金属Ni、FeNi包裹氧化铝复合微粉的制备

Preparation of Ni and FeNi-coated Al_2O_3 composite micro-powders

利用非均相沉淀包裹工艺,首先制备了前驱体碱式碳酸镍(NCH)包裹α-Al2O3或碱式碳酸铝铵(AACH)微粉,然后将前驱体在500℃下经氢气还原2h,成功制备了表面较光滑、致密的金属镍包裹氧化铝球形微粉.分析了非均相沉淀过程中前驱体包裹结构形成机理及影响因素,并初步确定了优化制备条件.通过采用α-Al2O3取代AACH或同时采用FeNi合金包裹解决了金属层易脱落问题.利用SEM、XRD及TG/DSC等手段表征了前驱体及还原产物的形貌、成分以及NCH/AACH热分解过程.Ni、FeNi包裹氧化铝复合结构球形微粉可应用于制备连续金属Ni或FeNi合金相三维网络结构氧化铝/金属复合陶瓷.非均相沉淀—热还原工艺可应用于陶瓷/金属封接中金属化层材料的制备.

Nickel carbonate hydroxide（NCH）-coated spherical alpha-Al2O3 or ammonium aluminum carbonate hydroxide（AACH） powders as the precursor of nickel-coated Al2O3 spherical micro-powders were synthesized by the aqueous heterogeneous precipitation method. Subsequently, nickel-coated alumina micro-powders were successfully prepared by reducing the as-prepared NCH-coated α-Al2O3 or AACH precursors in H2 atmosphere at 500℃ for 2 hours. The mechanism of nickel shell structural formation and processing factors were analyzed and the optimized parameters were determined. The spalling off for nickel shell from the α-Al2O3 core could be avoided by replacing AACH with α-Al2O3 or coating Fe-Ni alloy. The morphology and composition of the precursor and resultant powders were characterized by SEM and XRD. The thermal behavior of NCH/AACH was investigated by TG/DSC. These metal-coated alumina micro-powders will be used for advanced metaL/alumina composites with a three-dimensional metallic network structure, and the heterogeneous precipitation-thermal reduction process can be applied for fabrication of metallized ceramic composites for ceramic-metal seal.