【摘要】 以铝粉和AlN粉末为原料,按重量比60/40的比例进行混合,加入3wt％NH4F和3wt％碳黑,在8MPa的氮气气氛条件下进行高温自蔓延合成,合成产物为具有良好结晶形态的规则AlN颗粒.采用扫描电子显微镜(SEM)和X射线衍射仪(XRD)研究了加入NH4F和碳黑后合成产物形态和物相的变化情况.研究结果表明同时加入NH4F和碳黑使得燃烧过程出现了后烧现象,即样品可以维持在高温阶段较长的时间,促进了AlN气相的传输,最终使得AlN颗粒以较为规则的外形生长.更多还原

【Abstract】 Aluminium nitride (AlN) powders were prepared by self-propagating high-temperature synthesis (SHS). Aluminium and AlN powder mixtures with weight ratios of about 60/40, in the presence of 3wt% NH4F and 3wt% carbon powders were ignited in a nitrogen atmosphere of 8 MPa, resulting in highly crystalline AlN particles with regular hexagonal morphology. The microstructure development during the reaction and the influence of additives of NH4F and carbon were determined by SEM/EDS and XRD analysis of the resulting products. For the samples with NH4F and carbon, the combustion temperature could be kept on a high level for longer times compared to the sample without NH4F and carbon. This indicates that an after-burning phenomenon has occurred; Carbon apparently enhances vapour transport through a mechanism that involves reduction and then removal of the surface oxide layer of the particles during afterburning.更多还原