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The main applications of gas chromatography for investigation of catalysts and catalytic processes are considered. The development of the sampling method as well as the microcatalytic and pulsed methods is described in historical aspect. The paper presents the advanced and promising directions of gas chromatographic studies, and the instruments providing efficient separation of multicomponent mixtures of substances with the control of complex catalytic reactions.

Samples of carbon fiber T 700 were researched. They were subjected to impact damage, after which they were loaded with a static load until failure. Registration of defects was carried out using the method of acoustic emission (AE) and tensometry. In the process of loading the samples, the deformation and load were determined, at which the AE signals were located. An antenna consisting of piezoelectric acoustic emission transducers (PAE) and fiber optic sensors (FOS) was used to monitor defects. When the load changed from 80 to 100 kN, a jump in mechanical stresses was observed in the samples from 338 to 432 MPa, registered by the certified microprocessor-based high-speed tensometic system “Dynamics-3”. In this case, the average amplitude of the AE signals significantly decreased, starting from the load P = 80 kN, after which it increased at the load P = 110 kN. For sensors PAE 3 and VOD 2, located on the opposite side of the sample, where impact damage was absent, these changes in the amplitudes of the AE signals were less pronounced.

Abstract Comparative tests related to locating acoustic emission (AE) signals due to shock impacts on a T700 carbon fiber sample were carried out. Piezoelectric acoustic emission transducers (AETs) and fiber-optic sensors (FOSs) were installed on the sample, forming rectangular location antennas measuring $$360 \times 280$$ mm. Strikes were delivered with balls weighing 10 and 18.5 g. Antennas consisting of four AET sensors and four FOS sensors and an antenna consisting of two AET sensors and two FOS sensors were organized. When using the antenna containing four FOS sensors, the impact on the sample was produced by a load weighing 530 g dropped from a height of 400 mm. AE signals were recorded by the SCAD-16.10 system with “floating” selection thresholds when the ball was dropped and during its repeated bounces. Then AE signal clusters were formed and recorded during the impact of loads. The arrival times of AE signals to the antenna sensors were calculated using the threshold method, the root mean square (RMS) deviation method and the two-interval method. It is shown that the maximum error in locating AE signals is observed when a steel ball with a diameter of 16 mm is dropped from a height of 300 mm and the minimum error is when using an electronic simulator.

The results of full-scale strength tests of an aircraft spar made of carbon fiber with a corrugated wall are presented. Strength tests of the spar structure were carried out in three stages, including static and cyclic loading. During each stage of loading, acoustic emission (AE) and strain gauge control of the spar was carried out. Real-time location of AE signals characterized the most dangerous areas in the process of destruction of the root zone of the spar and was carried out using the "time window" algorithm moving along the implementation of the AE signal. To determine the time of arrival of the AE signal, two threshold levels were selected, one of which corresponded to the prehistory noise level, and the second level corresponded to the minimum signal energy level exceeding the noise level. Using tensometry, the maximum stresses were found in different zones of the spar, where the AE signals were located.

The article describes the main stages of the creation of the Siberian Aeronautical Research Institute (SibNIA) named after S. A. Chaplygin from 1941 to the nowdays. The main works on aerodynamics and strength under normal conditions, at high and cryogenic temperatures of hypersonic aviation, rocket and space technology are presented. The issues of creating a composite aircraft TVS-2DTS, which is a modernization of the An-2 aircraft, are considered, and examples of restoration of aircrafts form the Great Patriotic War times are given.

A method for monitoring the compression stress in a rail and a sample made of steel 20 using the effect of acoustoelasticity and strain gauge has been developed. Wire load cells were pasted to the opposite sides of the rail and the sample. Measurements, recording and processing of strain gauge information was carried out by a certified microprocessor strain gauge system MMTS-64.01 with accuracy class 0.2. To control the compression stress, the developed microprocessor-based ultrasonic system “Akusto-1” was used, which operates on the basis of the acoustoelasticity effect. The angle of input of ultrasonic vibrations, equal to 18°. This allowed to excite longitudinal, transverse and transformed waves in the object. Compressive stresses in the rail and steel sample were carried out by 250-ton loading machine “PSY-250”. Longitudinal and transformed ultrasonic waves were used to control compressive stresses. A comparative analysis of the experimental and calculated dependences of compressive stresses on the load obtained by acoustic, tensometric and computational methods is performed. The reliability of the experimental and calculated results was controlled by a certified microprocessor strain gauge system MMTS-64.01.

The results of experimental studies of a nondestructive testing method for assessing the loading of bearing rings on an axle journal using the acoustoelasticity effect based on measuring the characteristics of elastic surface waves are presented. Reference blocks for loading with a difference in pilot diameters in the range from 38 to 119 $$\mu {\text{m}}$$ with an error of no more than 7 µm have been developed and manufactured. A hydraulic testing bench for mechanical loading of bearing rings simulating their press fitting on an axle with loading of up to 46 microns was certified. The acoustoelastic coefficients $$\alpha = (5.48 \pm 0.14)$$ $${\text{TP}}{{{\text{a}}}^{{-1}}}$$ were experimentally determined for surface waves in steel ShKh15 based on the delay in the time of recording pulses that repeatedly (2–5 times) circled the ring. The correlation method is optimized for determining the delay time of a wave in a loaded ring relative to an unloaded one according to the condition of minimizing the uncertainty associated with a change in the pulse shape. The main reasons for errors and uncertainties in measuring the absolute time of propagation of a surface wave are established: the effect of waves reflected from the boundaries, surface curvature, and attenuation. The bearing rings loading was measured on loading reference blocks using the acoustoelasticity effect, and the estimation of the stress measurement uncertainty was made.

The issues are considered of acoustic emission (AE) signals location generated by various simulators (Su–Nielsen, electronic simulator, metal balls of various diameter from 0.5 to 1.5 mm, dropped from different heights). Signals generated by built-in electronic simulator with a frequency of 1 Hz location is analyzed performed by an antenna consisting of two Fabry–Perot fiber-optic sensors (FOS) and two piezoelectric transducers, mounted on samples made of duralumin and T800 carbon fiber. A carbon fiber reinforced plastic sample with the defined above antenna mounted was tested with a VEDS-10 vibration stand. AE signals were registered under the vibration frequency of 20…50 Hz in the acceleration range of 0.3…0.8g. The influence of the time drift recorded by the piezoelectric transducers on the measurement results is determined. It was found that the time drift was not recorded by fiber-optic FOS sensors, but their sensitivity is more than 14 times less than that of piezoelectric transducers.

Static tests of the samples of Torayca T700, T800 carbon fiber reinforced plastics consisting of nine monolayers with $$\left[ { \pm 45{\text{/}}90{\text{/}}{{0}_{3}}{\text{/}}90{\text{/}} \pm 45} \right]$$ stacking and geometric dimensions $$600 \times 100 \times 0.9$$ mm and $$500 \times 100 \times 1.4$$ mm were carried out. In the process of static and thermal loading, defects were monitored by the acoustic emission (AE) method. Two samples were statically loaded and simultaneously exposed to temperature $$T = 100$$ °C. Six samples were statically loaded at temperature $$T = 20$$ °C. The sources of AE signals corresponding to sample material destruction were localized in real time. For these signals, thin polished sections were prepared from location zones in the sample, and the fractography of the CFRP material was carried out. The analysis of the recorded AE information has been carried out. The main informative parameters of the AE signals localized in the working area of the samples are considered. Using cluster analysis by digital waveform, three types of clusters are identified for the AE signals. For the first type of clusters, the frequency of AE signals exceeded 175 kHz, and a relatively high level of the MARSE energy parameter was noted. In clusters of the second type, AE signals recorded under static loading and sample heating had lower MARSE values and a median frequency not exceeding 170 kHz. When testing samples with no heating, the median frequency did not exceed 140 kHz. The third type of clusters was formed by AE signals with the frequency not exceeding 400 kHz. Such clusters were typical only for samples tested at temperature $$T = 20$$ °C.

Investigations of three groups of samples from carbon fiber T 700 and the composite wing box of the aircraft were carried out. Samples with monolayers laying 0; 90; –45 were subjected to shock loads, which were applied at their center with a load in the form of a blunt tip weighing 0.53 kg. Loads were dumped from a height of 0,3; 0,5; 1 m per sample. Impact damage with an energy of 15 J was also applied to the upper surface of the carbon fiber wing box. Acoustic emission (AE) signals were recorded from the piezoelectric antenna sensors mounted on the wing samples and box both during the impact of the weight with the object under study and during rebounds. The locations where the shock load were applied were located and the parameters of the AE signals were analyzed. The influence of the type of monolayer laying on the process of cracking in the material of the samples arising at different energy of shock loads was determined.

Static tests of a two-spar T800 CFRP wing box have been carried out. The object was tested when loaded using the methods of acoustic emission (AE) and strain gaging. Strain in the material was determined in real time in the areas where strain gages were bonded (the panels of wing box, the walls of side members, and the shelves of stringers). The elements of the wing box have been established in which nonlinear strain change is observed and residual deformations are recorded after unloading. The AE method has been used to localize the sources of signals. The coordinates of the sources corresponded to the location of the third rib. Clustering recorded AE signals based on their digitized form has made it possible to group the signals and assign them to sources that correspond to structure failure. It is shown that in the process of loading the wing box, an increase in the structural coefficient of AE signals corresponding to CFRP delamination in the location zone is observed.

A procedure is proposed for rejecting girth welds based on an analysis of the main parameters of acoustic emission (AE) signals recorded during multiple-pass welding. The accuracy of locating AE signals recorded from defects and their filtering from noise and interference were ensured by the use of a modified tabular method and rejection grid. Normalized coefficients were calculated from the energy and amplitude of localized AE signals and used for in-process assessment of weld quality. Threshold values were determined for the normalized coefficients above which the weld is rejected. Defects in girth welds were identified using this procedure, and the possibility of determining defect hazardousness in real time was demonstrated.

The catalysts 1 wt% palladium supported on carbon nanoglobules (CNGs) were shown to be highly active in the liquid-phase hydrogenation of various nitroarenes and provided nearly 100% selectivity to aromatic amines at complete conversion under mild conditions (323 K, 0.5 MPa, 1 h). The catalytic activity (in terms of turnover frequency and substrate conversion) and selectivity depend on the kind of CNGs support, catalyst preparation method and the reaction conditions (solvent nature). The Pd/CNGs catalyst can be repeatedly used while maintaining the same catalytic performance. The excellent performances of Pd/CNGs catalysts can be due to the globular morphology of the supports as well as the absence of micropores and pronounced surface defects.

Acoustic emission (AE) control of defects was performed during testing of the T800 carbon fiber wing caisson. Static and shock loading of the structure was performed, and the location of AE signal sources was performed in real time. Under static loading, the coordinates of the localized sources corresponded to the location of the third rib. Clustering of AE signals based on their digitized form is performed. This allowed the formation of clusters corresponding to structural failure. It is shown that during the loading of the wing caisson, an increase in the structural coefficient of AE signals was observed, corresponding to the stratification of carbon fiber in the location zone. In the process of applying shock damage, AE information corresponding to shock loads was recorded.

The effects of positive and negative temperature and static load on the main informative parameters (structure coefficient, partial energy, location) of acoustic emission (AE) signals, which determined the mechanism for changing the structure of carbon fiber and the beginning of its destruction, are investigated. Tests of specimens of carbon fiber T800, made of nine monolayers with laying [±45/90/О3/90/±45], size 600x100x0.9 mm. Each sample was subjected to static loading and the effects of positive (+20, +40, +60, +80, +100 °С) or negative (–20, –40, –60, –80 °C) temperatures in the area of the concentrator in the form of a 12 mm diameter hole. Using fractography, changes in the structure of carbon plastic from the applied static load and temperature and changes informative parameters were analyzed. It was shown that the lamination of the material with simultaneous exposure to static load and temperatures from –80 to –20 °C and from +60 to +100 °C corresponded to an increase in the structural coefficient and partial energy, which caused an energy shift in the frequency range 125…250 kHz. Under the same static loads, but temperatures of +20 and +40 °C, informative parameters took on minimal values, that meant the energy was shifted to the frequency range 250…500 kHz, characterized the crumbling of the matrix and breaking of the fibers without lamination of the CFRP. Under all temperature conditions, the location of the signals began in the hole area and spread in the direction of the static load. The detection the disturbance of the CFRP structure by the informative parameters of AE signals makes it possible to reduce the risk of emergency situations during working of the composite construction.

Strength tests of T800 carbon-fiber specimens with geometrical dimensions 100×600×0.9 mm were performed. The CFRP material used a stacking of nine mono-layers [±45/90/03/90/±45]. In the central part of the samples, a stress concentrator was placed in the form of a hole with a diameter of 12 mm. The loading with a static tensile load was carried out by the loading machine MTS-100 with hydraulic grips. Simultaneously with static loading, the sample was affected by positive (+20; +100 °С) or negative (–20; –40; –60 °С) temperatures. Registration information was carried out using the method of acoustic emission (AE). In the process of loading the samples, the effect of static load and temperature on the main informative parameters (amplitude, dominant frequency, structural coefficient) of AE signals recorded during the loading of samples was studied. The structure coefficient, reflecting the energy at one frequency, and the coefficient, calculated as a partial energy, were compare.

Acoustic emission (AE) detection of 5005005 mm size St3 steel samples welding defects. The informative parameters of AE signals recorded during welding with inserts of titanium and aluminum inserted into the root of the weld are analyzed. AE-signals recording was performed by welding diagnostic unit with automatically changing “floating” selection threshold. For coordinates of defects estimation clustering was performed by digital form and AE signals parameters. A comparative analysis of the clustering results was performed for each cluster. In this case, the total count of AE signals, their energy, and threshold levels were set, which were determined in accordance with the proposed algorithm. The degree of danger of defects in the weld was monitored by exceeding AE signal energy threshold level. If the AE signal had a second energy peak and when it exceeds the energy selection thresholds, the weld was rejected. It was experimentally shown that the titanium insert was a dangerous defect when the threshold energy level was exceeded, which was detected both with a high total count of AE signals and with a small number of recorded signals. In accordance with the proposed method, when introducing an aluminum insert into the weld, the defect was not considered dangerous.

The analysis of the developed methods of cluster analysis of acoustic emission signals (AE), performed during the welding process and in the process of strength testing of composite samples and structures, was performed. Clustering in digital form, informative parameters of AE signals, front edge rise rate, as well as dynamic and two-stage clustering are considered. The examples of the use of the developed cluster analysis methods in the control of welding defects, composite samples and elements of aircraft structures during static and cyclic testing are shown. The advantages and disadvantages of various clustering methods for processing AE information are determined.

The results of testing samples made of T700 carbon fiber reinforced plastic with a stress concentrator in the form of a hole 14 mm in diameter are considered. Some of the samples were heated to a temperature of +100°C, followed by exposure to a static tensile load, with the remaining samples statically loaded at a temperature of +20°C. In the process of loading, information was recorded using the method of acoustic emission. At first, the samples were loaded statically up to 50 kN, which was 50% of the average breaking load. Then the load was increased in increments ΔP = 10 kN until sample failure. It was observed that the simultaneous exposure of samples to static and heat loads decreased the load capacity of the samples.

The MgAl layered double hydroxides (LDHs) were prepared by two-stage synthesis, which included mechanochemical activation at the first stage and the interaction of the resulting sample with distilled water at the second stage. The influence of the material of grinding bodies (steel and ceramics), the conditions of activation (activation time and the centripetal acceleration of balls), and the nature of initial compounds on the phase composition of the resulting products was investigated. It was established that the formation of a single-phase MgAl LDH was observed upon mechanochemical activation with the use of steel grinding bodies at an acceleration of 1000 m/s2 for 30 min. The samples prepared by a traditional coprecipitation method and a method that included a stage of mechanochemical activation possessed identical structural parameters. However, the mixed oxides formed upon the calcination of LDHs synthesized by mechanochemical activation were characterized by a more uniform pore space with a pore diameter of 4–5 nm with a developed specific surface.

Results of the strength tests of an aircraft wing spar made of Toray T1000 carbon fiber-reinforced plastic are presented. Construction failure zones have been inspected by the methods of acoustic emission (AE) and tensometry. Loading-induced changes in the stress-strain state (SSS) of wing-spar material have been analyzed. The coordinates of AE signal sources that correspond to the separation of the upper spar cap from the spar web have been determined. Algorithms for AE-data processing using wavelet transforms are considered. Connections have been established between changes in stresses emerging in CFRP material, AE signal structure, and the occurrence and propagation of spar fracture.

Mechanochemical synthesis of MgAl-layered double hydroxides (MgAl-LDH) with molar ratio MgAl = 3 was performed. The effect of the acceleration of milling bodies (500 and 1000 m s-2), activation time (5–90 min), and water addition on the phase composition of obtained samples, their structural parameters, as well as on the process of formation of mixed oxides, prepared after LDH calcination was studied. The conditions for the preparation of single-phase LDH were established. It was shown the possibility of the textural properties regulation of mixed oxides by change of the mechanochemical synthesis parameters of corresponding layered double hydroxides.

The Pt/MgAlO x catalysts, in which a mixed aluminum–magnesium oxide obtained by the heat treatment of corresponding layered double hydroxides was used as a support, were studied. The effects of the nature of active-component precursors ([PtCl6]2–, [PtCl4]2–, and [Pt3(CO)6] 6 2- ), and the Mg/Al ratio in the support on the anchoring of complexes, the disperse state of platinum, and the properties of the obtained catalysts in the reactions of propane and n-decane dehydrogenation were found.

The acoustic-emission method for inspecting flaws that form during laser bonding with the use of a CO2 continuous-wave laser with a power of up to 8 kW and characteristics that can be preadjusted prior to welding is considered. The structure of acoustic-emission signals registered in a specimen’s flawed domain has been analyzed using the wavelet transform. It has been shown that the structural coefficients of the acoustic-emission signals localized in specimen’s flawed sections become identical over time.

Relationship between the main informative parameters of acoustic-emission (AE) signals recorded during static loading of a CFRP sample and the process of material fracture has been investigated. Clusterization of AE signals by digitized shape has made it possible to locate a zone they originate from. Material was then cut out from this zone to prepare thin sections that were subjected to fractography. Fractography revealed fiber fracture, brittle cracking of the matrix, its exfoliation from the carbon fibers, etc.

Mechanochemical method was used to prepare layered double hydroxides (LDH) with different cationic composition MAl (M – Mg, Li, Co, Ni). Platinum chloride complexes [PtCl6]2- were anchored from an excess of an aqueous solution of hydrochloric platinum acid on mixed oxides obtained by LDH calcination at 550 °С. Transformations occurring in the structure of mechanochemically synthesized materials after the fixation of platinum complexes were studied by means of X-Ray diffraction analysis. It was shown that various transformations are observed in the phase composition of the samples depending on the cationic nature. Partial restoration of the layered structure occurred when [PtCl6]2- adsorbed at MgAl- and LiAl – mixed oxides. Anchoring of the platinum complexes on the NiAl-, Ni-MgAl- и CoAl- samples did not lead to the restoration of the layered structure.

Two types of Ni-containing layered double hydroxides (LDHs) were obtained by the eco-friendly mechanochemical method: double NiAl-LDHs and triple Ni-MgAl- LDHs with molar ratios of cations Ni/Al= 2, 3 and 4 and (Ni+Mg)/Al= 2, 3 and 4, respectively. Molar ratio Ni/(Ni+Mg) in triple LDHs was 0.5 The phase composition of the synthesized samples was investigated by XRD-method, and the lattice parameters were calculated. The catalysts obtained after calcination and reduction of Ni-containing LDHs were tested in the liquid-phase hydrogenation of furfural. A higher activity of three-component systems was shown compared to two-component systems. Moreover, for catalysts based on Ni-MgAl-LDH, the selectivity of the reaction products formation can be regulated by changing of (Ni + Mg)/Al ratio.

Ni(Mg)Al-layered double hydroxides (LDH) were synthesized by coprecipitation. Structural properties of LDH and mixed oxides Ni(Mg)AlOx, obtained by LDH calcination, were studied by XRD and SEM. Textural properties of Ni(Mg)AlOx were studied by the nitrogen adsorption-desorption method. It was found that the formation of the single-phase LDH was occurred for any nickel content in the samples. The mixed oxides have a high specific surface area, the value of which decreases with increasing nickel content in the samples. Ni(Mg)AlOx are characterized by high activity in furfural hydrogenation. Selectivity of the formation of different reaction products depends on the nickel content in the catalysts. The full furfural conversion with the furfuryl alcohol selectivity no more than 65% was observed for the catalyst with a low nickel content. At the same time an increase in selectivity for furfuryl alcohol up to 84% occurs for the NiAl-catalyst with a furfural conversion not exceeding 43%.

Titanium and duralumin inserts were introduced into a weld to imitate welding flaws in St3 steel samples. Analysis of the accuracy of locating the introduced flaws with different clustering methods (by digitized shape, main informative parameters, the rise rate of leading-edge envelope) has shown that these methods involve considerable time expenditures. The developed dynamic clustering has been combined with the clustering by main informative parameters and allowed in situ location of flaws during welding, while the weld has not been completed yet.

The effect of the cationic composition of MgAl(Ga) layered double hydroxides on the structure, texture, and acid–base properties of related oxide supports for platinum catalysts has been investigated. As gallium is progressively substituted for aluminum in the mixed oxide, the properties of the support change only slightly, while the activity of the Ga–Pt catalysts in propane conversion increases, the propylene selectivity remains high (99%), and C–C bond hydrogenolysis is hampered.

A modified tabular method for locating acoustic-emission signals, which is intended for determining the coordinates of flaws when inspecting a multiple-run welding process with a lower error rate, and the result of using this method for determining the coordinates of flaws when welding a circular contour using a piezoelectric antenna, which consists of four acoustic-emission transducers, are considered. It is shown experimentally that the application of the modified tabular method allowed an increase in the accuracy of determining the coordinates of introduced flaws when using the acoustic-emission testing method.