前驱体原始晶粒尺寸和聚集体形态影响α-Al2O3微粉球化的生长机制研究

Domestic α-Al2O3 micro-powders are mostly irregular shape with multi-edge-corner, which strictly restrict the performance of refractory and ceramic product. Up to now, researches on the spheroidizing mechanism of commercial α-Al2O3 micro-powders and its influencing factors are limited. This project aims at studying the dependence of spheroidizing mechanism of α-Al2O3 micro-powders and the primary grain size and aggregate geometry of precursors by mechanical milling and low-temperature heat-treatment. The influence of precursor species, precursor structure and its physical properties (strength, hardness), mass transformaiton mechanism, as well as the radius ratio of primary grains inside Al2O3 aggregates are investigated to illuminate the dependence of α-Al2O3 spheroidizing mechanism and the formation parameters of α-Al2O3 micro-powders. The expected achievements of this project will provide theoretical guideline for the industrialized controllable preparation of spherical-like α-Al2O3 micro-powders.

国产α-Al2O3微粉大多呈现多棱角的不规则形貌，严重制约了耐火材料和陶瓷等下游产品的性能。到目前为止，深入到工业α-Al2O3 微粉的球化机制及影响因素的研究很少。本课题通过低温轻烧与机械研磨的预处理来改变前驱体的原晶尺寸和聚集体形态与α-Al2O3球化机制的本质关系，弄清前驱体的种类（Al(OH)3、AlOOH 和γ-Al2O3）、前驱体结构和物理性能（强度、硬度）以及物质传输机制的改变和Al2O3聚集体内原始晶粒尺寸配比对α-Al2O3球化的影响规律，建立（类）球形α-Al2O3微粉生成参数与α-Al2O3球化机理的内在联系，为工业化制备不同粒度的（类）球状α-Al2O3微粉提供理论依据。

α-Al2O3是一种重要的无机非金属材料，α-Al2O3微粉形貌与制品性能及应用范围密切相关。因此，α-Al2O3微粉的形貌调控及生长机制研究具有重要意义。资助项目执行期间：①系统研究了原料预处理对工业前驱体在高温煅烧过程中物相转变和形貌演变影响，阐明了普通球磨预处理与低温轻烧对不同工业前驱体（Al(OH)3、AlOOH和γ-Al2O3）形貌演变的影响，确定前驱体的原始晶粒尺寸和聚集体形态与α-Al2O3微粉形貌的本质关系，制备了不同粒度的类球形α-Al2O3粉（0.5－2.0 μm）并分析了其球化机理。②对α-Al2O3微粉的生长机制作进一步研究，揭示了不同添加剂与α-Al2O3的物质传输机制及不同晶面生长速度的内在联系，成功制备了不同粒度的球状、片状、圆饼状、四方块状以及多面体状的α-Al2O3粉。③ 阐明高能球磨预处理对工业Al(OH)3和γ-Al2O3前驱体原始晶粒尺寸和聚集体形态的影响，在优化的煅烧条件下制备了粒度分布均匀的亚微米α-Al2O3粉（晶粒尺寸：~0.5 μm），并进一步结合NH4BF4 添加剂制备了1 μm 左右的类球状α-Al2O3粉。上述研究进展对工业化制备满足不同应用领域需求、形貌可控的优质α-Al2O3粉奠定了理论基础。