Melting Temperature Of Materials Research Articles

Parametric analysis of system performance and cost of heating systems with heat pump and latent thermal energy storage

This paper presents a parametric analysis examining the impact of phase change material (PCM) melting temperature, latent thermal energy storage (LTES) volume, and solar collectors’ surface area on the performance and costs of heating systems integrating a heat pump and LTES by using dynamic system simulations. The computational models, implemented in TRNSYS software, and the numerical procedure were validated by comparing the numerical results with experimental measurements. The computational models represent the entire heating systems and thus consider the mutual interaction of heat production, distribution and automatic regulation system as well as a building which represent the heat load, in transient boundary conditions. Two main system designs with different LTES roles were considered – a system in which the role of the LTES is to provide more favorable operating conditions and a system in which the LTES role is to store the heat on a sufficiently high temperature to be used directly for heating. System performance was analyzed in terms of the share of renewable energy in total delivered energy, power consumption, stored energy in LTES, seasonal performance factor, average solar collector efficiency and total annual costs. The results showed that, regarding the system in which LTES was used as a heat source for the heat pump, a better overall performance and lower costs were observed in systems with PCMs with melting temperatures in range between 19 and 29 °C, compared to systems with PCMs with melting temperatures outside this range. For system in which the heat from the LTES was used directly for heating, the highest values of system performance criteria and the lowest cost were achieved with the PCM of 54 °C melting temperature. Almost all of the considered system performance criteria and total costs were higher when the LTES volume and solar collector surface area were larger as well.

A Method for Predicting the Melting Temperature of Ionic Compounds.

Predicting the melting temperature of materials has always been a topic of great concern. This article proposes an alternative model for determining the melting temperature of materials based on the main idea of the Lindemann melting criterion combined with the first-principles calculations of density functional theory. To verify the accuracy of the melting model, this article selected typical ionic crystals of MgO and 10 alkali metal halides as the validation objects. The calculation results indicate that the melting temperature of the MgO crystals and I-VII compounds is in good agreement with the experimental results.

Effect of Potassium Feldspar Sodium-feldspar Composite Flux on The Sintering Performance of Fly Ash-coal Gangue-phosphogypsum Based Wall Insulation Materials

In this paper, fly ash and coal gangue as the main raw materials, potassium feldspar-albite as the composite flux, phosphogypsum as the bonding agent, the semi-melting method was used to prepare fly ash-coal gangue-phosphogypsum based wall insulation material, the effect of composite flux ratio and the amount of coal gangue added on the melting temperature of wall insulation material was studied. Through the visual of high-temperature deformation analyzer to observe the volume contraction, expansion, passivation, and globalization of different formulations of specimens at high temperatures, and record the corresponding temperatures of the occurrence of various situations, to study the composite flux ratio and gangue addition on the fly ash-gangue-phosphogypsum based wall insulation material melting temperature of the impact, to determine the appropriate ratio of the flux and the gangue addition for the solid waste-based will provide a theoretical basis for the preparation of solid waste-based wall insulation materials. The research results indicate that with the increase of coal gangue content, the initial melting temperature, spheroidization temperature, and passivation temperature of the sample all sharply decrease. With the increase of potassium feldspar: albite, the melting temperature range will significantly increase. When the additional amount of fly ash is 50%, the additional amount of coal gangue is 12%, the additional amount of phosphogypsum is 5%, and the ratio of potassium feldspar to albite is 1:1, the sintering temperature of the fly ash- gangue -phosphogypsum based wall insulation material is the lowest.

(Invited) Poly(lactic acid)-Nanodiamond Composites for Electroanalytical Applications

There has been an exponential increase in the popularity of 3D printing technology in the last few years, also in everyday life. Numerous applications are reported for poly(lactic acid) (PLA) based polymer composites with various conductive carbon fillers for electrochemical needs, such as sensors, batteries, water remediation, etc. The bulk of these reports is based on commercially available 3D printing filaments, with carbon black, graphene or carbon nanotubes as fillers. Regardless of good conductivity, these materials possess characteristics that are suboptimal for electrochemical applications, including charge transfer kinetics, stability to oxidation, electrolytic window, etc.3D printouts offer versatility in terms of ease of cheap and on-demand fabrication of free-standing multielectrode setups e.g. by dual-extruder printing. However, to fully embrace their advantages enhancement of charge transfer kinetics by removing an excess of PLA and uncovering the nanofillers, is needed. Recently we have demonstrated laser ablation for locally sculptured effective modification of the electrochemical response of these materials.There is a great focus on the development of new conductive filaments that exhibit better mechanical, electric, thermal, and electrochemical properties. We have evaluated for the first time various forms of conductive nanodiamonds (ND), i.e. detonation nanodiamonds and diamond-phase rich boron-doped carbon nanowalls, as fillers for PLA-based composites for 3D printing. The goal of the research was to investigate and thoroughly understand the interactions between composite components and those that affect the mechanical parameters and electrochemical characteristics of printed elements, studying how ND addition to PLA matrix affects material strength, rheology, and melting temperature. In particular, the enhancement of electrode kinetics and electrochemically available surface area by ND was revealed and discussed. The authors acknowledge the financial support by The National Science Centre (Republic of Poland) SONATA BIS 2020/38/E/ST8/00409.

Optimal design of lithium ion battery thermal management systems based on phase change material at high current and high environmental temperature

The market of electric storage systems is widely dominated by Lithium ion batteries, whose peculiarity is the need for a thermal management system, whose proper design is complicated by the interaction. among different design and operating parameters. A specific methodology for carrying out the task is still lacking. In this context, the present paper proposes a systematic framework for the design of passive and hybrid thermal management systems (TMSs) of Li-ion batteries. Thermal tests were carried out on Lithium-Titanate-Oxide cells under realistic operating conditions in a controlled environment to characterize the electrical and thermal behaviour. A thermofluid dynamics model of the battery was implemented in COMSOL Multiphysics. The experimentally validated model was used to evaluate the influence of different design and operating parameters (ambient temperature, charge/discharge current, phase change material thickness and melting temperature) using the Taguchi method (orthogonal arrays), and discussing inter-related effects of the studied parameters via interaction plots. Air temperature (45 °C) and/or discharge current (69–92 A) were identified as critical operating conditions beyond which thermal runaway issues occur. Starting from the optimal design conditions for a passive TMS, the same methodology was used to assess a hybrid PCM-liquid cooling system as an alternative configuration. The results indicate that, compared to the baseline case of natural cooling, the optimal designs of standalone PCM and hybrid cooling system led to a reduction in maximum cell temperature of 11 and 22 °C, respectively, showing the high potential of these TMSs.

Termoplastik Malzemelerin Neden Olduğu 3B Baskı Hatalarını Ortadan Kaldırmak İçin Gerçek Zamanlı Bir Takip Sistemi Tasarımı

Material-related printing errors are frequently encountered in 3D printers based on the Fused Filament Fabrication (FFF) technology. When the materials used are investigated, materials such as PLA, ABS, and Nylon are generally preferred at affordable prices. However, printing problems may occur due to the mechanical characteristics difference between the materials. Among the main reasons for this are parameters such as material characters, melting temperature, and extrusion speed. These errors cause problems such as filament breaking, nozzle clogging, and filament falling out of the holder. As a result, the filament flow is interrupted, and the printing process continues without extrusion of the filament because the 3D printer cannot detect this flow. 3D printers on the market do not have a system to detect possible printing errors. Therefore, in this study, a system design measures the filament weight via a load sensor and informs the user has been performed. 3D printers could stop the printing process since they can detect possible errors in advance with the developed system and prevent electricity consumption and time loss. In addition, the amount of used and remaining filaments, which are not yet common in 3D printers, can be followed by the user.

Optimization of the Reduction of Shrinkage and Warpage for Plastic Parts in the Injection Molding Process by Extended Adaptive Weighted Summation Method.

The consumer market has changed drastically in recent times. Consumers are becoming more demanding, and many companies are competing to be market leaders. Therefore, companies must reduce rejects and minimize their operating costs. One problem that arises in producing plastic parts is controlling deformation, mainly in the form of shrinkage due to the material and warpage associated with the geometry of the parts. This work presents a novel extended adaptive weighted sum method (EAAWSM: Extended Adaptive Weighted Summation Method) integrated into a Pareto front model. The performance of this model is evaluated against three other conventional optimization methods-Taguchi-Gray (TG), Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS), and Model Optimization by Genetic Algorithm (MOGA)-and compared with EAAWSM. Two response variables and three input factors are considered to be analyzed: material melting temperature, mold temperature, and filling time. Subsequently, the performance is compared and its behavior observed using Moldflow® simulation. The results show that with the EAAWSM method, the shrinkage is 15.75% and the warpage is 3.847 mm, regarding the manufacturing process parameters of a plastic part. This proposed deterministic model is easy to use to optimize two or more output variables, and its results are straightforward and reliable.

Thermal and Mechanical Characterization of Coir Fibre–Reinforced Polypropylene Biocomposites

In recent years, the growth of environmental awareness has increased the interest in the development of biocomposites which are sustainable materials with an excellent price–performance ratio and low weight. The current study aimed to obtain and characterize the biocomposites prepared by thermoforming using coir fibres as reinforcing material and polypropylene as matrix. The biocomposites were produced with different coir fibres/polypropylene ratios and were characterized by physical–mechanical indices, thermal analysis, crystallinity, attenuated total reflection-Fourier transform infrared spectroscopy analysis (ATR-FTIR), scanning electron microscopy (SEM), and chromatic measurements. Both tensile and bending strength of biocomposites decreased when the coir fibre content increased. The melting temperature of biocomposite materials has decreased with the increase of the coir fibre loading. Regarding the thermal stability, the weight loss and degradation temperature increased with decreasing coir fibre content. The ATR-FTIR and SEM analyses underlined the modifications that took place in the structure of the biocomposites by modifying the coir fibres/matrix ratio.

Experimental and numerical investigation of jet performance based on Johnson-Cook model of liner material

A comparative study of the shaped jets of six liner materials, namely, copper, Cu–Zn alloy, Steel1006, high nitrogen steel, and two titanium alloys, was conducted to investigate the influence of the macroscopic mechanical properties of the materials on the jet's performance. The X-ray experiment of the jet was performed, and the numerical calculation of the jet formation was carried out by means of simulation based on the Johnson–Cook model. Copper, Cu–Zn alloy, and Steel1006 formed cohesive jets, whereas the jets of the three other materials had different degrees of radial dispersion. The penetration depth of the jet has a significant negative correlation with its radial dispersion degree. In the numerical calculation, the head shape of the jet under the Euler algorithm can be used to judge its cohesion. Arrowheads or rounded oval heads symbolize cohesive jets, whereas blunt or even mouth-forward “bowl-shaped” heads indicate jets with radial dispersion. The degree of dispersion is positively correlated with the degree of dullness of the jet head. Simulation results show that the influence of material melting temperature and thermal softening effect on jet velocity, length, and diameter is particularly evident, whereas the influence ability of yield strength and strain rate effect is always at a very low level. Materials with small shear modulus, high yield strength, and significant strain effects are more prone to forming non-cohesive jets, which was verified by the jet forming experiments of amorphous alloy with these material characteristics.

(Digital Presentation) Electrothermal Modeling of Interfacial Phase Change Memory

Phase change memory (PCM) is a high-speed non-volatile memory that utilizes the reversible and fast transition between highly conductive crystalline phase and highly resistive (dielectric) amorphous phase of the phase change material to store information and the large electrical resistivity contrast between the two phases for retrieval of the stored data [1,2]. One of the main challenges for PCM is the large power required to heat the active region above crystallization or melting temperature. Lower energy and higher speed operations have been demonstrated with thin film superlattice stacks of phase change materials known as interfacial phase change memory (iPCM) [3-6]. The mechanisms behind the improved performance of iPCM are still under investigation but recent work indicates similar crystallization and melt-quench operation of these devices [5].In this work, we perform electrothermal finite element simulations of reset and set operations on iPCM structures consisting of alternately stacked Ge2Sb2Te5 (GST) and GeTe layers using COMSOL multiphysics [7-10]. Electrical pulses are applied for reset and set processes utilizing an internal circuit model where a transistor is used as an access device. Coupled electric current and heat transfer physics are employed to incorporate Joule heating and thermoelectric effects (Thomson heat within a single material and Peltier heat at material interfaces) with temperature dependent Seebeck coefficients, thermal conductivities, electrical resistivities, heat capacities and thermal boundary resistances (TBR) for each material / material pairs. Latent heat of fusion is included in the amorphous-crystalline and solid-liquid transitions [10], giving rise to heat release at the crystal-amorphous boundaries during crystal growth and heat absorption at the grain boundaries during amorphization. Grain boundaries and material interfaces have high energy sites, making them easier to melt, described as heterogeneous melting [10].iPCM [5] structures utilize engineered interfaces formed between nanometer scale thin-film stacks, promoting amorphization through increased number of material interfaces and reduced thermal conduction due to TBR. Furthermore, the melting temperature, electrical conductivity and Seebeck coefficient of the different materials within an iPCM device differ. Hence, such layered structures may have the advantage of melting of only one of the alternating layers assisted by local heating or cooling due to Peltier effect at the interfaces.Our results on iPCM and conventional PCM structures of same dimensions and geometry (20 nm wide, 150 nm high pore-cells) show ~ 50% reduction in reset times and more consistent set times for iPCM cells due to lesser variations in grain sizes and location of boundaries.Acknowledgment: This work is partially supported by the National Science Foundation under award DMR-1710468.

Design of a thermoelectric generator-assisted energy harvesting block considering melting temperature of phase change materials

Smart sensors in buildings require independent power supplies to measure the built environment data. To supply electricity to these smart sensors, an enhanced concept of a thermoelectric generator-assisted energy harvesting block was established in this study. An energy block comprising thermoelectric generators and phase change materials can convert the heat flux through building exteriors into electricity during the day and at night. The objective of this study was to derive appropriate phase change material design conditions to maximize the power generation performance of the energy harvesting block. Three energy harvesting blocks—case 1, case 2, and case 3—were constructed with phase change materials having melting temperatures of 26 °C, 38 °C, and 47 °C, respectively. Experiments were conducted to emulate solar radiation with the average so-air temperature profiles of 12 months, while the temperatures and open-circuit voltages were measured. Of the three cases, case 1 exhibited the largest generated energy under 12 sol-air temperature profiles. In addition, case 1 showed a 46.5% and 66.5% larger approximated annual generated energy than case 2 and case 3, respectively. The phase change material with a melting temperature of 26 °C in the energy harvesting block was appropriate for maximizing power generation under the temperature conditions of Seoul, South Korea.

Determination of the Efficiency of Hot Nano-Grinding of Mono-Crystalline Fcc Metals Using Molecular Dynamics Method.

Abrasive processes are essential to the manufacturing field, due to their capability of rendering high-quality surfaces with minimum effect on workpiece integrity. As it is especially difficult to perform sufficient experimental work, numerical studies can be successfully employed to evaluate techniques for the improvement of the efficiency of nanometric abrasive processes. In the present study, for the first time, cases of nanogrinding on workpieces of three different fcc metals, namely, copper, nickel, and aluminum are investigated under different preheating temperatures, in order to determine the efficiency of the hot nano-grinding technique. For the simulations, a molecular dynamics model for peripheral nanogrinding is developed including multiple abrasive grains and realistic grain trajectory and grinding forces, and chip characteristics and subsurface alterations are evaluated. The results indicate that using elevated preheating temperatures is beneficial for nanogrinding, as forces can be considerably reduced and material removal can be facilitated, especially for temperatures over 40% of the material melting temperature (Tm). However, the detrimental effect on workpiece integrity is also evident at higher preheating temperatures, due to the high temperature on the whole workpiece, posing limitations to the applicability of the hot nano-grinding technique. Based on the findings of this study, preheating temperatures in the range of 0.4–0.55 Tm are recommended.

Understanding softening of amorphous materials for FFF applications

Abstract The work explores the fundamentals of the softening process for amorphous materials expanding on the work presented by Stammers and Beek (Stammers, E. and Beek, W.J. (1969). The melting of a polymer on a hot surface. Polym. Eng. Sci. 9). The pressure induced melt removal process was studied in detail. The process, although fundamental, allows for an understanding of the phase transition of materials during the fused filament fabrication (FFF) process. Experimental results were analyzed using state-of-the-art equipment. A total of four materials were tested. PVC and PC are amorphous materials, and PA6 and PP are semi-crystalline materials. A setup was built to allow the application of a constant force. The resulting melt film was analyzed using computed tomography technology. The experimental results were compared with numerical simulation results originating from COMSOL Multiphysics and the analytical solution derived by Stammers and Beek. Rheological and thermo-mechanical tests were used to find the softening temperature of amorphous materials. Results showed a straightforward transition for the melting temperature of semi-crystalline materials and softening temperature of amorphous materials. It is suggested that for amorphous materials, the glass transition temperature can be used as the softening temperature (T s = T g ). When comparing all three results (experimental, analytical, and numerical), values are within the same range and magnitude. A good approximation was achieved for PA6 and PVC, which have semi-crystalline and amorphous structures, respectively. Results provide insights into the phase transition process and phase change mechanisms during the extrusion of materials in the fused filament fabrication process.

Study of the effect of nano ZrO2 and TiO2 and rotation speed on friction behavior of rotary friction welding of HIPS and PP

The purpose of this project was to introduce a way to improve the mechanical properties of dissimilar welded material, which provides benefits such as affordability, high speed, and a suitable bond property. This experimental project applies the friction welding method, including combining parameters, such as a numerical control machine, two different speeds, and three different cross sections, including flat, cone, and step surfaces. When the welding process was done, samples were implemented and prepared via a bending test of materials. The results have shown that, besides increasing the machining velocity, the surface friction increased, and so did the temperature. Considering the stated experimental facts, the melting temperature of composite materials increased. This provides the possibility of having a better blend of nanomaterial compared to the base melted plastics. Thus, the result showed that, besides increasing the weight percentage of nanomaterial contents and machining velocity, the mechanical properties increased on the welded area for all three types of samples. This enhancement is due to the better melting process on the welded area with the attendance of various nanoparticle contents. Also, the results showed that the shape of the welding area could play a significant role, and the results also change drastically where the shape changes. Optimum shape in the welding process has been dedicated to the step surface. The temperature causes the melting process, which is a significant factor in the friction welding process.

Friction stir welding and friction stir spot welding of polymethyl methacrylate (PMMA) to other materials: A review

Polymers are widely used in packaging and automobile industries because of their desirable properties such as lightweight, transparency, strength to weight ratio, good hardness and stiffness, low water absorption, ultraviolet rays' protection. Keeping Polymethyl methacrylate (PMMA) polymer in focus, this review research is being done here to collect the literature available best of our knowledge on the joining of PMMA to PMMA/Polymers/ Metal alloys by Friction stir welding/ Friction stir spot welding (FSW/FSSW). Friction stir welding is a solid-state joining process in which the temperature remains below the material's melting temperature. This friction stir welding technique is widely applied on materials that are difficult to weld by fusion welding, such as aluminium alloys, titanium alloys, and polymers. Friction stir welding is an ecological weld method and environmentally friendly as it does not produce harmful radiation toxic gases, requires less energy, produces less waste than conventional fusion welding processes. It was found out that by applying Friction stir welding/ Friction stir spot welding technique, the Polymethyl methacrylate can be welded to itself, to polymers, and metal alloys. In this review, efforts are made to point out the optimum level of process parameters of FSW concluded by researchers in their studies of PMMA joining. For each study, its parameter range and the optimum value of process parameters are presented in the form of tables and graphs, and explanations and discussions are made to better understand welding Polymethyl methacrylate polymer by Friction stir welding process.

No seamount subduction, no magmatic arc?

Water is essential for the formation of a magmatic arc by lowering the melting temperature of materials in the mantle wedge. As such, it is logical to attribute the absence of a magmatic arc to insufficient water released from the subducting plate, although a number of other factors may cause volcanic arc quiescence as well, such as a slab window or flat slab subduction. In this contribution, we present a possible but testable correlation between the occurrence of a magmatic arc and seamount subduction in light of bathymetric data obtained near trenches. This correlation, if it holds true, in turn means that a magmatic arc is unlikely to occur when the subducting slabs have not been severely fractured and that one of the main reasons for excluding effects such as the slab window or flat slab subduction may be that the plate is not accompanied by seamounts. Therefore, the role that seamount subduction plays in recycling water back into the mantle deserves more attention from the earth sciences community.

Single-Crystal Nanostructure Arrays Forming Epitaxially through Thermomechanical Nanomolding.

For nanostructures in advanced electronic and plasmonic systems, a single-crystal structure with controlled orientation is essential. However, the fabrication of such devices has remained challenging, as current nanofabrication methods often suffer from either polycrystalline growth or the difficulty of integrating single crystals with substrates in desired orientations and locations to create functional devices. Here we report a thermomechanical method for the controlled growth of single-crystal nanowire arrays, which enables the simultaneous synthesis, alignment, and patterning of nanowires. Within such diffusion-based thermomechanical nanomolding (TMNM), the substrate material diffuses into nanosized cavities under an applied pressure gradient at a molding temperature of ∼0.4 times the material's melting temperature. Vertically grown face-centered cubic (fcc) nanowires with the [110] direction in an epitaxial relationship with the (110) substrate are demonstrated. The ability to control the crystal structure through the substrate takes TMNM a major step further, potentially allowing all fcc and body-centered cubic (bcc) materials to be integrated as single crystals into devices.

Equation-of-state and melting curve of solid neon and argon up to 100 GPa

Equation-of-state and melting curve of neon and argon solids at high pressure are investigated based on the statistical moment method taking into account the anharmonicity contributions of thermal lattice vibrations. We have derived the analytical expression of equation-of-state and proposed a procedure to calculate melting temperature of materials at high pressure. We perform numerical calculations for neon and argon solids up to 100 GPa by using the Buckingham function (exp-6) to model the interaction between atoms. Our theoretical calculations reveal the strong dependence of the lattice constant and melting temperature on pressure of rare-gas solids, in particular at below 10 GPa. The derived equation-of-states of neon and argon go along with earlier experiments up to pressure 100 GPa. The present argon melting curve is in good agreement with previous measurements up to pressure 80 GPa. Our melting line of neon can reproduce well melting data points using W absorbers with thickness 8 μm and 6–8 μm up to pressure nearly 80 GPa, and differs from the measurements using W absorbers with thickness 4–6 μm.

Parsimonious neural networks learn interpretable physical laws

Machine learning is playing an increasing role in the physical sciences and significant progress has been made towards embedding domain knowledge into models. Less explored is its use to discover interpretable physical laws from data. We propose parsimonious neural networks (PNNs) that combine neural networks with evolutionary optimization to find models that balance accuracy with parsimony. The power and versatility of the approach is demonstrated by developing models for classical mechanics and to predict the melting temperature of materials from fundamental properties. In the first example, the resulting PNNs are easily interpretable as Newton’s second law, expressed as a non-trivial time integrator that exhibits time-reversibility and conserves energy, where the parsimony is critical to extract underlying symmetries from the data. In the second case, the PNNs not only find the celebrated Lindemann melting law, but also new relationships that outperform it in the pareto sense of parsimony vs. accuracy.

Material migration in W and Mo during bubble growth and fuzz formation

Growth of helium (He) induced bubbles and fuzz in tungsten (W) and molybdenum (Mo) is investigated using samples of W films on Mo substrates and Mo films on W substrates exposed to He-containing plasma in the temperature range of 340 to 1075 K, fluence range of 1.0–14 × 1025 He·m−2, and incident ion energy of <50 eV. No fuzz (only up to 2 nm diameter bubbles) and no material transport occur in W films at ⩽750 K, while precursors-of or fully-developed fuzz and material mixing occur in W and Mo films at ⩾800 K. This suggests that fuzz forms in multi-material systems as long as one material meets the conditions for fuzz formation, namely T s/T m ∼ 0.27–0.5 where T s and T m are the sample exposure and material melting temperatures, respectively. Larger He bubbles, more material mixing, and further-developed fuzz occur at higher temperature due to increased mobility of He atoms and small He clusters. Accumulation of substrate material at the surface of fuzzy W and Mo thin-film (<80 nm) samples suggests fuzz growth by material transport from the bubble layer in the bulk up to the fiber tip, likely by a two-step process: (i) diffusion of punched dislocation loops in the bulk toward the fuzz base and (ii) diffusion of adatoms along the fuzz base and fiber surface (with effective transport of adatoms upwards due to trapping of adatoms at curved surfaces of fiber tips and/or due to the continuous generation of adatoms at the fuzz base). While the bubble size and fuzz thickness increase with reduced W concentration in Mo thin-film samples at 838 K likely due to an increase in trap mutation and dislocation loop punching in Mo compared to W, the fuzz thickness decreases with reduced W concentration at 1075 K despite an increase in the bubble size likely due to slower diffusion of interstitial loops in Mo.