Binary Eutectic Phase Research Articles

The characteristics of Zn–5Al–2Mg coating on low carbon steel by two-step galvanizing method

The aim of this work is to characterize the complicated microstructure of a multilayer material that has been produced using a two-step batch galvanizing technique, with a particular focus on its extraordinary resistance to corrosion. The corrosion testing was performed using cyclic salt spraying, which involved the use of a salt mist chamber, wet chamber, and dry chamber. The results indicated that the Zn–5Al–2Mg (ZMA) coating system consists of four distinct layers: α, β, θ, and π layers. The top layer consisted of ternary and binary eutectic phases, whereas the central section had a branch-like Fe4Al13 phase. A continuous layer of Fe4Al13 was produced at an interface with the substrate. After undergoing 270 corrosion cycles, the coating demonstrated the capability to generate corrosion products that were dense and compact, including Zn5(OH)6Cl2H2O, Zn5(CO3)2(OH)6, and Mg6Al2(CO3)(OH)16⋅H2O. The corrosion products inhibited the corrosive substance from reaching the steel substrate, hence enhancing the durability of the coating.

Graphene nanoplatelets-infused binary eutectic phase change materials for enhanced thermal energy storage

Energy depletion for the thermal regulation of buildings is a major global concern. Herein, we develop a binary eutectic phase change material (EPCM) consisting of sodium sulphate decahydrate (SSD) and sodium phosphate dibasic dodecahydrate (SPDD) that were modified using borax, carboxymethyl cellulose (CMC), and graphene nanoplatelets (GNP). In the EPCM, SSD, and SPDD were blended at a proportion of 62:38 to obtain a eutectic point of 27.8 °C with a melting enthalpy of 202 J/g. Borax was a nucleating additive to lessen the issue of supercooling, CMC was a thickening agent to ensure phase stability, and GNP was added as a nanomaterial to enhance the thermal behavior of EPCM. Microtopography, chemical stability, optical transmissibility and absorptivity, phase transition characteristic, thermal conductivity, energy storage potential, degree of supercooling, and thermal stability over 200 thermal cycles were tested and determined. Using scanning electron microscopy, the GNP microstructure and its interaction with EPCM are visualized to present the dispersion and formation of the thermal network. The nanocomposite EPCM also has chemical stability, which is aided by a 571% increase in optical absorbance and an 83.8% decrease in transmissibility. With GNP as a nanomaterial, owing to the well-developed thermal network, we achieve a 106% increment in thermal conductance from 0.464 W/m⋅K to 0.956 W/m⋅K; likewise, GNP acts as a conducting binder and enhances the intermolecular interaction leading to an increase in melting enthalpy from 202.4 J/g to 226 J/g. Finally, a numerical simulation of EPCM heating a thermic fluid flowing within a concentric tube with focus on the temperature contour is conducted for elaborating the potential of PCM towards TES systems.

Binary eutectic phase change materials application in cooling asphalt: An assessment for thermal stability and durability

Organic eutectic phase change materials (PCM) show great promise as thermal storage agents for regulating the temperature of asphalt pavements. Assessing their aging characteristics and durability when integrated into asphalt is crucial and necessitates further in-depth research. This study evaluates the impact of aging on binders with acid/palmitic acid binary eutectic PCM (SA/PA-PCM). Aging was simulated using the rolling thin film oven (RTFO) and pressure aging vessel (PAV) devices. The current study leads to the conclusion that the use of SA/PA-PCM is promising. Specifically, the incorporation of SA/PA-PCM significantly improves the aging resistance, showcasing notable enhancements in thermal stability, fatigue performance, anti-cracking ability, and thermal regulation of asphalt. Only a 5 % decrease occurred in the melting enthalpy of the binder with 15 % SA/PA-PCM after 60 h of long-term aging (from 32.17 to 25.87 J/g), showing a stable thermal storage ability. The maximum temperature difference and lag is 9.3 °C and 46 min. respectively. To sum up, Asphalt with 15 % SA/PA-PCM surpasses other binders, displaying higher melting latent heat, reduced sulfoxide index, increased long-term aging resistance, and superior stress relaxation capabilities. This research confirms the potential of SA/PA-PCM in asphalt applications, providing a new path for durable and environmentally friendly road infrastructure.

Composition design and crystallization behavior of Zr–Cu–Ni–Al bulk metallic glasses

The Zr–Cu–Ni–Al system was explored in this study, and seven new compositions of Zr-based bulk metallic glasses (BMGs) were designed by combining different proportions of binary eutectic phases Zr38Cu62, Zr76Ni24 and Zr51Al49, and rod-like shape samples were prepared with different diameters using the copper mold casting method. Modifying the proportion coefficient of these eutectic units, the width of the supercooled liquid region was increased from 79 to 95 K, and the thermal stability of the prepared metallic glass was improved. Differential scanning calorimetry was used to investigate the non-isothermal and isothermal crystallization behavior of the prepared samples. Noticeably, there was a small low-temperature exothermic peak before the glass transition temperature Tg in the non-isothermal crystallization process, which was related to the structural relaxation. The crystallization transition activation energy fitted by the Kissinger equation had the same variation trend as that obtained by the Arrhenius equation. Among the four metallic glasses studied, the glassy phase of Zr55·5Cu23·25Ni9Al12.25 was more stable, showing higher glass transition activation energy and longer incubation time. In addition, the isothermal crystallization processes of four metallic glasses were studied according to the Johnson-Mehl-Avrami (JMA) model. The calculated average Avrami exponents were >2.5, indicating that the nucleation rate increased during the isothermal crystallization process.

Impact of cooling rates on the microstructure and cracking susceptibility of hot-dip galvanized Zn-12 wt% Al-5 wt% Mg coatings

Zinc-Aluminum-Magnesium (ZnAlMg) alloy coatings, applied through the hot-dip galvanizing process, are renowned for their superior corrosion resistance. This study investigated how different cooling rates affect the microstructure and cracking tendency of Zn-12Al-5Mg (in wt%) coatings. It was found that faster cooling rates lead to a more refined microstructure with primary MgZn2 grains but also increase the likelihood of cracking. This is primarily attributed to the finer distribution of primary MgZn2 grains and ternary eutectic (Zn/MgZn2/Al) regions, which allows micro-cracks originating from hard and brittle MgZn2 grains to easily propagate through the surrounding eutectic regions and develop into macro-cracks. Notably, we observed an epitaxial relationship between the primary and binary eutectic MgZn2 phases, shedding light on their crystallographic orientation and morphology. Additionally, our investigation revealed that cracking susceptibility depends on the crystallographic orientation of MgZn2 grains relative to the tensile axis. Fiber-like MgZn2 grains tend to crack along their basal planes, while hexagonal grains crack along other crystallographic planes. This insight into cracking behavior is crucial for designing ZnAlMg coatings with enhanced corrosion resistance and mechanical integrity. Overall, while faster cooling rates refine the microstructure, they can also increase the susceptibility to cracking in ZnAlMg coatings with Mg contents exceeding 3 wt%, emphasizing the need for a balanced approach in optimizing coating properties for different applications.

Reduced Graphene Oxide/Cellulose Sodium Aerogel-Supported Eutectic Phase Change Material Gel Demonstrating Superior Energy Conversion and Storage Capacity toward High-Performance Personal Thermal Management.

By virtue of their capacity to absorb and release energy during the phase change process, phase change materials (PCMs) are ideal for personal thermal management (PTM). The combination of reduced graphene oxide/cellulose sodium aerogel (rGCA) and lauric acid/myristic acid binary eutectic phase change gel (LMG) creates a composite phase change material that possesses outstanding photothermal conversion capabilities, electro-thermal conversion capabilities, energy storage capabilities, and shape-stable performance. The results showed that rGCA had a maximum adsorption efficiency of 99.7% with a melting latent heat of 124.6 J g-1. The high absorption rate of rGCA to LMG is a result of the capillary force, pore characteristics, hydrogen bonding, and the π-π interaction. Notably, rGCA and LMG composite material (rGCG) exhibited an excellent photothermal conversion efficiency of 96.5% and electro-thermal conversion of 82.3%. Results indicate that binary eutectic phase change materials are more suitable for temperature regulation than single phase change materials, making them more suitable for PTM. It is anticipated that the innovative thermal comfort solution, which provides thermal shielding, thermal energy storage, self-supporting characteristics, and wearability, will offer new possibilities for the next generation of wearable PTMs.

Thermophysical properties and rapid solidification mechanism of liquid Zr<sub>60</sub>Ni<sub>25</sub>Al<sub>15</sub> alloy under electrostatic levitation condition

In this study, the thermophysical properties and rapid solidification mechanism of highly undercooled liquid Zr<sub>60</sub>Ni<sub>25</sub>Al<sub>15</sub> alloy are investigated through the electrostatic levitation technique. The maximum undercooling of this alloy reaches 316 K (0.25<i>T</i><sub>L</sub>). Both density and surface tension display a linear relationship with temperature, while viscosity is related to temperature exponentially. When alloy undercooling is less than 259 K, two significant recalescence events are observed during solidification, corresponding to the formation of pseudobinary (Zr<sub>6</sub>Al<sub>2</sub>Ni + Zr<sub>5</sub>Ni<sub>4</sub>Al) eutectic and ternary (Zr<sub>6</sub>Al<sub>2</sub>Ni + Zr<sub>5</sub>Ni<sub>4</sub>Al + Zr<sub>2</sub>Ni) eutectic. The growth velocity of the binary eutectic phase gradually increases with further undercooling and reaches a maximum undercooling value of 259 K. In contrast, once undercooling exceeds 259 K, a single recalescence event occurs, leading to the independent nucleation of all three compound phases from alloy melt and the rapid growth of a ternary anomalous eutectic structure. Notably, the growth velocity of the ternary eutectic phase exhibits a gradual decline with further undercooling. This diminishing trend of the growth velocity suggests that further undercooling might entirely suppress crystal growth dynamically at a threshold of 385 K. With classical nucleation theory and the Kolmogorov-Johnson-Mehl-Avrami (KJMA) model, the onsets of crystallization for the three phases are calculated, thereby constructing a time–temperature-transformation (TTT) diagram. This diagram elucidates the competitive nucleation among the three phases in the undercooled melt. Both theoretical and experimental evidence reveal that Zr<sub>6</sub>Al<sub>2</sub>Ni phase is primarily nucleated at lower undercooling levels, whereas under higher cooling condition, it is possible for all three phases to nucleate simultaneously.

Effect of Al/Mg Ratio on the Microstructure and Phase Distribution of Zn-Al-Mg Coatings

In contrast with studies such as those on the effect of a single elemental variable on Zn-Al-Mg coatings, Mg/Al is considered a variable parameter for evaluating the microstructure of Zn-Al-Mg coatings in this work, and the combined effect of the two elements is also taken into account. The Mg/Al ratios in the continuous hot-dip plating of low-alumina Zn-Al-Mg coatings were 0.63, 0.75, 1.00, 1.25, and 1.63. respectively, and the microstructures of the different coatings were observed using scanning electron microscopy (SEM). The surface elemental distributions of the coatings were analyzed with energy dispersive spectrometry (EDS) and X-ray diffraction (XRD) analysis to understand the phase distributions of the coatings, which mainly consisted of a zinc monomeric phase, a binary eutectic phase (Zn/MgZn2), and a ternary eutectic phase (Zn/Al/MgZn2). Statistical calculations of the phase distributions in colored SEM images were performed using ImageJ-win64 software, comparative analysis of the solidification simulation results was carried out with thermodynamic simulation software (PANDAT-2023), and evaluation of the corrosion resistance of the platings was performed using macroscopic cyclic immersion corrosion experiments. The results show that with the increase in the Mg/Al ratio, the binary eutectic phase in the coatings gradually increased, the variation trend of the ternary eutectic phase was not obvious, and the corrosion resistance of the coatings gradually improved.

Expanded graphite intersperse reliable binary eutectic phase change material for low temperature thermal regulation systems

Inorganic phase change materials (PCMs) frequently stuck by ineffaceable thermal conductivity and degree of supercooling for thermal energy storage (TES) accomplishment. The present research work is dedicated to resolve this problem by developing a unique inorganic salt hydrate based binary eutectic PCM employing sodium sulphate decahydrate (SSD) and sodium phosphate dibasic dodecahydrate (SPDD) in eutectic mixture ratio 62:38 mass percentage. The peculiar eutectic composition of SSD/SPDD developed with melting and bath sonication technique manifests eutectic latent heat of 207.4 J/g and eutectic melting point of 27.8 °C. Furthermore, to elevate thermal performance and to descent degree of supercooling three dimension expanded graphite (EG) is interspersed as nanoparticle. Optical absorbance of composite PCM elevated from 0.16 for SSD/SPDD to 0.92 with SSD/SPDD + EG nanoparticles; inversely transmissibility of the composite reduced by 82.13 %. Heat flow curves ensures the melting temperature (26.9 °C–28.7 °C) of EG dispersed composite to be within the operating condition with latent heat of 220.4 J/g at 2.0 % of EG owing to the intermolecular binding force of attraction increases as nano-sized sheets effectively disperse with the base PCM. Subsequently, thermal conductance of nano composite eutectic PCM upraised from 0.453 to 0.855 W/m⋅K. After 200 thermal cycle's chemical optical and thermal stability of the PCM composite was degraded insubstantially due to the presence of impurities with longer service; this affirmed the stability thermal perks of nanocomposite PCM. Numerical analysis on heat transfer propagation of heat source within SSD/SPDD PCM layer with and without EG nanoparticle provides inference on the importance of thermal conductivity.

2D MXene based nanocomposites for solar driven renewable energy storage utilizing binary eutectic phase change material

In this study, we incorporated eutectic phase change materials (EUPCM) into MXene nanopowder to strengthen the thermal properties of EUPCM. Here, Ti3C2 MXene was synthesized from Ti3AlC2 MAX phases via mild chemical etching using microwave and doped at concentrations ranging from 0.2 % to 1 % into binary eutectic of PEG 6000 and PEG10000. The FESEM validated the existence of adequate pores in the MXene structure and DLS revealed that approximately 66 % of the measured nanoparticles had a size of 218 nm. The FTIR and XRD investigations affirmed that the interaction between EUPCM and MXene was predominantly physical in nature. Differential scanning calorimetry (DSC) analysis revealed fusion enthalpies ranging from 163.5 J/g to 159.3 J/g and freezing enthalpies varying from 155.1 J/g to 146.2 J/g for the nanocomposites, keeping melting and freezing temperature. The incorporation of MXene resulted in a consistent decrease in time required for heating and cooling of EUPCM. Furthermore, the nanocomposites exhibited durability as demonstrated by thermal cycling tests, with no significant variation in the chemical structure and only slight fluctuations in the enthalpies after 500 melt/freeze cycles. Consequently, MXene-based nanocomposites display relatively high heat transfer rates compared to EUPCM for the same amount of solar radiation and present promising prospects for integration into solar energy storage systems.

The Effect of Microstructure on Local Corrosion Product Formation during Initial SO2-Induced Atmospheric Corrosion of ZnAlMg Coating Studied by FTIR-ATR FPA Chemical Imaging

The initial atmospheric corrosion of ZM (ZnAlMg)-coated steel in humid air (85% RH) and humid argon (85% RH) containing 320 ppb SO2 was studied using in situ infrared reflection absorption spectroscopy (IRRAS), FTIR-ATR focal plane array (FPA) imaging and SEM-EDS. The corrosion products formed in humid air containing SO2 are mainly composed of magnesium sulphites and sulphates, with sulphite-containing corrosion products formed initially while the contribution from sulphates increased with exposure time. The results from FTIR-FPA imaging and SEM-EDS showed that the magnesium sulphite and sulphate are formed mainly on eutectic phases with a higher quantity of corrosion products formed on the binary eutectic (Zn-MgZn2) phases. This is due to presence of microgalvanic elements with the zinc-rich phases as the main sites for the cathodic oxygen reduction while the anodic reactions take place on the eutectic areas. Sulphate content is the highest on the binary eutectic phases, due to the microgalvanic effects and the production of oxidants by the cathodic reaction, which increases the oxidation of sulphite to sulphate.

Experimental evaluation of binary and ternary eutectic phase change material for sustainable thermal energy storage

Phase change materials (PCMs) are the active source for storing thermal energy in the form of latent heat. Inorganic salt hydrate based PCMs are regarded as high energy storage materials with high thermal conductivity and low flammability compared to organic PCM, whereas the major hindrances are supercooling and corrosivity which reduces service life. This encourages examining and developing new forms for inorganic-inorganic eutectic PCM with a focus on melting point and enthalpy. In this article we design, develop, and characterize, low temperature inorganic salt hydrate eutectic PCMs, using calcium chloride hexahydrate, sodium carbonate decahydrate, sodium sulphate decahydrate and sodium phosphate dibasic dodecahydrate. Schrader equations along with the thermophysical property of salt hydrates were adopted to determine eutectic phase transition temperature and eutectic mixtures proportions. Twenty-one different combination of PCMs mixture were numerically evaluated, out of which seven eutectic mixtures with a melting temperature between 21 and 28 °C (four binary and three ternary), were experimentally synthesised and characterized. Melting point, heating enthalpy, specific heat capacity and degree of supercooling of the pure salt hydrates and their eutectic mixtures were analysed using differential scanning calorimeter. The melting enthalpy of eutectic PCMs, were 200–215 J/g; furthermore, the degree of supercooling reduces by 10–13 °C for eutectic PCMs when compared to pure PCMs. The numerical values were supplemented with experimental results and ensured the suitability of the developed eutectic PCM for low temperature energy storage application with a focus towards building cooling.

Microencapsulated binary eutectic phase change materials with high energy storage capabilities for asphalt binders

Octanoic acid (OA) and tetradecane (TD) underwent mixing and the eutectic method to improve the energy storage capacities of phase change materials (PCMs) that were reduced by microencapsulation. A microencapsulated phase change material (MPCM) was synthesized by using nano-TiO2 and polyvinyl alcohol reinforced melamine formaldehyde resin as the wall and wrapping materials of OA–TD. The chemical composition, morphological structure, thermal properties, and thermal stability of the MPCM were analyzed. Additionally, the effects of microcapsules on asphalt properties and the ability to regulate asphalt temperature were investigated. The results showed that neither eutectic nor microencapsulated encapsulation produced new characteristic peaks. The MPCMs were transparent spheres with particle sizes of 1–50 μm and good formability. Compared with OA and TD, the enthalpy values of the exothermic phase transition process of OA–TD increased by 67.6% and 10.7%, respectively, and the phase transition temperature ranges increased by 53.5% and 26.7%, respectively. The exothermic enthalpy of the formed MPCM is 140.61 J/g, which provides latent heat and good thermal stability when mixed with asphalt. Temperature regulation tests demonstrated that MPCM effectively reduced the cooling rate and peak temperature of asphalt. The addition of MPCM to asphalt resulted in a decrease in penetration and ductility, but an increase in softening point. At high temperatures, MPCM enhanced the apparent viscosity, composite modulus, and rutting factor of asphalt, thereby improving its high-temperature deformation resistance.

Binary decanoic acid/polyethylene glycol as a novel phase change material for thermal energy storage: Eutectic behaviors and energy conservation evaluation

This work developed a novel decanoic acid/polyethylene glycol binary eutectic (DA-PEG) phase change material (PCM) for thermal energy storage, wherein the mass ratio of DA and PEG was 1:1. DSC results indicated that DA-PEG eutectic had a suitable phase transition temperature of 22.9 °C for building thermal comfort, and its latent heat of 173.9 J/g was relatively large. Moreover, DA-PEG eutectic PCM had a superior crystallinity as compared to pure PEG, which was confirmed by the results in terms of supercooling degree, relative exothermic capacity and crystallization kinetics. ATR-FTIR and Raman spectra were used to reveal the mechanism behind. It turned out that the improved crystallization behaviors of PEG were achieved by the promoting effect of the intermolecular hydrogen bonding between DA and PEG on the ordered arrangement of PEG long chain. Furthermore, DA-PEG eutectic PCM presented good thermal and chemical stability in long-term use. Besides, energy and environmental assessment suggested that DA-PEG eutectic exhibited high cost performance and great potentials for energy conservation and emission reduction used in solar passive building.

Preparation and characterization of binary eutectic phase change material laden with thermal conductivity enhancer for cooling steel slag asphalt pavement

The active asphalt pavement cooling strategy using phase change material (PCM) is crucial for mitigating urban heat island impacts and reducing high-temperature rutting distress. However, most PCM-incorporated pavements use single pure PCM for temperature regulation, resulting in either a discrepancy between phase change temperature and pavement rutting sensitive temperature or a low phase change enthalpy. Moreover, their unacceptable low thermal conductivity can dramatically lower the PCM thermal performance in cooing asphalt pavements. This study aimed to develop a novel PCM-incorporated cooling asphalt pavement, which consists of a binary eutectic mixture of fatty acid PCMs (palmitic acid (PA) and stearic acid (SA)), a supporting material (waste steel slag aggregate (SSA)), and a thermal conductivity enhancer (TCE, Nano Al2O3). The PCM composite of PA-SA was screened out first based on a binary eutectic system. The composite phase change steel slag aggregate (CPC-SSA) and the TCE-based CPC-SSA asphalt mixture were then designed and developed with three types of TCEs. The performance tests were finally conducted to examine the thermal and rutting resistance performance of the PCM-incorporated asphalt pavement. The test results showed that the pavement incorporated with the PCM composite of PA-SA and Nano Al2O3 is capable of effectively cooling asphalt pavement and alleviating its high-temperature rutting distress. The findings of this study are expected to promote sustainable resource utilization and cooling strategies developed for the mitigation of high pavement temperature distresses and urban heat island impacts.

Development of palmitic acid-lauryl alcohol as binary eutectic for cold thermal energy storage in buildings indoor thermal comfort application - Thermophysical studies and discharging characteristics

There has been a steep increase in cooling energy requirements in recent years owing to the growing demand for thermal comfort in buildings. Electric peak demand required to meet thermal comfort could be curtailed by integrating the Latent Heat Thermal Energy Storage (LHTES) system with conventional systems, resulting in lower greenhouse gas emissions and savings of precious fossil fuels. This paper focuses on the development of binary eutectic Phase Change Material (PCM) and property analysis to determine its compactness for indoor thermal comfort building applications. The investigated eutectic PCM comprises Palmitic acid (PA) –Lauryl alcohol (LA) in the composition 10:90 and the material is a viable system fitting the intended application. By DSC analysis, the phase transition temperature and latent heat of the eutectic PCM are discovered to be 20.25°C and 155.59 Jg−1, respectively. The present study involves various thermophysical studies including corrosion test, thermogravimetric test, thermal conductivity, FTIR analysis, and automated thermal cycling test to evaluate the long-term feasibility of the TES system. The study pays special attention to the corrosiveness of the developed PA-LA eutectic PCM confirming that stainless steel-316 and aluminium are recommended as ideal materials for the fabrication of heat exchangers with longer life. Further, the experimental discharging characteristic of the developed PCM carried out in a high-performance Vapour Absorption Refrigeration (VAR) chamber highlights the robustness of the developed material in terms of prolonged cooling retrieval duration. The developed system will elevate energy efficiency and curb the cooling energy demand when it is coupled with a conventional cooling system.

Experimental study of screening polyols and their binary eutectic phase change materials for long-term thermal energy storage

Polyols are appealing long-term thermal energy storage materials due to their severe supercooling properties and high energy density. However, spontaneous crystallization during storage and slow crystallization during crystallization hinder their reliability and applicability. In this article, two single polyols (xylitol and sorbitol) and nine binary eutectic mixtures, prepared by a method based on Gibbs excess energy, were screened as long-term thermal energy storage phase change materials. The results conclusively demonstrated that xylitol and its binary eutectic mixtures (xylitol + inositol, xylitol + mannitol, and xylitol + dulitol, with a 150 g bulk scale) could be stored at room temperature in isolation from the air for more than 300 days without any crystallization. However, other samples either transformed into a glassy state (xylitol + sorbitol and sorbitol + erythritol) or crystallized (sorbitol, xylitol + erythritol, sorbitol + inositol, sorbitol + mannitol, and sorbitol + dulcitol). The exothermic performance test showed that three additives (xylitol particles, ethanol, and acetone) could effectively trigger the crystallization of xylitol and its binary eutectic mixtures after reheating to an appropriate temperature before or after storage. This process excludes sorbitol and its binary eutectic mixtures. Simultaneously, the exothermic performance test also indicated that xylitol, xylitol + erythritol, xylitol + inositol, xylitol + mannitol, and xylitol + dulcitol had attractive crystallization heat (164.71, 165.56, 130.58, 145.56, and 147.89 kJ/kg), high maximum crystallization temperatures (84.94, 73.75, 83.85, 83.52, and 83.13 °C), short times to reach maximum crystallization temperatures (186, 477, 204, 198, and 183 s), and satisfactory energy efficiency (57.77%, 56.68%, 51.01%, 54.52%, and 54.84%). After 300 days of storage, the crystallization heat of the supercooled samples decreased by merely 4.377%, 3.358%, 4.511%, 4.314%, and 6.309%. Finally, 30 cyclic tests were conducted on newly prepared xylitol and xylitol + erythritol. The pair exhibited relatively stable crystallization heat (145.60–175.64 kJ/kg and 134.52–169.97 kJ/kg, respectively) and high maximum crystallization temperature (82.8–88.1 °C and 72.3–76.2 °C, respectively).

Effects of Al-Mg on the Microstructure and Phase Distribution of Zn-Al-Mg Coatings

In this work, the composition of the zinc–aluminum–magnesium alloy coating was designed to have a fixed aluminum–magnesium ratio of 1:1, while the content of aluminum and magnesium elements increases gradually within the range of 1–2 wt.%. The micro-morphology of the coating with different compositions was observed by a scanning electron microscope (SEM). Combined with the surface distribution results of energy dispersive spectrometer (EDS) analysis elements and the phase analysis results of diffraction of X-rays (XRD), the phase distribution of the coating is understood. The statistical calculation of the phase distribution was carried out after staining the SEM image by ImageJ, This is consistent with the solidification simulation results of the thermodynamic simulation software (PADAT). The influence of magnesium and aluminum elements on the microscopic morphology and phase distribution of the zinc–aluminum–magnesium (ZnAlMg) coating was studied, and the mechanism of action was analyzed. The results show that the volume ratio of binary eutectic phase (Zn/MgZn2) and ternary eutectic phase (Zn/Al/MgZn2) in the coating tends to increase as the contents of the two elements elevate. The quantity of MgZn2 is the critical factor for the corrosion resistance of the coating; the more MgZn2, the better the corrosion resistance.

Preparation and application of low-temperature binary eutectic lauric acid-stearic acidSiO2 phase change microcapsules

Most phase change materials developed in current research have high phase change temperatures, making them challenging to use in buildings. To solve this problem, the microencapsulated phase change materials (MPCMs) with low eutectic temperature were prepared by interfacial polymerization using binary eutectic of lauric acid (LA) and stearic acid (SA) as the core material and silica as the shell material. And the phosphogypsum-based phase change microcapsules (PG-MPCM) were prepared. Morphology, structure and thermal properties of microcapsules have been investigated. The differential scanning calorimetry (DSC) results indicate that the melting and freezing temperatures of MPCMs prepared under optimal conditions are 27.9 °C and 28.3 °C, and the latent heats of melting and freezing are 170.3 J/g and 155.7 J/g. The thermogravimetry (TG) analysis results confirm that the microcapsules have good thermal stability. There is no significant change in the latent heat of the microcapsules phase change after 300 melting/freezing cycling. The heat storage performance shows that PG-MPCMs have good heat energy storage capacity and temperature regulation ability. In general, the LA-SA/SiO2 microcapsule is suitable as the energy storage material for buildings.

Preparation and characterisation of binary eutectic phase change material/activated porous bio char/multi walled carbon nano tubes as composite phase change material

The primary purpose of the current work is to develop, fabricate, and characterise a novel composite phase change material for the medium temperature thermal energy storage systems. The proposed composite PCM is made up of a binary eutectic PCM (LiNO3 + NaCl), a supporting material (activated bio char), and thermal conductivity-improving particles (i.e., multi walled carbon nano tubes). XRD, FTIR, and SEM-EDS analysis was used to determine the chemical stability of the composite PCM samples. Using differential scanning calorimetry (DSC), the thermophysical parameters of the composite PCM samples, such as phase transition temperature and latent heat value, are evaluated. With the addition of activated biochar (A-BC) and multiwalled carbon nano tube (MWCNT) particles, the latent heat value of PCM is reduced, and the thermal conductivity enhancement value is increased to 116.11%. The findings demonstrate that employing A-BC and MWCNT nanoparticles ensures the stability of the eutectic chloride and prevents leak. The corrosion rate of the copper, aluminium, stainless steel, and Inconel 617 were determined by immersing it in pure PCM and composite PCM for 12 weeks. The metal specimens that were inserted in the composite PCM were found to have good corrosion stability.