An approach to analysis of advanced sensor materials based on cobalt oxide modified with zinc or nickel oxides is developed using X- ray fluorescence analysis (XRF) and inductively coupled plasma mass spectrometry (ICP-MS). It is shown that determination of Ni, Zn and  Co in novel materials based on cobalt oxide using ICP-MS in  solutions is possible, standard deviation being 0.06, 0.06, and 0.05,  respectively. The results of the ICP-MS determination of the  elements in solutions are used to certify the results obtained by XRF  method without sample preparation. It is shown that NixCo3–xO4–д  samples can be correctly analyzed without decomposition using X- ray fluorescence analysis. The results of the determination match  theoretically calculated values both for the samples obtained from  nitrates and from nickel and cobalt oxalates as well. However,  calibration based on the ICP-MS results is necessary for X-ray fluorescence analysis of ZnxCo3–xO4 samples. It is shown that zinc content in the samples exceeds the theoretical determined value by  10 – 30% due to incomplete precipitation of cobalt from the solution upon synthesis.

At present, high-temperature composites of the Nb-Si-system are the most promising for use as High-temperature composites of Nb –  Si-system are among the most promising materials to be used as heat-resistant structural materials and as an alternative to high- temperature nickel-based alloys that have largely exhausted their  ability to increase the operating temperature. The next generation of high-temperature materials for casting blades of gas turbine  engines should provide a temperature of about 1350°C or higher  which can significantly improve the efficiency of engines and  contribute to their environmental performance. Nb – Si composites  are obtained by traditional methods of ingot production and powder  metallurgy. Statutory regulations impose heavy demands on  the chemical composition of aviation materials used for manufacturing heavy-duty parts of gas turbine engines. We present a technique for  determination of the alloying elements Si, Ti, W, Mo, Hf, Cr, and Al in advanced high-temperature Nb – Si based composite materials (CM)  using inductively coupled plasma-atomic emission spectroscopy  (ICP-AES) and microwave sample preparation. Conditions of sample  dissolution, method of calibration line construction, and analytical  lines free of significant spectral overlapping are specified to  determine all the alloying elements of Nb – Si-based composites. To  assess the metrological characteristics of the developed technique  we used model solutions of Nb – Si composites prepared from state standard reference sample of solutions of ions of the elements. The repeatability of the technique does not exceed 1% rel., the  intermediate precision does not exceed 3% rel.

Microwave and traditional methods of dissolving charge and single crystals of complex borates Ca3Y2(BO3)4,Ca3Nd2(BO3)4,Ca3Gd2(BO3)4 are proposed. The advantages and prospects of using microwave heating for solubilization  of complex borates are shown. Procedures for determination of the macrocomponents Ca, Y, Nd, Gd, B in complex borates are  developed. Correctness of determination of the main components in  complex borates is confirmed on model solutions in spiking tests  method and on the real samples using the method of sample weight variation

Advantages of direct laser cladding of metal consisting in the possibility of directional crystallization of 316L stainless steel  samples are shown. Direct laser cladding of metal offers exciting  possibilities for  production of single crystal structures by directional  crystallization of the deposited metal. The growth direction of  dendritic crystals is driven by the thermal center determined by the  position of the laser spot. We present a technique of manufacturing  stainless steel products by direct laser deposition using the  developed algorithm which allowed us to connect the movement of  the robotic cell and turntable with a sample, laser switching and  feeding of the gas powder mixture. The possibility of x-ray tomographic quality control of the obtained products, determination  of the parameters of the laser spot on the substrate surface using  high-speed photography, estimation of the phase composition of the  deposited metal using x-ray diffraction analysis is demonstrated. The structure of obtained metal samples is represented by dendritic  crystals oriented in the direction of the thermal center. The sample structure in the sample cross section is represented in the form of a  honeycomb formed by the first order axes of dendritic crystals. It is  shown that 200-мm thickness of the deposited layer in the central part of the sample does not interfere with the development of the  dendritic structure and promotes the possibility of obtaining single- crystal structures free of pores and cracks. The possibility of estimating the inclination angle of dendritic crystals in the metal  relative to the symmetry axis of the sample using a metallographic  software package for analysis of digital images of the  microstructures is shown. It is demonstrated that the roughness of  the obtained samples is determined by the size of the powder particles and can be eliminated by the mechanical treatment.

The issues regarding the reliability of assessing health of the oiled joints of aircraft gas turbine engines (GTE) proceeding from the  results of spectral and ferrographic measurement of the parameters  of wear particles are considered. It is shown that, due to design  features of the oil system analysis of the oil sample does not provide  enough information about the wear processes in the GTE  joints. Growth of the number of diagnostic parameters (particle  concentration, form and size) does not significantly in- crease the  reliability of health assessment, whereas analysis of the oil filter  wipe sampling provides full information about engine wear  processes. The main measurement instrumentation requirements are considered. High reliability of diagnostic results can be attained  when the parameters of wear particles are measured over the full range of their variation. Issues regarding the recurrence of engine health assessment in case of using fine-meshed oil filter with 600-h  lifetime are discussed. The use of expendable oil filters with a  diagnostic layer can solve the problem. Diagnostic potentials of some promising methods of assessment and prognosis of the oiingl system health in aircraft GTE are evaluated.

Substantiation of using fractal analysis in studying the images of Palmquist microcracks is presented. The numerical values of the  fractal dimension of the Palmquist microcracks (PMC) at various sites of crack propagation (the Vickers indenter) are determined. A  sintered carbide alloy (cermet) based of titanium carbonitride with  nickel-molybdenum binder (KNT12) was taken as a test object. A  method of quantitative analysis in the study of the PMC images  obtained using scanning electron microscope is considered. An  example of the length measurements in which the measured value  depends on the scale of measurements (Richardson coastline  paradox) is taken as a basis. We used a simple method of covering the curve image on the plane by the squares of different sizes to determine the fractal dimension of the curve. Fractal dimension  (parameter) of the image of the PMC contour was determined in two  ways: i) at a constant magnification and ii) using series of images  with a monotonically varying magnification.

A computational and experimental modeling of the scatter in technologies is presented for steel 15Kh2NMFA at room temperature  to reveal possible variations in the ultimate strength at a limited number of melts. The developed method of step-by-step  “mixing” of technological samples (up to seven samples) is used to  determine and assess the values of the parameters of the  distribution functions and probability density functions. An increase  in the total number of samples and melts makes it possible to  improve the accuracy of the determination of the material  characteristics in the region of large and small probabilities (1 – 5%) and estimate the features of intra-melt scattering. The results showed that with the extension of the range of distribution functions  to probabilities of 1 – 99% with increasing number of samples and  the number of melts, the normal distribution functions of the mechanical properties usually remain similar and close to the two- threshold distribution both for single melt and for the sum of several  melts (a trend to 3 – 3.5 -fold increase of intra-melt scattering is  observed). “Heavy tails” can appear on the distribution curves at low  probabilities (below the defective level). Presence of “heavy  tails” interferes with direct use of the minimum guaranteed roperties without relevant tests and leads to violation in strength and resource calculations. The considered problems also touch on the analysis of safety and risks.

Conditions of brittle fracture arrest occurring in rolled sheet of low-alloyed steels at a specific temperature are considered. The problem of  revealing correlation between this temperature, thickness of testing  specimen and material properties is analyzed using finite element  method for computer simulation of unstable crack propagation in 3D  setting with specified local criteria of brittle and ductile fracture.

The issues of deformation processing of low-carbon steel billets using combined impact of extrusion and screw pressing (ESP) are  considered. The results of low-temperature tensile tests of steel  samples are  presented. It is shown that the characteristics of strength and plasticity  (ductility) of steel subjected to ESP at lower test temperatures (213 K)  are higher than that at room temperature. A fractographic study of the  destruction mechanisms of the steel in as-received condition and after  ESP processing at room temperature and at a test temperature of 213 K revealed a ductile (viscous) character of the destruction mechanism with micro pits and pits present in all areas of the fracture surface.

The problems of correct and effective choice of the methods and means used for leakage monitoring by penetrating substances  (gases) on the basis of certain criteria are considered. Methods of  mathematical statistics are used for classification analysis of the  main characteristics of the leakage test methods and approaches in  the framework of general theoretical research to prioritize them in  compliance with current GOST 51780–2001. In other words, an  attempt has been made to search for and identify the effective ways  of ordering the classification structure from the main characteristics  of the methods and means of leak testing necessary for the  researcher at the preparatory stage of testing. This is partly due to  the lack of clear recommendations in this standard regarding the  significance of these characteristics for leakage control in real conditions and possibility of its implementation. The procedure rests on the proposed nonparametric algorithm which includes  classification of the characteristics based on pairwise clustering. The  expert evaluation method is used for effective addressing the  problem of nonparametric analysis. Solutions of multivariate analysis are given for the problem of inverse reduction of characteristics to a  small number of groups formed on the basis of generalizing features  using discriminative analysis on the basis of nonparametric criteria to check statistically significant difference. Comparatively high posterior probability of attributing the classification features to the groups distributed among six clusters is determined as a result of studying  characteristics pertaining mainly to the leakage test facilities (as the  most numerous ones compared to test methods). We also consider and assess the possibility of introducing some clarifications to refine the current standard.