定向金属氮化纯铝熔体表面Mg蒸气传质行为

Magnesium Vapor Diffusion Behavior over Al Molten Surface in Directed Metal Nitridation Process

从热力学角度分析并模拟了Mg蒸气在定向金属氮化法制备AlN材料中的相转变过程,证实了在高纯氮气气氛下Mg蒸气层的存在。按照气体扩散传质动力学原理,求出了Mg蒸气层的厚度关系式。研究表明:熔液距坩埚上沿距离、反应前沿的氧分压和初始Mg含量均影响着Mg蒸气层厚度。氧分压降低,初始镁含量的增加,Mg蒸气层厚度增加,有利于铝熔液的渗透氮化。

Phase transformation of Mg vapor was simulated according to thermal dynamics during the fabrication of AlN composite in directed metal nitridation process, which further proves the presence of Mg vapor layer over the melt. Therefore, the thickness of Mg vapor layer was investigated using the principle of gas flow diffusion dynamics. The result shows that the thickness of Mg vapor layer is related to the distance from molten surface to upper fringe of crucible, oxygen partial pressure and original Mg concentration. With the decrease of oxygen partial pressure or increase of original Mg concentration, the thickness of Mg vapor layer increases, which benefits the penetration and nitridation of Al melt.