The results suggest that predicting the difficulty of questions is more challenging. Notably, our top performing methods consistently include the question text, and benefit from the variability of LLM answers, highlighting the potential of LLMs for improving automated assessment in medical licensing exams. We make our code available https://github.com/ana-rogoz/BEA-2024.Comment: Accepted at BEA 2024 (NAACL Workshop

Structure and Physicomechanical Properties of NbN-Based Protective Nanocomposite Coatings: A Review

This review summarizes the present-day achievements in the study of the structure and properties of protective nanocomposite coatings based on NbN, NbAlN, and NbSiN prepared by a variety of modern deposition techniques. It is shown that a change in deposition parameters has a significant effect on the phase composition of the coatings. Depending on the magnitude of negative potential on the substrate, the pressure of nitrogen or a nitrogen–argon mixture in the chamber, and the substrate temperature, it is possible to obtain coatings containing different phases, such as NbN and SiNx (Si3N4), AlN, and NbAl2N. It is found that, in the case of formation of the ε-NbN phase, the coatings become very hard; their hardness achieves values on the order of 53 GPa. At the same time, they remain thermally stable at temperatures of up to 600°C, chemically inert, and resistant to wear. The effect of the nanograin size, the volume fraction of boundaries and interfaces, and the point defect concentration on the physicomechanical properties of these coatings is described. Niobium nitride-based coatings can be used in superconducting systems and single-photon detectors; they are capable of operating under the action of strong magnetic fields of up to 20 T; they can be used in integrated logic circuits and applied as protective coatings of machine parts, edges of cutting tools, etc