Elevated Temperature Environments Research Articles

Effect of Hydrogen Charging on the Mechanical Properties of High-Strength Copper-Base Alloys, Austenitic Stainless Steel AISI 321, Inconel 625 and Ferritic Steel 1.4511

Hydrogen embrittlement (HE) poses the risk of premature failure for many metals, especially high-strength steels. Due to the utilization of hydrogen as an environmentally friendly energy source, efforts are made to improve the resistance to HE at elevated pressures and temperatures. In addition, applications in hydrogen environments might require specific material properties in terms of thermal and electrical conductivity, magnetic properties as well as corrosion resistance. In the present study, three high-strength Cu-base alloys (Alloy 25, PerforMet® and ToughMet® 3) as well as austenitic stainless AISI 321, Ni-base alloy IN 625 and ferritic steel 1.4511 are charged in pressurized hydrogen and subsequently tested by means of Slow Strain Rate Testing (SSRT). The results show that high-strength Cu-base alloys exhibit a great resistance to HE and could prove to be suitable for materials for a variety of hydrogen applications with rough conditions such as high pressure, elevated temperature and corrosive environments.

Sustainable engineering of human hair fiber-composite in engineering application

The hybrid composite material, resulting from the fusion of human hair and Kevlar 29 synthetic fiber in a 10:1 ratio, reinforced with epoxy resin using the hand layup technique, underwent meticulous mechanical and thermal testing. The investigation encompassed tensile, flexural, and impact property evaluations, elucidating a notable enhancement in mechanical strength with a diminishing synthetic fiber content. Concomitantly, the composite exhibited commendable heat resistance in heat deflection tests, making it potentially suitable for applications in elevated temperature environments. Water absorption properties were scrutinized, revealing a correlation between reduced synthetic fiber content and diminished water absorption, implying heightened durability in diverse conditions. Microstructure analysis through SEM provided intricate insights into the internal composition. In summation, the composite, featuring a higher proportion of natural fibers and a lower proportion of synthetics, demonstrated superior mechanical attributes, optimal heat resistance, and reduced water absorption, showcasing its applicability in automotive and engineering domains, particularly in the fabrication of vehicle panels and components. The aim of this research represents a significant advancement in composite materials, offering a cost-effective solution that balances mechanical strength and thermal resistance. It suggests the potential for high-performance materials by combining natural and synthetic fibers, promising versatility across various applications.

Morphological and plastic deformation study on impact strength of AA7075 and 316LSS in friction stir welding

The Impact of Friction stir Welding (FSW) in two dissimilar materials particularly in 316L Stainless Steel (SS) and AA7075 is very challenging due to its inherent properties when exposed to elevated temperature environment. The 316L SS is the grade generally used for deep drawing process of various SS applications. The Aluminum which generally provides the oxide formation when subjected to friction stir welding and develops the proper patter of stir zone in the heat affected environment. General preheating is required for SS before exposing it to the FSW process. The temperature might be of around 350˚ C is required for SS, so that the developmental of thermal gradient and weld quality between the two metals will achieve in proper pattern. As the Impact study will provides the aluminum and Stainless steels in the welded zone or Heat Affected Zone (HAZ) with different cracking and nucleation behavior. This phenomenon enhances the mechanical property in the Aluminum zone. After the various literature study, the FSW welded region of the metal provides improper pattern due to same start of welding at the mid of the dissimilar joints. In this phenomenon the FSW can start its process from the steel side of the joint and completing it to the Aluminum joint will reduces the growth of void and nucleate the agglomeration of oxides fromAA7075 to 316LSS.

High-temperature oxidation behavior of TA15 aerospace titanium alloy at 500 °C and 800 °C

This study investigates the high-temperature oxidation behavior and performance of TA15 Ti alloy subjected to 500 and 800 °C service conditions. The oxidation process, microstructural evolution, mechanical property changes, and comprehensive performance were analyzed. At 500 °C, the alloy developed a distinctive blue-colored surface primarily composed of Ti6O, indicating a slow growth rate of the oxide layer. In contrast, the 800 °C condition led to severe oxidation with notable TiO2 and Al2O3 phases and extensive peeling of the oxidation layer. Microstructural analysis revealed that at 500 °C, there was minimal surface oxidation, and the microstructure showed a shallow heat-affected zone. At 800 °C, repeated oxidation and peeling cycles resulted in grain growth and a significant decrease in the β-phase proportion. Mechanical property assessments indicated an increase in micro Vickers hardness at both temperatures, with the 800 °C sample exhibiting higher values. However, tensile strength decreased significantly at 800 °C due to the severe oxidation layer peeling, reducing the effective thickness during tensile testing. In summary, TA15 demonstrated good high-temperature service performance at 500 °C, while at 800 °C, severe oxidation and peeling adversely affected the overall performance. This research provides insights into the differential high-temperature behavior of TA15, crucial for applications in elevated temperature environments.

Experimental research on mechanical, material, and metallurgical properties of Inconel 600: Application in elevated temperature environment

Experimental research on mechanical, material, and metallurgical properties of Inconel 600: Application in elevated temperature environment

Investigations on tensile mechanical properties of rigid insulation tile materials at elevated temperatures based on digital image correlation algorithm

This work investigates the tensile mechanical properties of rigid insulation tile (RIT) materials at room temperature (26 °C) and elevated temperatures (700–1000 °C) through experimental and digital image correlation (DIC) methods. Experimental results indicate that the tensile strength of RIT materials changes nonlinearly with increasing temperature and that the primary fracture mode under tension load is fiber root fracture. In terms of the DIC algorithm, this work builds an elevated-temperature DIC test system. A zero-mean Gaussian filtering algorithm and an image gradient difference square sum algorithm (SSDGI) are proposed to improve the precision of the DIC algorithm. The derived tensile stress-strain curve of RIT materials reveals that the elastic modulus changes nonlinearly with increasing temperature. The reliability and precision of the DIC algorithm are confirmed through the tensile test of silicon carbide particle-reinforced aluminum matrix composites. Hence, this work provides guidance for evaluating mechanical properties of RIT materials under elevated temperature environments.

Flexural–torsional buckling of steel circular arches with I-section under central concentrated load in elevated-temperature environment

This article reports the fire resistance experiments conducted on I-section circular steel arches, as well as the observed out-of-plane flexural–torsional buckling (FTB) behavior and in-depth finite element numerical simulation results. The test was carried out using a large fire test furnace to provide a real fire environment with a nonuniform temperature field. A specially designed loading device allowed for unconstrained out-of-plane deformation of the specimens inside the furnace, thereby achieving effective load conditions and noncoupled response of the components. Numerical analyses were performed using a combination of the general codes Fluent and Abaqus, with the former used for heat transfer analyses, and a structural FE model including the loading device and complex geometric imperfections was established based on the measured data. Thus, accurate simulation of the out-of-plane behavior of the steel arches at elevated temperature was achieved. On this basis, an in-depth parametric study was carried out to investigate the effects of temperature field variations, load ratio (LR), and geometric imperfection. The analysis results show that FTB occurs at nonuniform temperatures for the arches under concentrated load, and the difference in temperature distribution in fire has a minimal effect on the FTB behavior. LR is negatively correlated with critical temperature; the smaller the LR, the more significant the weakening of critical loads by fire. The effect of initial geometrical imperfections on FTB at elevated temperatures is similar to that at ambient temperatures, and the effect on the critical temperature of FTB can almost be ignored when the imperfection amplitude is less than S/400.

Themomechanical Response of an Additively Manufactured Hybrid Alloy by Means of Powder Bed Fusion

The laser powder bed fusion (L-PBF) technique was utilized to manufacture a hybrid M789-N709 alloy by depositing M789 steel on wrought N709 steel. The tensile strength of the M789-N709 interface generated during the process has been established to be higher than that of the base materials. In the previous work of the current authors, extensive characterization of the M789-N709 interface (before and after heat treatment) was performed by means of electron backscatter diffraction, electron probe microanalysis, transmission electron microscopy with energy dispersive spectroscopy, and atom probe tomography analyses, to understand the mechanisms associated with its superior strength. In the present work, since the application of the hybrid alloy is targeted towards an elevated temperature environment, the individual high-temperature mechanical properties of M789 and N709 steels were acquired at various temperatures and strain rates using a Gleeble 563 thermomechanical system. Then, based on the flow curves, phenomenological-, and physical-based constitutive material models were established. These constitutive models can be utilized to accurately assess the high-temperature response of the hybrid alloy system using finite element analysis programs. This work demonstrates the application of thermomechanical processing and constitutive modeling in the field of metal additive manufacturing.

Enhanced Thermal and Dielectric Properties of Polyarylene Ether Nitrile Nanocomposites Incorporated with BN/TiO2-Based Hybrids for Flexible Dielectrics.

Outstanding high-temperature resistance, thermal stability, and dielectric properties are fundamental for dielectric materials used in harsh environments. Herein, TiO2 nanoparticles are decorated on the surface of BN nanosheets by internal crosslinking between polydopamine (PDA) and polyethyleneimine (PEI), forming three-dimensional novel nanohybrids with a rough surface. Then, an ether nitrile (PEN) matrix is introduced into the polyarylene to form polymer-based nanocomposite dielectric films. Meanwhile, the structure and micromorphology of the newly prepared nanohybrids, as well as the dielectric and thermal properties of PEN nanocomposites, are investigated in detail. The results indicate that TiO2 nanoparticles tightly attach to the surface of BN, creating a new nanohybrid that significantly enhances the comprehensive performance of PEN nanocomposites. Specifically, compared to pure PEN, the nanocomposite film with a nanofiller content of 40 wt% exhibited an 8 °C improvement in the glass transition temperature (Tg) and a 162% enhancement in the dielectric constant at 1 kHz. Moreover, the dielectric constant-temperature coefficient of the nanocomposite films remained below 5.1 × 10-4 °C-1 within the temperature range of 25-160 °C, demonstrating excellent thermal resistance. This work offers a method for preparing highly thermal-resistant dielectric nanocomposites suitable for application in elevated temperature environments.

Sensing performance of β-Ga2O3 metal–semiconductor-metal deep ultraviolet photodetectors with refractory TiW electrodes at high temperatures

Given the critical impact of high-temperature environments on the detection performance and stability of deep ultraviolet (DUV) photonic devices, especially in urgent demands from fields including high-temperature industries and flame detection, the research on high-temperature resistant DUV photodetectors (PDs) has become of utmost importance. Due to its intrinsic high-temperature resistance, β-Ga2O3 holds significant potential in the field of DUV photodetection under elevated temperature environments. The conventional electrode material, titanium, typically exhibits poor high-temperature performance, while interfaces are susceptible to degradation at elevated temperatures. In this study, we fabricated β-Ga2O3 metal–semiconductor-metal (MSM) PDs using the refractory metal TiW as the electrode, and investigated their DUV detection performance across the temperature range of 300 to 800 K. Favorable performance was achieved at room temperature, with a photo-to-dark current ratio (PDCR) of 3.1 × 106, a responsivity (R) of 0.2 A/W, a detectivity (D*) of 8.3 × 1013 Jones, and an external quantum efficiency (EQE) of 102.3 %. However, an increase in operating temperature led to a continuous rise in dark current (Idark) and a decrease followed by an increase in photocurrent (Iphoto). In an 800 K operating environment, the PDCR decreased to 4.4 × 102, R increased to 0.7 A/W, D* dropped to 2.0 × 1012 Jones, and EQE improved to 343.7 %. Furthermore, the temperature-dependent rise and decay times were investigated, and a detailed analysis of the relevant recombination and transport mechanisms under high-temperature conditions was conducted. By achieving high-performance and stable operation of β-Ga2O3 PDs at 800 K, this study provides prospects for the application of β-Ga2O3 PDs in harsh environments.

In-situ synthesis of hierarchically high porosity ZrB2 ceramics from carbon aerogel template with excellent performance in thermal insulation and light absorption

This work introduces an innovative methodology combining the in-situ boron/carbon thermal reduction (BCTR) reaction and replication carbon aerogel template to synthesize hierarchically high porosity ZrB2 ceramics. The meticulously designed ceramic liquid-phase precursor ensures higher solubility of solutes while reducing the temperature requisite for boron/carbon thermal reduction. An additional carbon source is incorporated in the precursor to ensure the uniformity of resulting ZrB2 grains, concurrently maintaining ZrB2 phase purity. The ultimate prepared ZrB2 porous ceramics present a uniform microstructure, with grain sizes at the hundred-nanometer scale, and exhibit a hierarchical pore structure. The ZrB2 porous ceramics exhibited high porosity (85.4–92.9%), low density (0.264–0.482 g/cm3), reasonable compressive strength (0.26–0.51 MPa), low thermal conductivity (0.103–0.212 W/m·K), and efficient light absorption in the range of 400–2000 nm (>94%). The fabricated ZrB2 porous ceramics hold significant promise for applications in high-temperature insulation and light absorption within elevated-temperature environments.

Design-oriented dynamic model of deployable fin under time-varying elevated temperature environment

AbstractCoupling of clearance joint and harsh aerodynamic heating environment is an inevitable nonlinear factor in folding mechanism of the fin of high-speed aircrafts that remarkably modifies natural frequencies and modes of vibration from the initial design state. However, accurately predicting dynamic properties of deployable fin with full consideration of these effects is not common industry practice. A practical semi-analytical model based on Hertz contact theory and ESDU-78035 model is proposed in this study to investigate high-temperature connection stiffness of local hinged–locked mechanisms. Material property degradation and clearance variation caused by thermal expansion are comprehensively considered and quantified in this model. Vibration characteristics of the assembled deployable fin are then solved using finite element method (FEM). The real-time evolutionary process of thermal mode of the fin is discussed. And natural frequencies of fixed-value and time-varying connection stiffness are compared. The simulation results of this study demonstrate that the relative error of structure temperature between the sequential approach and fully coupled simulations is less than 6.98%. The connection stiffness (slope of the load-displacement curve) of the folding mechanism under high temperature conditions decreases by 3.52%, and the variation is mainly caused by the degradation of the elastic modulus of the material, while the clearance change due to the thermal expansion has no significant effect on the slope. The natural frequency of the deployable fin exhibits an inverse correlation with the temperature change trend, and the first three frequencies decrease by 1.67, 7.75, and 16.28 Hz compared to the initial value, respectively.

Flexural behavior of carbon/glass inter-ply hybrid FRP composites under elevated temperature environments

Abstract In this research work, the three-point flexural performance of carbon and/or glass inter-ply hybrid epoxy composite by altering the hybrid ratio and stacking position was studied. These materials were tested at various temperatures (30 °C, 50 °C, 70 °C and 110 °C). The test results of hybrid composites results were compared with neat glass/epoxy and carbon/epoxy composites. The stacking position of carbon fibers in hybrid composite plays a vital role while doing a flexural test. Incorporation of two stiffer carbon fibers in glass/epoxy composite i.e., C2G3 and C1G3C1, resulted in a remarkable increment in the case of flexural strength. All composites exhibited ductile behavior at 110 °C. The fractured surfaces revealed the failure mechanism of the composites.

Dynamic viscoelastic behavior and interlaminar performance of glass/epoxy composites with binary nano‐fillers at different in‐situ elevated temperature environments

AbstractFor commercial civil applications of laminated composite material, characterizations to forecast the interlaminar shear behavior and viscoelastic response across a wide temperature range are essential. In this study, the interlaminar shear strength (ILSS) of glass/epoxy (GE) composites dispersed with binary nanofillers nanosilica‐multilayer graphene (NS‐MLG) and nanosilica‐nanoclay (NS‐NC) was analyzed at an in‐situ testing temperature of 20, 70, and 110°C. Further, the viscoelastic property of the composites was studied using a dynamic mechanical thermal analyzer (DMTA) in the temperature range of 35–165°C. An increase in the ILSS value of around 9% and 10% was observed at room temperature for GE/MLG‐NS and GE/NC‐NS, respectively, compared to control GE composites. In contrast, the trend was seen to change at higher temperatures. There was a slight decrement in the storage modulus (E′) of GE/MLG‐NS and GE/NC‐NS composites in the glassy region compared to control GE composites. The mean Tg of the GE composite (control) was nearly 107.3°C when the E′ decline onset temperature was taken into account, but after the addition of MLG‐NS, it was 10.1°C below. The mean Tg of GE/NC‐NS was determined to be 106.3°C, and in the glass transition as well as rubbery regions, it was observed to compete with the E′ value of the control GE composites. Fractography was done using micrographs obtained from environmental scanning electron microscope (ESEM). Traces of polymeric material found at the fiber surface certified the improved interfacial adhesion between glass fiber and polymer in the matrix‐modified composite samples.

High-temperature resistant drilling fluid of Sodium-based rectorite modified by organic laponite

This research aims to resolve some specific limitations of drilling fluid in dry hot rock geothermal energy high-temperature Wells, such as complex formulation, inconvenient preparation, and unstable high-temperature performance. Several common slurry clays were modified by organic laponite. Sodium-based rectorite modified by organic laponite is chosen to be the primary slurry under high-temperature environments (210℃). We developed a set of simple system structures and relatively stable fluid formulas based on the modified Sodium-based rectorite in elevated-temperature environments. At the same time, XRD, FTIR, TGA, and ESEM were used to compare the microstructure of the modified Sodium-based rectorite and the original one. Results indicate that a modified formula of sodium-based rectorite modified by organic laponite can overcome the problem of unstable performance of drilling fluid formulas that solely rely on additives at high temperatures, presenting new ideas and solutions for the technical challenges of drilling fluids used in geothermal energy exploration.

The effect of thermal exposure on the microstructure and mechanical properties of cast Al-Si alloy for the cylinder head

Cast Al-Si alloy is widely used in cylinder head structures and long-term service in 200–250 °C elevated temperature environments, which is easy to cause the deterioration of alloy properties. In this study, the thermal stability of the alloy during thermal exposure at 200 °C and 250 °C is investigated through the microstructure characterization and the mechanical properties test. The results show that the thermal exposure leads to the damage evolution of the precipitates in the microstructure. With the coarsening of the precipitates, the dislocation changes from cutting precipitates to bypassing precipitates, resulting in a weakening of the precipitation strengthening effect. The T6 alloy is in the insufficient peak aging state, and the alloy first reaches the peak aging state and then enters the over aging stage during the thermal exposure. Overall, with the increase in thermal exposure time and temperature, the Al matrix hardness, ultimate tensile strength (UTS), and yield strength (YS) decrease gradually and finally tend to be stable. As the thermal exposure progresses, the alloy fracture characteristic transitions from brittle fracture to ductile fracture, and the elongation of the alloy increases. In addition, the coarsening process of the thermal exposure alloy is described based on the Lifshitz-Slyozov-Wagner (LSW) theory, and the modified coarsening kinetic model can be divided into the rapid roughening stage and the stable roughening stage. Further, the damage parameter is defined as the relative change of precipitation strengthening to describe the deterioration degree of the mechanical properties for thermal exposure alloy.

Electronic, Optical, Thermoelectric and Elastic Properties of RbxCs1-xPbBr3 Perovskite.

Inorganic halide perovskites of the type AMX3, where A is an inorganic cation, M is a metal cation, and X is a halide anion, have attracted attention for optoelectronics applications due to their better optical and electronic properties, and stability, under a moist and elevated temperature environment. In this contribution, the electronic, optical, thermoelectric, and elastic properties of cesium lead bromide, CsPbBr3, and Rb-doped CsPbBr3, were evaluated using the density functional theory (DFT). The generalized gradient approximation (GGA) in the scheme of Perdew, Burke, and Ernzerhof (PBE) was employed for the exchange-correlation potential. The calculated value of the lattice parameter is in agreement with the available experimental and theoretical results. According to the electronic property results, as the doping content increases, so does the energy bandgap, which decreases after doping 0.75. These compounds undergo a direct band gap and present an energies gap values of about 1.70 eV (x = 0), 3.76 eV (x = 0.75), and 1.71 eV (x = 1). The optical properties, such as the real and imaginary parts of the dielectric function, the absorption coefficient, optical conductivity, refractive index, and extinction coefficient, were studied. The thermoelectric results show that after raising the temperature to 800 K, the thermal and electrical conductivities of the compound RbxCs1-xPbBr3 increases (x = 0, 0.25, 0.50 and 1). Rb0.75Cs0.25PbBr3 (x = 0.75), which has a large band gap, can work well for applications in the ultraviolet region of the spectrum, such as UV detectors, are potential candidates for solar cells; whereas, CsPbBr3 (x = 0) and RbPbBr3 (x = 1), have a narrow and direct band gap and outstanding absorption power in the visible ultraviolet energy range.

Design Considerations for Boron-Diffused and Implanted 4H-SiC Epitaxial Neutron Detectors for Dosimetry and Monitoring Applications

Thermal-neutron detectors based on 4H-SiC semiconductor and 10B converter reactions have many advantages for neutron dosimetry and monitoring applications. These radiation-resistant detectors are capable of stable operation in elevated-temperature environments up to 700 °C for extended periods. The recent development of SiC detectors where the 10 B is incorporated into the detector by ion implantation or diffusion leads to interesting application-specific design possibilities. The design of boron-diffused detectors is discussed as well as ways to optimize their design.

Irradiation-Induced Degradation of Surface Acoustic Wave Devices Fabricated on Bulk AlN

Here, recent work to evaluate the prospects for surface acoustic wave (SAW) devices fabricated on bulk aluminum nitride (AlN) for elevated temperature and radiation environments is reported and discussed. The design and fabrication of an array of SAW devices using commercial wafers is described, including the non-standard fabrication approach taken to overcome the stress-induced warpage of the 50 mm diameter AlN substrates. Radio frequency performance characterization of the SAW devices, with resonance frequencies ranging from 0.5 GHz to 1.5 GHz, is described. The linear temperature coefficient of frequency (TCF) near room temperature was measured and is compared to theoretical results from other investigators. The effects of 8 MeV Al ion irradiation at 300°C and 500°C to damage levels of 0.01, 0.1 and 1 displacements per atom (dpa), as a proxy for neutron irradiation, was investigated. The ion irradiation damage was observed to decrease the SAW resonant frequency, and this effect is characterized and discussed. Significant degradation in the conductivity of the Ti/Al electrodes of the SAW devices was also observed and characterized. These experimental results provide a basis for further investigation of the prospects for development of SAW sensor devices in bulk AlN material for application in elevated temperature and radiation environments.

Recent progress in oxidation behavior of high-entropy alloys: A review

Recent advancements in high-entropy alloys (HEAs) and high-entropy materials (HEMs) show promising potential for different fields of applications. The emergence of HEAs and HEMs has gained significant interest for their exciting nature and properties. As they consist of five or more elements in considerable amounts, properties vary depending on the synergistic effect of combinations of elements. By selecting proper elements and manufacturing methods, better properties can be tuned. Although many unique behaviors of HEAs and HEMs are reported due to their mixing entropy, sluggish diffusion, severe lattice distortion, and multi-metallic cocktail effects, it is necessary to summarize the data to map their feasibility and potential. For example, the combined properties of high thermal stability, thermal fatigue, creep resistance, higher stiffness, and better corrosion resistance for elevated-temperature environments in aerospace applications are pursued. Moreover, gaining the environmental compatibility and longevity of service-life-oxidation behavior of these materials is one of the crucial aspects and, hence, has been recently explored. Therefore, this Research Update aims at summarizing the recent developments and findings in oxidation behavior and highlighting the challenges and controversies for future research perspectives, particularly, on the sustainability for different applications. Moreover, besides the bulk structure, the performance of the HEAs/HEMs coatings is also reviewed.