Preparation of AlN with low agglomeration using polyethylene glycol and emulsifier to disperse the ultrafine raw powders

Abstract

In this study, aluminium nitride (AlN) powder was prepared by the carbothermal reduction–nitridation method using ultrafine alumina and carbon black as the raw materials. A polyethylene glycol (PEG) and emulsifier (OP-10) disperse system was used to distribute the raw powders during ball milling. The mixing slurries and as-received AlN products were investigated using a viscometer, X-ray diffraction, field emission scanning electron microscopy, oxygen nitrogen hydrogen analyser, TG analysis and a laser particle size analyser. The results showed that the OP-10/PEG composite system reduced the viscosity of the slurry containing alumina and carbon during ball milling and significantly improved the wettability of water on the carbon black powder. The viscosity decrease improved the distribution of alumina and carbon under the same ball-milling conditions. At the same time, a dispersed structure was formed in which the OP-10 micelles separated alumina particles with carbon particles. Furthermore, the micelles with carbon were separated by the long PEG chains. This increased the number of primary particles below 2 μm and decreased the number of agglomerates above 5 μm in the final CRN AlN products. Based on the experimental results, herein the dispersion mechanism of the OP-10/PEG composite system on fine alumina and carbon black is proposed. Moreover, the rationality of the composite system is discussed.