Aluminum Nanopowder Research Articles

The effect of hygrothermal aging on the adhesion performance of nanomaterial reinforced aluminium adhesive joints

Adhesive joints are subjected to various environmental factors such as humidity and temperature, depending on their use in industrial applications. It is important to examine and improve the performance of adhesive joints formed with polymeric adhesives, which are known to be sensitive to humidity and temperature parameters, under these conditions. For this reason, in this study, FPL-etched AA7075-T6 aluminium adherends bonded with nonreinforced and BNNP (boron nitride nanopowder), ANP (alumina nanopowder) and MWCNT (multiwalled carbon nanotubes) reinforced epoxy adhesive as a single lap adhesive joint. Thereafter, performance of the adhesive joints that exposed hygrothermal aging conditions of 1, 2, 4 and 6 weeks at 100% relative humidity (RH) and 60 °C were investigated. Glass transition temperature (Tg) values of nonreinforced and reinforced epoxy adhesives before and after hygrothermal aging were determined by DSC (Differential Scanning Calorimeter) analyses. Depending on the nanomaterial types, the tendency of the adhesive joints to water uptake was determined and compared with nonreinforced adhesive joints. When the shear strength findings were investigated, it was defined that the adhesive joints reached almost saturation after 2 weeks of hygrothermal aging. In addition, the most effective nanomaterial type against hygrothermal aging was determined as MWCNT. After 2 weeks hygrothermal aged, the shear strength decreases of MWCNT reinforced adhesive joints were 21.77% and 16.97% less than BNNP and ANP reinforced adhesive joints, respectively. Although the adhesive deteriorates chemically after hygrothermal aging, its adhesion performance improved with the physical benefits of nanomaterials. However, ANP, which is cheaper in terms of price/shear strength performance in long-term aging times, showed similar results with MWCNT. In addition, fracture mechanisms were examined in more detail with SEM (Scanning Electron Microscope) analyses before and after aging, and the effects of hygrothermal aging on the adhesive joints were determined.

Influence of the mold type on the mechanical properties of the piston alloy with nano alumina in casting and metal mold

This research is an experimental comparison study to show the influence of mold type casting on mechanical properties. The study considers the aluminum alloy of a gasoline engine piston with nanoparticles alumina Al2O3 size 25 nm manufactured in two types of molds. Sand mold and cast-iron mold were selected to cast the aluminum composite components. A systematic comparative study of tensile strength and hardness properties of cast aluminum components is made on sand and metal molds production. The nano powder can add to enhance the mechanical properties must not exceed 4 % for metal and sand mold casting. According to data for hardness, adding nano alumina powder has minimal impact on metal mold casting, but it significantly improves sand casting. From a financial standpoint, metal casting provides higher economic values for making piston aluminum castings. The hardness rises as the alumina content does in two molds as compared to the obtained specimen. It demonstrates that the highest hardness occurs at 4 % alumina in the sand-casting mold and at 6 % alumina in the metal. When the compositions of the casting materials are the same, a comparison of the fracture morphology between sand and mold casting reveals more ductile fractures for metal molds compared to brittle fractures in sand cast by large silicon separation grains because of higher grain growth in sand casting by longer solidification time. The same is seen in mold casting, which exhibits reduced ductility due to the alumina nanoparticles' dispersion strengthening process in the aluminum matrix. This arises as a result of nano alumina dispersion acting as barriers to dislocation motions in the aluminum matrix, enhancing strength but reducing ductility.

Experimental Investigations and Effect of Nano-Powder-Mixed EDM Variables on Performance Measures of Nitinol SMA.

In the present study, the effect of alumina (Al2O3) nano-powder was investigated for the electrical discharge machining (EDM) of a Nitinol shape memory alloy (SMA). In addition to the nano-powder concentration, other parameters of pulse-on-time (Ton), pulse-off-time (Toff), and current were selected for the performance measures of the material removal rate (MRR), surface roughness (SR), and tool wear rate (TWR) of Nitinol SMA. The significance of the design variables on all the output measures was analyzed through an analysis of variance (ANOVA). The regression model term has significantly impacted the developed model terms for all the selected measures. In the case of individual variables, Al2O3 powder concentration (PC), Toff, and Ton had significantly impacted MRR, TWR, and SR measures, respectively. The influence of EDM variables were studied through main effect plots. The teaching–learning-based optimization (TLBO) technique was implemented to find an optimal parametric setting for attaining the desired levels of all the performance measures. Pursuant to this, the optimal parametric settings of current at 24 A, PC at 4 g/L, Toff at 10 µs, and Ton of 4 µs have shown optimal input parameters of 43.57 mg/min for MRR, 6.478 mg/min for TWR, and 3.73 µm for SR. These results from the TLBO technique were validated by performing the experiments at the optimal parametric settings of the EDM process. By considering the different user and application requirements, 40 Pareto points with unique solutions were generated. Lastly, scanning electron microscopy (SEM) performed the machined surface analysis. The authors consider this to be very beneficial in the nano-powder-mixed EDM process for appropriate manufacturing operations.

Physical treatment of paraffin in existence of nanoparticles using computational simulation

Development of numerical code for evaluating the solidification of water has been scrutinized in this work. The container has two circular and sinusoidal cold walls at bottom and top surfaces. Galerkin-based code has been employed to model this phenomenon. To elevate the conductivity of phase change material (PCM), alumina particles with nanosized were utilized with incorporating different shapes. The conductivity of nanoencapsulated phase change material (NEPCM) is a function of concentration and shapes of nanoparticles. The freezing process is mainly dominated by conduction and selecting curved shaped and adding nanoparticles can affect this mechanism. Verification test reveals the good accommodation and applying adaptive grids leads to higher accuracy. As shape coefficient increases, the period of process declines around 10.65% owing to stronger conduction. Also, mixing water with alumina nanopowders with blade shape causes decrement in needed time around 32.51%. Besides, outputs reveal that utilizing blade shape of powders has more effect on required time than that of cylindrical shape.

Discovery of Discrete Stages in the Oxidation of exo-Tetrahydrodicyclopentadiene (C10H16) Droplets Doped with Titanium-Aluminum-Boron Reactive Mixed-Metal Nanopowder.

Titanium (Ti), aluminum (Al), and boron (B) reactive mixed-metal nanopowders (Ti-Al-B RMNPs) represent attractive additives to hydrocarbon fuels such as exo-tetrahydrodicyclopentadiene (C10H16; JP-10) enhancing the limited volumetric energy densities of traditional hydrocarbons, but fundamental mechanisms and combustion stages in the oxidation have been obscure. This understanding is of vital significance in the development of next-generation propulsion systems and energy-generation technologies. Here, we expose distinct oxidation stages of single droplets of JP-10 doped with Ti-Al-B-RMNP exploiting innovative ultrasonic levitator technology coupled with time-resolved spectroscopic (UV-vis) and imaging diagnostics (optical and infrared). Two spatially and temporally distinct stages of combustion define a glow flame stage in which JP-10 and nanoparticles combust via a homogeneous gas phase (Al) and heterogeneous gas-surface oxidation (Ti, B) and a slower diffusion flame stage associated with the oxidation of JP-10. These findings enable the development of next-generation RMNP fuel additives with superior payload delivery capabilities.

Two-step sintering of alumina nano-powders: A discrete element study

Avoiding grain growth during sintering of ceramic nano-powders is of great technological interest. Although two-step sintering is an effective technique to achieve this goal, the mechanisms at play are not well understood. This study adapts our previous discrete model to investigate the conventional and two-step sintering of nano-powders. The densification and grain growth results agree qualitatively well with experimental data on α-alumina. Simulations confirm that faster heating rates retard grain growth in conventional sintering of nano-alumina. Our results support the hypothesis that the success of nano-alumina two-step sintering relies on the sharp increase in the activation energy of the grain boundary mobility at low temperatures. Simulations indicate a transition temperature of 1100 °C and that at least a 2.5-fold increase in activation energy is required to explain the suppression of grain growth. The relative weights of surface diffusion and of grain boundary motion for grain growth are clarified.

Combined effect of surface pretreatment and nanomaterial reinforcement on the adhesion strength of aluminium joints

Nowadays, it is known that adhesive and cohesive forces should be developed in order to improve the mechanical performance of adhesive joints. In this context, while the adhesive forces are improved with surface pretreatments applied to the adherends, the adhesive and cohesive forces are improved with the nanomaterial reinforcement to the adhesive. For this purpose, in this study, AA7075-T6 aluminium alloy adherends were combined with epoxy adhesive as a single lap joint. As a preliminary study, abrading and FPL-etching (Forest Products Laboratory) surface pretreatments were applied to aluminium alloy adherends and after two different surface pretreatments, the changing surface morphology (with optical microscope, contact angle, profilometer measurements) and shear strength were compared. With abrading and FPL-etching surface pretreatments, an increase of 40.83% and 69.63%, respectively, was determined in the shear strength compared to untreated adhesive joints. After the preliminary study, in order to increase the mechanical performance of the adhesive joints, nano sized ANP (alumina nanopowder), MWCNT (multiwalled carbon nanotubes) and SNP (silica nanopowder) were added to the adhesive. Thus, it was investigated how the combined effect of different surface pretreatments and nanomaterial types at various reinforcement ratios changed the shear strength of the adhesive joints. After shear tests, significant increase in shear strength was observed in FPL-etched adhesive joints compared to abraded adhesive joints in all reinforcement nanomaterial types and reinforcement ratios. And also, significant improvements in the shear strength of adhesive joints were determined in all types of nanomaterial reinforcements. The highest shear strength was obtained at 10.0 wt % SNP reinforcement with 104.32% improvement in FPL-etched adhesive joints compared to nonreinforced FPL-etched adhesive joints. The evaluation of shear strength was supported by the failure images taken from the fracture surfaces after shear tests, and it was determined that the failure type was changed from adhesive to cohesive with nanomaterial reinforcement compared to nonreinforced adhesive joints.

Surface oxidization effect on the mechanical behavior of aluminum nanopowders under triaxial compression test

In this paper, the impression of surface oxidization on the aluminum nanopowders is investigated using the reactive molecular dynamics (MD) method under the triaxial compression tests. Validation of the computational model is examined with the experimental results, which demonstrates an acceptable accuracy of the numerical simulations. The MD simulations are performed in three stages; relaxing the nanopowders at 300 K and 0.1 MPa, confining the nanopowders under hydrostatic pressure, and imposing the deviatoric stress through the triaxial compression. Evolutions of the relative density with pressure, stress with strain, and dislocation density with strain are derived together with the distributions of the radial distribution function and the pressure contours to characterize the mechanical behavior of nanopowders during the compression tests. The effect of the oxide shell thickness of the nanopowders at different compression paths is studied from the mechanical and crystallographic points of view. The results highlight that the hardness of nanopowders increases, and its ductility decreases as the oxide shell thickness increases. The microstructural analysis demonstrates that the crystalline structure of the alumina shell changes mainly during the hydrostatic pressure, while the crystalline structure of the aluminum core is primarily affected during the triaxial compaction.

Mechanical and Thermal Properties of Aluminum Matrix Composites Reinforced by In Situ Al2O3 Nanoparticles Fabricated via Direct Chemical Reaction in Molten Salts

The development of novel methods for industrial production of metal-matrix composites with improved properties is extremely important. An aluminum matrix reinforced by “in situ” α-Al2O3 nanoparticles was fabricated via direct chemical reaction between molten aluminum and rutile TiO2 nanopowder under the layer of molten salts at 700–800 °C in air atmosphere. Morphology, size, and distribution of the in situ particles, as well as the microstructure and mechanical properties of the composites were investigated by XRD, SEM, Raman spectra, and hardness and tensile tests. Synthesized aluminum–alumina composites with Al2O3 concentration up to 19 wt.% had a characteristic metallic luster, their surfaces were smooth without any cracks and porosity. The obtained results indicate that the “in situ” particles were mainly cube-shaped on the nanometer scale and uniform matrix distribution. The concentration of Al2O3 nanoparticles depended on the exposure time and initial precursor concentration, rather than on the synthesis temperature. The influence of the structure of the studied materials on their ultimate strength, yield strength, and plasticity under static loads was established. It is shown that under static uniaxial tension, the cast aluminum composites containing aluminum oxide nanoparticles demonstrated significantly increased tensile strength, yield strength, and ductility. The microhardness and tensile strength of the composite material were by 20–30% higher than those of the metallic aluminum. The related elongation increased three times after the addition of nano-α Al2O3 into the aluminum matrix. Composite materials of the Al-Al2O3 system could be easily rolled into thin and ductile foils and wires. They could be re-melted for the repeated application.

Modeling of thermal storage enclosure with applying finite element method in presence of nanomaterial

In this article, trapezoidal enclosure has been involved with applying three-lobed inner cold wall and finite element method was utilized in order to simulating this unsteady problem. The all walls except the vertical ones are cold and domain was full of liquid water. Inclusion of nano-powders was assumed as technique of accelerating the solidification in this article. Moreover, the efficacy of shape of alumina nano-powders on expedition of process has been simulated. As nanoparticles added to water, required time declines around 5.97 %. Also, change of particle style to platelet shape results in reduction of period of freezing around 11.56 %. The particles with higher m can affect freezing more about 2.5 % than that of m = 3. The quickest process takes 688.39 s to be completed when m = 5.7, ϕ = 0.04.

Application of Statistical Methods to Accurately Assess the Effect of Gamma Aluminum Oxide Nanopowder on the Hardness of Composite Materials with Polyester-Glass Recyclate.

Polymer composites are materials that are used in many industries. Their wide application has a direct impact on the amount of post-production and post-consumer waste. The global problem with recycling, especially of fiber-reinforced polymeric materials, has prompted research into methods of their use. Previous research on composite materials with polyester–glass recyclate showed a decrease in mechanical properties. The construction material should have the highest mechanical properties. Based on the literature, it was found that the use of nanoadditives may have a positive effect on the parameters of the materials. The use of gamma aluminum nanopowder, in a small amount can significantly increase the mechanical properties of composites with polyester–glass recyclate, and thus can affect the application of these materials to structural elements. The article is devoted to the research on the hardness of composite materials with polyester–glass recyclate and gamma aluminum nanopowder. The main goal is to investigate the possibility of using a nanoadditive as a material, increasing the mechanical properties of composites with polyester–glass recyclate, so as to create a recycled material with the highest possible strength parameters. Hardness tests were performed using the Barcol method. For each composite material, 30 measurements were made in order to subject the results to a statistical analysis. Using parametric statistical tests it was shown that the obtained hardness values at the assumed level of statistical significance pv = 0.05 for comparisons for the samples of the reference material (B0) do not differ by chance, while for the comparisons in the configurations of the reference material (B0) with the modified materials, (R10, A2, R10A2) they do not differ by accident. Studies have shown that the addition of 2% gamma aluminum nanopowder slightly lowers the hardness of a pure polyester–glass composite, but the same additive allows the hardness of composite materials to be increased with the addition of glass recyclate. This is of particular importance for the development of the optimal composition of polyester–glass composites with the addition of recyclate, which will have good strength properties and at the same time enable the reuse of composite waste.

Generating Self-Shaped 2D Aluminum Oxide Nanopowders.

The thermal-assisted exfoliation phenomena of boehmite particles under moderate heating rates were examined. The exfoliation that generated flakes of 5–6 nm in thickness can be achieved because of the perfect cleavage on the boehmite particles that are stripped when thermal treatments bring about dehydration and γ-Al2O3 formation in sequential phase transformation of boehmite. Examinations of the exfoliation effects were carried out on calcined boehmite single crystal particles, which were about 500 nm in diameter, and obtained at three heating rates 0.5, 1.0, and 2.0 °C/min with the heating schedules. The TEM techniques, BET-N2 measurements, XRD-Scherrer equation, and AFM images were employed in the examination. That the BET values increased as increasing of exfoliated flakes reflected two stages of exfoliation. In the beginning stage, during which the BET values were <40 m2/g, the exfoliation resulted from the stress produced by dehydration. In the second stage, the increased rate of surface area was due to the additional force, which originated from the γ-Al2O3 formation. Exfoliation occurred on the cleavage planes {010}, the side pinacoid of the boehmite particle. The generation of flakes resulted in the thinning of boehmite particles. Some of the flakes preserved the external form of boehmite crystals. From the surface energy evaluations of boehmite and γ-Al2O3, it can be inferred that exfoliation is a natural way of thermal treatment.

ТЕРМОСТОЙКОСТЬ ПОСАДОК ПОДШИПНИКОВ КАЧЕНИЯ, ВОССТАНОВЛЕННЫХ ЭЛАСТОМЕРНЫМИ НАНОКОМПОЗИТАМИ

The heat resistance of the polymer material for restoring bearing fits is its most important operational property. The thermal stability of nanocomposites when filling elastomers with nanoparticles varies ambiguously and depends on the type of rubber that is the basis of the elastomer. To restore bearing fits, fillers, in addition to copper nanoparticles, use aluminum nanoparticles, as well as carbon nanotubes in nanocomposites. The effect of carbon nanotubes and aluminum nanoparticles on the heat resistance of elastomers was investigated. The change in the deformation-strength properties of the F-40S elastomer and nanocomposites based on it before and after high-temperature aging was experimentally studied. Composition No. 1: F-40S elastomer – 100 mass parts, Taunit carbon nanotubes – 0.1 mass parts. Composition No. 2: F-40S elastomer – 100 mass parts, aluminum nanopowder – 0.075 mass parts. Samples were made in the form of polymer films. Thermal aging of the samples was carried out under conditions of limited oxygen access to air. The heat resistance of the nanocomposite of composition No. 1, in comparison with the F-40S not filled with elastomer, has increased. The aging coefficient of the nanocomposite in strength, in comparison with the unfilled elastomer, increased by 1.2 times, and in terms of deformation, it increased by 1.38 times. The aging coefficient of the nanocomposite composition No. 2 in strength, in comparison with the unfilled elastomer, increased by 1.17 times, and in terms of deformation, it increased by 1.2 times, which confirms the increase in its heat resistance. Experimental studies have established that the Townit-M carbon nanotubes and aluminum powder nanoparticles are inhibitors of the elastomer thermal oxidation process F-40S and therefore increase the heat resistance of nanocomposites based on it.

Effect of synchrotron radiation on thermochemical properties of aluminum micro- and nanopowders

Thermochemical properties of aluminum micro- and nanopowders after exposure to synchrotron radiation with energy in the range 15.5–20.6 keV has been investigated. The method of thermal analysis was used to study the change in the thermochemical parameters of the aluminum powder. In comparison with initial aluminum powders the specific thermal effect of oxidation of aluminum micro- and nanopowders after irradiation increased by a maximum of 8.0 and 37.4 %, correspondingly. The degree of oxidation of the irradiated samples corresponding to the maximum effect was 60.6 % for aluminum micropowder and 80.5 % for aluminum nanopowder. A possible mechanism of energy storage in aluminum powders and modification their properties under the action of synchrotron radiation is discussed.

The Dynamic Properties at Elevated Temperature of the Thermoplastic Polystyrene Matrix Modified with Nano-Alumina Powder and Thermoplastic Elastomer.

The performance improvement of advanced electronic packaging material is an important topic to meet the stringent demands of modern semiconductor devices. This paper studies the incorporation of nano-alumina powder and thermoplastic elastomer (TPE) into thermoplastic polystyrene matrix to tune the thermal and mechanical properties after injection molding process. In the sample preparation, acetone was employed as a solvent to avoid the powder escape into surrounding during the mechanical mixing in a twin-screw mixer. The pressure and shear force were able to mix the composite with good uniformity in compositions. The samples with different compositions were fabricated using injection molding. The measured results showed that adding 5 wt.% of TPE into the simple polystyrene was able to raise the melt flow index from 12.3 to 13.4 g/10 min while the thermal decomposition temperature remained nearly unchanged. Moreover, the addition of small amount of nano-alumina powder could quickly improve the mechanical property by raising its storage modulus. For example, the addition of 3 wt.% of nano-alumina powder had an increase of 7.3% in storage modulus. Over doping of nano-alumina powder in the composite, such as 10 wt.%, on the other hand, lowered the storage modulus from 2404 MPa to 2069 MPa. The experimental study demonstrated that the tuning in the polystyrene’s thermal and mechanical properties is feasible by composition modification with nano-alumina powder and TPE. The better concentration of the additives should be determined according to the specific applications.

Effect of sintering temperature on microstructure and property of AA6061/SiCp composite prepared by ultrahigh pressure sintering

This study aimed to investigate the effect of sintering temperature on microstructures and properties of AA6061 reinforced with SiC particles composites fabricated by Ultra high-pressure sintering. Results show that little agglomeration exists in AA6061 reinforced with SiC particles with the method of SiC particles coated by nano-aluminum powders. Al4C3 formed at the interface between AA6061Al and SiCp in the composite sintered above 600 °C. In the sintering temperature range of 450 ∼ 650 °C, the maximum relative density and highest hardness could reach 99.58% and 52 HRA, and the wear resistance is also the best for the AA6061 reinforced with SiC particles sintered at 600 °C.

Effect of Humidity on the Thermal Properties of Aluminum Nanopowders with Different Surface Coatings

To investigate the effect of surface coating materials on the humidity stability of aluminum (Al) nanopowders, three kinds of core–shell structure Al nanopowders with an Al2O3 passivation coating, carbon coating, and plasticizer dioctyl sebacate (DOS) coating were prepared through laser-induction complex heating method. After one year’s storage at 95% relative humidity, their thermal properties were tested through differential scanning calorimeter (DSC) and thermal gravimeter (TG) analysis. The results show that the thermal properties of Al2O3-passivated Al nanopowders are entirely lost under high humidity because the Al2O3 passivation coating is very sensitive to moisture. The thermal properties of carbon-coated Al nanopowders are not well-protected under a high humidity due to the uneven thickness and structural defects of carbon coatings. However, the thermal enthalpy of DOS-coated Al nanopowders remains at 3.56 KJ/g under high humidity, which indicates that an organic DOS coating with a hydrophobic nature has an excellent protective effect on the thermal properties of the Al nanopowders. Given the good forming performance of organic DOS coatings and other components of propellants, DOS-coated Al nanopowders are a kind of energetic material with potential application value.

Investigation of nanosized alumina‐binder feedstock rheology for ceramics injection molding (CIM) and survey spark plasma sintering of output green body to obtain transparent alumina

The purpose of this work is to optimize the feed containing alumina-binder nanoparticles for ceramics injection molding to create transparent alumina parts. In this research, two Alumina with and without MgO as sintering aid fabricated via the spark plasma sintering method. Feed fluidity, fracture toughness, density, IR, and visible transmission of SPSed bodies of the sintered pieces were measured. Furthermore, a pin on the disc test was used on the disk to examine the alumina friction coefficient. The results of feed rheology showed that the sample prepared at 90°C had the best conditions as a pseudo-plastic fluid for the CIM method. The results showed that a combination of CIM and SPS methods causes more visible transmission than conventional SPS of alumina nanopowder. Also, the fracture toughness and hardness of as-obtained transparent alumina were in the range of 3.6 MPam0.5 and 20.1 MPa, respectively. The wear rate of the as-obtained transparent sample (4.5 × 10−7 mm3/N.m) was proportional to the alumina grain size (1-4 μm). This article is protected by copyright. All rights reserved

Nano-bulk aluminum fabrication from nano powder mixed with micro powder by explosive consolidation

Explosive Consolidation Method has unique advantages with well prospects in the preparation and processing of bulk materials. In this paper, self-designed structure was employed to study the influence of the mass ratio of nano aluminum powder to aluminum powder on the mechanical properties of nano-bulk aluminum material prepared by explosive consolidation. And the mechanical properties and microstructure of prepared nano-bulk aluminums under various conditions were compared and evaluated based on FMCE method. The results show that for processing single nano-powder through explosion consolidation, hardly any Al powder can be oxidized into Al2O3, and the particle size can still remain at the nanometer order of magnitudes; with the increase from 0 to 100% of the proportion of nano-aluminum powder, the hardness and the compressive strength of nano-bulk aluminums increases, and the density decreases firstly, followed by subsequently increases; and nano-bulk materials prepared by single nano-powder have optimal performance by ranking the comprehensive scores of nano-bulk aluminum materials prepared by explosive consolidation under 6 conditions.

A hierarchical multiscale model of heat transfer between nano-alumina powder and noble gases

Hierarchical multiscale modeling and simulations are conducted to study heat transfer between nano-alumina powder and noble gases. The noble gases considered in this study are helium, argon, and xenon. Density functional theory (DFT) computations are conducted to predict adsorption energies of noble gases on alumina slab for eight different sites. Using the adsorption energy data, new interatomic pair potential functions that describe gas-slab interactions are developed. Classical molecular dynamics (MD) simulations are then conducted to compute energy accommodation coefficients (EACs) for a gas temperature of 300 K and slab temperatures in the range of 1000–2800 K. For a solid alumina slab, the computed average EACs are 0.16, 0.40 and 0.36 for helium, argon and xenon, respectively. An abrupt jump in the EAC is observed upon melting of the slab. For a liquid alumina slab, the computed average EACs are 0.29, 0.63, and 0.66 for helium, argon, and xenon, respectively. The observed EAC trends are reasoned by independently probing the effects of potential well-depth and gas atom mass. The MD derived EACs are fed as inputs to the transition regime heat transfer model to predict the time evolution of the temperature of nano-alumina powder in noble gas environments. The capability of the hierarchical multiscale model and the validity of the Altman's EAC bounds are assessed by comparing the model predictions with the experimental data.