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The matrix asphalt was modified with graphene, and the high temperature properties of the modified asphalt with different contents of graphene were analyzed. The dispersion of graphene in the asphalt was analyzed by scanning electron microscopy. The experimental results show that graphene can improve the PG grade of modified asphalt, and the penetration of modified asphalt decreases with the increase of graphene content, while the softening point and dynamic viscosity increase. When the content of graphene exceeds 3%, the increase of complex shear modulus of modified asphalt at high temperature is limited when the dosage of graphene exceeds 3%. When the dosage exceeds 4%, the specimen cannot be formed due to excessive viscosity. Considering cost and road performance. it is recommended that the dosage of graphene should be 2%. [ABSTRACT FROM AUTHOR]

With the application of shrouds made of silicon carbide ceramic matrix composite（SiC-CMCs），the abradable coating technology suitable for SiC-CMCs is urgently needed. The four-layer structure of BSAS（Ba0.75Sr0.25Al2Si2O8）-polyester-based abradable environmental barrier coating （A/EBCs） was prepared by atmospheric plasma spraying. The influence of process parameters on the porosity and the structural evolution of the layer at 1300 ℃ were investigated. The phase structure，microstructure and coating composition were characterized by XRD，SEM，EDS and TEM respectively. The results show that the porosity of BSAS-polyester abradable top layer is 26.4%-36.8%. And the temperature-sensitive parameters of BSAS-polyester particles are primary gas （argon） flow，second gas （hydrogen） flow and spraying distance. In contrast，the speed-sensitive parameters are primary gas （argon） flow. The primary gas （argon） flow has the opposite effect on the particle temperature and velocity of the BSAS-polyester. The abradable surface layer is oxidized at 1300 ℃ for 300 h and maintains monoclinic phase structure，stable stucture and composition，and locally precipitates spherical amorphous silicon oxide particles. Furthermore，the coating abradability was evaluated by high-temperature and high-speed scraping test. Nano-scale Ni-based superalloy particles adhesion on the surface of the coating are found，and the blade incursion depth ratio （IDR） is 20%，which meets the requirements of the abradable sealing coating.

Spinel LiMn2O4-based lithium-ion batteries are widely applied in electric two-wheeler and low-speed vehicles due to their low cost and low toxicity. Nevertheless, the Mn deposition at the anode originated from Mn dissolution of LiMn2O4 causes a poor elevated temperature cycle life of graphite/LiMn2O4 batteries. Herein, a graphite/LiFePO4 cell with specific Mn2+ added in the electrolyte is provided as an efficient evaluation method to research Mn2+ deposition. Besides, an effective strategy by adding a ligand hexamethylenetetramine (HMTA) as an electrolyte additive is proposed to prevent Mn2+ depositing. HMTA effectively "locks in" Mn2+ through strong coordination, as confirmed by Raman spectroscopy and density functional theory (DFT) calculations. Moreover, the CV and XPS results indicate that the adsorption of HMTA is able to significantly inhibit side reactions at the anode/electrolyte interface. By adopting this strategy, the capacity retention of graphite/LiMn2O4 cell is enhanced from 68.9% to 79.0% at 0.5 C after 100 cycles under 60 °C when adding 0.5% HMTA additive into the blank electrolyte. This work provides a new insight into revealing the mechanism of Mn2+ regulation by introducing HMTA and improving the electrochemical performance of graphite/LiMn2O4 batteries at elevated temperature. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Aeronautical Materials is the property of Editorial Board of Journal of Aeronautical Materials and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to investigate the rheological behavior and the influence of solid waste coal gangue powder on the high-temperature performance of cold recycled Emulsified Asphalt Mastics (EAM), Dynamic Shear Rheometer (DSR) and Multiple Stress Creep Recovery (MSCR) tests were conducted using three different fillers and four powder-to-binder ratios of EAM. Evaluation indexes such as rutting factor (G*/sinδ), improved rutting factor (G*/1−1/sinδ∙tanδ), Unrecoverable Creep Compliance (Jnr), Cumulative Strain (CS) and Creep Recovery Ratio (R) were used to analyze the influence of filler type and dosage on high temperature of EAM, and the effectiveness of these indexes to evaluate high temperature is considered. Moreover, atomic force microscopy experiments were carried out to study on interaction mechanism between the fillers and emulsified asphalt. Finally, grey relational analysis method was used for quantitative assessment of these indexes for EAM. The results indicate that all three fillers effectively improve the high-temperature performance, with a larger improvement observed as the filler dosage increases, among which the tunneling coal gangue powder is the most significant. Under a stress level of 0.1 KPa, the coal gangue filler mastic appears the best deformation recovery ability, whereas under a stress level of 3.2 KPa, the cement filler mastics appears the best deformation recovery ability. The additional fillers significantly influence the nano-scale surface morphology of the residues, and the tunneling coal gangue powder appears a stronger adsorption capacity for free polar components compared to the cement and limestone mineral powder. It is suggested that the Jnr and CS can be used as evaluation indexes of high temperature evaluation index of EAM, instead of G*/1−1/sinδ∙tanδ or G*/sinδ or R.

Ultra-high performance concrete (UHPC) is a cementitious composite characterized by its ultra-high durability attributes and mechanical properties. It is primarily used in large-span and ultra-high-rise structures for control of deflections. However, its mechanical properties decrease significantly after exposure to fire or high temperatures, limiting its applicability. In this paper, the exceptional characteristics of glazed hollow beads (GHBs), including their lightweight, high strength, and thermal insulating properties, were utilized to develop a novel fire-resistant UHPC. UHPC specimens with varying GHB content were prepared, and the corresponding mass loss, thermal performance degradation, and compressive strength after exposure to high temperatures were evaluated. The test results demonstrate that adding GHBs can improve the fire resistance of UHPC. With 40 % (by volume) GHB addition, the resulting UHPC could retain 47 % of its original compressive strength even after exposed to 800°C. The effects of temperature on the UHPC microstructure were analyzed using scanning electron microscopy and X-ray computed tomography. It was found that the combination of polypropylene fibers and GHBs created a release channel for vapor pressure within the concrete, thereby enhancing its high-temperature resistance. This study proposes a practical solution to enhance the high-temperature resistance of UHPC.

ABSTRACTA hybrid laser polishing post-treatment was introduced to enhance the surface quality and high-temperature performance of laser directed energy deposition (LDED) Inconel 718 samples. The surface morphology and microstructure were analysed before and after laser polishing, and the result showed that the surface roughness was reduced by 97.4% and the grains of the recrystallized layer were refined through this post-treatment. Furthermore, the wear resistance, corrosion behaviour, and tensile strength of the laser polishing LDED Inconel 718 samples at the high-temperature of 650°C were investigated detailed. The result showed that the high-temperature tensile strength saw an increase of 14.97%, while both the high-temperature wear resistance and corrosion performance of Inconel 718 exhibited improvements compared to the as-fabricated samples.

Copyright of Journal of Guangdong University of Technology is the property of Journal of Guangdong University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Rutting is a prevalent issue in the Gussasphalt (GA) mixture layer of steel bridge deck pavements. This study aims to investigate the correlation between the rheology of GA mastic and the high-temperature performance of the GA mixture. To achieve this objective, GA mastic underwent temperature and frequency sweep tests, along with multiple stress creep and recovery tests employing a dynamic shear rheometer. Additionally, indentation tests, uniaxial penetration tests, and Lueer fluidity tests were conducted on the GA mixture. The Grey Relational Analysis method was employed to evaluate the relationship between asphalt mastic rheology and the high-temperature deformation resistance of the GA mixture. The findings reveal that the addition of mineral filler enhances the deformation resistance of both GA mastic and the mixture. The percent difference in non-recoverable creep compliance (Jnr-diff) was minimized when the weight ratio of filler to asphalt binder (F/B) was 2.5. Furthermore, increasing the F/B ratio from 2.0 to 3.5 resulted in a more than twofold increase in the GA mixture’s shear strength. Asphalt type emerged as a significant factor affecting the indentation parameter of the GA mixture, with an F-value reaching 8.82 based on ANOVA analysis. The rheological properties of GA mastic exhibited a significant correlation with the high-temperature performance of the mixture. The highest Grey Relational Grade of 0.87 was observed between the non-recoverable creep compliance at a 3.2 kPa stress level (Jnr3.2) and indentation. In future research, greater emphasis can be placed on exploring the micromechanical properties of the GA mastic-aggregate interface.

In order to explore the applicability of environment -friendly polyurethane (EPU) in modified asphalt, the EPU modified asphalt was prepared by in - situ polymerization with polycarbonate diol ( PCDL ) as the soft segment and diphenylmethane diisocyanate (MDI) and butanediol (BDO) as the hard segment. FTIR test was used to analyze the chemical composition of EPU modified asphalt. The penetration, softening point, ductility, and viscosity were used to evaluate the physical properties of the modified asphalt. The compatibility of modified asphalt was evaluated by softening point difference. Dynamic shear rheological test was used to investigate the high temperature rheological properties of modified asphalt. Differential scanning calorimetry and bending rheometer experiments were used to investigate the creep mechanism of modified asphalt at low temperature. The results show that EPU molecules react with asphalt molecules in asphalt to form transaction structures. The addition of EPU can effectively improve the physical properties and high temperature properties of asphalt, and the compatibility is good. EPU has a lower glass transition temperature, so EPU also shows excellent improvement effect on the low-temperature performance of asphalt. This study can provide a new idea for the production of EPU modified asphalt. [ABSTRACT FROM AUTHOR]

To make supercapattery devices feasible, there is an urgent need to find electrode materials that exhibit a hybrid mechanism of energy storage. Herein, we provide a first report on the capability of lithium manganese sulfates to be used as supercapattery materials at elevated temperatures. Two compositions are studied: monoclinic Li2Mn(SO4)2 and orthorhombic Li2Mn2(SO4)3, which are prepared by a freeze-drying method followed by heat treatment at 500 °C. The electrochemical performance of sulfate electrodes is evaluated in lithium-ion cells using two types of electrolytes: conventional carbonate-based electrolytes and ionic liquid IL ones. The electrochemical measurements are carried out in the temperature range of 20–60 °C. The stability of sulfate electrodes after cycling is monitored by in-situ Raman spectroscopy and ex-situ XRD and TEM analysis. It is found that sulfate salts store Li+ by a hybrid mechanism that depends on the kind of electrolyte used and the recording temperature. Li2Mn(SO4)2 outperforms Li2Mn2(SO4)3 and displays excellent electrochemical properties at elevated temperatures: at 60 °C, the energy density reaches 280 Wh/kg at a power density of 11,000 W/kg. During cell cycling, there is a transformation of the Li-rich salt, Li2Mn(SO4)2, into a defective Li-poor one, Li2Mn2(SO4)3, which appears to be responsible for the improved storage properties. The data reveals that Li2Mn(SO4)2 is a prospective candidate for supercapacitor electrode materials at elevated temperatures. [ABSTRACT FROM AUTHOR]

In order to improve the high-temperature performance of mullite ceramic materials, mullite ceramic bodies were placed in closed containers with AlF3 · 3H2 powder and kept at 1 600 °C for 6 h. AlF3 · 3H2O reacts with O2 to produce gaseous compounds AlOF and F, which penetrate into the bodies, promote Al2O3 and SiO2 to form mullite whiskers, and strengthen the mullite ceramic materials. The results show that the mullite ceramics have enhanced hot strength, increased bulk density and declined apparent porosity by adding a certain amount of AlF3 · 3H2 in a closed container. When the addition of AlF3 · 3H2 is 6%, the bulk density of the ceramic material reaches the maximum and the apparent porosity is the lowest; and when the addition of AlF3 · 3H2 is 8%, the hot strength of the material is the highest. [ABSTRACT FROM AUTHOR]

Recycling waste tires, crushing them into crumb rubber (CR) and adding them to asphalt can effectively improve the performance and prolong the service life of asphalt pavement. However, the crumb rubber modified asphalt (CRMA) prepared by aforementioned process is prone to segregation during storage and transportation. The terminal blend rubber asphalt (TB) prepared with fine rubber powder by high-speed shearing at high temperature for long time, which effectively improves the storage stability and working performance of crumb rubber modified asphalt, but reduces the high-temperature performance. In this study, grafting activated crumb rubber (GACR) was incorporated into TB to improve its high temperature performance without impairing storage stability. Using shearing temperature, shearing time and grafting activated crumb rubber content as influencing factors, the response surface method (RSM) was carried out to optimize the preparation process. The results indicated that 180°C was a critical temperature, and the swelling of crumb rubber dominated with the temperature below it, but the desulfurization prevailed with the temperature above it. The extension of time favored the swelling of crumb rubber at low temperature but promoted desulfurization at high temperature. With the increase of crumb rubber content, the high temperature performance of modified asphalt improved whereas the storage stability deteriorated. According to the determination of response values and the prediction of optimal values, the suitable preparation conditions and parameters were recommended as shearing temperature of 190°C, shearing time of 90 min, and GACR content of 15%. The composite modified asphalt prepared through the optimized process showed good high temperature stability and storage stability.

Copyright of New Building Materials / Xinxing Jianzhu Cailiao is the property of New Building Materials Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the context of the global pandemic of COVID-19, the use and disposal of medical masks have created a series of ethical and environmental issues. The purpose of this paper is to study and evaluate the high temperature properties and thermal storage stability of discarded-mask (DM)-modified asphalt from a multi-scale perspective using molecular dynamics (MD) simulation and experimental methods. A series of tests was conducted to evaluate the physical, rheological, thermal storage stability and microscopic properties of the samples. These tests include softening point, rotational viscosity, dynamic shear rheology (DSR), Fourier transform infrared (FT-IR) spectroscopy and molecular dynamics simulation. The results showed that the DM modifier could improve the softening point, rotational viscosity and rutting factor of the asphalt. After thermal storage, the DM-modified asphalt produced segregation. The difference in the softening point between the top and bottom of the sample increased from 2.2 °C to 17.1 °C when the DM modifier admixture was increased from 1% to 4%. FT-IR test results showed that the main component of the DM modifier was polypropylene, and the DM-modified asphalt was mainly a physical co-blending process. MD simulation results show that the DM modifier can increase the cohesive energy density (CED) and reduce the fractional free volume (FFV) of asphalt and reduce the binding energy between base asphalt and DM modifier. Multi-scale characterization reveals that DM modifiers can improve the high temperature performance and reduce the thermal storage stability of asphalt. It is noteworthy that both macroscopic tests and microscopic simulations show that 1% is an acceptable dosage level. [ABSTRACT FROM AUTHOR]

Transient liquid phase (TLP) diffusion bonding of MGH956 to GH3230 superalloy was conducted using BNi5 amorphous foil as the interlayer. The effect of bonding temperature and holding time on the interfacial microstructure and mechanical properties of the bonded joints was investigated at room and high temperature, respectively. The resultant MGH956/BNi5/GH3230 TLP joints fabricated at 1200 °C/2 h consisted of diffusion affected zone α (DAZ α), isothermal solidification zone (ISZ) and diffusion affected zone γ (DAZ γ). In DAZ α, no second phase was formed in the diffusion affected zone, but some oxide particles accumulated at the MGH956/BNi5 interface. In DAZ γ, massive Cr–W borides formed at the grain boundaries while granular and needle borides precipitated in the grain of diffusion affected zone. The microstructure evolution of the weld seam during TLP diffusion bonding was deduced as: L → γ-Ni + L → γ-Ni + (Cr, Fe)B + (Cr, W)B → γ-Ni + (Cr, W)B → γ-Ni + (Ni, Fe)Al. With the increase of holding time, the tensile strength of the bonded joint at 950 °C decreased first and then increased, which was opposite to the tensile strength at room temperature. The tensile strength at room temperature reached 715 MPa when the joint was bonded at 1170 °C for 1 h. The joints failed at the MGH956 base material with a ductile fracture mode. Meanwhile, the tensile strength of the resultant joint tested at 950 °C reached 89 MPa. The results of the fracture analysis suggested that oxide particles aggregated at the interface of MGH956/BNi5 exhibited low resistance to crack at 950 °C, resulting in failure with brittle intergranular fracture characteristics. [Display omitted] • Successful TLP diffusion bonding of MGH956 to GH3230 with BNi5 interlayer was conducted. • The effect of bonding parameters on the tensile strength of joints at room and high temperatures was considered. • The connection between the microstructure and mechanical properties of bonded joint at room and high temperature was established. • Reasonable control of holding time can avoid Cr–W boride coarsening and obtain joints with room temperature tensile strength equal to the base material. [ABSTRACT FROM AUTHOR]

The nickel-based superalloys prepared by additive manufacturing (AM) commonly exhibit inferior mechanical properties at high temperatures, particularly in terms of ductility and creep resistance, compared to the corresponding conventional manufactured (CM)alloys, and this significantly hinders the widespread application of AM nickel-based superalloys in the aerospace industry. To address this problem, a novel nickel-based superalloy for additive manufacturing, Hastelloy X-AM (HX-AM), using the yttrium (Y) alloying strategy has been developed in this work. The results show that the Y element is present in the matrix as Ni 5 Y phase and yttrium oxide nanoparticles after laser additive manufacturing, exerting a significant inhibitory effect on the precipitation and coarsening of detrimental second phases at grain boundaries (GBs) during subsequent heat treatment or service processes. The HX-AM alloy exhibits an exceptional matching relationship between strength (ultimate tensile strength = 315 ± 3 MPa) and ductility (total elongation = 56 ± 1.7 %) at 900 °C. What's more, the creep performance of HX-AM alloy is significantly improved simultaneously compared with CM Ni-based alloys at 900 °C, overcoming the longstanding challenge of inferior creep performance in AM nickel-based superalloys at high temperature. The fatigue lifetime of HX-AM alloy reaches 295.6 h at 900 °C/40 MPa, showing over fifteenfold enhancement compared to that of CM Hastelloy X alloy. [ABSTRACT FROM AUTHOR]

The integration of a phase change material in mortar promises to improve thermal comfort and reduce energy consumption. Assessing mortar behavior under diverse temperature conditions, especially high ones encountered in unforeseen disasters or accidents, is essential for evaluating their reliability and resilience in safeguarding building safety and longevity. This research examines the behavior of cement-based mortar, containing a sustainable PCM incorporated into porous aggregates from processing waste, when exposed to different temperatures (i.e., 20, 200, 600 °C). A comprehensive study on the physical properties of the cement-based mortar formulations (with and without the phase change materials) has been conducted, revealing an increase in the flexural and compressive strengths for a temperature exposure of 200ºC, due to the acceleration of the hydration process of the binder. However, a decrease in flexural and compressive strengths, as well as adhesion, for the temperature exposure of 600ºC was observed, due to the microcracks developed due the high thermal gradient. This behavior is observable even in mortars that do not contain any phase change material. Thermal cycle test of the phase change material involved in this work (i.e., Polyethylene-glycol of molecular weight 1000) has been carried out: stable melting and crystallization temperatures were recorded with a maximum enthalpy variation of 5 %. • Cement mortars incorporating a novel composite form-stable PCM were developed. • The thermal cycles tests performed affirmed the PCM's thermal stability over time. • The influence of form-stable PCM at high temperature exposure was evaluated. • The behavior of mortars containing PCM towards water has been assessed. • Mechanical and adhesion strengths at different temperature were evaluated. [ABSTRACT FROM AUTHOR]

To make supercapattery devices feasible, there is an urgent need to find electrode materials that exhibit a hybrid mechanism of energy storage. Herein, we provide a first report on the capability of lithium manganese sulfates to be used as supercapattery materials at elevated temperatures. Two compositions are studied: monoclinic Li2Mn(SO4)2 and orthorhombic Li2Mn2(SO4)3, which are prepared by a freeze-drying method followed by heat treatment at 500 °C. The electrochemical performance of sulfate electrodes is evaluated in lithium-ion cells using two types of electrolytes: conventional carbonate-based electrolytes and ionic liquid IL ones. The electrochemical measurements are carried out in the temperature range of 20–60 °C. The stability of sulfate electrodes after cycling is monitored by in-situ Raman spectroscopy and ex-situ XRD and TEM analysis. It is found that sulfate salts store Li+ by a hybrid mechanism that depends on the kind of electrolyte used and the recording temperature. Li2Mn(SO4)2 outperforms Li2Mn2(SO4)3 and displays excellent electrochemical properties at elevated temperatures: at 60 °C, the energy density reaches 280 Wh/kg at a power density of 11,000 W/kg. During cell cycling, there is a transformation of the Li-rich salt, Li2Mn(SO4)2, into a defective Li-poor one, Li2Mn2(SO4)3, which appears to be responsible for the improved storage properties. The data reveals that Li2Mn(SO4)2 is a prospective candidate for supercapacitor electrode materials at elevated temperatures.

In order to improve the thermal shock resistance of MgO-AI-C materials, three low-expansion coefficient silicon-based raw materials such as silicon, fused quartz, and SiC were introduced, and their influences on the properties of MgO-AI-C materials were studied by XRD and SEM. The results show that: (1) at high temperatures, Si transforms into SiC and SiO2, and SiO2 reacts with magnesia forming forsterite, improving the hot strength, the thermal shock resistance and the oxidation resistance of the materials; (2) fused quartz can significantly improve the thermal shock resistance of the materials, but the softening at high temperatures and the crystal transformation of fused quartz are not conducive to the hot strength and the oxidation resistance;(3)the addition of SiC can improve the thermal shock resistance, the hot strength and the oxidation resistance of the materials; when the addition of SiC exceeds 10 mass%, there are many microcracks in the material due to thermal mismatching, which affects its thermal shock resistance and oxidation resistance. [ABSTRACT FROM AUTHOR]

In order to explore the effect of nano-SiO2 on asphalt properties, modified asphalt mixtures with different nano-SiO2 doping contents were prepared. The properties of nano-SiO2 modified asphalt mixtures were characterized by rutting test, water immersion Marshall test, freeze-thaw splitting test and low temperature cracking resistance test. The results show that the modified asphalt with 5wt% doping content of nano-SiO2 has the lowest penetration and higher softening point and viscosity. Compared with the base asphalt, the rutting depth of 5% (mass fraction) nano-SiO2 modified asphalt mixture was reduced by 45.90% and 52.27% at 45 and 60 min, respectively, the dynamic stability was improved by 60.57%, and the residue was stable after immersion in water for 48 h. The tensile strength is up to 90.69%, the freeze-thaw splitting strength ratio is up to 91.24%, the flexural tensile strength is increased by 17.70%, the maximum flexural tensile strain is increased by 11.36%, and the bending stiffness modulus is increased by 8.86%. On the whole, the high temperature performance, water stability and low temperature crack resistance of 5wt% nano-SiO2 modified asphalt mixture have been significantly improved, and it has good road performance and application prospects. [ABSTRACT FROM AUTHOR]

High-temperature microwave-absorbing materials are crucial for achieving radar stealth in high-speed equipment. In response to this necessity, we investigated xLa 0.9 Sr 0.1 MnO 3 /(1-x)Ba 3.75 La 9.5 Ti 18 O 54 composite ceramics under variable temperatures, where x ranges from 20 to 50 wt%. X-ray diffraction analysis indicates the coexistence of La 0.9 Sr 0.1 MnO 3 and Ba 3.75 La 9.5 Ti 18 O 54 when x ranges from 20 to 30 wt%, transforming into a perovskite-structured solid solution with a higher proportion of La 0.9 Sr 0.1 MnO 3. Variable-temperature direct current conductivity reveals a controllable transition from dielectric behavior to semiconductor behavior, resulting in the dielectric properties of composite ceramics shifting from low-loss to high-loss characteristics. For x values ranging from 20 wt% to 40 wt%, there consistently exists a corresponding temperature and frequency range ensuring specific absorption performance. Notably, the composite ceramic with x=30 wt% and a thickness of 1.1 mm demonstrates an effective absorption bandwidth (RL<-10 dB) of 1.75 GHz within the temperature range of 400–600℃. These findings suggest that composite ceramics comprising La 0.9 Sr 0.1 MnO 3 and Ba 3.75 La 9.5 Ti 18 O 54 hold promise as high-temperature microwave-absorbing materials. • Composite ceramic with strong dielectric polarization and conductivity loss has been designed and prepared. • The controllable dielectric properties are very beneficial for high temperature microwave absorbing materials. • Composite ceramics exhibit ultrathin and wideband high-temperature microwave absorption properties. [ABSTRACT FROM AUTHOR]

To investigate the effects of different structures on the cutting performance of AlCrBN/AlCrN multilayer coatings, AlCrBN/AlCrN coatings with different multilayer structures (single layer, 10 bilayers, and 20 bilayers corresponding to T1 coating, T10 coating, and T20 coating) were synthesized using multi-arc ion plating technology. Grazing incidence X-ray diffraction (GIXRD) and transmission electron microscopy (TEM) results showed that the coatings were mainly composed of fcc -(Cr, Al) N phases located on the (111) and (200) crystal planes. All coatings exhibited a good indentation adhesion to the substrates. The hardness of the T10 coating (32.6 GPa) and T20 coating (31.2 GPa) was significantly higher than that of the T1 coating (28.0 GPa). Annealing experiments show that no phase composition evolution was revealed at 800 °C. High-speed milling tests imply that the milling life of the T10 coating (13 m) and the T20 coating (10 m) was increased by 62.5% and 25.0% compared to the T1 coating (8 m), respectively. In high-speed dry turning tests, the T10 coated tool also showed the longest lifetime (16 mins), an improvement of 23.1% over T1 or T20 coated tools (13 mins). SEM analyses of wear coated tools indicated that a multilayer structure enhanced their resistance to abrasion and adhesion wear, and led to better cutting performance, probably because of their excellent mechanical properties and thermal stability. • AlCrN/AlCrBN multilayer coatings were constructed by combining B-coatings and multilayer structures. • These multilayer coatings exhibited enhanced hardness and superior thermostability. • AlCrN/AlCrBN coatings extended the milling life by 62.5% and turning life by 23.1%. • Developed high-performance AlCrN/AlCrBN multilayered coatings for extended tool life. [ABSTRACT FROM AUTHOR]

In this study, the engineering properties of Ordinary Portland Cement (OPC) and alkali-activated slag (AAS) mortar with electric arc furnace ladle slag (EAFLS) were investigated to reveal the effects of EAFLS on the expansion of cementitious mortars. Additionally, the effects of these two types of mortar were explored based on their compressive strength, especially at high temperatures. EAFLS in OPC mortars significantly reduced the compressive strength and caused serious soundness problems in the mortars after autoclaving due to the presence of free-CaO and free-MgO in the EAFLS slag. On the other hand, the AAS mortars produced with EAFLS had compressive strength comparable to ordinary OPC mortars and maintained soundness after autoclaving. During a 550 °C heat treatment, the OPC mortar cracked and lost residual strength, but the AAS mortar retained more than 90% of its residual strength. Even after an 800 °C heat treatment, the AAS mortar maintained 14% of its residual strength (about 4 MPa), sufficient to prevent the collapse of the specimen structure. The main reason is that alkali-activated technology can accelerate the hydration process and solve the delayed hydration problem. The results of this study indicated that EAFLS is suitable to partially replace the binder used in the production of AAS mortars, and the resulting AAS mortars have high volume stability, high compression strength, and good high temperature resistance. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To study the effect of LKW-Ⅱwarm mix additive on the rheological performance of rubber powder/SBS modified asphalt, Fourier Transform Infrared Spectroscopy（FTIR） test, Dynamic Shear Rheology（DSR） test, Multi-stress Repeated Creep Recovery（MSCR） test and low-temperature Bending Beam Rheology（BBR） test were conducted to analyze the influence of LKW-Ⅱwarm mix additive on the rheological performance. The experimental results showed that: LKW-Ⅱ warm mix additive can effectively control the rheological performance under high temperature conditions. When the mixing amount was 0.1%, the improvement effect was the best, and the other mixing amount was relatively close in experiment. Warm mix rubber powder/SBS modified asphalt had better elastic recovery ability, 0.1% LKW-Ⅱ mixing amount under 12.8 kPa stress would not cause structural damage, and was the least sensitive to stress. LKW-Ⅱ warm mix additive could improve low-temperature performance. At the same temperature, 0.3% LKW-Ⅱ mixing amount produced the least internal stress and had the best stress relaxation ability. When using a little mixing amount of LKW-Ⅱ warm mix additive, it could effectively control the high temperature rheology and improve the low temperature rheology. [ABSTRACT FROM AUTHOR]

Precipitation and evolution behavior of phases in Inconel 625 superalloy were reviewed, and the various types of phases in the alloy were emphatically introduced, including the γ' phase, γ″ phase, δ phase, Ni2(Cr,Mo) phase, three types of MC,M6C,M23C6 carbides and Laves phase. The precipitation and evolution behavior of phases in different forming processes, heat treatment and high temperature creep were elucidated. Further, the effects of different types of phases on the properties of the alloys were discussed. The main factors causing cracks during rapid forming and welding in Inconel 625 alloy were pointed out and it was proposed that an important development direction in the future is how to improve the thermal strength and thermal fatigue properties of the Inconel 625 alloy by selecting and controlling the phase precipitation.

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Henan University of Science & Technology, Natural Science is the property of Editorial Office of Journal of Henan University of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

High‐temperature dielectric materials for capacitive energy storage are in urgent demand for modern power electronic and electrical systems. However, the drastically degraded energy storage capabilities owing to the inevitable conduction loss severely limit the utility of dielectric polymers at elevated temperatures. Herein, a new approach based on the in situ preparation of oxides onto polyimide (PI) films to high‐temperature laminated polymer dielectrics is described. As confirmed by computational simulations, the charge injection at the electrode/dielectric interface and electrical conduction in dielectric films are substantially depressed via engineering the in situ prepared oxide layer in the laminated composites. Consequently, ultrahigh dielectric energy densities and high efficiencies are simultaneously achieved at elevated temperatures. Especially, an excellent energy density of 1.59 J cm−3 at a charge–discharge efficiency of above 90% has been achieved at 200 °C, outperforming the current dielectric polymers and composites. Together with its excellent discharging capability and cyclic reliability, the laminate‐structured film is demonstrated to be a promising class of polymer dielectrics for high‐power energy storage capacitors operating at elevated temperatures. The facile preparation method reported herein is readily adaptable to a variety of polymer thin films for energy applications under extreme environments. [ABSTRACT FROM AUTHOR]

In the context of the global pandemic of COVID-19, the use and disposal of medical masks have created a series of ethical and environmental issues. The purpose of this paper is to study and evaluate the high temperature properties and thermal storage stability of discarded-mask (DM)-modified asphalt from a multi-scale perspective using molecular dynamics (MD) simulation and experimental methods. A series of tests was conducted to evaluate the physical, rheological, thermal storage stability and microscopic properties of the samples. These tests include softening point, rotational viscosity, dynamic shear rheology (DSR), Fourier transform infrared (FT-IR) spectroscopy and molecular dynamics simulation. The results showed that the DM modifier could improve the softening point, rotational viscosity and rutting factor of the asphalt. After thermal storage, the DM-modified asphalt produced segregation. The difference in the softening point between the top and bottom of the sample increased from 2.2 °C to 17.1 °C when the DM modifier admixture was increased from 1% to 4%. FT-IR test results showed that the main component of the DM modifier was polypropylene, and the DM-modified asphalt was mainly a physical co-blending process. MD simulation results show that the DM modifier can increase the cohesive energy density (CED) and reduce the fractional free volume (FFV) of asphalt and reduce the binding energy between base asphalt and DM modifier. Multi-scale characterization reveals that DM modifiers can improve the high temperature performance and reduce the thermal storage stability of asphalt. It is noteworthy that both macroscopic tests and microscopic simulations show that 1% is an acceptable dosage level.

[Display omitted] • LiFePO 4 with various morphologies was tunable synthesized using phytic acid. • The material with hierarchical structure exhibited outstanding electrochemical performance. • The reaction mechanism was proposed through time-dependent experiments. • The mechanism will provide a new development for preparing electrode materials. LiFePO 4 has been widely considered as a promising cathode material for lithium ion batteries because of its nontoxicity, high specific capacity, good safety characteristics and low cost. However, the actual fabrication of LiFePO 4 typically uses LiH 2 PO 4 , NH 4 H 2 PO 4 or H 3 PO 4 as phosphorus sources, possibly leading to the corrosion of the experimental facilities and release of toxic gas during the synthesis process. Hence, we use phytic acid (PhyA) as a new eco-friendly and sustainable phosphorus source to synthesize LiFePO 4. Results show that the reaction time and temperature have significant effects on the morphology. LiFePO 4 prepared at 180 °C for 4 h (LFP-4) shows unique hierarchical structure and exhibits best electrochemical performance over a wide test temperature (25–55 °C). Through time-dependent experiments to explore the reaction mechanism of LiFePO 4 , it is found that an intermediate Fe 3 (PO 4) 2 is produced that acts as the substrate for the subsequent preparation of LiFePO 4. After carbon coating, LFP/C-4 (after carbon coating, LFP-4 labeled as LFP/C-4) shows an outstanding initial discharge capacity (156.9 mAh g−1, 1C at 25 °C) and high temperature behavior (147.1 and 126.8 mAh g−1 at 1C and 2C under 55 °C). This result is highly important for the controllable synthesis and improvement of electrochemical characteristics of LiFePO 4 cathode material. [ABSTRACT FROM AUTHOR]

To enhance high-temperature oxidation resistance, Al was introduced into lamellar porous Ti 3 SiC 2 , reducing wall porosity from 16% to 7%, signifying wall densification. DFT calculations revealed that Al substitution for Si in the silicon layer caused lattice distortion, raising lattice parameter (d) from 0.2278 to 0.2289 nm, and disrupting energy, weakening bonds and reducing fracture energy absorption. Consequently, diffusion activation energy dropped from 370 kJ/mol to 230 kJ/mol, significantly impacting high-temperature stability. Yet, Al doping improved wall and oxide film densification, lowering the oxidation rate from 0.0097 to 0.0073 mg2/cm4·h, leading to remarkable high-temperature electromagnetic shielding with SSE of 71.1 dB. [Display omitted] • Doublet porous microlaminated Ti 3 Si(Al)C 2 had been prepared by freeze casting. • Al doping densifies walls, induces structural mismatch, and reduces fracture energy. • Al doping reduces activation energy, promoting diffusion and high-temp decomposition. • Al doping densifies walls and oxide layers, enhancing high-temp oxidation resistance. • Unique porous Ti 3 Si(Al)C 2 shows durable high-temp electromagnetic shielding. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Rutting is one of the main distresses of highway asphalt pavement in China. Evaluating the high temperature performance of asphalt pavement during its service period is a major problem for road management departments. The purpose of this paper is to investigate the effect of rutting development levels on the high temperature performance of each layer in asphalt pavement and provide guidance for rutting distress evaluation of highway asphalt pavement. The field cores were obtained from the sections with different rutting development levels (different Equivalent Single Axle Loads and rutting depths) under the same service life. Based on the thickness measurement of field cores, the rutting contribution rate (RCR) of each layer was calculated. Dynamic creep test was performed on the surface layer SMA-13 and binder layer SUP-20 mixtures. Finally, dynamic modulus test was conducted to analyze the influence of rutting development levels on the viscoelastic properties of the binder layer asphalt mixture. The results show that the surface layer is largely responsible for the rutting in the initial rutting stage (rutting depth is less than 10 mm), the RCR of the binder layer increases gradually and exceeds that of the surface layer as the rutting develops. For the selected pavement structure, when the rutting depth of whole pavement is more than 15 mm, the binder layer SUP-20 behaves more like viscoplastic body in high-temperature/low-frequency range. The RCR value of binder layer is more than 40% and its resistance to deformation at high temperature starts to degrade rapidly. The high temperature performance of the surface layer remains relatively stable under different rutting depths. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Zhengzhou University: Engineering Science is the property of Editorial Office of Journal of Zhengzhou University: Engineering Science and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The aim of the research is to quantify the property of asphalt mortar and asphalt mixture containing municipal solid waste incineration (MSWI) fly ash. The potential of partially replacing mineral fillers with MSWI fly ash in asphalt mixture production was investigated. Five different MSWI fly ash replacement ratios, which include 0%, 25%, 50%, 75%, and 100%, were adopted to assess the influence of fly ash dosage, and the optimum fly ash replacement ratio was proposed. The rheological characteristics of asphalt mortar with MSWI fly ash were assessed with the dynamic shear rheometer (DSR) and bending beam rheometer (BBR). The high temperature properties of the mixture with MSWI fly ash were assessed with the Marshall stability test and the rutting test. The low temperature cracking property was determined with the indirect tensile strength test at low temperatures. The moisture stability property was identified with the immersed Marshall test and the freeze-thaw cycles conditioned indirect tensile strength test. Based on the test results, the addition of fly ash and mineral filler remarkably increased the ǀG*ǀ of the asphalt mortar. The δ of asphalt decreased as the dosage of fly ash and mineral filler increased. The addition of fly ash and mineral filler degraded the low temperature characteristics of the mortar. Fly ash improved the high temperature characteristics of the asphalt mixture. The asphalt mixture with MSWI fly ash was more susceptible to thermal cracking than the control sample. The addition of fly ash weakened the moisture stability of the asphalt mixture. In order to guarantee the low temperature characteristics and the moisture susceptibility of the asphalt mixture, the fly ash replacement ratio was recommended to be set around 25%. With proper mixture design and fly ash dosage, the asphalt mixture would have adequate performance, as well as reduced environmental impact.

The effect of Sm on the microstructure and tensile properties of Mg-4Al-4 (La, Ce) alloy was studied. The Mg-4Al-4 (La, Ce) alloy was mainly composed of α-Mg and Al11(La, Ce)3. With the addition of Sm, a new phase of Al2(La, Ce, Sm) was revealed in the alloy. The results showed that at room temperature (RT), after Sm addition, the ultimate tensile stress and the elongation decreased, while the yield stress increased slightly; the elongation increased with the Sm addition and the yield stress was basically the same, but the ultimate tensile stress decreased at an elevated temperature of 150 °C. The change in the mechanical properties of the alloy was mainly related to the change in microstructure and phase. With the increase in Sm content, the volume fraction of Al2(La, Ce, Sm) phase increased and the Al11(La, Ce)3 eutectic volume fraction decreased significantly, which led to a change in the mechanical properties of the alloy. The 1 wt.%Sm-addition alloy exhibited greater elongation than the Sm-free alloys.

This study shows a rapid and systematic approach towards identifying full density and peak hardness for an Al-Mg-Sc-Zr alloy commonly known as Scalmalloy®. The alloy is tailored for the laser powder bed fusion process and has been shown to be printable with >99.8% relative density. The microstructure suggests Al grain refinement in melt pool boundaries, associated with formation of primary Al3(Sc,Zr) particles during solidification. Peak hardening response was identified by heat treatment tests at 573,598 and 623 K between 0 and 10 h. A peak hardness of 172 HV0.3 at 598 K for 4 h was identified. The mechanical properties were also tested with yield and ultimate strengths of 287 MPa and 364 MPa in as-printed and 468 MPa and 517 MPa in peak hardened conditions, respectively, which is consistent with the literature. Such an approach is considered apt when qualifying new materials in industrial laser powder bed fusion systems. The second part of the study discusses the thermal stability of such alloys post-peak-hardening. One set of samples was peak hardened at the conditions identified before and underwent secondary ageing at three different temperatures of 423,473 and 523 K between 0 and 120 h to understand thermal stability and benchmark against conventional Al alloys. The secondary heat treatments performed at lower temperatures revealed lower deterioration of hardness over ageing times as compared to the datasheets for conventional Al alloys and Scalmalloy®, thus suggesting that longer ageing times are needed.

Evotherm3G and EC120 warm agents were added into the matrix and SBS modified asphalt to prepare warm mixed asphalt. The multi-stress creep recovery test was used to evaluate the high temperature performance of warm mixed asphalt before and after short-term aging. The results show that the effects of two warm agents on the high temperature performance of asphalt are obviously different. By adding Evotherm3G warm agent,the strain of asphalt is increased, and the creep recovery rate of asphalt is decreased with improved non-recoverable creep compliance of asphalt. By adding EC120 warm agent,the strain of asphalt is decreased, and the creep recovery rate of asphalt is improved with decreased non-recoverable creep compliance of asphalt. Adding EC120 warm agent can improve the high temperature performance of asphalt better than adding Evotherm3G warm agent, while both warm agents can improve the stress sensitivity of asphalt with different degrees. The short-term aging improves the high temperature performance of matrix asphalt, but weakens the high temperature performance of modified asphalt. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Materials Engineering / Cailiao Gongcheng is the property of Journal of Materials Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The purpose of this study is to gain a deeper understanding of PPA modified asphalt and to investigate the effect of PPA concentration on the high and low temperature performance of the asphalt. Four different concentration levels of PPA modified asphalt were prepared. The zero-shear viscosity (ZSV) at 60 ℃ was measured using a dynamic shear rheometer (DSR) to evaluate its high temperature performance. The creep parameters were measured using a bending beam rheometer (BBR), and the creep compliance derivative (J ′ (t)) was calculated based on the Burgers model to evaluate its low temperature performance. The statistical analysis method was used to discuss the significant difference in the effect of PPA concentration on the high and low temperature performances of asphalt. The modification mechanism of asphalt by PPA concentration was revealed using gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). The results show that there is a significant difference in the effect of PPA concentration on viscosity. As the concentration increases, the viscosity also increases, leading to a more obvious improvement in high temperature performance. PPA can slightly improve the low temperature performance of asphalt, but the effect of PPA concentration on low temperature performance is not significant. PPA narrows the distribution range of asphalt molecular weight, and a large proportion of small molecular size is converted to medium molecular size, which increases the average molecular weight. There is a good linear relationship between the weight-average molecular weight (M w) of PPA modified asphalt at different concentrations and the corresponding viscosity value. The glass transition temperature (T g) of the PPA modified asphalt is slightly lower than that of the original asphalt. However, there is no notable difference in T g among the PPA modified asphalts at different concentrations. These findings provide valuable guidance for the selection of raw materials for PPA modified asphalt. • To study the effect of polyphosphoric acid concentration variables on the high and low temperature performance of asphalt. • To investigate the significant difference of PPA concentration on the high and low temperature performance of asphalt. • The link between macroscopic performance and microscopic mechanism of PPA modified asphalt was established. [ABSTRACT FROM AUTHOR]

• The high temperature performance of WCO/OMMT modified asphalt materials was studied. • The multi-scale correlation of high temperature performance was analysed. • Bio-oil addition significantly reduces the rutting resistance of asphalt materials. • OMMT addition can make up for the loss of high-temperature performance. • The correlation of RTFO asphalt mortar J nr3.2 index and flow number is good. Asphalt binder as a by-product of petroleum is a finite resource. Hence, finding an alternative material for asphalt binder is a potential topic in the road engineering. Performance of compound-modified asphalt material at high temperatures, by waste cooking oil (WCO) and organic montmorillonite (OMMT) was investigated in this study, and the multi-scale correlation evaluation was conducted. The findings revealed that the bio-oil significantly reduces the barrier to rutting of asphalt materials within multi-scales, and rutting resistance was reduced with increased content. High-temperature performance can be regained or even better than that of base asphalt materials when WCO Bio-oil: OMMT is 1:1, and OMMT can compensate for the loss of high-temperature performance. Besides, the multi-scale correlation analysis shows that the J nr3.2 index of OMMT composite modified bio-asphalt mastic, asphalt mixtures' resistance to rutting at high temperatures can be predicted using their short-term aging condition. [ABSTRACT FROM AUTHOR]

• The distribution of voids and skeleton microstructure of six kinds of asphalt mixture is analyzed and evaluated from multiple aspects. • Establish the link between the mesostructure of asphalt mixture and macroscopic properties. • Different macroscopic properties of asphalt mixtures are characterized by specific mesostructural parameters. The distribution characteristics of the mesostructure of asphalt mixtures have an important influence on the macroscopic performance of asphalt mixtures. In this study, by means of industrial computed tomography and voxel analysis, the distribution of voids and skeleton microstructure of asphalt mixture is characterized from multiple perspectives. The relationship between mesostructural characteristic parameters and macroscopic properties of asphalt mixtures was established by the indirect tensile test, uniaxial compression test, and digital image correlation test. The results show that the mesostructural distribution of the voids of different types of asphalt mixtures shows a certain degree of transverse isotropy. Air voids content and fractal dimension of voids are the mesostructural characteristic parameters that affect the cracking resistance of asphalt mixtures at low temperatures. The air voids content has a negative exponential relationship with the strength of asphalt mixture. When the void fractal dimension is 1.3, the splitting tensile strength of asphalt mixture reaches the maximum value. Skeleton structure is a mesostructure characteristic parameter that affects the high temperature stability of asphalt mixture. The lower voids in coarse aggregate skeletons and degree of anisotropy are positively correlated with the uniaxial compressive strength. After voids in coarse aggregate skeletons are lower than 35 %, the uniaxial compressive strength of asphalt mixture is significantly improved. The proposed skeleton evaluation index can effectively characterize the material composition differences of different types of asphalt mixtures. The strain cloud diagram of the digital correlation experiment shows the place where the void distribution first reached the maximum strain of about 0.003 during loading, and the high strain area corresponds to the void centroid distribution. The air voids centroid distribution is the mesostructural characteristic parameter of the indirect tensile strain distribution. [ABSTRACT FROM AUTHOR]