Solution Temperature Research Articles

Influences of solution temperature on microstructures and performance of electron beam welded joints of laser powder bed fusion TC11 thin-walled samples

The effects of subtransus treatment (750 °C, 800 °C, 850 °C, 900 °C, and 950 °C) as well as supertransus treatment (1100 °C) on the microstructures and mechanical performance of electron beam welded (EBW) joints of laser powder bed fusion (LPBF) TC11 alloy were investigated. At a solution temperature of 950 °C, globular α phases and transformed β phases were observed in the joint. When the solution temperature exceeded the β transus temperature (Tβ), α colonies and massive α phases emerged in the joints, resulting in Widmanstatten structures. The base metal (BM) exhibited the highest microhardness, followed by the heat affected zone (HAZ), whereas the fusion zone (FZ) demonstrated the lowest microhardness. As the solution temperature increases, the microhardness of joints decreases at first and then increases. Notably, the joint subjected to a solution temperature of 850 °C exhibited the lowest microhardness. When the solution temperature was ≥900 °C, transformed β phases emerged within the joints, resulting in an elevation of microhardness. Below Tβ, the elongation of welded joints gradually augmented while the tensile strength reduced at first and then increased with the rising solution temperature. Microstructures in joint with solution temperature of 950 °C consisted of lamellar α phases, globular α phases, and transformed β phases. As a result, the joint exhibited an optimal balance between strength (1103.1 ± 34.9 MPa) and plasticity (9.37 ± 0.20%). Ductile fracture characteristics with dimples on the fracture surface were observed in the tensile samples. Therefore, it can be concluded that a solid solution temperature of 950 °C is optimal for LPBF TC11 alloy.

Effect of solution temperature on the microstructure and properties of ceramic coating on the surface of 2024 aluminum alloy

This study investigates the influence of the 2024 aluminum alloy was treated with solution before ceramic treatment on the microstructure and characteristics of ceramic coatings applied to 2024 aluminum alloy substrates. The microhardness, corrosion resistance, and microstructural properties of these ceramic coatings were assessed using a microhardness tester, an electrochemical workstation, and a scanning electron microscope. The findings indicate that pre-treatment involving solution treatment significantly enhances the hardness and corrosion resistance of 2024 aluminum alloy ceramic coatings. Notably, when the solution temperature was maintained at 460 °C, the most rapid decrease in current density was observed during the ceramization process, resulting in the attainment of the lowest final stable current density. This particular condition yielded ceramic coatings with optimal hardness and corrosion resistance, with hardness exhibiting a remarkable increase of 48.9 HV, self-corrosion potential rising by 0.207 V, and polarization resistance surging by 5310.7 Ω. Moreover, the surface of the ceramic coating displayed remarkable smoothness and was devoid of discernible defects such as cracks or looseness. In light of these findings, it can be concluded that the optimum solution temperature for achieving these desirable properties is 460 °C. This conclusion is derived from a comprehensive analysis encompassing both the morphology and corrosion resistance of ceramic coatings.

Sustainable Zn2+ removal using highly efficient, novel, and cost-effective chitosan-magnetic biochar composite.

This study focused on the development of a sustainable and low-cost adsorbent derived from the chitosan-biochar composite for the removal of Zn2+ from an aqueous solution. Biochar was prepared from cotton stalk residue by pyrolysis at 600°C for 2h, modified with FeCl3, and composed with chitosan in various ratios (1:3, 1:1, 3:1), leading to the formation of an efficient, thermally stable, and rich with functional groups chitosan-biochar composite denoted as CHB-Fe-CS. Functional groups (hydroxyl, carboxyl, and amine) were identified as key contributors to the adsorption mechanism. Langmuir isotherm (R2 = 0.99) and Pseudo-Second order (R2 = 0.99) were best fitted models with the experimental results indicating chemisorption-driven monolayer adsorption. The results revealed CHB-Fe-CS (3:1) composite obtained the highest adsorption capacity of 117.50mg/g for Zn2+ under optimal conditions viz., 180min batch time, 500mg/l metal concentration, 4g/l adsorbent dosage, 40°C solution temperature, and 5.0 pH. Regeneration of the used adsorbent was performed using 0.2mol/l HCl and obtained desorption efficiency of 67.48% and 51.48% after the 4th and 8th cycles. The adsorption mechanisms were dominated by ion exchange, surface complexation, and electrostatic attraction compared to intra-particle diffusion and physisorption. The CHB-Fe-CS demonstrated an economical, environment friendly, and good performing adsorbent for water decontamination.

On-demand catalysed n-doping of organic semiconductors.

A new approach to control the n-doping reaction of organic semiconductors is reported using surface-functionalized gold nanoparticles (f-AuNPs) with alkylthiols acting as the catalyst only upon mild thermal activation. To demonstrate the versatility of this methodology, the reaction of the n-type dopant precursor N-DMBI-H with several molecular and polymeric semiconductors at different temperatures with/without f-AuNPs, vis-à-vis the unfunctionalized catalyst AuNPs, was investigated by spectroscopic, morphological, charge transport, and kinetic measurements as well as, computationally, the thermodynamic of catalyst activation. The combined experimental and theoretical data demonstrate that f-AuNPs is inactive at room temperature both in solution and in the solid state, catalyst activation occurs rapidly at mild temperatures (~ 70 °C) and the doping reaction completes in few seconds affording large electrical conductivities (~ 10 - 140 S cm-1). The implementation of this methodology enables the use of semiconductor+dopant+catalyst solutions, will broaden the use of the corresponding n-doped films in opto-electronic devices such as thin-film transistors, electrochemical transistors, solar cells, and thermoelectrics well as guide the design of new catalysts.

Preparation and performance evaluation of intelligent plugging agent for thermo‐sensitive water‐based drilling fluid

AbstractIn the process of unconventional oil and gas exploitation, the invasion of a large amount of drilling fluid into the formation is one of the most critical reasons leading to wellbore instability. A temperature‐sensitive polymer (AOS) was synthesized from acrylamide, oligo (ethylene glycol) methyl ether methacrylate (OEGMA), and sodium p‐styrene sulfonate by emulsion polymerization. The material is a solid‐free fluid with good fluidity at room temperature, after injection into the formation, the fluid is gradually transformed into hard gel above the lower critical solution temperature (LCST) (90°C), thus blocking micro‐fractures and improving wellbore stability. Infrared and NMR characterization confirmed the successful preparation of the target product. The transmittance of AOS with ambient temperature was measured by UV–vis spectrophotometer, and the LCST behavior of AOS was verified by rheological and viscoelastic measurements. The interaction mechanism between AOS and sodium bentonite was evaluated according to the American Petroleum Institute standard. The results show that after aging at 180°C, the filtration loss is reduced by 93%, and the medium permeability (100, 200 mD) formation is effectively plugged, with a plugging efficiency is as high as 74.7%.

Investigation on work hardening rate of Al-Zn-Mg-Cu alloy under solid solution process and thermomechanical coupled multi-step fast aging process

In this paper, the work hardening rate of Al-Zn-Mg-Cu alloy in the conditions of solid solution and thermo-mechanical coupled fast aging were investigated separately, and the main research content and results are as follows. Under the solid solution processes at different temperatures, the uniaxial tensile test curves of work hardening rate are relatively dispersed at a lower strain rate, and the work hardening rate increases with the increase of solution temperature. Then, as the strain rate increasing, the work hardening rate curves at each solution temperature gradually converge, until all curves intersect at a common intersection point. The above mechanism is attributed to the comprehensive effect of precipitates, solid solutions, and dynamic strain aging in the matrix. For the thermo-mechanical coupled aging, the work hardening rate has a great different with that of solid solution process. Consequently, the influence of pre-deformation on the work hardening rate were investigated, which concludes the curve shape type and the softening coefficient. The introduction of dislocation have some significant influences on the work hardening rate. Firstly, it makes the shape of work hardening rate curves change from shape 1 to shape 2. On the other hand, as the pre-deformation increasing, the variation law of softening coefficient shows an abnormal trend that is different from the ordinary law, which is due to the coordinated effect between dislocation density and dislocation induced precipitation. Furthermore, in order to reveal the internal mechanism in depth, the microstructure are observed by TEM (Transmission electron microscope). Finally, a targeted set of analytical models for work hardening rate were established, especially the mathematical explanation of the multicollinearity phenomenon of work hardening rate curves in the solid solution condition.

Synthesis of novel stimuli-responsive hydrogels based on polyurethane

This article describes the study of a thermo-responsive hybrid systems based on polyurethane (PU) modified with sensitive acrylamide derivates. The hybrid systems were synthesized using PU and two acrylamide derivatives (N-isopropylacrylamide (NIPA) and N-isopropylmethacrylamide (NIPMA)) in different proportions. The systems were characterized using infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dynamic light scattering (DLS). Water-uptake capacity and sedimentation rate were also determined. The results showed that the hybrids with 30% acrylamide derivate (AD) showed a T50 of approximately 360 °C indicating that thermal degradation decreased with the addition of NIPA and NIPMA. Additionally, the incorporation of AD increases the glass transition temperature from −34 to −22 °C when 30% AD was used. The hybrids with 30% AD showed a variation in the diameters (above 60%) when the temperature was decreased from 50 to 22 °C. These changes were attributed to the hydrophilic → hydrophobic transition that occurs when measuring below and above the low critical solution temperature (LCST) of the polymer. Furthermore, the extra methyl group in the structure of NIPMA makes the collapse less pronounced than in NIPA, decreasing the relative diameter change by 10%. Sedimentation tests showed that the addition of the hybrid hydrogels in the sand increased the time of decantation by 60%. So, the combination of two thermo-responsive polymers to alter the hydrophilic/hydrophobic balance allows these polymers to modify their conformation at a specific temperature and could be potentially useful as self-suspending support agents or drug delivery systems.

Ion‐Mediated Gelation of Thermo‐Responsive Cellulose Nanofibril/Poly(N‐isopropylacrylamide) Hybrid Hydrogels with Tunable De‐Swelling Kinetics

AbstractThe tunability of the lower critical solution temperature (LCST) of poly(N‐isopropylacrylamide) (PNIPAM) to lower or higher temperatures, as well as the ease of modulation of the LCST phase transition kinetics broadens the scope of application of PNIPAM‐based materials in biomedical fields. This work reports a facile approach to formulate a smart, injectable cellulose nanofibril (CNF)/PNIPAM hybrid gel. Hofmeister salts are used to induce ion‐mediated gelation of the nanofibrils and PNIPAM chains, resulting in an interpenetrating network (IPN) structure. From rheological measurements, the hybrid material displays excellent structural integrity at room temperature and tunable thermo‐stiffening around body temperature. De‐swelling kinetics can be modulated by varying the nature and concentration of the Hofmeister ion used. The successful realization of the IPN hybrid gel structure is dependent on the molecular weight of PNIPAM used. Moreover, the hybrid gels show good thermo‐reversibility during thermal cycling, as well as excellent injectability and remarkable self‐healing post‐injection, owing to shear‐thinning and thixotropic characters. Since rheology is a crucial technique in the analysis of soft matter and flow behavior is fundamental for the design and synthesis of application‐specific viscoelastic materials, the work reported herein provides a rheological basis for careful design and synthesis of smart gels.

Lipidation alters the phase-separation of resilin-like polypeptides.

Biology exploits biomacromolecular phase separation to form condensates, known as membraneless organelles. Despite significant advancements in deciphering sequence determinants for phase separation, modulating these features in vivo remains challenging. A promising approach inspired by biology is to use post-translational modifications (PTMs)-to modulate the amino acid physicochemistry instead of altering protein sequences-to control the formation and characteristics of condensates. However, despite the identification of more than 300 types of PTMs, the detailed understanding of how they influence the formation and material properties of protein condensates remains incomplete. In this study, we investigated how modification with myristoyl lipid alters the formation and characteristics of the resilin-like polypeptide (RLP) condensates, a prototypical disordered protein with upper critical solution temperature (UCST) phase behaviour. Using turbidimetry, dynamic light scattering, confocal and electron microscopy, we demonstrated that lipidation-in synergy with the sequence of the lipidation site-significantly influences RLPs' thermodynamic propensity for phase separation and their condensate properties. Molecular simulations suggested these effects result from an expanded hydrophobic region created by the interaction between the lipid and lipidation site rather than changes in peptide rigidity. These findings emphasize the role of "sequence context" in modifying the properties of PTMs, suggesting that variations in lipidation sequences could be strategically used to fine-tune the effect of these motifs. Our study advances understanding of lipidation's impact on UCST phase behaviour, relevant to proteins critical in biological processes and diseases, and opens avenues for designing lipidated resilins for biomedical applications like heat-mediated drug elution.

Reverse mode LCPG films with self-assembly support of gel networks

ABSTRACT Liquid crystal physical gels (LCPG) with a 3D network structure show considerable promise as novel functional materials with a great impact on scientific and practical applications. LCPGs are not characterised by high hardness and high strength, but this mild nature is capable of forming dynamic supramolecular structures with the self-assembly ability of various non-covalent bonds such as hydrogen bonding, π-π stacking, and van der Waals forces. In addition to anisotropic changes under optical and electrical stimulation, it enables to be one of the candidates for display devices. When the isotropic-anisotropic transition temperature of LCPG solution (TIA) is higher than the sol-gel transition temperature of gel molecules (TSG), the gelation can anchor the orientation of liquid crystal molecules to achieve the alteration of transparency and scattering of the film. In this paper, reverse mode LCPG films with high contrast, low driving voltage, and excellent cycle life were prepared using oriented liquid crystal cassettes and LCPG solutions, it also focused on the effects of chiral compounds (S)-octan-2-yl 4-((4-(hexyloxy)benzoyl)oxy)benzoate (S811) and gel 1,3:2,4-bis-0-(3,4-dimethylbenzylidene)sorbitol (DMDBS) content on electro-optical properties of LCPG films as well as the different functions of TIA and TSG on film orientation.

Optimizing Nickel Electroplating in Low-Ni Environments for Efficient Source Production in Small Plating Baths

Electroplating nickel-63, a radioactive isotope used in betavoltaic batteries and random number generators, requires precise control due to its limited availability and the generation of radioactive waste. To minimize waste and ensure effective plating, small plating baths are employed, optimizing the process within constrained conditions. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) were utilized to determine the optimal plating conditions and limiting conditions for nickel electroplating in a small plating bath. This study focuses on the use of low-concentration nickel solutions and small plating equipment, in contrast to the common industrial practice of using high concentrations of nickel. Here, it is important to optimize the plating parameters, especially the nickel concentration, current density, and bath temperature. An average thickness of 1.8 μm was found when plating with a nickel concentration of 0.06 M, a current density of 5 mA/cm2, and a solution temperature of 40 °C, while ideal conditions were found to achieve the theoretical maximum energy and 90% release rate when plating with nickel-63 instead of Ni.

Design and development of shape memory polyurethane coated fabric with excellent memory performance

AbstractIn this study, we investigate the fabrication of ambient room temperature responsive shape memory polyurethane (SMPU)‐coated fabric using a simple dip coating method, aiming to enhance the shape memory response of smart textiles. Two SMPU were synthesized using different chain extender 1,4 butanediol (BDO‐SMPU) and polyethylenimine (PEI‐SMPU). Critical parameters such as SMPU concentration, dwell time, and coating solution temperature are optimized to ensure exceptional shape memory performance while also maintaining the fabric's handle, comfort, and durability. We determined that PEI‐SMPU/Cotton fabric exhibits superior memory performance, with a 90.2% shape recovery at a 1% PEI‐SMPU concentration. Conversely, BDO‐SMPU fabric demonstrated a 75.8% shape recovery under different conditions (10% SMPU concentration, 50°C solution temperature). Furthermore, shape recovery is influenced by programming temperature and load; at 35°C and 10 N load, PEI‐SMPU/Cotton significantly outperforms BDO‐SMPU/Cotton, showing about 20% improvement in shape recovery. This study indicates that modifying SMPU from BDO‐SMPU to PEI‐SMPU can notably enhance shape recovery performance at 35°C, marking a significant advancement in human body temperature responsive smart fabric technology.

Investigation of conjugate heat and mass transfer in a sleeve-type hollow fiber membrane for liquid desiccant dehumidification

In adiabatic conditions, the dehumidification capacity of hollow fibre membranes decreases as solution temperature rises. To address this limitation, this study proposed a novel approach based on sleeve-type hollow fibre membranes. The study focused on three distinct fluid streams and the sleeve-type hollow fibre membrane tube. A three-dimensional model of the dehumidifier was created, and the dehumidifier's heat transfer, mass transfer, and fluid flow characteristics were thoroughly analyzed and experimentally validated. The results showed that the average values of the Sherwood number and Nusselt number on the air side are significantly influenced by the Reynolds number. On the solution side of the sleeve-type hollow membrane, the average Nusselt number and Sherwood number are approximately 4.0 and 4.6, respectively. According to the research, 76 % of the resistance is accounted for by the mass transfer resistance on the membrane side. The study's conclusions provide insightful information for improving the design of sleeve-type hollow fibre membrane dehumidifiers.

Cartilage-Inspired, High-Strength, and Heat-Tolerant Lubricating Hydrogels by Macrophase Separation.

Hydrogels are considered as a potential cartilage replacement material based on their structure being similar to natural cartilage, which are of great significance in repairing cartilage defects. However, it is difficult for the existing hydrogels to combine the high load bearing and low friction properties (37 °C) of cartilage through sample methods. Herein, we report a facile and new fabrication strategy to construct the PNIPAm/EYL hydrogel by using the macrophase separation of supersaturated N-isopropylacrylamide (NIPAm) monomer solution to promote the formation of liposomes from egg yolk lecithin (EYL) and asymmetric template method. The PNIPAm/EYL hydrogels possess a relatively high compressive strength (more than 12 MPa), fracture energy (9820 J/m2), good fatigue resistance, lubricating properties, and excellent biocompatibility. Compared with the PNIPAm hydrogel, the friction coefficient (COF 0.046) of PNIPAm/EYL hydrogel is reduced by 50%. More importantly, the COF (0.056) of PNIPAm/EYL hydrogel above lower critical solution temperature (LCST) does not increase significantly, exhibiting heat-tolerant lubricity. The finite element analysis further proves that PNIPAm/EYL hydrogel can effectively disperse the applied stress and dissipate energy under load conditions. This work not only provides new insights for the design of high-strength lubricating hydrogels but also lays a foundation for the treatment of cartilage injury as a substitute material.

Poly(N-isopropylacrylamide)-based hydrogel carrier containing Prussian blue for thermally controlled release

A hydrogel consisted of poly(N-isopropylacrylamide-co-acrylic acid) (PNIPAAm-co-AA) and Prussian blue (PB) was synthesized for a cargo carrier by controlling the release of organic dye under near infrared (NIR) light. The AA moiety of the hydrogel provided chemical bonding with Fe (III) ions for further PB formation. Biocompatible, NIR-responsive PB generated heat and the heat was transferred to the hydrogel. The NIPAAm moiety in the hydrogel was shrunken because of the low critical solution temperature behavior of the hydrogel, and the hydrogel released the loaded dye with 62%. These results suggest dye-loaded hydrogel as a prospective platform for light-triggered carriers.

Effect of a novel metal-free green synthesis catalyst on the positive role of microwave irradiation in hydrogen production from the hydrolysis of sodium borohydride

This study demonstrates the synthesis of hydrochar, a high-value material, from watermelon seed husk, a low-value waste material, using the hydrothermal synthesis method. The microwave power effect plays an important role in the use of metal-free and environmentally friendly catalysts for the hydrolysis of sodium borohydride. The XRD, BET, SEM, and FTIR analyses characterized the catalyst. X-ray diffraction revealed the catalyst structure to be cellulosic. The surface area and total pore volume were 1.063 m2/g and 0.0195 cm3/g, respectively, in BET analysis. According to the IUPAC classification, the catalyst conformed to the type III isotherm. This study investigated how good the catalyst for the hydrolysis of sodium borohydride was when it was exposed to microwave irradiation at different microwave powers, solution temperatures, and catalyst amounts. The Langmuir-Hinshelwood and nth-order kinetic models calculated the activation energies to be 82.192 and 83.35 kJ/mol, respectively. The use of bio-waste hydrochar as a catalyst in the hydrolysis of sodium borohydride in the microwave environment shows promising results in the search for metal-free catalysts.

Effect of precursor solution temperature on the morphology and electrochemical performance of electrodeposited MnO2 nanofilms for lithium-ion batteries

ABSTRACT This study investigated the impact of precursor solution temperature on the electrodeposition of MnO2 material, which were prepared on a nickel substrate using the electrodeposition method under varying precursor solution temperatures of 25°C, 40°C, 50°C, and 60°C, respectively. These materials were subsequently employed as anodes in lithium-ion batteries to study their electrochemical performance. The results indicate that an increase in temperature induces preferential aggregation and growth of MnO2 nanosheets towards specific orientations, which is advantageous for enhancing the electrochemical performance of MnO2 electrode materials. Notably, the electrode material prepared at a solution temperature of 50°C exhibited optimal performance. Additionally, the charge transfer impedance was lower, which could be attributed to the growth of the highly conductive β-MnO2 main phase under 50°C. This study presents a novel approach for effectively improving electrodeposited nanomaterials, offering insights into the optimisation of electrochemical performance.

Material corrosion characteristics of heat-treated SLM-ed Hastelloy X in electrochemical machining process

Selective laser melting (SLM) technology and electrochemical machining (ECM) offer new methods for producing nickel-based superalloys with complex structures and high surface quality, including Hastelloy X parts. However, SLM-fabricated parts exhibit significant anisotropy, and there are no effective criteria for evaluating material corrosion characteristics in actual ECM due to the detachment of research and application, making the parameter selection challenging in actual ECM. To address this issue, this article proposes a comprehensive evaluation system based on the corrosion characteristics in the actual machining process and investigates the effect of heat treatment temperature on the corrosion characteristics of Hastelloy X in ECM. The results show that at a heat treatment temperature of 1000°C, machining efficiency, accuracy, and localization can all be achieved at a good level with good consistency in different directions at the expense of a certain machining accuracy. The 800℃ heat-treated specimen exhibits strong corrosion resistance, providing a significant advantage in machining localization and accuracy. When the heat treatment temperature exceeds the solid solution temperature (more than 1175℃), the mechanical properties and corrosion characteristics of the specimen are significantly degraded. The results of various material testing methods, including electrochemical testing, EBSD, XRD, and EDS indicate that changes in grain size due to recrystallization and the galvanic effect of precipitates are the primary causes of these changes.

The overlooked reaction of H2O2 decomposition over carbonaceous cathodes

Electrochemical 2-electron oxygen reduction over carbon cathode is an important method to produce H2O2 in situ. Besides the H2O2 generation rate, the H2O2 decomposition rate is also crucial to the cumulative concentration of H2O2. It is generally believed that H2O2 decomposition will produce H2O and O2 by electro-reduction or carbon catalysis. Herein, a new H2O2 decomposition pathway is proved: carbonaceous materials may react with H2O2 spontaneously to release CO2 and CO at room temperature and atmospheric pressure. At low H2O2 concentrations, the reaction produced CO mainly and then CO2. But at high H2O2 concentrations, CO2 was a preponderant product over CO. The reaction was exothermal which causes the rise of solution temperature, promoting H2O2 decomposition to produce O2. The continuous decomposition of H2O2 raised the pH value, while the generated CO2 dissolved in the solution to reduce the pH value. These two effects together determined pH tendency. With the increase of pH value, H2O2 decomposition triggered by alkaline conditions produced H2O and O2. The applied negative voltage accelerated H2O2 decomposition via reacting with charcoal. Furthermore, this reaction showed universality to carbonaceous materials. The above results are of great value for understanding the decomposition mechanism of H2O2 and setting a reasonable target for cumulative H2O2 concentration via electrochemical oxygen reduction.

Effect of Temperature and NaClO on the Corrosion Behavior of Copper in Synthetic Tap Water

The corrosion behavior of copper was investigated in synthetic tap water with and without sodium hypochlorite (NaClO) at different temperatures during immersion for 70 d by using scanning electron microscopy (SEM), X-ray diffraction (XRD), and electrochemical measurement techniques. The weight loss corrosion rate and pit depth of copper first increase and then decrease with the change in solution temperature from 25 to 80 °C. This is mainly related to the corrosion products formed on the copper surface. The main corrosion products change from Cu2O and Cu2(OH)2CO3 to CuO with the increase in solution temperature. The presence of 3 ppm NaClO slightly increases the weight loss corrosion rate and pit depth of copper under all temperatures except for 50 °C and reduces the temperature of the maximum corrosion rate from 50 to 40 °C. Free chlorine reduction accelerates the cathodic reaction of the corrosion process.