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In the present work, thermal exposure was performed on the 7B50-T7451 aluminium alloy friction stir welding (FSW) joints at different temperatures (150 °C, 175 °C and 220 °C) for 200h. The results show that the microstructure and mechanical properties of as-welded joints along the thickness direction of the plate are heterogeneous. The hardness and strength of FSW joints decrease while the elongation continuously increases with increasing thermal exposure temperature. Compared with the base material, the joints present much higher hardening capacity which is further increased with increasing temperature. The precipitates in the heat-affected zone (HAZ) exhibit continuous coarsening and the precipitate distribution becomes broader as the temperature rises. The transformation from η' phase to η phase is obvious at 220 °C. The weld nugget zone (WNZ) re-precipitates a large number of nano-scale η particles subjected to 200h thermal exposure at 150 °C and re-precipitated η phase in WNZ of the double-sided joint has reached micron-sized at 175 °C and 220 °C. When exposed at different temperatures, all FSW joints show typical ductile fracture features. Fracture positions at different thermal exposure temperatures are inconsistent and this variation is closely related to different microstructural characteristics.

Previous studies have shown, in the United States (U.S.), that communities of color are exposed to significantly higher temperatures in urban environments than complementary White populations. Studies highlighting this disparity have generally been cross-sectional and are therefore “snapshots” in time. Using surface urban heat island (SUHI) intensity data, U.S. Census 2020 population counts, and a measure of residential segregation, this study performs a comparative analysis between census tracts identified as prevalent for White, Black, Hispanic and Asian populations and their thermal exposure from 2003 to 2018. The analysis concentrates on the top 200 most populous U.S. cities. SUHI intensity is shown to be increasing on average through time for the examined tracts. However, based on raw observations the increase is only statistically significant for White and Black prevalent census tracts. There is a 1.25 K to ~2.00 K higher degree of thermal exposure on average for communities of color relative to White prevalent areas. When examined on an inter-city basis, White and Black prevalent tracts had the largest disparity, as measured by SUHI intensity, in New Orleans, LA, by 7.00 K) and Asian (

In the present study, the morphological evolution of eutectic Si particles subjected to extended thermal modification and chemical treatment has been investigated for Zr containing A354 and A356 alloys along with its effect on the mechanical properties. Thermal modification of silicon particles proved to be more effective in the Sr-modified alloys rather than their Sr-free counterparts. The evolution of silicon particles during extended solution treatments followed the same trends and sequences for non-modified and Sr-modified 354- and 356-type alloys, at different evolution rates. The coarsening of eutectic Si particles occurred through particle coalescence and Ostwald ripening mechanisms. While both mechanisms were active at the same time, however, they operated independently and additively. The pinholes observed in the silicon particles derive from the impression or imprint left behind from the collision of small particles with, and their diffusion into, larger particles. With respect to the tensile test data obtained at room temperature, solution heat treatment improved the UTS and ductility values of both Sr-modified and non-modified alloys in the first 100 h of the treatment followed by reduction in the values as a result of the morphological changes in the Si particles; however, YS values remained almost unchanged. Morphological changes in the Si particles had a very limited effect on the high temperature tensile properties and, surprisingly, this limited effect extended to the ductility values as well.

Представлены результаты исследования влияния мелиорантов (цеолит, известь, гумат калия) в модельных экспериментах для оценки экологического состояния бурозема после термического воздействия. Были изучены активность ферментов из класса оксидаз (каталаза, пероксидаза) и гидролаз (уреаза, инвертаза), содержание органического углерода, кислотность и фитотоксичность почв. Выявлено, что внесение извести через 90 суток приводит к наибольшему положительному эффекту активности пероксидазы в среднем на 23-24% за счет снижения обменной кислотности с повышением pHKCl почвы до слабокислых и нейтральных значений во всех исследуемых вариантах. Также после внесения извести наблюдали стимулирование роста корней тест-культуры на 14-18%. Внесение мелиорантов почву после термического воздействия не привело к достоверным изменениям содержания органического углерода. На активность каталазы наибольший положительный эффект оказало внесение извести и цеолита с увеличением значений по сравнению с буроземом после термического воздействия в 3 и 8,5 раз соответственно. Стимулирование активности уреазы отмечается при внесении цеолита, извести в почве без термического воздействия почти на 105 и 91% соответственно и гумата калия в буроземе после термического воздействия на 12%. К тому же внесение гумата в бурозем после термического воздействия оказало стимулирующее влияние на рост корней на 26% относительно контрольных значений., The results of a study of the influence of ameliorants (zeolite, lime, potassium humate) in model experiments to assess the ecological state of burozem after thermal exposure are presented. The activity of enzymes from the class of oxidases (catalase, peroxidase) and hydrolases (urease, invertase), the content of organic carbon, acidity and phytotoxicity of soils were studied. It was found that the introduction of lime after 90 days leads to the greatest positive effect of peroxidase activity by an average of 23-24% due to a decrease in exchangeable acidity with an increase in soil pHKCl to slightly acidic and neutral values in all studied variants. Also, after the introduction of lime, the growth of the roots of the test culture is stimulated by 14-18%. The introduction of ameliorants into the post-pyrogenic soil did not lead to significant changes in the content of organic carbon. The greatest positive effect on the activity of catalase is caused by the introduction of lime by 8.5 times compared with post-pyrogenic burozem without ameliorants and zeolite by 3.6 times. Stimulation of urease activity is observed with the introduction of zeolite, lime in the soil without thermal exposure by almost 105 and 91% and potassium humate in burozem after thermal exposure by 12%. In addition, the introduction of humate into burozem after thermal exposure had a stimulating effect on root growth by 26% higher relative to control values.

Al-Si-Cu-Mg cast (354) alloys are used in the automotive sector owing to their remarkable properties which are achievable after applying appropriate thermal treatments. Zirconium, Nickel, and Manganese were added to this category of Al-alloys to preserve good mechanical properties while being exposed to elevated temperatures for long times. The ultimate and yield strength values obtained at room temperature for the stabilized (thermally-exposed) T5-treated condition were comparable to those of the stabilized T6-treated condition, whereas the same properties for T5-treated alloys were higher than those of T6-treated ones for elevated-temperature tensile testing. Interestingly, the results showed that the addition of 0.75 wt.% Mn was competitive with the addition of 2 and 4 wt.% Ni with respect to the elevated-temperature and ambient temperature strength values, respectively. In addition, the Mn-containing alloy M3S exhibited improved ductility values at ambient temperature and at 250 °C, compared to the Ni-containing alloys. Examination of the fracture surface of tested samples revealed the advantageous role of sludge particles in enhancing the performance of Mn-containing alloys through their resistance to the propagation of cracks that developed in many intermetallic phases. This finding is considered to be economically significant in view of the lower price of manganese compared to that of nickel.

Using a dynamic mechanical analyzer, the comparative studies of a low-cycle bending fatigue were carried out for AISI 1022 low-carbon steel after extreme thermal exposure, simulating the severe beyond-design-basis accident at nuclear power plants. In the as-delivered state, the steel has a high resistance to low-cycle fatigue (the fatigue strength at N = 3.5 × 104 cycles (σNf) was 360 MPa). Long-term thermal exposure led to a slight decrease in the resistance to low-cycle fatigue of steel: σNf is decreased by 9%. The influence of AISI 1022 steel structure on the characteristics of fatigue strength and fracture mechanisms is analyzed.

In this study, the long-term thermal microstructural stability and related stress rupture lives of a new Re-containing Ni-based single-crystal superalloy, DD11, were investigated after high-temperature exposure for different lengths of time. The results show that the γ' precipitates retained a cuboidal morphology and the γ' size increased after short thermal exposure for 50 h at 1,070 °C. As the thermal exposure time was prolonged to 500 h, the cuboidal γ' gradually changed into irregular raft-like morphology due to particles coalescence, and the morphology of the microstructure was almost unchanged after further thermal exposure up to 3,000 h. The stress rupture experiments at 1,070 °C and a tensile stress of 140 MPa showed that the rupture lives increased significantly after thermal exposure for 50 h and dropped dramatically with increasing exposure time up to 500 h but decreased slowly after exposure for more than 500 h. These results imply that stress rupture properties did not decrease when the γ' remained cuboidal but degraded to different extents during the γ' coarsening process. The coarsening of the γ' precipitates and change in morphology were regarded as the main factors leading to the degradation of the stress rupture lives. This study provides fundamental information on the high-temperature long-term microstructural stability and mechanical performance, which will be of great help for DD11 alloy optimization and engineering aeroengine applications.

The present study deals with the effects of high temperature expositions and subsequent cathodic hydrogen charging of dissimilar martensitic/bainitic weldment on its local mechanical properties and fracture behaviour at room temperature. Circumferential welded joint under investigation was produced by tungsten inert gas welding of X10CrWMoVNb9-2 martensitic and 7CrMoVTiB10-10 bainitic steels tubes with Ni-based filler metal and the application of subcritical postweld heat treatment. Hardness profile measurements revealed pronounced hardness peaks in over-heated regions of the individual steels heat-affected zones which remained preserved also during subsequent expositions at 600?C for up to 5000 hours. Gradual microstructural degradation of these regions included precipitate coarsening and the formation of new secondary phases during thermal exposure. The combined effects of thermal and hydrogen embrittlement of the studied weldment resulted in deleterious effects on its tensile and fracture behaviour.

Microstructure and mechanical properties of novel Ni-20Co-12Cr superalloys, with and without Nb addition, were systematically studied during long-term thermal exposure. With increased exposure time, the average diameter of the γ′ precipitates increased in both alloys in succession, this is more obviously observed in alloy containing 1 wt% Nb (1Nb). It is suggested that Nb increased the γ′ coarsening rate by accelerating the diffusion of Al and Nb in γ matrix. In addition, the γ′ phase fraction is increased by about 4% in 1Nb compared to the alloy without Nb (0Nb). The morphology of the γ′ phase changed from near-spherical to cuboidal shape during exposure in both alloys. Due to the increased γ/γ′ lattice misfit by Nb addition, 1Nb alloy showed an earlier tendency of shape change. Vickers hardness results revealed that the overall hardness decreased with the exposure time because the size increment of the γ′ precipitate weakened the precipitates strengthening and Orowan strengthening.

Transparency, illumination, aesthetic and energy requirements have considerably increased the use of glass in modern high-rise buildings. During fire exposure, fracture and shattering of windows and facades accelerate the spread and severity of fire, which increases the risk for the occupants and the amount of structural damage. This paper aims at analyzing the effect of non-uniform thermal gradients on the flexural capacity of ordinary glass panels. Both transparent and tinted glass panels are considered to account for widely-used glass compositions. The bending response of fire-damaged glass panels is experimentally explored considering different durations of thermal exposure. The thermal breakage due to non-uniform temperature distributions over the height is also assessed. A finite element investigation is then conducted to further explore the experimental findings.

В данной статье рассматриваются способы увеличения прочности снега при строительстве зимних дорог, анализируются их преимущества и недостатки, а также возможность их применения при различных состояниях снежного покрова и условиях окружающей среды. В статье показаны три способа повышения прочности снега: уплотнение, рыхление с последующим уплотнением и рыхление с последующим тепловым воздействием и уплотнением. Также представлены устройства, применяемые для упрочнения снега при данных способах, а именно: устройства для уплотнения (волокуши, пневмокатки, виброуплотнители), для рыхления (бороны, ребристые катки и фрезы), а также тепловые установки различных конструкций для теплового воздействия. В результате анализа данных способов было выявлено, что наибольшая прочность снега достигается при использовании последнего способа, и он наиболее применим для строительства автозимников., The article considers ways of snow strengthening for winter road construction and analyses their advantages, disadvantages and possibility of application for different conditions of snow and environment. Three ways of snow are shown strengthening in the article. It is compaction, loosening follow by compaction and loosening follow by thermal exposure and compaction. Equipments are shown for snow strengthening with these ways also. They are equipments for compaction (scrapers, rubber-tired compactors, vibratory compactors), for loosing (harrows, harrow rolls, cutters) and thermal equipments of different designs for thermal exposure. The analysis is stronger of these ways revealed that snow if last way is used. This way is more applicable for winter snow road construction.

The effect of long-term thermal exposure on the carbide evolution in a Ni-16Mo-7Cr base superalloy was investigated. The results show that M12C carbides are mainly precipitated on the grain boundaries during thermal exposure, and the primary massive M6C carbides can be completely transformed to M12C carbides in situ at temperatures above 750 °C for long-term thermal exposure. The transformation from M6C carbides to M12C carbides is attributed to the release of C atoms from M6C, which results in the morphology changes of massive carbides, and stabilization of the sizes of M12C carbides precipitated on the grain boundaries.

The effects of ageing and hydrogen charging on the notch tensile properties and fracture behaviour of individual heat-affected zones (HAZ) and Ni-based weld metal (Ni WM) of T91/TP316H weldments were investigated. After the post-weld heat treatment at 750 °C for 1 h the weldments were annealed at 600 °C for 1000 h and 5000 h, respectively. All heat-treated states were studied in condition without as well as with hydrogen charging. Thermal expositions led to additional precipitation and microstructure coarsening but their influence on tensile strength was insignificant. In contrast, remarkable plasticity decrease and the fracture mode transition from ductile dimple tearing to transgranular cleavage were observed. The combined effects of thermal exposure and hydrogen charging were more complex. Whereas the regions of Ni WM and TP316H HAZ did not show any significant change in strength, the hydrogen effect caused the strength increase in T91 HAZ. Although the hydrogen embrittling effects were clearly manifested by decreasing plasticity, their significance was getting smaller with increasing annealing duration. The fracture behaviour of thermally exposed and hydrogen charged regions exhibited mixed fracture modes including transgranular cleavage, intergranular dimple fracture and intergranular decohesion.

Potentiometric method based on the sharp change of electrode potential for the ferricyanide/ferrocyanide mediator system after addition of the seminal or follicular fluid sample into the measuring electrochemical cell has been developed to enable the easy assessment of the oxidant/antioxidant status of these kind of biological fluids. Platinum screen printed electrode has been used as an indicator. Essential advantage of the proposed method is simultaneous use of the both forms of the ferricyanide/ferrocyanide mediator system (oxidized and reduced ones) that allows estimating oxidant and antioxidant components of the seminal or follicular fluids samples which were obtained, respectively, from 99 male and 27 female subjects. Oxidant activity of seminal fluids has been observed in pathology conditions of reproductive system of male studied subjects and related with possible male infertility symptoms. © Brainina et al.

Thermo-kinetic simulation of precipitate evolution during long-term thermal exposure in ferriticmartensitic heat-resistant power plant steels (P91 and P92) is carried out using MatCalc software, in combination with a Gibbs energy database and a mobility database for steels that come with MatCalc. MX and M 23C 6 are predicted to remain as major precipitates during long-term thermal exposure in these steels. Average size of MX precipitate is found to vary between 10 and 50 nm in both steels, while M 23C 6 exceeds 100 nm in the case of P91 after 1000,000 h of thermal exposure at 600 �C. The simulated precipitation sequence and precipitate size evolution during thermal exposure are in good agreement with available experimental data. It is expected that the calculations presented here give insight into long-term microstructural stability of ferriticmartensitic steels under service conditions, which is otherwise difficult to establish by experiments alone. � 2011 Elsevier Ltd. All rights reserved.

cited By 0; Conference of 6th European Conference on Neutron Scattering, ECNS 2015 ; Conference Date: 30 August 2015 Through 4 September 2015; Conference Code:124367; International audience; A specific lithic manufacturing of flints has emerged in the South of France from 4200 to 3500 ca B.C. This treatment involving a smooth thermal exposure procures an improvement of the ease of detachment and of the cutting properties of the flints. The origin of these new properties remains misunderstood. High resolution large angle neutron scattering (Barotron detector) is used to describe the structural modifications occurring after the thermal treatment. The comparison of the scattering exhibited by native silica flints and flints treated at the Neothilic age does not show a structural change but indicates a significant increase of the quantity of liquid water trapped in the treated flint. It is suggested that the Neolithic treatment was proceeded in several steps including a prior wetting of the flint and then a thermal treatment closing the porosity and trapping the liquid water inside the silica flint.

A short and facile entry to the 2, 3-unsaturated O-arylglyco sides via microwave induced Ferrier rearrangement of acetylated glucal is reported.

Сформулированы принципы формирования наноструктурированных многослойных покрытий для работы в условиях высокоэнергетических воздействий. На этой основе разработаны теплозащитные и износостойкие покрытия системы Si–Al–N/Zr–y–O., Principles of the design of nanostructured multilayer coatings for operation under high-energy exposure were formulated. Using these principles as the base, heatand wear-resistant Si–Al–N/Zr–y–O coatings were developed.

This paper presents ail evaluation of thermal comfort in ail extended road trial study. Automobile seats play an important role in improving the thermal comfort. In the assessment of thermal comfort in autos, in general subjective and objective measurements are used. Testing on the road is very difficult but real traffic conditions affect the comfort level directly, as well as the driver's experience to real conditions. Thus, for such cases real traffic situations should not be neglected in the evaluation of comfort. The aim of this study was to carry out, on an extended road trial study, ail evaluation of thermal comfort using human subjects. In the experiments used, the 100% polyester seat cover had three different cover materials, which were velvet, jacquard and micro fiber. All experiments were carried Out on a sunny day with tell participants over I h. They were carried out at air temperatures of 25 degrees C in a Fiat Marea 2004, which had an automatic climate function. Skin temperature at eight points and skill wettedness at two points on the human body were measured during the trials. Participants were required to complete a questionnaire of 15 questions, every 5 min. It can be concluded that there was negligible difference in participants' reported thermal sensation between the three seats. According to objective measurement results, all seat cover materials have the same degree of thermal comfort. Oil the road the participants feel warmer around their waist than any other area of the body. It was suggested that the effects of real traffic conditions must be accounted for in comfort predictions.