Al Nanoparticles Research Articles

Elevated-temperature high-strength h-BN-doped Al2014 and Al7075 composites: Experimental and theoretical insights

High-strength Al2014 (Al2) and Al7075 (Al7) series composites with and without addition of hexagonal BN ( h -BN) flakes (1, 3, and 5 wt%) were fabricated from the powder mixtures of individual elements using a combination of high-energy ball milling (HEBM) and spark plasma sintering (SPS). Phase compositions of Al2 and Al7 composites were different from standard alloys obtained via casting and subsequent heat treatment. Thorough structural study revealed the presence of the following phases: Al(Mg,Si,Mn,Fe,Cu), AlCu x , MgO x , and Al 5 Cu 6 Mg 2 [Al2], Al(Mg,Si,Mn,Fe,Cu), AlCu x , Al 5 Cu 6 Mg 2 , Al 6 CuMg 4 , MgO 2 , AlB 2 , and SiN x [Al2-BN], Al(Cu,Zn,Mg), Fe(Al,Cu), AlCu 3 , Al 2 Cu/Fe 3 Al, Al 5 Cu 6 Mg 2 , Al 4 Cu 9 , MgO 2 [Al7], and Al(Cu,Zn,Mg), AlCu x , MgO x , MgN x O y , MgB 2 , Mg 3 (BO 3 ) 2 , BN, and BNO [Al7-BN]. The important role of h -BN additives in the microstructure formation during HEBM and SPS was demonstrated. Classical molecular dynamics simulations were carried out to estimate critical shear stress between Al nanoparticles with and without intermediate h -BN layers. The obtained results indicated that the h -BN nanosheets had provided solid lubrication, prevented nanoparticle agglomeration during HEBM, led to a reduced porosity and more homogeneous reinforcing phase distributions in the powder mixtures and resultant composites. Structural analysis showed, that during SPS, one part of BN additives had reacted with Al, Si, and Mg to form AlB 2 , SiN x , and MgB 2 /Mg 3 (BO 3 ) 2 inclusions, while the other part remained unreacted and contributed to the material strength. Doping with 3 wt% of BN led to an increase in hardness from 76 HV 10 to 123 HV 10 (Al2 series), and from 97 HV 10 to 130 HV 10 (Al7 series). The maximum room-temperature tensile strength of 310 MPa (Al7-BN) and 235 MPa (Al2-BN) was observed for the samples with 3 wt% of BN, which corresponds to an increase in strength by approximately 74% and 16%, respectively. At elevated temperatures, the tensile strength values were 227 MPa (350 °C) and 221 MPa (500 °C) for Al2–3%BN, and 276 MPa (350 °C) and 187 MPa (500 °C) for Al7–3%BN. The superior mechanical properties were attributed to the combination of high thermal stability of the reinforcing phases, solid solution hardening, and Orowan (precipitation) strengthening.

A Study on the Release of Nanoparticles to the Environment from Nano-Enabled Asphalt by Weathering Experiment

Researches in the field of nanotechnology is continuously gaining a lot of interest due to its wide range of applications. This study focused on the incorporation of halloysite nanotubes (HNT’s) on asphalt and on the investigation of the release of the said nanoparticles from the asphalt to the environment through accelerated weathering experiment. Two (2) samples were prepared: asphalt with HNT (A1) and asphalt only (A2). SEM-EDX results showed that A1 initially had nanoparticles on the surface which can be attributed to the added HNT. SEM images further showed the changes on the surface morphologies of A1 and A2 after accelerated weathering experiment. These changes can be further correlated to the intercalation and exfoliation reactions that happened on the surface of asphalt during UV irradiation. Release studies revealed that Al and Si nanoparticles were being released on the surface due to the layer by layer degradation of the asphalt matrix. Hence, continuous exposure of asphalt could result to further degradation of asphalt, leading to the surfacing and release of more nanoparticles.

Influence of Al content on ZnO/Al bilayer-structure ultraviolet photodetector

As a potential optoelectronic material, the use of ZnO in ultraviolet (UV) photodetectors is attracting significant attention. In this study, aluminum (Al) nanoparticles of different content and ZnO films are sequentially sputtered to form ZnO/Al bilayer UV photodetectors. The responsivity of the ZnO/Al bilayer photodetector, with a maximum of 380.9 A W−1 at 320 nm and 5 V bias, is higher than that of the single-layer ZnO photodetector. The enhanced responsivity of the ZnO/Al bilayer UV photodetectors can be attributed to the local surface plasmon resonance effect and the introduction of oxygen vacancies. Meanwhile, the different size and distribution density of Al nanoparticles determines the different enhanced mechanisms. Our work provides a promising route to design and fabricate a high-performance photodetector.

Alcohol-thermal synthesis of approximately core-shell structured Al@CuO nanothermite with improved heat-release and combustion characteristics

Metastable intermolecular composites (MICs), also called nanothermites, are attracting wide attention mainly due to the increased interfacial contact area of the fuels and oxidants therein. In this study, an alcohol-thermal technique is adopted to synthesize approximately core-shell structured Al@CuO MICs, in which process copper acetate is used as the precursor of CuO while Al powder with a wide size distribution (50 nm−5 µm in diameter) is used as cores. The energy-release characteristics of the materials are studied by performing thermal analysis, constant-volume combustion cell tests, and high-speed camera imaging of the combustion process. The results show that Al nanoparticles are surrounded by CuO nanoparticles that are with an average diameter of about 10 nm, while micron-sized Al particles are coated by a continuous layer of nanoplatelets that are assembled from CuO nanoparticles. Benefiting from the enhanced interfacial contact compared with that of ultrasonically mixed counterpart, Al@CuO shows a lower apparent activation energy of solid-state interfacial reaction, a higher light intensity, a shorter burning time, a larger pressure output, and a higher pressurization rate. It is also found that equivalent ratio has a great effect on the combustion process, and a slightly fuel-rich formulation is preferred in this study. The synthesis method developed in this study may also be adapted to the preparation of other core-shell structured MICs.

Photocurrent improvement of an ultra-thin silicon solar cell using cascaded cylindrical shape plasmonic nanoparticles

The main aim of this research work is to significantly improve the photocurrent of an ultra-thin silicon solar cell. Here, cylindrical shape cascaded plasmonic nanoparticles are used to design an ultra-thin silicon solar cell. The main idea is to manipulate the absorption spectra of a thin absorber by applying four cascaded cylindrical shape nanoparticles from different materials with different radii and heights. At first, a cell with one nanoparticle at the surface and another one with a nanoparticle at the bottom side are simulated, and their photocurrents are determined. Then, a cell with four cascaded Ag, Al, Ag-Al, and Al-Ag nanoparticles is simulated. The maximum photocurrent density and efficiency of 23.46 mA cm−2 and 13.95%, respectively, are obtained for a cell in which Ag and Al’s nanoparticles are used alternatively from top to bottom. The photocurrent density is 8.2 mA cm−2 for a cell without any nanoparticles. The simulated results show that cascaded nanoparticles significantly enhance the photocurrent. Finally, the generation rate is presented at different wavelengths.

The molecular dynamics study of aluminum nanoparticles effect on the atomic behavior of argon atoms inside zigzag nanochannel

Aluminum (Al) nanoparticles effects on the atomic behavior of Argon (Ar) fluid inside the zigzag nanochannel are described in this study. For this purpose, Molecular Dynamics (MD) approach is used with a LAMMPS package. Computationally, Ar base fluid and ArAl nanofluid is modeled with Universal Force Field (UFF) and Embedded Atom Model (EAM). Total energy, density, velocity, and temperature profiles for the atomic behavior of base fluid/nanofluid are presented. Results show that the Al nanoparticles cause increasing of the density, velocity, and temperature profiles value to 0.106 atom/Å3, 0.044 Å/ps, and 551.02 K, respectively. So we conclude the Al nanoparticles adding to Ar atoms in non-ideal (zigzag) nanochannel can change atomic behavior of the base fluid effectively and optimize the Ar performance for heat/mass transfer applications.

High-energy Al/graphene oxide/CuFe2O4 nanocomposite fabricated by self-assembly: Evaluation of heat release, ignition behavior, and catalytic performance

As part of our ongoing search for high-performance nanoenergetic materials, we herein used self-assembly guided by negatively charged graphene oxide (GO) to fabricate a high-energy Al/GO/CuFe2O4 nanocomposite with a dense layered structure featuring evenly mixed Al and CuFe2O4 nanoparticles uniformly loaded on the GO surface. Investigation of the effects of the equivalence ratio (Φ ​= ​1.00–1.75) showed that the heat release achieved at the optimal value of Φ ​= ​1.50 (3175 ​± ​65 ​J·g−1) exceeded that of most known thermites, while the fierce ignition process of this composite was characterized by an ignition delay time of (0.025 ​± ​0.002) s, a flame propagation speed of (14.3 ​± ​3.8) m·s−1, and a continuous reaction duration of (33 ​± ​0.58) ms. In addition, the nanocomposite with Φ ​= ​1.00 effectively catalyzed the thermal decomposition of 1,3,5-trinitroperhydro-1,3,5-triazine (RDX) and ammonium perchlorate (AP), decreasing their decomposition temperatures by 7.4 and 64.8 ​°C, respectively, reducing their apparent activation energies of decomposition by 118.7 and 18 ​kJ·mol−1, respectively. And the constant-volume combustion enthalpies of RDX and AP increase with the addition of Al/GO/CuFe2O4. The reason of this enhanced performance was probed by analyzing the nanocomposite assembly process, and a plausible assembly mechanism was proposed.

Atomic-scale identification of microexplosion of aluminum nanoparticles as highly efficient oxidation

In this work, it was proposed to employ the particle dispersion velocity (νD), pressure, heat release rate, delay time, and the numbers of Al-clusters and Al–O bonds derived from reactive molecular dynamics simulations to atomically identify the microexplosion of Al nanoparticles (ANPs), which is feasible to reduce agglomeration and promote the combustion efficiency in applications. The microexplosion is significantly different from common oxidation in terms of the evolution of morphology, reactivity, and energy, since it can be strengthened with an increase in O2 content and temperature and a decrease in particle size. That is, the microexplosion causes the more rapid increase in νD, pressure, heat release, and the number of Al-clusters and Al–O bonds, and the decrease in delay time compared to common oxidation. Meanwhile, the methods for assessing the intensity of the microexplosion and the promotion effect of the microexplosion on ANP oxidation were successfully established in this work. Importantly, the promotion efficiency was ascertained using the heat release rate (0.05 ​kJ·g−1·ps−1) and the ratio of the number of Al–O bonds to the number of Al atoms at the early stage of oxidation (0–50 ps). This work is expected to present a comprehensive perspective of the oxidation of ANPs in O2 under different O2 content, temperatures, and particle sizes, which may be instructive for other violent oxidation of various metal-based fuel nanoparticles.

Structural, Optical and Electrical Properties of Al+MoO3 and Au+MoO3 Thin Films Prepared by Magnetron Codeposition.

Structural, optical and electrical properties of Al+MoO3 and Au+MoO3 thin films prepared by simultaneous magnetron sputtering deposition were investigated. The influence of MoO3 sputtering power on the Al and Au nanoparticle formation and spatial distribution was explored. We demonstrated the formation of spatially arranged Au nanoparticles in the MoO3 matrix, while Al incorporates in the MoO3 matrix without nanoparticle formation. The dependence of the Au nanoparticle size and arrangement on the MoO3 sputtering power was established. The Al-based films show a decrease of overall absorption with an Al content increase, while the Au-based films have the opposite trend. The transport properties of the investigated films also are completely different. The resistivity of the Al-based films increases with the Al content, while it decreases with the Au content increase. The reason is a different transport mechanism that occurs in the films due to their different structural properties. The choice of the incorporated material (Al or Au) and its volume percentage in the MoO3 matrix enables the design of materials with desirable optical and electrical characteristics for a variety of applications.

Impact of gamma‐irradiation on space charge and charge trap characteristics of Al/epoxy nanocomposites

AbstractEpoxy nano Al composites were prepared using epoxyresin, hardener, and Al nanoparticles with required proportions and irradiated with gamma rays of required dosage. Surface potential measurements and space charge studies were employed to investigate the charge trapping properties of gamma‐irradiated specimens. The surface potential decay with DC voltage was sluggish for the gamma‐aged specimens irrespective of the polarity of the applied voltage. Trap distribution characteristics showed that trapped charge carriers occupy the energy range from 0.7 to 0.9 eV and revealed the existence of deep traps for the gamma‐irradiated samples. The mean lifetime and trap depth have followed the direct correlation. Space charge accumulation increased with the dosage of gamma irradiation but did not vary when space charge accumulation reached saturation. Space charge decay rate as well as saturated space charge density is higher for gamma‐aged specimens vs. unaged counterparts. Deep traps inhibited the space charge decay process. Permittivity and loss tangent measurements indicate that dielectric properties were altered with nanofiller inclusions and gamma irradiation.

Molecular dynamics study of sintering of Al nanoparticles with/without organic coatings

Sintering is one of the key factors limiting the application of aluminum nano particles (ANPs) as additives in solid propellant. Because of its high specific surface area and the surface is covered by atoms with low coordination number, ANPs are prone to aggregate or sinter even during the production process which blocks the energy release of ANP during combustion. We perform reactive molecular dynamics simulations to study sintering behaviors for bare and ethanol coated ANPs. Several parameters including shrinkage ratio, gyration radius and moment of inertia are responsible for judging the progress of particle sintering process. A three-stage sintering process has been observed. ANPs follow different sintering laws below and above their melting temperatures. At the same temperature, the smaller the ANP size, the faster the sintering process ends. Before melting, the effect of raising temperature on the sintering degree is not obvious. The coated ANPs show an excellent anti-sinter behavior even when temperature is above their melting point. Different heating rates (1012 K/s–1014K/s) are used to simulate different ignition environments and results show a slow heating rate can make ANPs enter sintering process earlier. For the organic coating layer, carbon and oxygen atoms hinder the formation of the neck region which is an important step in the sintering process. Hydrogen atoms tend to diffuse into the interior of ANPs rather than stay on the surface.

A comparative DFT study of the oxidation of Al crystals and nanoparticles.

The thermodynamic and kinetic behaviors of O atoms on and in different Al nanoparticles (ANPs) and Al crystals have been systematically studied using first-principles calculations. The O adsorption strength on clean Al surfaces follows the order of (111) > ANPs > (110) > (100). The O adsorption strength on ANPs approaches that on Al(111) as the cluster size increases. The three-fold fcc-like sites on ANPs rather than the corner and edge sites are more favored by O* adatoms, which is due to the larger deformation energy related to the geometry change of ANPs when O is adsorbed at the corner and edge sites. The O adsorption behaviors on ANPs are different both from previous studies based on reactive force fields (ReaxFFs) and from those on transition metal clusters. The effective O-O interaction is short ranged (<5 Å), isotropic (in-plane and across-layer) and attractive over different Al surfaces and subsurfaces. The attraction is always about -0.1 eV per O pair at the first nearest neighboring (1NN) sites unless there is evident surface curvature or restructure. Due to the universal attraction, the O* adatoms either on the surface or in the subsurfaces prefer to form islands. In addition, any O diffusion away from the O islands will experience a much higher energy barrier than on a clear (sub)surface. Besides the most stable (Al2O3)n fragments, the metastable Al oxidation fragments are AlO4 monomers and (AlO2)n oligomers, which may be formed during intense oxidation and all feature tetra-coordinated Al and bi-coordinated O atoms.

Neuroprotective effects of insulin like growth factor-1 on engineered metal nanoparticles Ag, Cu and Al induced blood-brain barrier breakdown, edema formation, oxidative stress, upregulation of neuronal nitric oxide synthase and brain pathology.

Military personnel are vulnerable to environmental or industrial exposure of engineered nanoparticles (NPs) from metals. Long-term exposure of NPs from various sources affect sensory-motor or cognitive brain functions. Thus, a possibility exists that chronic exposure of NPs affect blood-brain barrier (BBB) breakdown and brain pathology by inducing oxidative stress and/or nitric oxide production. This hypothesis was examined in the rat intoxicated with Ag, Cu or Al (50-60nm) nanoparticles (50mg/kg, i.p. once daily) for 7 days. In these NPs treated rats the BBB permeability, brain edema, neuronal nitric oxide synthase (nNOS) immunoreactivity and brain oxidants levels, e.g., myeloperoxidase (MP), malondialdehyde (MD) and glutathione (GT) was examined on the 8th day. Cu and Ag but not Al nanoparticles increased the MP and MD levels by twofold in the brain although, GT showed 50% decline. At this time increase in brain water content and BBB breakdown to protein tracers were seen in areas exhibiting nNOS positive neurons and cell injuries. Pretreatment with insulin like growth factor-1 (IGF-1) in high doses (1μg/kg, i.v. but not 0.5μg/kg daily for 7 days) together with NPs significantly reduced the oxidative stress, nNOS upregulation, BBB breakdown, edema formation and cell injuries. These novel observations demonstrate that (i) NPs depending on their metal constituent (Cu, Ag but not Al) induce oxidative stress and nNOS expression leading to BBB disruption, brain edema and cell damage, and (ii) IGF-1 depending on doses exerts powerful neuroprotection against nanoneurotoxicity, not reported earlier.

Enhanced photocurrent in bimetallic/TiO&lt;sub&gt;2&lt;/sub&gt; nanotube composite structures

In recent years, due to the shortage of fossil energy and environmental pollution, the harvesting and conversion of solar energy using semiconductors has attracted more and more attention. Among many kinds of traditional semiconductor photocatalysts, the titanium dioxide (TiO&lt;sub&gt;2&lt;/sub&gt;) has become one of the most popular semiconductor photocatalysts because of its low cost, good stability and environmental friendliness. However, TiO&lt;sub&gt;2&lt;/sub&gt; has a relatively wide band gap (i.e., 3.2 eV for anatase and 3.0 eV for rutile), which can only absorb ultraviolet light with a wavelength less than 387 nm, and has a low utilization rate of sunlight. Moreover, the photo-generated electron-hole pairs in the system of TiO&lt;sub&gt;2&lt;/sub&gt; film and particle are easy to recombine, which makes the photocatalytic efficiency of the material relatively low. In order to solve these problems, TiO&lt;sub&gt;2&lt;/sub&gt; structure with porous (such as nanotube) is used to restrain the recombination of photo-generated electron-hole pairs due to its large specific surface area and good charge transfer characteristics, thereby improving its photocatalytic efficiency. In addition to changing the structure of traditional semiconductor materials, using the surface plasmon resonance effect of metal micro-nano structures to improve its photoelectric conversion efficiency has many potential applications in the fields of photovoltaic, photocatalysis and photoelectric detection. In this paper, we prepare different metallic nanoparticles loaded TiO&lt;sub&gt;2&lt;/sub&gt; nanotube composite structures by atomic layer deposition method and electron beam thermal evaporation technology and investigate the photocatalytic properties of the composite structures. It is shown that comparing with the pure TiO&lt;sub&gt;2&lt;/sub&gt; nanotubes, the photocurrent of TiO&lt;sub&gt;2&lt;/sub&gt; nanotubes loaded with Au nanoparticles increases by about 400% under 568 nm visible light irradiation; the photocurrent of TiO&lt;sub&gt;2&lt;/sub&gt; nanotubes loaded with Al nanoparticles increases by about 50% under 365 nm ultraviolet (UV) irradiation; the photocurrent of TiO&lt;sub&gt;2&lt;/sub&gt; nanotubes loaded with bimetallic Au and Al nanoparticles increases by about 50% in the whole UV-visible light region: it is significantly enhanced. Based on the fact that the surface plasmon resonance frequency of Au and Al nanoparticles are complementary, not only is the optical absorption of TiO&lt;sub&gt;2&lt;/sub&gt; nanotubes enhanced and broadened, but also the photocurrent is enhanced from ultraviolet to visible light. We believe that these results will contribute to the further development of photocurrent in semiconductor nanotubes.

Localized surface plasmon resonance and field enhancement of Au, Ag, Al and Cu nanoparticles having isotropic and anisotropic nanostructure

The localized surface plasmon resonance and field enhancement for noble metal (Au, Ag, Al and Cu) nanostructures is studied using the Finite Difference Time Domain (FDTD) method. From the simulation results, optimum dimensions for RIS and field enhancement are calculated for nanosphere and nanorod structure which serves as a guide in making the optimum choice for a low-loss plasmonic material in various applications mainly plasmonic sensor and SERS. The calculated result shows RIS factor follow sequence as Ag > Al > Au > Cu in DUV–Visible-NIR region i.e. covering the entire range of EM spectrum. By optimizing the structure and material high sensitivity can be obtained in the entire range of the EM spectrum.

Surface roughness and substrate induced symmetry-breaking: influence on the plasmonic properties of aluminum nanostructure arrays.

The surface topography is known to play an important role on the near- and far-field optical properties of metallic nanoparticles. In particular, aluminum (Al) nanoparticles are commonly fabricated through evaporation techniques, therefore exhibiting elevated surface roughness additionally to their native oxide layer. In this study, the mode-dependent influence of surface roughness on the plasmonic properties sustained by Al nanodisks (NDs) is first numerically investigated using a realistic model taking into account the thin native oxide layer. Due to the symmetry-breaking induced by the supporting dielectric substrate to Al ND, it appears that the roughness affects differently the substrate-induced out-of-plane quadrupolar mode (below 300 nm) and the in-plane dipolar mode sustained by the Al ND. By increasing the top surface roughness of the Al ND, the substrate-induced quadrupolar mode is significantly damped especially in the ultraviolet regime, while the dipolar resonance is broadened and redshifted. The explanation of these effects relies in the decoherence and dissipation of the collective electronic oscillations as a result of the top surface roughness to the different near-field distribution of the out-of-plane quadrupolar mode and in-plane dipolar mode. Moreover, the influences of the diameter of Al ND, dielectric substrate with different refractive index, and the oxidation of Al ND on these two modes are also investigated. Particularly, the quadrupolar mode disappears with surface roughness and oxidation, explaining why this mode is very weak and sometimes barely visible on evaporated Al nanostructures reported in the literature. Finally, these results are experimentally confirmed by characterizing the optical properties of periodic Al ND arrays.

Linewidth narrowing of aluminum breathing plasmon resonances in Bragg grating decorated nanodisks.

Plasmon resonances with high-quality are of great importance in light emission control and light–matter interactions. Nevertheless, inherent ohmic and radiative losses usually hinder the plasmon performance of metallic nanostructures, especially for aluminum (Al). Here we demonstrate a Bragg grating decorated nanodisk to narrow the linewidth of breathing plasmon resonances compared with a commensurate nanodisk. Two kinds of plasmon resonant modes and the corresponding mode patterns are investigated in cathodoluminescence (CL) depending on the different electron bombardment positions, and the experimental results agree well with full wave electromagnetic simulations. Linewidth narrowing can be clearly understood using an approximated magnetic dipole model. Our results suggest a feasible mechanism for linewidth narrowing of plasmon resonances as well as pave the way for in-depth analysis and potential applications of Al plasmon systems.

Plasmon nanoparticle effect to improve optical properties of perovskite thin film

Noble metal material, size, period and position are key parameters to affect optical absorption property of perovskite thin film, which was numerically investigated in this paper by finite element method. It demonstrates that Al nanoparticles show larger enhancement ability of light absorption than that of Au and Ag under AM1.5 illumination with the same geometry parameter. The light absorption enhancement after introducing Al nanopheres is optimized by nanosphere size, period and position being placed either on top (case I), in perovskite layer (case II), or simultaneously on top and in perovskite layer (case III), which mechanism isdiscussed in terms of the corresponding electric field and power loss density distributions. The maximal light absorption enhancement is revealed to ∼1.41 fold that of without Al nanosphere case. The SiO2, Al2O3 and TiO2 dielectric-nanoshell encapsulating effects on incident light trapping ability and photocurrent of the above optimized case are discussed as well. The present work holds great promise for choosing appropriate plasmonic material, size, period and position to facilitate designing perovskite solar cells and photo detectors.

Enhanced heat-resistance property of aluminum-coated carbonyl iron particles as microwave absorption materials

Nano aluminum (Al)-coated carbonyl iron particles (CIPs) with high microwave absorption capacity and heat-resistance property were prepared by ball-milling. To test the performance of Al@CIPs, raw CIPs were also processed under the same ball-milling process for comparison. Afterwards, both materials were subjected to the same heat treatment process in order to examine their heat resistance. The morphology, structure, electromagnetic and microwave absorption properties were evaluated by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and vector network analysis, respectively. The bond properties of CIPs- or Al@CIPs-based coatings were determined through pull-out test. Morphological and structural analysis results indicated that Al nanoparticles were homogeneously distributed on the surface of CIPs. Compared with raw CIPs, Al@CIPs composites had the better oxidation resistance. The significant improvement in the antioxidation capacity was mainly attributed to the compact and dense alumina layer formed at the higher temperature, which further prevented oxygen in the air from entering the CIPs core. The ball-milling method proposed in the study can uniformly coat Al on the surface of CIPs in a simple and effective way and provide an efficient way to prepare antioxidized CIPs as microwave absorption materials.

The Potentials of Aluminium Nanoparticles: Novel High Energy Density Material for Underwater Explosions

The destructive parameters of underwater explosives (i.e. shock wave energy, maximum pressure, and bubble radius) are limited to explosion heat; that is comparatively low. One approach for enhanced heat output can be accomplished by integrating reactive metal particles (i. e. Aluminium). However conventional aluminium particles (µm size) would contribute only with combustion gaseous products behind detonation wave front. Underwater, there is no oxygen for such contribution to take place. Furthermore, conventional Al particles could decrease the detonation velocity. So far, full exploitation of aluminium particles in underwater explosions has not been accomplished. Aluminium nanoparticles would combust more efficiently within detonation wave front, offering smaller critical diameter, high reaction rate, and high heat release rate. Consequently, Al nanoparticles could be ideal high energy density material for underwater explosion. Ship model with positive metacentric height, GMT = 4.7 cm for ship transverse stability, and GML = 19.3 for ship longitudinal stability was designed. Ship model offers large angle stability (heeling angles = 0-70 deg.). 2 g of explosive charge was detonated underneath the developed naval structure. Upon explosion, the acceleration of the naval structure was measured using shock accelerometer VC tri-axial, high frequency, 5000 ground acceleration, Dytran, Inc. While, Al particles (10 µm) offered an increase in mono-hull acceleration by 16 % compared to TNT; Al nanoparticles offered an acceleration increase by 49 %. This novel finding can be ascribed to the efficient combustion of Al nanoparticles within detonation wave front offering ideal detonation reaction with enhanced destructive effect.