Investigation of the effects of phase transformations in micro and nano aluminum powders on kinetics of oxidation using thermogravimetric analysis

Saceleanu, Florin; Atashin, Sanam; Wen, John Z.

doi:10.1039/c7cp02692g

Cited by 26 publications

(15 citation statements)

References 33 publications

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“…Up to now, the controlling mechanism in low‐temperature oxidation is not understood in deep. It has been suggested that at the temperature below the melting point, a slow oxidation process is controlled by the diffusion of oxygen through the oxide shell . Based on the core–shell model as shown in Figure , herein, we use Fick's first law of diffusion to evaluate the diffusive flux of O 2

\frac{d N_{{normalO}_{2}}}{d t} = - 4 π r^{2} D (T) \frac{\partial {normalc}_{{normalO}_{2}}}{\partial r}

where r is the radius of ANPs, D(T) is the effective diffusion coefficient of O 2 in Al 2 O 3 or FAS‐17, and

{normalc}_{{normalO}_{2}}

is the molar concentration of O 2 .…”

Section: Discussionmentioning

confidence: 99%

Superhydrophobic Fluorine‐Containing Protective Coating to Endow Al Nanoparticles with Long‐Term Storage Stability and Self‐Activation Reaction Capability

Guo²,

Gou³

et al. 2019

Adv Materials Inter

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The stability of aluminum (Al) nanoparticles (ANPs) is a key issue that can determine the energetic properties of Al‐based energetic materials. In this study, a surface functionalization approach is employed, using the chemical adsorption and auto polymerization effects of the 1H, 1H, 2H, 2H‐perfluorodecyltriethoxysilane (FAS‐17), to set up a highly stable barrier coating to water and further endow ANPs with long‐term storage stability and self‐activation reaction capability. The FAS‐17‐modified ANPs (AFNPs) with a superhydrophobic surface show their excellent stability in air and unique strengths in corrosion resistance to water by enhancing diffusion resistance of O2 and preventing the hydration reaction. In terms of energetic performances, compared to the two‐step slow oxidation of ANPs, the heat‐release rate of AFNPs is significantly enhanced, resulting in a drastic oxidation process profiting from the surface reaction between the FAS‐17 and alumina (Al2O3) layer. More importantly, the ignition and combustion properties of AFNPs are also greatly improved, which can undergo self‐propagation combustion with a fairly high energy output even after stored in water. At last, the possible mechanisms of oxidation resistance and self‐activation reaction capacities are also proposed.

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\frac{d N_{{normalO}_{2}}}{d t} = - 4 π r^{2} D (T) \frac{\partial {normalc}_{{normalO}_{2}}}{\partial r}

where r is the radius of ANPs, D(T) is the effective diffusion coefficient of O 2 in Al 2 O 3 or FAS‐17, and

{normalc}_{{normalO}_{2}}

is the molar concentration of O 2 .…”

Section: Discussionmentioning

confidence: 99%

Superhydrophobic Fluorine‐Containing Protective Coating to Endow Al Nanoparticles with Long‐Term Storage Stability and Self‐Activation Reaction Capability

Guo²,

Gou³

et al. 2019

Adv Materials Inter

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“…where α is the reaction progress and m is a parameter that describes the nucleation and growth dimension based on ingestion and interface‐restricted nucleation and growth. This model was also used to describe the simultaneous phase transformations and oxidation of Al particles in an oxidizing atmosphere . The g ( α ) function for the power law model is given by

g ((), α) = α^{1 / m},

…”

Section: Resultsmentioning

confidence: 99%

“…The resulting kinetic parameters are apparent and dependent on the extent of the reaction (eg, species concentration or pressure, heat flow rates, etc). Meanwhile, it is possible to use Arrhenius equation with varying activation energy to describe the sequential thermally activated processes such as nucleation, growth, and diffusion in a heterogeneous reacting system …”

Section: Theoretical Approachesmentioning

confidence: 99%

“…Meanwhile, it is possible to use Arrhenius equation with varying activation energy to describe the sequential thermally activated processes such as nucleation, growth, and diffusion in a heterogeneous reacting system. 30,31…”

Section: Theoretical Approachesmentioning

confidence: 99%

“…This model was also used to describe the simultaneous phase transformations and oxidation of Al particles in an oxidizing atmosphere. 30 The g(α) function for the power law model is given by…”

Section: Activation Energy and Mechanism Of The Reactionmentioning

confidence: 99%

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Tunable kinetics of nanoaluminum and microaluminum powders reacting with water to produce hydrogen

et al. 2019

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Summary This paper reports on the kinetics and reaction processes of 40‐nm and 1‐μm aluminum powders with water to produce hydrogen at atmospheric pressure. This reaction produces aluminum hydroxide with irregular morphologies as by‐products. It was found that the nucleation and growth of the aluminum hydroxides affect the kinetics of the reaction and thus the hydrogen production. The heat release in isothermal microcalorimetry and hydrogen production in a nonisothermal batch reactor were used to determine the rate‐determining steps of the reaction mechanism and the corresponding activation energies. Model and model‐free methods have been implemented to describe the reaction sequence between aluminum particle and water while the phase of newly produced aluminum hydroxide in the system plays an important role. The reaction of nanoaluminum particles and water, being more sensitive to temperature, goes to completion to produce bayerite, Al (OH)3 at 30°C, and boehmite, AlOOH at 50°C, whereas the microaluminum particles do not react completely and produce only bayerite at 30°C and also low‐amount boehmite at 50°C. Nevertheless, these processes exhibit two distinct and sequential stages: a kinetically controlled stage with the apparent activation energy (Ea) of 100 to 110 kJ/mol, where nucleation and growth are limited by the chemical reactions on the surface of aluminum, and a diffusion controlled stage with Ea of 44 kJ/mol for the 40‐nm Al/water reaction and 86 kJ/mol for the 1‐μm Al/water reaction, where growth is limited by the mass diffusion through the aluminum hydroxide by‐products. The separation of these two stages is more obvious under isothermal conditions. For nonisothermal conditions, two stages are overlapped, and the one with a lower Ea dominates.

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Modulating Surface Chemistry of Al Powders for Elastomeric Composites with Applications in Electronic Cooling

Zhang

Ren

et al. 2023

Adv Materials Inter

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are generated, the intervention of thermal management via thermal interface materials (TIM) is much required in order to prolong working life and increase reliability. [2] Elastomeric composites are widely used as thermal interface materials in electronics due to their flexibly deform under an applied load and further exhibit elastic recovery. [3] Among them, silicone pads, available in solid soft matter, provide low component stress, rework simplicity, process flexibility, in-application stability, and efficient thermal conductivity. [4] Silicone pads can be prepared by preform and curing or by dispensing silicone gels that, once dispensed, hold their shape and are ideal for applications where high gap stability is required. [5] Upon cure, the silicone pads provide a soft, thermally conductive material capable of reducing air voids and gaps with the capability to withstand warpage. Therefore, mechanical and thermal properties are important indicators for assessing the performance of silicone pads. The crosslinking and entanglement of polymer chains endow elastomers with good mechanical properties, [6] but the irregular chain arrangement also introduces countless interfacial thermal resistance and hinders the heat transfer. [7] Thermal conductivity of bulk elastomers is normally lower than 0.3 W mK −1 . [8] Hence, fillers with high thermal conductivity are added to the elastomers in order to enhance the heat transfer ability while damaging the mechanical performance. In commercial silicone pads, high content (>80 wt%) of aluminum, alumina, zinc oxide, or their combinations are used to build up thermally conductive networks within the composites. In this case, the optimization of the mechanical performance of elastomeric composites is mainly dependent on silicone matrix and filler-matrix interface. The technical scope for modulation by varying the molecular structure of the silicone matrix is limited. [9] Therefore, modulating the surface chemistry of fillers to ameliorate the interface is the main strategy to solve the challenge. [10] In our previous study, [4c] we have modified Al via silane coupling agents with varied chain lengths and explored the corresponding effect on the overall performance. The results indicated the grafting of dodecyltrimethoxysilane (DTS) led to the strongest interface bonding between Al and silicone matrix. However, the deeper effect of different DTS grafting densities Elastomeric composites are an important class of thermal interface materials as they are shape-adaptive, which can fit uneven interfaces and achieve ideal interfacial heat transfer in electronic cooling. There is often a trade-off between mechanical and thermal performances in highly filled composites. Here, the surface chemistry of Al powders via introducing dodecyltrimethoxysilane (DTS) upon different grafting densities is precisely controlled. The results show that the DTS grafting density of 0.24 molecule nm −2 endows the composites with optimized mechanical properties. The tensile stress, elongation at break, a...

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Investigation of the effects of phase transformations in micro and nano aluminum powders on kinetics of oxidation using thermogravimetric analysis

Cited by 26 publications

References 33 publications

Superhydrophobic Fluorine‐Containing Protective Coating to Endow Al Nanoparticles with Long‐Term Storage Stability and Self‐Activation Reaction Capability

Superhydrophobic Fluorine‐Containing Protective Coating to Endow Al Nanoparticles with Long‐Term Storage Stability and Self‐Activation Reaction Capability

Tunable kinetics of nanoaluminum and microaluminum powders reacting with water to produce hydrogen

Modulating Surface Chemistry of Al Powders for Elastomeric Composites with Applications in Electronic Cooling

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