Elevated Temperatures Research Articles

Enhanced thermal stability of amorphous Al-Fe alloys by addition of Ce and Mn

The thermal stability of mechanically alloyed amorphous Al-Fe-based alloy powders, with nominal compositions Al82Fe16Ce2 and Al82Fe14Mn2Ce2, was investigated using differential scanning calorimetry (DSC), x-ray diffraction (XRD), and scanning electron microscopy (SEM) complemented by energy-dispersive x-ray spectroscopy (EDX). Analysis through DSC indicated that both Al82Fe16Ce2 and Al82Fe14Mn2Ce2 alloys undergo a two-stage crystallization process. Notably, the initial crystallization temperatures for the Al82Fe16Ce2 and Al82Fe14Mn2Ce2 alloys were determined to be approximately 525 °C and 550 °C, respectively. This high thermal stability is attributed to the delayed nucleation process induced by the presence of Ce and Mn within the Al-Fe matrix. During polymorphic crystallization, distinct phases such as β-AlFe, Al13Fe4 for Al82Fe16Ce2, and β-Al(Fe, Mn), Al13Fe4, Al10CeMn2 for Al82Fe14Mn2Ce2 were identified. Furthermore, post-annealing of these amorphous alloy powders at elevated temperatures of 600, 700, and 800 °C led to distinct morphological characteristics based on the alloy composition. For Al82Fe16Ce2, the particles preserved a nearly spherical morphology, with size distributions ranging from 1 to 5 μm. In contrast, for Al82Fe14Mn2Ce2, the particles exhibited an irregular shape with a broader size range of 1 to 15 μm.

The comparison of decay rates of infectious SARS-CoV-2 and viral RNA in environmental waters and wastewater

The comparison of decay rates of infectious SARS-CoV-2 and viral RNA in environmental waters and wastewater

Exploring enhanced high-temperature resistance: Analyzing the combined impact of fibers and nanoparticles in mortars

This study aims to explore the potential synergistic effect of polypropylene (PP) fiber and different types of nanoparticles to improve the high-temperature resistance of cementitious materials. For that, mortar samples with different PP fiber percentages, 0.6 wt% and 1.2 wt%, were produced. Different percentages of both colloidal nano-silica (CNS), 0.3 %, 0.6 %, and 0.9 %, and nano calcium carbonate (NCC), 0.5 %, 1 %, and 2 %, were used in the study. To test the resistance to elevated temperatures, mortar samples were exposed to different peak temperatures of 300°C, 600°C, and 900°C for 2 h, using unexposed samples as reference. Flexural and compressive strength, water absorption, surface electrical resistivity, and thermogravimetric analysis (TGA) of the heated and unheated samples were conducted. Results showed that, at 300°C heating regime, all samples with 0.6 % PP fiber exhibited an increase in flexural and compressive strength compared to their corresponding reference samples. For instance, specimens containing 0.6 % PP fiber and 2 % NCC content exhibited a 19 % increase in flexural strength compared to the unheated sample, whereas samples with 0.6 % PP fiber and 0.5 % NCC increased 32 % their compressive strength. In contrast, at 600°C, there was a major decline in mechanical properties in all samples, with samples containing NCC exhibiting the lowest amount (average of 61 % reduction in flexural strength and 32 % decrease in compressive strength). In general, a higher dosage of nanoparticles and lower PP fiber content will be better to resist temperatures up to 600 °C.

The influence of rapid-diffusive β-stabilizers on the microstructure formation and superplasticity of titanium-based alloys

The superplasticity of Ti-based alloys is improved due to grain refinement, an increase in grain size stability, and an increase in the β-phase fraction up to ∼0.5. Alloying with β-stabilizers reduces the β-transus temperature and increases the β-phase fraction at low forming temperatures, thus improving the superplasticity and lowering its temperature. Both grain growth and superplastic deformation mechanisms are diffusion-controlled phenomena, and, therefore, the diffusivity of the alloying elements should have a significant effect on superplasticity. This work deals with the influence of the high-diffusive elements Fe, Co, and Ni on the grain structure and superplasticity of titanium alloys. For this purpose, the Ti-Al-Mo-V alloy, and alloys with proportional replacement of low-diffusive Mo by Fe, Co, or Ni, exhibiting an interstitial diffusion mechanism, were studied. The alloying elements content was selected to ensure the same β-phase fraction at a deformation temperature of ∼875 °C. The microstructure evolution after thermomechanical processing, annealing, and superplastic deformation, as well as post-deformation room-temperature mechanical properties of the studied alloys, were compared. The actual phase ratio was reconstructed by comparing scanning electron microscopy images in backscattered electrons and electron backscatter diffraction data for the same fragments. It was found that Mo replacement for highly diffusive elements accelerated dynamic grain growth during superplastic deformation at an elevated temperature of 875 °C but improved superplasticity at a lower temperature of 775 °C. The results confirmed that alloying with high-diffusive elements is a promising strategy for the design of low-temperature superplastic forming alloys.

Microstructure Characteristics and Elevated Temperature Mechanical Properties of a B Contained β-solidified γ-TiAl Alloy

Microstructure Characteristics and Elevated Temperature Mechanical Properties of a B Contained β-solidified γ-TiAl Alloy

Fabrication of energy efficient P-i-G structure with novel dysprosium-doped yttrium calcium borate (Dy: Y2CaB10O19) phosphors: Highly efficient materials for cool white light emission conducive to green technology

Novel polycrystalline phosphor-yttrium calcium borate doped with dysprosium ions (Dy3+: Y2CaB10O19) was synthesized for the first time by solid-state reaction technique. The crystal structure was found to be monoclinic having C2 space group. SEM was performed to analyze the surface morphology of the phosphor materials and to assess the distribution of phosphor particles in the glass matrix. Fourier transform infrared (FTIR) spectroscopy of the samples was studied to know the molecules present. The emission spectra by 350 nm excitation possessed characteristic peaks at 480 nm (blue) and 577 nm (yellow). The CIE chromaticity co-ordinate and correlated color temperature (CCT) were deduced to be (x = 0.3384, y = 0.3823) and 5297 K respectively. Luminescence decay time for the optimized phosphor was determined to be 0.70 ms. The prepared phosphors were embedded in the glass matrix at an elevated temperature of 1000 °C. The transmittance spectra of the prepared glass materials were recorded to analyze its transparency in the visible region. The internal quantum yield was deduced to be 53.91 %.

Behavior of reinforced concrete columns made with seawater and glass FRP bars and subjected to high temperatures

This study presents experimental and analytical investigations on the axial capacity of 12 heat-damaged glass fiber-reinforced polymer reinforced concrete columns. The columns were prepared with dimensions of 200 × 200 × 1000 mm and 3 replacement ratios of seawater for concrete mixing and curing (0%, 50%, and 100%). At the age of 3 months, the columns were subjected to an elevated temperature of 500 °C for 30, 60, and 90 min and subsequently cooled and tested. The experimental results demonstrated that the compressive strength of concrete increased by 35% and 45% at seawater replacement ratios of 50% and 100%, respectively. In addition, seawater-concrete mixes exhibited a lower rate of strength development compared to the reference mix. Moreover, 100% seawater concrete columns reported an increase of 28% in the cracking and ultimate loads. However, columns at seawater replacement ratios of 0%, 50%, and 100% exhibited a drop of 27%, 53%, and 50% in the cracking load after being exposed to 500 °C for 90 min. Additionally, the columns exposed to elevated temperatures showed a reduction of 5%–20% in the ultimate load. Furthermore, the analytical models of ACI 440.11–22 and CAN/CSA-S806-12 significantly underestimated the axial capacity of all columns. The most accurate prediction for the columns’ axial capacity was associated with the analytical model of Mohamed et al. with mean, standard deviation, and coefficient of variance of experimental-to-predicted ratios of 1.17, 0.12, and 9.98%, respectively.

Multifunctional particle additives for simultaneous enhancement of toughness and biodegradation of poly(lactic acid)

A multifunctional biodegradable additive powder has been created for simultaneous enhancement of toughness and compostability of the biopolymer poly(lactic acid) (PLA). PLA has promising strength and stiffness compared to commodity plastics, but the neat polymer is not a direct replacement for petroleum-based plastics in consumer products due to its brittle fracture and low ductility. Although officially certified as biodegradable, PLA suffers from a slow composting rate and is not considered compostable outside of specialized environments such as those found in industrial composters (where temperatures approaching 60°C are used). A powder-based additive has been developed that increases both the elongation at break and the composting rate of PLA to enhance the attractiveness of PLA over current commodity plastics. In this study, various amounts of the additive are compounded into PLA using a single screw extruder. Test specimens are prepared using the additive manufacturing method of fused filament fabrication. The PLA-based composites show a minimal loss of strength and stiffness as compared to plasticized PLA resins, and the additives provide tunable properties to the material in the ability to control elongation versus strength and stiffness. Direct tensile testing of 3.75mm filament for additive manufacturing to compare material properties is also investigated. The composting behavior is investigated using specimens made by extrusion as part of an additive manufacturing model system. Composting studies show an increase in composting rate under elevated temperature of 58°C and 50% relative humidity under modified ASTM D5338 soil contact testing. Microbial analysis indicates that the additive particles support the growth of specific degraders and shifts the composition of the microbial population of bacteria and fungi and has potential for enhancing the compostability in home compost.

Paracoccus kondratievae produces poly(3-hydroxybutyrate) under elevated temperature conditions.

As part of ongoing efforts to discover novel polyhydroxyalkanoate-producing bacterial species, we embarked on characterizing the thermotolerant species, Paracoccus kondratievae, for biopolymer synthesis. Using traditional chemical and thermal characterization techniques, we found that P. kondratievae accumulates poly(3-hydroxybutyrate) (PHB), reaching up to 46.8% of the cell's dry weight after a 24-h incubation at 42°C. Although P. kondratievae is phylogenetically related to the prototypical polyhydroxyalkanoate producer, Paracoccus denitrificans, we observed significant differences in the PHB production dynamics between these two Paracoccus species. Notably, P. kondratievae can grow and produce PHB at elevated temperatures ranging from 42 to 47°C. Furthermore, P. kondratievae reaches its peak PHB content during the early stationary growth phase, specifically after 24 h of growth in a flask culture. This is then followed by a decline in the later stages of the stationary growth phase. The depolymerization observed in this growth phase is facilitated by the abundant presence of the PhaZ depolymerase enzyme associated with PHB granules. We observed the highest PHB levels when the cells were cultivated in a medium with glycerol as the sole carbon source and a carbon-to-nitrogen ratio of 10. Finally, we found that PHB production is induced as an osmotic stress response, similar to other polyhydroxyalkanoate-producing species.

Phase and microstructure evolutions of fiber reinforced aerogel composites with different fiber components during calcination

In the high temperature industry, controlling the external surface temperature of the kiln shell is crucial for reducing heat loss, energy consumption, and carbon emissions. While aerogels are esteemed for their superior thermal insulation properties and considered as optimal materials in the thermal insulation layer of energy saving lining for burning zone of cement rotary kiln, their structural integrity at elevated temperatures confines their applications to medium and low temperature settings. To overcome this limitation, the fiber-reinforced aerogel composites have been developed to bolster the high-temperature endurance of aerogel products. Notably, composites containing ZrO2-enhanced fibers exhibit significantly higher resistance to thermal degradation from local overheating, such as flame impingement, compared to their counterparts without ZrO2. However, the mechanisms of performance degradation and the reinforcing role of ZrO2 in fiber reinforced aerogel composites at high temperatures especially above 1000 °C, remain unclear. This study specifically focuses on the thermal conductive properties of commercial aerogel felts, both with and without the inclusion of ZrO2 across a range of temperatures, and examines the subsequent phase transitions and microstructural evolutions upon thermal treatment. Critical analyses of heat flow, mass change, density, linear shrinkage, and pore size distribution during the calcination process were conducted. After 6 hours of heat treatment, composites with ZrO2-enhanced fibers retained an 81.44% porosity, unlike composites without ZrO2 which sintered and became denser. The experimental findings demonstrate that the performance of fiber reinforced aerogel composites mainly depends on the fiber’s framework microstructure and fiber-aerogel reactions, which provides the references for developing excellent aerogel composites and evaluating of the usability in high temperature zone of kiln.

Enhancing fire resistance: Investigating mechanical properties of biochar-infused concrete under elevated temperatures

Biochar (BC) generated by pyrolysis at high temperature is a kind of porous material with great potential for carbon sequestration. The incorporation of BC into mortar as a substitute for cement can not only improve the mechanical properties of mortar, but enrich the means of carbon sequestration technology. However, the performance of concrete utilizing BC as a replacement for cement, particularly when exposed to elevated temperatures, has yet to be fully understood. Here, we provide an experimental investigation on the mechanical properties of biochar concrete (BCC) after exposure to elevated temperatures. 168 concrete specimens were poured with four different BC addition (0 %, 3 %, 5 % and 10 %) to test the mechanical strength at 7 and 28 days, and the mass loss, the residual strength, microstructures, and stress-strain curve of BCC after high temperature were obtained. The results showed that a small amount (3 %) of BC significantly improved the mechanical properties under conventional conditions. The apparent morphology of BCC after high temperature is similar to that of ordinary concrete, however, its mass loss, residual strength and peak stress have great changes. The addition of 3 % BC can increase the residual compressive strength of concrete at 300 °C, 500 °C and 700 °C by 4.8 %, 26.3 % and 25 %, respectively, compared to the BC-free one. Based on the findings, it is speculated that replacing a portion of cement with BC will be a feasible alternative to improve the performance of concrete at elevated temperature and curtail CO2 emissions that generate with the cement production.

Interfacial microstructure evolution and mechanical behavior of W/steel joints diffusion bonded with CoCrFeNi interlayer

In the nuclear industry and military field, diffusion bonding between tungsten (W) and steel has received extensive attention, in which selecting and developing new joining materials is of great significance. In this paper, a high entropy alloy CoCrFeNi with excellent ductility and high melting point, is used as interlayer material for the electric-field assisted diffusion bonding between W and steel. Effects of diffusion bonding time on interfacial microstructure and mechanical performance was investigated. Under the diffusion bonding conditions of 950 °C for 5, 15, 30 and 45 min, no cracks or discontinuities appeared in the joints. Element diffusion occurred at interfaces and metallurgical bonding was realized between interlayer and substrates. At W/CoCrFeNi interfaces, in addition to the solid solution phase, intermetallic compounds were detected for the joint bonded with holding time longer than 30 min. Only solid solution phase formed for all the CoCrFeNi/steel interfaces. The room temperature tensile strength of the W/CoCrFeNi/steel joint was determined to be 270 MPa, exceeding the values documented in prior studies. The elevated temperature (400 °C and 600 °C) tensile strength was found to be higher than that at room temperature. In addition, similar microhardness distribution across the joints bonded for different holding times were observed, and there was no obvious difference in the hardness of the interlayer and metal substrates in these joints.

Effects of Composition and Polymerization Conditions on the Electro-Optic Performance of Liquid Crystal-Polymer Composites Doped with Ferroelectric Nanoparticles.

The presence of a polymer network and/or the addition of ferroelectric nanoparticles to a nematic liquid crystal are found to lower transition temperatures and birefringence, which indicates reduced orientational order. In addition, the electro-optic switching voltage is considerably increased when a polymer network is formed by in situ polymerization in the nematic state. However, the resulting polymer network liquid crystal switches at similar voltages as the neat liquid crystal when polymerization is performed at an elevated temperature in the isotropic state. When nanoparticle dispersions are polymerized at an applied DC voltage, the transition temperatures and switching voltages are reduced, yet they are larger than those observed for polymer network liquid crystals without nanoparticles polymerized in the isotropic phase.

Enhancing casein micelle dissociation in diluted skim milk systems using combined processing techniques

The present work aims to evaluate the dissociation of casein micelles in diluted skim milk (SM) systems after undergoing solvent- or emulsifying salt-based dissociation coupled with ultra-high-pressure homogenization (UHPH). Specifically, Part I evaluated dilute SM solutions combined with varying ethanol concentrations (0- 60%) at varying temperatures (5 - 65°C) in combination with UHPH (100-300 MPa), and Part II evaluated dilute SM solutions combined with varying concentrations (0-100 mM) of either sodium hexametaphosphate (SHMP) or sodium citrate (SC) in combination with UHPH (100-300 MPa). In Part I, high concentrations of ethanol (40-60% vol/vol) at elevated temperatures (45-65°C) achieved extensive dissociation of casein micelles, especially in combination with UHPH at ≥200 MPa, as shown by an ca. 6-fold reduction in sample absorbance and an ca. 3-fold reduction in casein particle size compared with the control (ca. dilute SM, 65°C) under optimum conditions (dilute SM, 60% ethanol, 65°C, ≥ 200 MPa). In Part II, the level of casein micelle dissociation using emulsifying salts (ES) was dependent on the ES type and concentration. Considerable casein micelle dissociation in dilute SM systems was achieved with SHMP concentrations ≥1 mM and SC concentrations ≥10 mM, resulting in decreased sample absorbance (>6-fold decrease in absorbance), bimodal casein size distributions, and increased hydrophobicity (ca. 2-fold increase in intrinsic fluorescence) compared with the control (dilute SM). This dissociation was further enhanced with UHPH (≥200 MPa). These results indicate that both solvent- and ES-based casein dissociation techniques can be optimized when used in combination with UHPH. Together, these processing techniques can be used to extensively dissociate casein micelles with the potential to use these altered systems for value-added applications such as functional ingredients or encapsulation agents.

Heteroepitaxially grown homojunction gallium oxide PN diodes using ion implantation technologies

Although advancements in n- and p-doping of gallium oxide (Ga2O3) are underway, the realization of functional pn diodes remains elusive. Here, we present the successful fabrication of a Ga2O3 pn diode utilizing ion implantation technology. The Ga2O3 epilayers were grown on c-plane sapphire substrates by metalorganic chemical vapor deposition (MOCVD). P-type conductivity Ga2O3 epilayer, confirmed by Hall effect analysis, was achieved by phosphorus (P) ion implantation followed with a rapid thermal annealing (RTA) process. This p-Ga2O3 epilayer reveals a significant reduction in resistivity (<106) compared to undoped Ga2O3, demonstrating the successful inclusion and activation of P within the crystal lattice. X-ray diffraction analysis shows that the Ga2O3 epilayers were grown in high crystal quality. Although the crystallinity of Ga2O3 was slightly degraded after P ion implantation, the structure was recovered to high-quality crystal after RTA treatment. For the device structure, p-type Ga2O3 was formed first, followed n-type Ga2O3 regrowth to create a pn junction diode. The obtained results demonstrate a built-in voltage of 4.8 V, 4.2 V, and 4.308 V from simulation, fabricated pn diodes measured by I–V and C–V, respectively. A high breakdown voltage of 900 V was also obtained for the lateral pn diode grown on sapphire substrate. As concerning temperature stability, I–V curves of Ga2O3 pn diode were measured from 25oC to 150oC in steps of 25 °C. At elevated temperatures, for both forward and reverse biases, consecutive increasing currents were measured. These could be resulted from dominant diffusion and drift currents over recombination current at a given bias. In addition, the reverse current saturated (@V > 3kT/q) and remained very low at 2✕10−8 A, as the diode operated at 150oC. The behavior could be due to Ga2O3 being a wide bandgap material.

Formation, Structure and Reactivity of a Beryllium(0) Complex with Mgδ+-Beδ- Bond Polarization.

Attempts to create a novel Mg-Be bond by reaction of [(DIPePBDI*)MgNa]2 with Be[N(SiMe3)2]2 failed; DIPePBDI*=HC[(tBu)C=N(DIPeP)]2, DIPeP=2,6-Et2C-phenyl. Even at elevated temperatures, no conversion was observed. This is likely caused by strong steric shielding of the Be center. A similar reaction with the more open Cp*BeCl gave in quantitative yield (DIPePBDI*)MgBeCp* (1). The crystal structure shows a Mg-Be bond of 2.469(4) Å. Homolytic cleavage of the Mg-Be bond requires ΔH=69.6 kcal mol-1 (cf. CpBe-BeCp 69.0 kcal mol-1 and (DIPPBDI)Mg-Mg(DIPPBDI) 55.8 kcal mol-1). Natural-Population-Analysis (NPA) shows fragment charges: (DIPePBDI*)Mg +0.27/BeCp* -0.27. The very low NPA charge on Be (+0.62) compared to Mg (+1.21) and the strongly upfield 9Be NMR signal at -23.7 ppm are in line with considerable electron density on Be and the formal oxidation state assignment of MgII-Be0. Despite this Mgδ+-Beδ- polarity, 1 is extremely thermally stable and unreactive towards H2, CO, N2, cyclohexene and carbodiimide. It reacted with benzophenone, azobenzene, phenyl acetylene, CO2 and CS2. Reaction with 1-adamantyl azide led to reductive coupling and formation of an N6-chain. The azide reagent also inserted in the Cp*-Be bond. The inertness of 1 is likely due to bulky ligands protecting the Mg-Be unit.

The dual modification of La and Zr of Ni-rich cathodes for improved cycling stability at elevated voltage and temperature

Nickel-rich layered oxides are regarded as a promising cathode material for next-generation lithium-ion batteries (LIBs) with advanced power capabilities. However, their poor cycling performance, especially under high voltage and temperature conditions, has seriously limited their large-scale application. In this work, a simple and effective strategy is proposed to enhance the structural and interface stability of Ni-rich materials by La4NiLiO8 coating and Zr doping. The interfacial side reactions and intergranular microcracks of the modified material are inhibited, which is helpful in improving the electrochemical performance. Therefore, the initial capacity of dual modification of La and Zr of Ni-rich cathode is 196.4 mA h g−1 at 4.5 V and exhibits excellent cycling performance with a capacity retention of 82.1 % after 200 cycles. Moreover, at 50 °C, the initial capacity of the modified material is 239.0 mA h g−1, and the capacity retention is 63.1 % after 100 cycles, representing a significant improvement of 94.8 % over the unmodified sample.

Replacement of Fine Aggregate with Refractory Brick Residue in Concrete Exposed to Elevated Temperatures

Replacement of Fine Aggregate with Refractory Brick Residue in Concrete Exposed to Elevated Temperatures

Heat sources for Variscan high‐temperature–low‐pressure metamorphism: Petrochronological constraints from the Trois Seigneurs massif, French Pyrenees

AbstractHigh‐temperature–low‐pressure metamorphism is commonly associated with intermediate to felsic magmatism in continental orogenic belts. The heat budgets and transfer mechanisms responsible for such elevated temperatures and partial melting of the upper crust are uncertain. The Trois Seigneurs massif, French Pyrenees, preserves a structurally continuous record of Variscan high‐temperature–low‐pressure metamorphism through a sequence of upper‐to‐mid‐crustal Paleozoic metasedimentary rocks. Conventional thermobarometry and phase equilibria calculations show that metamorphic conditions span ~2.5 kbar, 575°C to suprasolidus conditions of ~6 kbar, 700°C. Peak temperatures depend strongly on depth: temperature gradients of 50–60°C/km are present through the uppermost 12 km of the section; deeper portions (12–20 km) define restricted temperature conditions of ~650–700°C. The lowest‐grade metamorphic rocks preserve the largest spread in monazite 206Pb*/238U dates, from c. 325–285 Ma, while the spread in dates is restricted to c. 305–290 Ma in the highest‐grade rocks. Within this spread, each sample yields a well‐defined population of monazite 206Pb*/238U dates with peaks at c. 305 Ma in the andalusite schists, 295 Ma in the sillimanite schists, and 300 Ma in the migmatite sample. Monazite trace‐element compositions capture a systematic change with decreasing date and increasing metamorphic grade, including a more negative Eu‐anomaly and decreasing Sr concentrations, consistent with co‐crystallizing feldspar; increasing HREE and Y contents, consistent with xenotime breakdown; and decreasing Th/U, reflecting increasing U content during breakdown of inherited zircon. Zircon rims from a granite unit that formed via partial melting of the Paleozoic sedimentary package yields a 206Pb/238U‐207Pb/235U concordia age of 304.1 ± 3.73 Ma. These rims have trace‐element compositions reflecting cogenetic apatite and zircon growth during granite formation. Zircon from a calc‐alkaline granodiorite intrusion preserves a 40 Ma record of melt‐related activity in the lower crust that preceded the regional thermal climax. We interpret these petrochronological data to show that the Trois Seigneurs field gradient including andalusite schist and biotite granite samples represents a genuine geotherm through Variscan orogenic crust during the regional thermal climax at 305 Ma. When combined with constraints from other Pyrenean massifs, the form of the geotherm is consistent with a thermal scenario in which heat is advected to the upper crust by intermediate‐composition magmas generated in the lower crust. A simple thermal model for this process indicates that anatexis in the upper crust may plausibly occur within 10 Ma of the initiation of the lower‐crustal melting. Such a thermal scenario, however, requires focusing of melt through a fertile lower crust and an elevated Moho heat flux. We suggest that this process may have controlled the attainment of high‐temperature–low‐pressure metamorphic conditions along the Variscan belt and may currently be operating in zones of post‐orogenic continental extension.

Application and study on preparation of bio-asphalt by modified phenolic resin from corn straw tar

XPS, GPC, FT-IR, and GC–MS analyses were conducted on corn straw tar and 70# petroleum asphalt. The results indicate that the sulfur content in corn straw tar is lower than that in petroleum asphalt, potentially mitigating the volatilization of harmful substances upon substituting petroleum asphalt. This finding serves as evidence for the substantial presence of phenolic substances in corn straw tar. Upon employing the BOX-Behnken response surface analysis and utilizing resin yield as the evaluation index, the significance of three factors was established as follows: reaction time > phenol molar ratio > straw tar content. Based on the secondary multiple regression model, the optimal conditions for synthetic resin production are a phenolic mole ratio of 0.8, a reaction time of 125 min, and a straw tar dosage of 10 %. An assessment of resin viscosity at different VI temperatures reveals that corn stover tar can partially replace phenol and formaldehyde in the condensation reaction. Additionally, viscosity improvement is observed at elevated temperatures. Thermal gravimetric(TG) spectroscopy indicates lower mass loss in B-PF resin at high temperatures compared to PF resin or corn stover tar. In the evaluation of biological bitumen performance, it is discerned that the mixing amount of the prepared biological bitumen should be controlled at approximately 10 % of its performance. This ensures optimal efficacy without adversely affecting the performance of petroleum bitumen.