Preparation of aluminum nitride by combustion of a Mg-Al alloy

Abstract

Abstract Aluminum nitride (AlN) was synthesized by combustion of spherical Mg–Al alloy particles in air. Alloy powder was freely poured on a sample table, which formed a cone with a diameter of 1-2 cm. A commercial electro-thermal furnace was used to ignite the cone to start the synthesis. During the combustion, the temperature was measured and the actual burning process was recorded by a video camera. The morphology and phase makeup of the raw powders and the synthesized AlN powders were analyzed by scanning electron microscopy and X-ray diffraction. The thermodynamic properties and ignition temperatures were studied using differential scanning calorimetry and thermogravimetric analysis. Moreover, the effects of the Mg–Al alloy particle size (212.8 μm, 124.1 μm, 61.1 μm, and 29.5 μm) on the morphology of AlN were investigated. The results show that the combustion of Mg greatly promoted the nitridation of Al and that Al in both large and small alloy particles could be completely converted into AlN. The combustion products of the alloy consisted of two different layers: an upper white layer containing MgO and a lower black layer containing AlN. More AlN whiskers formed when small particles were used. However, very small Mg–Al alloy particles hindered the formation of AlN whiskers.