Thermal Shock Research Articles

Potentials of single nucleotide polymorphisms and genetic diversity studies at HSP90AB1 gene in Nigerian White Fulani, Muturu, and N'Dama cattle breeds.

The study was aimed at genetic characterization of Nigerian breeds of Muturu, N'Dama, and White Fulani cattle breeds at heat shock protein 90AB1 locus. Also, the goal of the study was to detect the presence of single nucleotide polymorphisms (SNPs) at HSP90AB1 locus and consequently recommend them as bio-markers for thermo-tolerance potentials in Nigerian cattle breeds when exposed to assaults of thermal conditions/heat shock of tropical environment. Based on the previously published potentials of this candidate gene to lower assaults of thermal conditions/heat shock such as heat stress, the detected SNPs of HSP90AB1 within the population of the Nigerian cattle in this study will be recommended for population-based screening with a view to genetically improving those zebu cattle breeds that are more vulnerable to heat shock and assaults of thermal conditions. Total number of 200 blood samples were randomly collected from White Fulani (84 samples), Muturu (73 samples), and N'Dama (43 samples) breeds of cattle. Out of these, 20 DNA samples were randomly selected from each of the three cattle breeds and were used for DNA extraction and downstream analyses to further confirm findings of previous study, hence the goal of our study. DNA was extracted from the blood samples using the Zymo-bead DNA extraction kit and DNA sequencing of our samples was performed. A total number of 9 SNPs (within exons 5-6 coding regions) and 11 SNPs (within exons 12-13 coding regions) were detected at HSP90AB1 locus using the codon code aligner software. ARLEQUIN 2.0001 software was used to estimate the basic population genetic statistics while the DnaSP version 5.10.01 was used to estimate the genetic diversity indices. This study detected new SNPs (polymorphic sites) at HSP90AB1 locus within the DNAs of Nigerian White Fulani (WF), Muturu (MU), and N'Dama (ND) breeds of cattle. Within exons 5-6 coding regions, the N'Dama (ND) cattle breed had the highest for number of SNPs (5) and genetic diversity indices while White Fulani (WF) and Muturu (MU) had the least (2) number of SNPs each. Within exons 12-13 coding regions, WF had the highest numbers of SNPs (7) and genetic diversity indices while MU had the least number of SNPs (1) and genetic diversity indices. Some of the detected SNPs at HSP90AB1 locus were shared among the three breeds, suggesting that these three Nigerian cattle breeds showed shared ancestral alleles and lineage. Our study further revealed that HSP90AB1 is highly polymorphic/variable and diverse among the three Nigerian cattle breeds examined. Based on the previously documented thermo-tolerance potentials of members of HSP90 sub-family including the findings of our study, we hypothesize therefore that the presence of SNPs of HSP90AB1 within the DNAs of these three breeds of Nigerian cattle (WF, ND, and MU) may confer them thermo-tolerance potentials for thermal assault conditions and heat shock of the tropics at HSP90AB1 locus. Therefore, the detected SNPs can be recommended as bio-markers to improve the thermo-tolerance potentials of Nigerian breeds of zebu cattle raised under the challenges of heat shock for better adaptation and survival.

Simulation and modeling of polymer concrete panels using deep neural networks

The most often utilized construction material worldwide is concrete. Extensive experiments are carried out each year to study the physical, mechanical, and chemical properties of concrete, which are costly and time-consuming. This study focuses on avoiding redundant tests by applying the machine learning (ML) method to predict temperature-dependent polymer concrete qualities. In this work, as a strong tool of the ML method, a deep neural network (DNN) is used to examine the five temperature-dependent mechanical characteristics of concrete, including Poisson's ratio, Young's modulus, specific heat, coefficient of thermal expansion, and thermal conductivity. A 5-fold cross-validation method was used to verify the strategy in this research and get rid of split bias in testing and training. This study demonstrates the material properties of temperature-dependent polymer concrete followed by mathematical modeling of a steel-polymer concrete panel used for various civil applications. Temperature-dependent equations are determined using constitutive heat transfer and Cartesian coordinates. In addition, a thermal shock load acts on the upper part, and the lower part becomes an isothermal state with no heat flow. In order to account for the limited speed at which temperature waves travel, two distinct theories of generalized thermoelasticity are employed: the Lord-Shulman (LS) and the Green-Lindsay (GL) theories. The Fast Laplace Inverse Transform Method (FLITM) is used to transfer the results from the Laplace domain to the time domain. In addition, a three-dimensional differential quadrature approach (3D-DQA) using three Chebyshev-Gaussian-Robat functions for solving temperature-dependent equations is presented. In conclusion, some suggestions for improving the stability of polymer concrete panels are detailed and will be compiled in a future manual.

Numerical simulation of hydraulic fracture propagation after thermal shock in shale reservoir

The scale of propagation of hydraulic fractures in deep shale is closely related to the effect of stimulation. In general, the most common means of revealing hydraulic fracture propagation rules are laboratory hydraulic fracture physical simulation experiments and numerical simulation. However, the former is difficult to meet the real shale reservoir environment, and the latter research focuses mostly on fracturing technology and the interaction mechanism between hydraulic fractures and natural fractures, both of which do not consider the influence of temperature effect on hydraulic fracture propagation. In this paper, the hydraulic fracturing process is divided into two stages (thermal shock and hydraulic fracture propagation). Based on the cohesive zone method, a coupled simulation method for sequential fracturing of deep shale is proposed. The effects of different temperatures, thermal shock rates, and times on the scale of thermal fractures are analyzed. As well as the effects of horizontal stress difference and pumping displacement on the propagation rule of hydraulic fractures. The results show that the temperature difference and the thermal shock times determine the size and density of thermal fractures in the surrounding rock of the borehole, and the number of thermal fractures increases by 96.5% with the increase of temperature difference. Thermal fractures dominate the initiation direction and propagation path of hydraulic fractures. The main hydraulic fracture width can be increased by 150% and the length can be increased by 46.3% by increasing the displacement; the secondary fracture length can be increased by 148.7% by increasing the thermal shock times. This study can provide some inspiration for the development of deep shale by improving the complexity of hydraulic fractures.

Thermal shock fracture in a cracked strip: Incorporating convective heat transfer between lateral surfaces and ambient environment

This paper presents a comprehensive analysis of transient temperature and thermal stress around a thermal insulated crack in a finite thermoelastic strip subjected to thermal shock based on the dual-phase-lag (DPL) heat conduction. A detailed investigation of the effect of convective heat exchange between the lateral surfaces of the strip and the ambient environment is conducted. By employing integral transform technique, the thermoelastic crack problem is reduced to a set of singular integral equations, and solutions for the transient temperature distribution and dynamic stress intensity factors (SIFs) at the crack tips are then obtained. Numerical results reveal a considerable temperature gradient near the heating surface when both the high convective heat transfer coefficient and thin strip are involved. Consequently, the SIFs in such scenarios where cracks are located close to the heating surface are significantly larger compared to those calculated by neglecting the convective heat loss. Furthermore, during the initial period following a thermal shock, the SIFs may exhibit higher magnitudes than the steady-state values. These findings emphasize the importance of accounting for the influence of convective heat exchange with the ambient environment in material design and optimization to enhance fracture resistance under transient thermal loading.

Coverage and reliability improvement of copper metallization layer in through hole at BGA area during load board manufacture

Abstract The dimple of ball grid array (BGA) area with 70 mm × 70 mm size on load board for high performance integrated circuit final test is investigated by shadow moire at first, the dimple of BGA area decreases from 184.3 to 97.1 μm when six additional prepregs with 60 mm × 60 mm size are added at BGA area before hot lamination process. The micromorphology and stress/strain simulation are conducted to improve the coverage and reliability of copper metallization layer in through hole at that BGA area. The microcracks of electroless copper layer at the position of glass fiber and inner layer copper pad, which leads to serious crack after solder float, are well covered by subsequent electroplating copper layer. When the through holes at BGA area with 0.2 mm diameter and 7.0 mm depth are fabricated based on insulating dielectric material used for high-speed signal transmission, the simulation results point out that IT968 is better than M6G for the thermal shock reliability of through hole metallization layer. A load board vehicle with 126 layers and 8.3 mm thickness based on IT968 shows good interconnection structure reliability after 12 times 288°C solder float.

Enhanced thermal shock resistance of low-carbon Al2O3-C refractories by aggregate/matrix interface design with MgAl2O4/CNTs layer

Aggregate/matrix interface microstructure design to guide more cracks propagating within it favors improved thermal shock resistance of refractories. A MgAl2O4/CNTs interfacial layer was formed between the aggregate and matrix in low-carbon Al2O3-C refractories fabricated by core-shell corundum aggregates. The microstructural evolution of aggregate/matrix interface with increased contents of nickel nitrate hexahydrate catalyst in the interfacial layer and its effects on the thermal shock resistance of refractories were investigated. The results show that the highest amount of CNTs within the interfacial layer was obtained with the catalyst concentration of 0.5 wt%. The catalyst also promoted the growth of AlN whiskers that bridging the aggregate and matrix. Cracks impinging the interface are prone to be deflected by the interfacial layer and propagate within it. The deflection of cracks by the MgAl2O4 layer, the bridging and pulling out mechanism of the CNTS and AlN whiskers all contribute to the enhanced thermal shock resistance.

Evaluating the versatility of stainless steel flakes and magnetite powder as polyvalent additives for wood paints

The objective of this study is to evaluate how various fillers, specifically stainless steel flakes and magnetite powder, affect the visual attributes, durability and versatility of a water-based wood paint. To examine the influence of these two specific pigments on the overall look of the coatings, colorimetric measurements were carried out. The impact of these distinct fillers on the durability of the layers was assessed by subjecting the samples to xenon arc light exposure and cyclic thermal shocks, followed by colorimetric inspections and adhesion tests. Furthermore, the fillers' impact on the coating's ability to act as a barrier was assessed through liquid resistance and water uptake tests. Additionally, the Buchholz hardness indentation test and the Taber test were conducted to quantify how these functional additives affect the mechanical properties of the coatings, such as hardness and resistance to abrasion. Lastly, two specific tests revealed the fillers' role in introducing unique electrical conductivity and magnetic attractive properties to the paint. In conclusion, this study underscores the intriguing influence of stainless steel flakes and magnetite powder, which not only impart vibrant colors and distinct visual characteristics to the paint but also maintain the coating's protective barrier properties, enhance the mechanical properties of the composite layer, and introduce specific multifunctional features to the coating.

Screening and Structural Characterization of Heat Shock Response Elements (HSEs) in Entamoeba histolytica Promoters.

Entamoeba histolytica (E. histolytica) exhibits a remarkable capacity to respond to thermal shock stress through a sophisticated genetic regulation mechanism. This process is carried out via Heat Shock Response Elements (HSEs), which are recognized by Heat Shock Transcription Factors (EhHSTFs), enabling fine and precise control of gene expression. Our study focused on screening for HSEs in the promoters of the E. histolytica genome, specifically analyzing six HSEs, including Ehpgp5, EhrabB1, EhrabB4, EhrabB5, Ehmlbp, and Ehhsp100. We discovered 2578 HSEs, with 1412 in promoters of hypothetical genes and 1166 in coding genes. We observed that a single promoter could contain anywhere from one to five HSEs. Gene ontology analysis revealed the presence of HSEs in essential genes for the amoeba, including cysteine proteinases, ribosomal genes, Myb family DNA-binding proteins, and Rab GTPases, among others. Complementarily, our molecular docking analyses indicate that these HSEs are potentially recognized by EhHSTF5, EhHSTF6, and EhHSTF7 factors in their trimeric conformation. These findings suggest that E. histolytica has the capability to regulate a wide range of critical genes via HSE-EhHSTFs, not only for thermal stress response but also for vital functions of the parasite. This is the first comprehensive study of HSEs in the genome of E. histolytica, significantly contributing to the understanding of its genetic regulation and highlighting the complexity and precision of this mechanism in the parasite's survival.

Exceptionally low ablation rates realized in the cellular-structured MCMB@WC composites via biomimetic design

Thermal protection materials (TPMs) with extra-low ablation rate in long-term are ungently required in reusable spacecrafts. However, the ablation property and operation life of conventional graphite/carbon-based composites with ultra-high temperature ceramic coatings are rather limited. Inspired by the self-healing behavior of plants, we designed and fabricated cellular-structured tungsten carbide (WC) reinforced graphite composites via the combination of molten salt coating and spark plasma sintering. Owing to the intelligent biomimetic structure and regeneration of WC during the ablation process, the composites exhibited not only excellent thermal shock resistance but also exceptionally low ablation rates. In the cyclic ablation test under 4.18 MW·m−2 for 360 s, the linear and mass ablation rates of the composite at the last ablation period decreased to 0.33 mg·s−1 and 0.17 μm·s−1, respectively. The biomimetic structural design offers new insights for fabricating graphite-based composites with exceptionally low ablation rates, which are promisingly applied in reusable spacecrafts.

Effects of Sr and Mg doping on elastic, mechanical, and optical properties of hydroxyapatite: A first-principles study

Hydroxyapatite (HAp), with the chemical formula Ca10(PO4)6(OH)2, is a bioactive ceramic material typically used in the treatment of bone defects owing to the excellent biocompatibility and the ability to bond with bone tissues. Mechanical properties of HAp have drawn pronounced attention because of the crucial roles in the medical applications. Based on density functional theory (DFT), this work reports the structural, formation energy, mechanical, Vickers hardness, electronic properties, and optical properties of hydroxyapatite (HAp), strontium-substituted HAp (Sr-HAp), and magnesium-substituted HAp (Mg-HAp). The results reveal that the Sr2+ and Mg2+ ions mainly replace the Ca2+ ion at the Ca-1 site in HAp. Resistance to hydrostatic compression followed the order Mg-HAp > HAp > Sr-HAp. Sr-HAp has the capability to enhance thermal shock resistance and lattice thermal conductivity. In addition, the electronic properties of HAp change upon substitutional Sr2+ and Mg2+ doping. In comparison with pristine HAp, the energy gap of Sr-doped HAp relatively increases, whereas that of Mg-doped HAp decreases. Nevertheless, both Sr-HAp and Mg-HAp remain insulators. Intriguingly, Sr-HAp possesses the improved hardness by 11.31 % owing to the hybridization of the Sr (4p) and O (2p) states, which contributed to its high shear modulus and high hardness. Beyond that, we further investigate their optical properties. The presence of Mg states at approximately 10 eV in the conduction band leads to enhanced absorption within the 14 – 20 eV for Mg-doped HAp. Similarly, the presence of a deep Sr(4p) level in Sr-HAp amplifies absorption within the 20–25 eV range. These findings have raised a potential avenue for selectively boosting the optical absorption of HAp, thus improving its photocatalytic properties.

Superior toughness of thermal barrier coating caused by co-doping of trivalent and pentavalent oxides

The zirconia-based thermal barrier coating co-doped with trivalent and pentavalent oxides was deposited on DD 90 single crystal superalloy using air plasma spraying. The coating is composed of cubic and tetragonal phases denoted by bi-phase solid solution (BPS) ceramic coating. The microstructure, cross-sectional morphology, and cracks evolution of BPS coatings, before and after 1200 °C thermal cycling, were investigated compared with 8YSZ coating. The BPS coating is intact after 250 thermal cycles, and the phase constitution is consistent with as-sprayed state. On the contrary, the brittle monoclinic phase can be observed in the thermal cycled 8YSZ coating, and severe exfoliation occurred. The propagation and splitting of the cracks are inhibited by the randomly distributed nanocrystalline clusters, and the cracks are inclined to grow longitudinally, which are beneficial to improve the toughness and thermal shock resistance of thermal barrier coating.

Nucleotides supplementation (Nucleoforce fish™) in Caspian roach (Rutilus caspicus) diet: Growth performance, skin mucosal immune response, and resistance to salinity stress

In this study, the growth, epidermal mucosal immunity, expression of growth-related genes, cross-protection, and resistance to salinity stress of Caspian roach were scrutinized in response to dietary levels of nucleotides (NT). Accordingly, 1200 fish (0.51 ± 0.01 g) were fed ad libitum with a basal diet (38.88 % crude protein and 10.04 % crude lipid in dry basis) containing incremental levels of NT at 0 (NT-0; control), 0.3 g kg−1 (NT-0.3), 0.6 g kg−1 (NT-0.6), and 1.2 g kg−1 (NT-1.2) for 8 weeks in triplicates. The growth performance was significantly increased in the fish fed with NT-0.6 and NT-1.2 diets compared to the control group (p < 0.05). A significant elevation in the growth hormone and insulin-like growth factor-I gene expression was recorded in NT-added groups at 0.6 and 1.2 g kg−1 compared to the control group (p < 0.05). In contrast to the control group, feeding on NT-0.6 and NT-1.2 diets had a remarkable effect on the skin mucus soluble protein and immunoglobulin levels (p < 0.05). After the feeding trial, we examined how salinity stress (15 g/l salinity) lonely and salinity stress under non-lethal thermal shock (+10 °C) affected heat shock protein (HSP70). Then, the mRNA expression of HSP70 gene from the gill was analyzed at 0, 2, 8, and 24 h post-challenge tests. The HSP70 gene expression level was approximately up-regulated more than 2-fold in NT-6 and NT-1.2 treatments compared to the control group under the salinity stress. Altogether, this research represents that the addition of NT at 0.6 and 1.2 g kg−1 in Caspian roach diet can improve overall performance and resistance to salinity stress.

Reliability Evaluation of EB-PVD Thermal Barrier Coatings in High-Speed Rotation and Gas Thermal Shock

The uncertain service life of thermal barrier coatings (TBCs) imposes constraints on their secure application. In addressing this uncertainty, this study employs the Monte Carlo simulation method for reliability evaluation, quantifying the risk of TBC peeling. For reliability evaluation, the failure mode needs to be studied to determine failure criteria. The failure mode of high-speed rotating TBCs under gas thermal shock was studied by combining fluid dynamics simulations and experiments. Based on the main failure mode, the corresponding failure criterion was established using the energy release rate, and its limit state equation was derived. After considering the dispersion of parameters, the reliability of TBCs was quantitatively evaluated using failure probability and sensitivity analysis methods. The results show that the main mode is the fracture of the ceramic layer itself, exhibiting a distinctive top-down “step-like” thinning and peeling morphology. The centrifugal force emerges as the main driving force for this failure mode. The failure probability value on the top side of the blade is higher, signifying that coating failure is more likely at this location, aligning with the experimental findings. The key parameters influencing the reliability of TBCs are rotation speed, temperature, and the thermal expansion coefficient. This study offers a valuable strategy for the secure and reliable application of TBCs on aeroengine turbine blades.

ScB2C2: The first high damage tolerant ultra-high temperature ceramic with hydrolysis resistance

The first high damage resistant ultra-high temperature ceramic ScB2C2 with excellent hydrolysis resistance was successfully prepared through boron carbon thermal reduction and hot pressing sintering using Sc2O3, B4C and graphite as raw materials. The Vickers hardness, flexural strength, fracture toughness, Young’s modulus, shear modulus, bulk modulus and Poisson’s ratio of as-prepared ScB2C2 ceramic are 6.0 ± 0.2 GPa, 246 ± 17 MPa, 4.11 ± 0.18 MPa·m1/2, 240 GPa, 101 GPa, 127 GPa and 0.18, respectively. In the a-b plane (B2C2 sheet) and along the c-axis direction, ScB2C2 exhibits extremely strong anisotropy of chemical bonds and elastic properties. The high residual strength, damage tolerance factor Dt and fracture toughness to strength ratio KIc/σf indicates that ScB2C2 has excellent damage tolerance. In addition, ScB2C2 displayed remarkable thermal shock resistance and hydrolysis resistance. These unique features endow ScB2C2 with significant potential for future ultra-high temperature applications.

Fabrication and mechanical properties of TiC coated short carbon fiber reinforced Ti5Si3–TiC composites

Ti5Si3-based composites reinforced with TiC-coated Cf and TiC particulate (TiC@Cf/Ti5Si3–TiC) were fabricated by spark plasma sintering. The performance of the TiC@Cf/Ti5Si3–TiC composite was comprehensively evaluated by investigating its mechanical properties at room temperature, as well as the thermal shock resistance, oxidation resistance and flexural strength at high temperatures. By employing optimal process parameters obtained through response surface methodology, the TiC@Cf/Ti5Si3–TiC composite exhibited a maximum room-temperature fracture toughness of 9.32 ± 1.05 MPa m1/2, which represented a significant increase of 261.2% and 23.1% compared to monolithic Ti5Si3 and TiC@Cf/Ti5Si3 composite, respectively. The flexural strength of the TiC@Cf/Ti5Si3–TiC composite measured at room temperature, 1000 °C, and after quenching from 1200 °C was 531 ± 61 MPa, 299 ± 43 MPa, and 138.4 ± 15 MPa, achieving an improvement of 221.8%, 128.2%, and 295.4% compared to monolithic Ti5Si3. The incorporation of TiC particulates appeared to mitigate the fiber-matrix interfacial reaction more effectively than that observed in the TiC@Cf/Ti5Si3 composite previously investigated. Consequently, the reinforcing mechanism of fiber pulling-out and debonding, crack blocking, deflection, and bridging was fully operational at heightened sintering temperatures. These essential factors play a vital role in remarkably enhancing the mechanical properties of the TiC@Cf/Ti5Si3–TiC composite.

Assessing indoor air quality and health risks of air conditioner usage in residential buildings under hot and arid climatic conditions: insights from field studies and questionnaire analysis

Abstract The prevalence of air conditioners (ACs) in regions with hot and arid climates raises significant health concerns for users. This study investigates the impact of AC usage on health and indoor air quality in Kenadsa, Bechar, located in southwest Algeria. A questionnaire survey was conducted among 300 residents to identify symptoms associated with AC use. Additionally, dust accumulation in filters was measured in 20 households with varying occupancy types to assess the relationship between particle generation and room usage. Temperature and relative humidity were also recorded in two rooms, one equipped with an evaporative cooler and the other with a split-type AC, to compare their thermal performance. The findings reveal that occupant behavior and building usage significantly contribute to particle generation, with AC operating speed notably impacting filter contamination. Evaporative coolers increase temperature and humidity levels compared to split-type ACs, with their effectiveness depending on proper ventilation. Most respondents begin using ACs in May, prefer operating them during midday and nighttime, and express concerns about thermal shock and AC lifespan. Furthermore, many participants are lax in dust removal, potentially worsening indoor air pollution. A significant portion of respondents report various health issues linked to prolonged exposure to conditioned air but show limited awareness of AC filter maintenance and its health implications. This study highlights the complex interplay between human behavior, AC usage patterns, and indoor air quality, emphasizing the need for targeted interventions to promote responsible AC use, improve filter maintenance practices, and mitigate associated health risks in hot and dry climates.

Synergistic roles of Ru, CeO2, and HZSM-5 in a ternary-active center catalyst for catalytic destruction of dichloromethane

Developing well-qualified industrial catalysts with excellent oxidation ability, selectivity, and resistance is still a challenge for chloroalkane destruction. Herein, we optimized the composition of multi-component catalysts with diverse active sites to adjust their acidic and redox properties for reasonable catalytic performance. The synergy of redox center Ru, activation center CeO2, and acid center HZSM-5 endowed the ternary catalyst Ru/CeO2/HZSM-5 with superior low-temperature activity (30 ∼ 60 °C lower for 50 % conversion), promoted stability and chlorine tolerance (100 % conversion for at least 30 h), and less toxic by-products for dichloromethane (DCM) destruction compared with the binary ones, promising for industrial application under tough conditions (e.g., thermal shock, HCl, H2O). The strong interaction of Ru and CeO2 enhanced the redox property of Ru/CeO2/HZSM-5 and thus promoted the deep oxidation of DCM and intermediates, thereby generating more CO2 and less dechlorinated by-products (e.g., CH3Cl). The synergistic effects of Ru, CeO2, and HZSM-5 facilitated chlorine removal and suppressed the generation of polychlorinated by-products (e.g., CHCl3) over the Ru/CeO2/HZSM-5 catalyst by improving redox capacity and inhibiting reactivity of chlorine. Notably, the introduction of CeO2 weakened the hydrophilicity of Ru and HZSM-5, improving the water resistance of the catalyst. The corresponding monolithic catalyst could achieve complete oxidation of DCM at 400 °C with the total concentration of dioxins measured at 0.026 ng I-TEQ kg−1 after continuous operation at 250 °C for 30 h.

A new strategy for improving TBCs performance through tailoring the bond coating interface with laser texturing

The parallel micro-hole texture was manufactured to tailor the bond coating interface morphology by a one-step process with the assistance of nanosecond pulsed laser technique. It is demonstrated that the interface stability of the laser-textured TBCs was improved through the evaluation of high-temperature isothermal oxidation under different durations and water-quenching thermal shock at 1050 ℃. The interfacial TGOs formed in the laser-textured TBCs were composed of the continuous alumina strip and grew more slowly compared to that of the as-sprayed TBCs during isothermal oxidation. In addition, as for the laser-textured TBCs, no transverse cracking was noticed along the TGOs interface and the alumina-only TGOs developed a thickness of approximately 1.4 µm after thermal shock testing. The high surface density of micro holes on the bond coating interface enhanced the interfacial toughness and suppressed TGOs growth, which contributed to improving the TBCs durability.

Enhanced thermal shock resistance of low‐carbon Al2O3‐C refractories via CNTs/MgAl2O4 whiskers composite reinforcement

AbstractThe CNTs/MgAl2O4 whiskers composite reinforcement was prepared by catalytic carbon‐bed sintering and added to low‐carbon Al2O3‐C refractories to enhance the thermal shock resistance of refractories. The effects of Ni(NO3)2·6H2O content on the phase and microstructure of CNTs/MgAl2O4 were investigated. The nano‐indentation technology was used to quantitatively evaluate the effect of CNTs/MgAl2O4 on the thermal shock resistance of low‐carbon Al2O3‐C refractories, and the toughening mechanism of CNTs/MgAl2O4 on refractories was further investigated. The results revealed that the inner and outer diameters of the CNTs were approximately 5.69 and 16.26 nm, respectively. The CNTs winded around interlocking structural MgAl2O4 whiskers with a high aspect ratio (&gt;100), which was beneficial to the dispersion of CNTs in the refractory matrix. The thermal shock resistance of low‐carbon Al2O3‐C refractories was significantly improved by adding 3.0 wt.% of CNTs/MgAl2O4 (named C3). The specific fracture energy of refractory matrix and residual strength ratio of C3 reached 141 N·m−1 and 39.2%, which were 29.4% and 97.0% higher than those of the blank sample (109 N·m−1 and 19.9%), respectively. This is because the refractory matrix was significantly reinforced by CNTs and MgAl2O4 whiskers, promoting the occurrence of “bridging” and “crack deflection” and the generation of microcracks in the refractory matrix.

Effect of thermal shock on ZnO/Ag/ZnO nano-multilayers: Photoelectric property degradation

We investigated the degeneration at photoelectric properties of typical multilayer transparent conductive electrodes (TCEs) of ZnO/Ag/ZnO under thermal shock by experiments and simulation. The experimental data indicated a reduction in the visible region transparency and an increase in sheet resistance for ZnO/Ag/ZnO after undergoing thermal cyclic shock. This resulted in a significant decrease in the Haacke figure of merit (FOM) from 30.7 × 10-3 Ω−1 to 7.8 × 10-3 Ω−1. We identified oxygen diffusion into Ag at the ZnO/Ag interface using molecular dynamics (MD) simulations. Concurrently, density functional theory (DFT) simulations showed that interstitial oxygen creates impurity charge centers within Ag, indirectly causing the deterioration of the photoelectric properties of ZnO/Ag/ZnO. This finding highlights the challenge of maintaining optoelectronic stability in TCO/metal/TCO (OMO) thin films for practical applications and provides both experimental and theoretical support for designing highly reliable optoelectronic devices.