Activation of combustion synthesis of aluminum nitride powder

Rosenband, Valery; Gany, Alon

doi:10.1016/j.jmatprotec.2003.12.017

Cited by 49 publications

(39 citation statements)

References 12 publications

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“…Thus, it was difficult to reach complete nitriding due to the coagulation and aggregation of Al particles with each other (due to the low melting point of Al (660°C) 18) ). This prevents the continuous nitrogen access to the entire of the particles to realize the complete nitriding.…”

Section: )mentioning

confidence: 99%

Synthesis of Cubic Aluminum Nitride Coating from Al2O3 Powder in Reactive Plasma Spray Process

et al. 2013

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Plasma spraying is a versatile technique for producing abradable and protective ceramic coatings. However, it was difficult to fabricate aluminium nitride (AlN) coating by conventional plasma spray processes. It is due to the thermal decomposition of the feedstock AlN powder during spraying without a stable melting phase. Reactive plasma spraying (RPS) has been considered as a promising technology for in-situ formation of AlN thermally sprayed coatings. This study investigated the feasibility of reactive plasma spraying of Al 2 O 3 powder in N 2 /H 2 plasma upon fabrication of AlN coating. It was possible to fabricate a cubic-AlN (c-AlN)/Al 2 O 3 composite coating and the fabricated coating consists of c-AlN, ¡-Al 2 O 3 , Al 5 O 6 N and £-Al 2 O 3 . Furthermore, the AlN content was improved with increasing the flight time (spray distance), due to increasing the reaction time between the Al 2 O 3 particles and the surrounding N 2 /H 2 plasma. It was possible to fabricate coating contains about 97% of c-AlN. However, it was difficult to clarify the in-flight reaction during the coating process, due to losing the particles shape and features after colliding and flattening on the substrate surface. The sprayed particles were collected into a water bath to maintain its particle features in order to investigate the in-flight reaction. It was clear from the microstructure and the cross section observation of the collected particles that, the nitriding reaction started from the surface. During the coating process, the sprayed particles were melted, spheroidized and reacted in the high temperature N 2 /H 2 plasma and formed aluminum oxynitride (Al 5 O 6 N) which have cubic structure. The particles collided, flattened, and rapidly solidified on a substrate surface. The Al 5 O 6 N is easily converted to c-AlN phase via continuous nitriding (both have the same cubic symmetry: cubic and closely packed) during the rapid solidification and plasma irradiation on the substrate. The high quenching rate of the plasma flame prevents the AlN crystal growth to form the hexagonal phase. Therefore, it was possible to fabricate c-AlN/Al 2 O 3 composite coatings through reactive plasma nitriding of Al 2 O 3 powder and the nitriding process of the Al 2 O 3 particle as well as the formation process of cAlN phase were investigated.

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Section: )mentioning

confidence: 99%

Synthesis of Cubic Aluminum Nitride Coating from Al2O3 Powder in Reactive Plasma Spray Process

et al. 2013

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“…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%

“…Some other studies have mixed Al powder with a dispersion agent such as carbon black [25] or ammonium chloride (NH 4 Cl) [26,27] and then nitrided the mixture under high temperature conditions. The addition of a dispersion agent to the starting Al powder can prevent the formation of Al agglomerates and promote the formation of AlN powder.…”

Section: Introductionmentioning

confidence: 99%

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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“…It has been proven to be an efficient technique for the synthesis of a variety of materials such as nitrides [9,10], hydrides [11], oxides [12,13], and many intermetallics [14][15][16][17]. The CS of β-SiAlON powders is usually performed in a high-pressure N 2 atmosphere under a pressure ranging from 2 to several tens of MPa [18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%