Fast Melting Research Articles

Microstructure evolution and properties of 7075 aluminum alloy recycled from scrap aircraft aluminum alloys

A large quantity of scrap aircraft aluminum alloys in retired aircraft was used to produce cast aluminum alloys as raw material, resulting in a decrease of the value. In this work, the mixture of scrap aircraft aluminum alloys has been grade-maintaining recycled into 7075 aluminum alloy to maximize its recovery value. After melting, composition adjusting, refining and casting, the composition of recycled AA7075 ingots meet the requirements of GB/T 3190-2008, and the final melt is of great cleanliness. Four kinds of recycled AA7075 profiles were prepared by extrusion and T6/T73 heat treatment. The mechanical properties of all recycled profiles are superior to ASTM B209-14 and B221M-13 requirements. The T6-treated bars have the highest tensile strength (591 MPa), yield strength (534 MPa), elongation (10.0%), and stress-corrosion susceptibility factor (44.8). Nevertheless, the stress corrosion cracking, exfoliation corrosion and inter-granular corrosion resistance of the T6-treated bars still meet the requirements of aviation aluminum alloys. Scrap aircraft aluminum alloys can be regarded as master alloys for containing Zn, Mg, Cu, etc., and they have low melting point, fast melting speed, and uniform microstructure. Thus, high-quality 7075 aluminum alloys can be obtained by recycling the scrap aircraft aluminum alloys. Furthermore, the recycling process can provide some guidance for the industrial application of recycling scrap aircraft aluminum alloys.

Potential Impact of Phosphorylation on Malate Dehydrogenase and Citrate Synthase Protein‐Protein Interaction

Fine tuning of metabolic protein pathways is an insightful way to learn about the progression of diseases linked to metabolism, such as Alzheimer’s disease. Analyzing specific protein interactions in a structure‐function relationship, opens the discussion for potential therapeutic interventions. Malate Dehydrogenase (MDH) and Citrate Synthase (CS) interact in human mitochondria forming a metabolon found within the Krebs Cycle. While the interaction between MDH and CS is not novel, the complete interface between MDH and CS is not yet determined. Furthermore, how these interactions may be modulated by post‐translational modification has yet to be investigated. This study attempts to investigate if key residues driving isoform specific interactions between the MDH and CS are regulated by phosphorylation. Published docking models of MDH and CS highlight several potential sites of interaction, but the key residues of MDH in the interface are not experimentally determined. We performed additional docking predictions using Hawkdoc and SwissDock with published cross‐linked lysine residues of MDH‐CS. Interaction between cytosolic MDH and CS is reported to be much weaker, thus a primary structure alignment highlights the areas of unique residues that might be critical for mitochondrial MDH‐CS interactions. Meta‐analysis of phosphorylation databases from mammalian cells/tissues have identified several sites of phosphorylation with unknown function. To examine the key sites of interaction between MDH and CS and its regulation, we selected several putative phosphorylation sites specific to mitochondrial MDH; S45, T85, S222, and T224, and generated phosphomimic S/T to D mutants. Utilizing his‐tagged recombinant human MDH and CS, we measured interaction using fast thermal melt assays with the presence and absence of crowding agents (10% glycerol; 20% PEG) to determine regulation of phosphomutant interactions. Lastly, we conducted pull‐down assays to illustrate the possible changes in interactions with CS in the wild‐type and phosphomimic MDH‐CS pairs. In determining the interface and post‐translational modification between MDH and CS with these key residues, we can clarify where and how the governing mechanism regulates MDH and CS interaction. This will enable us to gain insight into the modulation of the binding interface interaction and contribution towards altering various metabolic disease pathways.

Effect of temperature history during additive manufacturing on crystalline morphology of PEEK

Additive manufacturing parameters of high-performance polymers greatly affect the thermal history and consequently quality of the end-part. For fused deposition modeling (FDM), this may include printing speed, filament size, nozzle, and chamber temperatures, as well as build plate temperature. In this study, the effect of thermal convection inside a commercial 3D printer on thermal history and crystalline morphology of polyetheretherketone (PEEK) was investigated using a combined experimental and numerical approach. Using digital scanning calorimetry (DSC) and polarized optical microscopy (POM), crystallinity of PEEK samples was studied as a function of thermal history. In addition, using finite element (FE) simulations of heat transfer, which were calibrated using thermocouple measurements, thermal history of parts during virtual 3D printing was evaluated. By correlating the experimental and numerical results, the effect of printing parameters and convection on thermal history and PEEK crystalline morphology was established. It was found that the high melting temperature of PEEK, results in fast melt cooling rates followed by short annealing times during printing, leading to relatively low degree of crystallinity (DOC) and small crystalline morphology.

Design and optimization of silymarin loaded in lyophilized fast melt tablets to attenuate lung toxicity induced via HgCl2 in rats

The present study aimed to develop fast melting tablets (FMTs) using silymarin (SM) owing to FMTs rapid disintegration and dissolution. FMTs represent a pathway to help patients to increase their compliance level of treatment via facile administration without water or chewing beside reduction cost. One of the methods for FMTs formulation is lyophilization. Optimization of SM-FMTs was developed via a 32 factorial design. All prepared SM-FMTs were evaluated for weight variation, thickness, breaking force, friability, content uniformity, disintegration time (DT), and % SM released. The optimized FMT formula was selected based on the criteria of scoring the fastest DT and highest % SM released after 10 min (Q10). Optimized FMT was subjected to Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), and scanning electron microscopy (SEM) besides investigating its lung-protective efficacy. All SM-FMT tablets showed acceptable properties within the pharmacopeial standards. Optimized FMT (F7) scored a DT of 12.5 ± 0.64 Sec and % SM released at Q10 of 82.69 ± 2.88%. No incompatibilities were found between SM and excipients, it showed a porous structure under SEM. The optimized formula decreased cytokines, up-regulated miRNA133a, and down-regulated miRNA-155 and COX-2 involved in the protection against lung toxicity prompted by HgCl2 in a manner comparable to free SM at the same dosage.

A study of sea ice regime in the Obskaya guba Bay using modern satellite data in 2007–2017

The Obskay guba Bay is a region of rapidly developing oil and gas exploration. Knowing the current sea ice conditions including dangerous phenomena e. g. ridges and stamukhas is important for the safety of coastal and underwater construction as well as for ecological risk assessment. With this study, we aim to obtain new data on sea ice seasonal cycle in the southern and central part of the Obskay guba Bay for 10 years (from 2007 to 2017) and to demonstrate the capacity of satellite data in obtaining varying sea ice characteristics in the region. Analyzing daily visual MODIS and available Sentinel-1 SAR imagery, we derived dates of sea ice and fast ice formation, fast ice breakup and melt onset and the onset of ice-free period. For this purpose the satellite data were analyzed manually by sea ice expert. In addition, of sea ice ridges were derived and the sea ice drift data wea automatically processed in order to locate motionless sea ice features — stamukhas. The distribution of sea ice floes and field size in the region was derived from MODIS data. The analysis showed that there is a tendency towards a shorter ice covered period based on the data from 2007 to 2017. Overall, the formation of sea ice starts 9 days later and fast ice breakup occurs 16 days earlier compared to the long-term mean (1947–2010). The majority of ridges were located in the central part of the region and directed along the coast. The analysis confirmed absence of large stamuhas visible to be applied method (with a horizontal size of 100 m). The predominant sea ice field size range lies 500–1500 m. The study shows that a combination of images obtained in the optical range of the survey with radar data makes it possible to supplement the classical visual assessments with the results of automatic methods for detecting fast ice, detecting stamukha, as well as ice drift and deformation.

Study on the optical and thermal properties of a new mid-infrared TeO2-Ta2O5-La2O3 glass

A new mid-infrared tellurite ternary glass with small glass formation area was prepared by modified melt quenching. A high-throughput, simple and fast glass melting process is realized by erecting the tube furnace sideways. The forming range of glass can be quickly and efficiently explored. Moreover, the equipment is convenient for stirring in the melting process, and can effectively reduce bubbles and stripes in the molten glass, thus preparing the matrix glass with excellent performance. The maximum phonon energy of the glass is 765 cm−1, and the appropriate phonon energy is beneficial to achieve intense mid-infrared luminescence or laser. The density of glass is 5.385 g/cm3, indicating high refractive index of this new glass. The glass transition temperature is 428 °C, and there is no obvious crystallization thermal effect before the glass melts. The thermal expansion coefficient of TeO2-Ta2O5-La2O3 (TTL) glass is 12.5 × 10−6K−1 (25–300 °C). The refractive index of glass is 2.01 and the Abbe number is 21.48. The maximum transmittance in the near infrared range is between 76.44% and 80.85%, while the theoretical transmittance is 80.08% (2700 nm). Therefore, this glass is a promising laser glass matrix material in the 2.0–2.7 μm band.

How Do Dark Streams of Arctic Glacial Meltwater Affect Plankton?

In the last decades, the temperatures of Earth’s atmosphere and its oceans have increased significantly. Warming strongly affects the Arctic, where we can observe fast glacial melt during the summer. Meltwater brings debris from the land into the coastal ocean, creating zones with brown water. This seawater darkening can affect the living conditions of marine organisms and possibly threaten marine life in the future. To address this issue, we studied the particles that make the seawater dark and the effect that seawater darkening has on the tiny plants and animals in the coastal waters of the European Arctic. Open, clear waters were greenish and full of life, while in muddy brown zones, we observed intensive “snowstorms” of particles. Our study taught us about how marine organisms interact with these particles. Based on our observations, we can design computer models to help us predict the fate of the coastal waters in a future, warmer Arctic.

Biocompatible lithium zinc borate glasses activated with Sm3+/Eu3+ for glass greenhouse

A series of (Sm3+/Eu3+) co-activated lithium zinc borate glasses were procured by a fast and simple melt quenching technique to obtain remarkable red luminescent materials for glass greenhouses. The synthesized glasses are transparent under daylight and can radiate a strong reddish-orange emission under ultraviolet excitation. By exciting with 403 nm, the (Sm3+/Eu3+) co-activated glasses exhibit enhanced ravishing reddish orange emission at 612 nm as correlated with individually (Eu3+) doped glass. The reddish-orange emission pertaining to Eu3+ ions has been remarkably enhanced by codoping with Sm3+ ions through an energy transmission from Sm3+ to Eu3+. The enhanced luminescence bands of the co-activated glasses from 580 to 700 nm were well matched with the chlorophyll absorption spectral domain. In vitro Prestoblue assay results confirm the non-cytotoxicity with appreciable biocompatibility. From the results, the procured non-cytotoxic (0.75Sm3+-1.0Eu3+) co-activated glass has been found to be a biocompatible greenhouse glass for plant cultivation.

Value addition to ice cream by fortification with okara and probiotic

Synbiotic ice cream offers sufficient viable probiotics and value-added nutrients to satisfy health needs. This study aimed to formulate the optimum synbiotic ice cream incorporated with okara (1–3%) and the probiotic, Lactobacillus plantarum (ATCC 8014). Results showed a viscous texture was produced when more than 2% okara was added to ice cream. This formulation also minimally caused ice cream to melt for around 90 min at a melting rate of 19–76%. Furthermore, ice cream incorporated with okara had an increase in protein content (>5%) and a decrease in fat content (>13%) compared with the control (no okara), indicating that it is a low-fat item. The addition of more than 2% okara increased the viability of L. plantarum on day 60. Overall, 1% okara addition showed significant acceptability for potential symbiotic ice cream formulation. Novelty impact statement One of the greatest challenges in the ice cream manufacturing industry is the short shelf-life and fast melting rate of milk-based ice cream, as it lowers a storage period and affects the textural characteristic. To overcome the said problems, the use of soybean by-product (okara), a potential prebiotic for dietary fiber source, was found to minimally caused ice cream to melt and was able to increase the viability of Lactobacillus plantarum. The function of dietary fiber is not only able to support the growth of probiotics, but also scientifically proven to strengthen the digestive system and reduce the possibility of developing diseases including cardiovascular diseases, diabetes, constipation, and bowel cancer.

Melt pool forming a buttonhole in tailored blank welding with multiple laser spots

Laser beam welding of tailored blank butt joints of different sheet thickness generates asymmetric melt pool conditions. By employing two, three or four tailored laser beams, additional options for shaping the melt pool conditions can be offered. As observed by high speed imaging, in most multi-spot cases a large stable buttonhole was generated, by the trailing laser beams asymmetrically towards the thinner sheet. Correspondingly, the ablation pressure from the multiple boiling fronts has generated a fast melt jet, particularly along the thicker sheet. In many cases the boiling front kept open to the keyhole rear. The buttonhole differs from the Catenoid-like shape reported earlier. The walls are steeper and the horizontal shape can be asymmetric. The melt pool can switch between different stable modes. Inclined arrangement of three beams enabled even two separate, parallel boiling fronts and melt jets, combining behind the opening. Despite the large buttonhole, sound welds were achieved. Solely for four equal laser beams, arranged as a square, a melt pool without buttonhole was generated. Provided the driving forces from the ablation pressure along with the melt flow are sufficiently explored and understood, new opportunities to optimize the welding process are available.

The Effect of Zr Addition on Melting Temperature, Microstructure, Recrystallization and Mechanical Properties of a Cantor High Entropy Alloy.

The effect of Zr addition on the melting temperature of the CoCrFeMnNi High Entropy Alloy (HEA), known as the “Cantor’s Alloy”, is investigated, together with its micro-structure, mechanical properties and thermomechanical recrystallization process. The base and Zr-modified alloys are obtained by vacuum induction melting of mechanically pre-alloyed powders. Raw materials are then cold rolled and annealed. recrystallization occurred during the heat treatment of the cold-rolled HEA. The alloys are characterized by X-ray diffraction, electron microscopy, thermal analyses, mechanical spectroscopy and indentation measures. The main advantages of Zr addition are: (1) a fast vacuum induction melting process; (2) the lower melting temperature, due to Zr eutectics formation with all the Cantor’s alloy elements; (3) the good chemical alloy homogeneity; and (4) the mechanical properties improvement of re-crystallized grains with a coherent structure. The crystallographic lattice of both alloys results in FCC. The Zr-modified HEA presents a higher recrystallization temperature and smaller grain size after recrystallization with respect to the Cantor’s alloy, with precipitation of a coherent second phase, which enhances the alloy hardness and strength.

Fast melt expulsion from crystal-rich mushes via induced anisotropic permeability

Catastrophic eruptions of rhyolitic super volcanoes require large volumes of silicic magma to be extracted from a crystal-rich mush at high rates. However, fast melt extraction is thought to be difficult because of the low permeability of mushes and the high viscosities of silicic melts. Here, we show that induced ephemeral high permeability pathways in the mush may be critical. During uniaxial compression of the mush, driven by the impingement of recharging magmas from below, melt within the mush can be redistributed preferentially into vertical melt pockets. This redistribution of melt can increase vertical permeability by a factor of 10-100 times, which leads to rapid expulsion of melt. As melt is expelled, the permeability rapidly declines. The end result is a fast, short-lived pulse of melt extraction that can grow a 1 km thick silicic magma reservoir in 10 kyr. Our analysis shows how the incursion of deep-seated magmas into the base of a crystal-rich mush in the crust can trigger the expulsion of silicic melts that may lead to an eruption.

Melt-spun Sn1−−Sb Mn Te with unique multiscale microstructures approaching exceptional average thermoelectric zT

SnTe has attracted worldwide attention as a non-toxic candidate material for thermoelectric applications; however, un-modified SnTe possesses inferior thermoelectric properties. Herein, we report the significantly improved thermoelectric performance in Sb, Mn-codoped SnTe synthesized by energy-efficient melt spinning. Sb segregation was observed at the grain boundaries of Sb-doped and Sb, Mn-codoped SnTe melt-spun ribbons, leading to grain refinement; subsequent sintering promotes the diffusion of Sb while retains Sb-rich particles. Initially, intensified phonon scattering from unique multiscale microstructures, including point defects, Sb-rich particles and high-density dislocations generated after Sb doping, effectively diminishes the lattice thermal conductivity of SnTe, leading to a substantially low value of 0.55 W m −1 K −1 in Sn 0.84 Sb 0.16 Te at 300 K. Further, the power factors are significantly enhanced via Mn doping owing to valence band convergence, verified by first-principles calculation. Consequently, a peak zT of ~ 1.27 at 773 K and an exceptional average zT of ~ 0.89 over 300–873 K are obtained in Sn 0.72 Sb 0.16 Mn 0.12 Te, which are ~ 110% and ~ 340% higher than those of SnTe, respectively. This study provides an effective pathway to synergistically improve the thermoelectric performance of SnTe by microstructure and band structure engineering, and establishes melt spinning as a controllable synthetic method to high-performance thermoelectrics. Sb and Mn co-doped SnTe materials, synthesized by combining fast melt spinning and hot pressing, achieve synergistically diminished lattice thermal conductivity and improved power factor, due to enhanced phonon scattering from unique multiscale microstructures and band convergence, respectively. Notably, the Sn 0.72 Sb 0.16 Mn 0.12 Te sample delivers an excellent average zT of ~ 0.89 in the temperature range of 300–873 K. • Synthesizing Sb and Mn codoped SnTe by energy-efficient melt spinning. • Clarifying the vital role of Sb doping in grain refinement of melt-spun SnTe. • Diminishing the lattice thermal conductivity by multiscale microstructures. • Optimizing thermoelectric properties by structure and band engineering. • Obtaining an exceptional average zT of 0.89 (300–873 K) in Sn 0.72 Sb 0.16 Mn 0.12 Te.

Investigate the fast melting process of 2D SiC model by molecular dynamics

This paper presents the results of the study of fast melting process of 2-dimensional SiC by MD simulation with a sample of 400 atoms which consists of 200 Si atoms and 200 C atoms. The model is melted from 300K to 8000K at a rate of 1013 K/s. Investigation of energy dependence on temperature shows a jump of the average total energy of SiC model at temperature T = 5090K. Investigation of material microstructure by a radial distribution function, ring distribution, bonding angle distribution, even distribution number distribution showed that the phase transition temperature was about 5090K.

Preparation and characterization of oleogels with tallow and partially hydrolyzed tallow as organogelators

The aim of this study was to evaluate the organogelation potential of tallow fat (TF) and partially hydrolyzed tallow fat (HTF) against saturated monoglyceride (MG) and a saturated monoglyceride + diglyceride mixture (MDG) as the organogelators. TF itself created oleogel at a 30% addition level, while HTF, MG and MDG oleogels were prepared at 10% addition levels. Fatty acid composition data showed that the oleogel of HTF (HTFO) was quite similar to those of MG and MDG oleogels. Solid fat content, free fatty acidity and peroxide values were found to be in acceptable ranges for HTFO. Thermal properties, crystal morphology and X-ray diffraction patterns were also evaluated. Rheological analyses indicated that all oleogels had higher storage modulus (G´) than loss modulus (G´´). The time-sweep test showed that after applying higher shear rates, the gels re-formed at rest. Further, all oleogels maintained their gelled consistency until around 54 °C. The results suggest that HTF could be a cheap, efficient, fast melting, safe and readily available organogelator.

Zircon stability grids in crustal partial melts: implications for zircon inheritance

Zircon inheritance is a common phenomenon in igneous rocks, although more frequent in granitoids. Zircons inherited from granite magmas mostly come from the source, not from wall rocks or xenoliths. Consequently, they can provide invaluable information about the source materials, melting temperature, and melt segregation conditions. Miller et al. (Geology 31:529–532, 2003) divided granite rocks according to their zircon saturation temperature (TZr) into “hot” (TZr > 800 °C, with little or no inherited zircon) and “cold” (TZr < 800 °C; with abundant inherited zircon). Nevertheless, we have found that coeval and neighboring two-mica granites with TZr < 750 °C, presumably derived from similar sources, may have a radically different inheritance, from about 95 to near 0%. This paper aims to understand the reasons for these differences, in particular, and the survival of source zircons in granitoids, in general. To this end, we modeled the relationships between source composition, temperature, pressure, water content, zircon solubility, and melt fraction, on one hand; and melt production and zircon solution rates, on the other hand. Our results foresee that zircon survival during crustal melting is more probable if the source is a fertile peraluminous metasedimentary rock than if it is a metaluminous source with similar SiO2. Elevated zircon inheritance is characteristic of mid-crustal S-type, water-rich granite magmas generated within 4.5 and 6 kbar. Moderate or no inheritance is characteristic of water-poor granite magmas, because their sources require higher temperatures to produce the same melt fraction. Fast melt extraction does not cause perceptible effects on our models, because melt generation is slower than zircon dissolution, except in the case of crustal underplating by hot mafic magmas. We propose to refine the “hot” and “cold” classification by splitting the “cold” granites (TZr < 800 °C) into two categories, “dry” with little inheritance and “wet” with a very high zircon inheritance. Wet granites require a source water-fluxed from outside. They are characteristic of mid-crustal anatectic complexes with highly fertile gneisses alternating with unfertile mica-rich metapelites. We suggest that the extra water should come in most cases from dehydration reactions in the unfertile metasedimentary rocks beneath the crustal section undergoing anatexis.

A REVIEW ON FAST DISSOLVING TABLETS

A REVIEW ON FAST DISSOLVING TABLETS Jyoti Saxena*, Digvijay Singh, Amrita Bisht, Arvind Negi, Aman Verma GRD Institution of Management & Technology (Pharmacy), Dehradun, Uttarakhand, India ABSTRACT As we are aware of the fact that Fast dissolving tablets have made an appearance as one of the most greatly welcomed dosage form, exceptionally between the pediatric patients and also among the geriatric patients, as both the category of patients have weaker muscular and the nervous system in comparison to adults as well as struggle to consume tablets and capsules. In the case of geriatric patients, Parkinson’s disorder and hand tremors are a major concern and Fast dissolving tablet is one of the most convenient dosage forms. The oral route is considered one of the best-preferred route to administer the drug in animal body but it also has few limitations too. For example, drugs have to go through first-pass metabolism, not preferred in psychiatric and bedridden patients. The FDTs are structured in a way to dissolve very quickly in saliva and this is the most celebrated property of FDTs, that these tablets disintegrate or dissolve in saliva in less than a minute and this process does not need water. Superdisintegrants like Crosscarmellose Sodium and Sodium Starch Glycolate are the backbones of the FDTs, which amplify the rate of disintegration of tablets inside the buccal cavity, results in faster absorption and finally improved bioavailability. There are a number of advantages are offered by FDTs which includes trouble-free transportation and manufacturing, error-free dose, remarkable physical and chemical stability, and above all, its acceptance among pediatrics and geriatric patients. FDTs provide the benefits of both the conventional tablets as well as of liquid dosage forms. FDTs can be manufactured by a number of conventional and patented technologies such as melt granulation, sublimation, direct compression freeze-drying or lyophilization, cotton candy process, etc. These techniques yield the rapid disintegration of tablets which dissolve in the buccal cavity in five seconds and do not need water and chewing. This review includes the definition, needs, advantages, and limitations, challenges to formulate and to manufacture the FDTs, and also some formulations of fast dissolving tablets which are available in market. Keywords: Fast Dissolving Tablet, drug delivery system, rapid disintegrating, fast melting Full Text Article

Combined Effect of the Preparation Method and Compression on the Physical Stability and Dissolution Behavior of Melt-Quenched Amorphous Celecoxib.

In an earlier investigation, amorphous celecoxib was shown to be sensitive to compression-induced destabilization. This was established by evaluating the physical stability of uncompressed/compressed phases in the supercooled state (Be̅rziņš . Mol. Pharmaceutics, 2019, 16(8), 3678-3686). In this study, we investigated the ramifications of compression-induced destabilization in the glassy state as well as the impact of compression on the dissolution behavior. Slow and fast melt-quenched celecoxib disks were compressed with a range of compression pressures (125-500 MPa) and dwell times (0-60 s). These were then monitored for crystallization using low-frequency Raman spectroscopy when kept under dry (∼20 °C; <5% RH) and humid (∼20 °C; 97% RH) storage conditions. Faster crystallization was observed from the samples, which were compressed using more severe compression parameters. Furthermore, crystallization was also affected by the cooling rate used to form the amorphous phases; slow melt-quenched samples exhibited higher sensitivity to compression-induced destabilization. The behavior of the melt-quench disks, subjected to different compression conditions, was continuously monitored during dissolution using low-frequency Raman and UV/vis for the solid-state form and dissolution properties, respectively. Surprisingly the compressed samples exhibited higher apparent dissolution (i.e., higher area under the dissolution curve and initial celecoxib concentration in solution) than the uncompressed samples; however, this is attributed to biaxial fracturing throughout the compressed compacts yielding a greater effective surface area. Differences between the slow and fast melt quenched samples showed some trends similar to those observed for their storage stability.

The Splashing of Melt upon the Impact of Water Droplets and Jets

Small-scale experimental studies of melt splashing upon the impact of water are presented here, with a focus on the fluid dynamics and thermal aspects of these interactions. Gravity-accelerated droplets and forced short-duration water jets interacted with liquid Rose’s alloy superheated to 100–200 degrees above its melting point. A repeatability study was performed for better-control of the gravity fall of a droplet. The amount of perturbation on the melt surface was obtained from a video recording, and indicated the existence of three principal stages of interaction. The cases using the forced water jet demonstrated the occurrence of a cumulative jet of melt following the collapse of the cavity caused by the water impact. Also, it was shown that numerous small-diameter melt droplets were scattered by the primary impulse, and small-scale micro-eruptions were observed, which generated small but fast melt droplets at the later stages of interaction.

Variations of interfacial thermal conductance at melting and crystallization of an indium micro-particle in contact with a solid

The heat transfer between a micrometer-sized particle, as used in laser-assisted additive manufacturing, and a substrate strongly depends on the variations in interfacial thermal conductance (ITC), among other thermophysical parameters of the sample and substrate. Variations of ITC were measured on a millisecond time scale during fast melting and crystallization of an indium micro-sized sample with a mass of about 1 ng. Fast scanning nanocalorimetry was simultaneously applied with high-speed infrared thermography. The ITC between the sample and the sensor membrane was obtained. Therefore, the evolution of the temperature difference at the sample/membrane interface during fast melting and crystallization of the micro-sized indium droplet was measured. An unusual effect of gradual variation of ITC in the melting experiment was found. The method can be applied for ITC measurements during fast processes with 0.26 ms resolution. The quantification of ITC allows, for example, the optimization of melting during additive manufacturing.