A modified direct nitridation method for formation of nano-AlN whiskers

Radwan, Mohamed; Bahgat, M.

doi:10.1016/j.jmatprotec.2006.03.045

Cited by 45 publications

(35 citation statements)

References 13 publications

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“…6(c)]. Growth of the agglomerates was initiated from AlN nuclei, formed at the interface between Al melt and N 2 bubble, 10 toward the gas-melt interface due to the gradient of dissolved N. The appearance of the agglomerates was similar to that of the surface of nitrided Al powder at the temperature below 1273 K, 30,33 indicating limited growth of AlN crystals due to the relatively low temperature.…”

Section: Discussionmentioning

confidence: 98%

In situ synthesis of cold-rollable aluminum–aluminum nitride composites via arc plasma-induced accelerated volume nitridation

Lee

Park

2016

J. Mater. Res.

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Our study proposes in situ synthesis of cold-rollable aluminum nitride (AlN) reinforced aluminum matrix composites with attractive thermal properties via arc plasma-induced accelerated volume nitridation (APAVN). Within three minutes of repeated APAVN using commercial nitrogen gas, volume fraction of AlN increased up to 40 vol%, which is the highest value ever reported by in situ nitridation of pure aluminum. The composites contained homogeneously dispersed AlN particulates with strong interfacial bonding and low interfacial thermal resistance, which resulted in unique combination of a relatively low coefficient of thermal expansion and high specific thermal conductivity. APAVN resulted from instantaneous chemisorption of dissociated nitrogen, enhanced diffusion of dissolved nitrogen, and improved wettability, which led to much more AlN formation, ;2.94 Â 10 À1 g/(min cm 3 ), which is about 400 times higher than that in the gas bubbling method. These results would ultimately give us a promising strategy for continuous production of in situ Al-AlN composites for heat sink applications through cost-effective processing.

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Section: Discussionmentioning

confidence: 98%

In situ synthesis of cold-rollable aluminum–aluminum nitride composites via arc plasma-induced accelerated volume nitridation

Lee

Park

2016

J. Mater. Res.

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“…Generally, during the direct nitriding of Al powder, molten and semi-molten particles react with the surrounding N 2 gas species through a liquid-gas mechanism according to the following equation [27]: Figure 11. Average hardness of the fabricated coatings vs. AlN content.…”

Section: Discussionmentioning

confidence: 99%

“…The feedstock hexagonal AlN phase started to appear in the fabricated coatings when spraying the 30 wt% AlN/Al mixture as shown in the XRD spectra in Figure 1 This means that using AlN additives and simple mixing has no significant effect on the RPS process using Al powder. Thus, the Al particles in the mixture easily coalesce and coagulate together after colliding on the substrate due to the low melting point of Al (660 °C) [20,26,27]. This prevented continuous nitrogen access and the realization of complete nitriding.…”

Section: Spraying Of Simply Mixed Al/aln Powdersmentioning

confidence: 99%

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In Situ Fabrication of AlN Coating by Reactive Plasma Spraying of Al/AlN Powder

et al. 2011

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Abstract:Reactive plasma spraying is a promising technology for the in situ formation of aluminum nitride (AlN) coatings. Recently, it became possible to fabricate cubic-AlN-(c-AlN) based coatings through reactive plasma spraying of Al powder in an ambient atmosphere. However, it was difficult to fabricate a coating with high AlN content and suitable thickness due to the coalescence of the Al particles. In this study, the influence of using AlN additive (h-AlN) to increase the AlN content of the coating and improve the reaction process was investigated. The simple mixing of Al and AlN powders was not suitable for fabricating AlN coatings through reactive plasma spraying. However, it was possible to prepare a homogenously mixed, agglomerated and dispersed Al/AlN mixture (which enabled in-flight interaction between the powder and the surrounding plasma) by wet-mixing in a planetary mill. Increasing the AlN content in the mixture prevented coalescence and increased the nitride content gradually. Using 30 to 40 wt% AlN was sufficient to fabricate a thick (more than 200 µm) AlN coating with high hardness (approximately 1000 Hv). The AlN additive prevented the coalescence of Al metal and enhanced post-deposition nitriding through N 2 plasma irradiation by allowing the nitriding species in the plasma to impinge on a larger Al surface area. Using AlN as a feedstock additive was found to be a suitable method for fabricating AlN coatings by reactive plasma

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“…Generally, AlN nanowires, nanobelts, nanolayers, whiskers, nanorods, nanotips, nanofluid [33][34][35] and nanotubes have been synthesized mainly by several methods: an arc discharging process [36], direct nitridation [37,38], chloride-assisted growth [39], carbothermal reduction [40], gas reduction [41], a sublimation process (recrystallization) [42], metal-organic chemical vapor deposition [43], and catalytic growth using aluminum and carbon complex, among others [23,44,45]. Among the methods for synthesizing AlN, direct nitridation of aluminum powder is attractive because of the low cost of the raw materials and the simple nitridation setup.…”

Section: Introductionmentioning

confidence: 99%

Studies on Preparation and Characterization of Aluminum Nitride-Coated Carbon Fibers and Thermal Conductivity of Epoxy Matrix Composites

Kim

Lee

Chung³

et al. 2017

Coatings

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Abstract:In this work; the effects of an aluminum nitride (AlN) ceramic coating on the thermal conductivity of carbon fiber-reinforced composites were studied. AlN were synthesized by a wet-thermal treatment (WTT) method in the presence of copper catalysts. The WTT method was carried out in a horizontal tube furnace at above 1500 • C under an ammonia (NH 3 ) gas atmosphere balanced by a nitrogen using aluminum chloride as a precursor. Copper catalysts pre-doped enhance the interfacial bonding of the AlN with the carbon fiber surfaces. They also help to introduce AlN bonds by interrupting aluminum oxide (Al 2 O 3 ) formation in combination with oxygen. Scanning electron microscopy (SEM); Transmission electron microscopy (TEM); and X-ray diffraction (XRD) were used to analyze the carbon fiber surfaces and structures at each step (copper-coating step and AlN formation step). In conclusion; we have demonstrated a synthesis route for preparing an AlN coating on the carbon fiber surfaces in the presence of a metallic catalyst.

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A modified direct nitridation method for formation of nano-AlN whiskers

Cited by 45 publications

References 13 publications

In situ synthesis of cold-rollable aluminum–aluminum nitride composites via arc plasma-induced accelerated volume nitridation

In situ synthesis of cold-rollable aluminum–aluminum nitride composites via arc plasma-induced accelerated volume nitridation

In Situ Fabrication of AlN Coating by Reactive Plasma Spraying of Al/AlN Powder

Studies on Preparation and Characterization of Aluminum Nitride-Coated Carbon Fibers and Thermal Conductivity of Epoxy Matrix Composites

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