前驱体法制备Ta4HfC5超纯超细纳米粉体

Synthesis of an Ultrafine and Pure Ta4HfC5 Powder From Ceramic Precursor

利用实验室自制铪酸酯和钽酸酯为原料,经水解缩合后得到了含铪钽元素的聚合物PHT,引入酚醛(PF)作为C源,制备了Ta4HfC5前驱体,经固化、高温裂解后,获得了超纯超细Ta4HfC5纳米粉体。通过XRD、元素分析和SEM对不同工艺条件下陶瓷产物的晶相组成和微观形貌进行了表征;对陶瓷粉体进行了粒度分析。结果表明,合成的前驱体结构稳定,常温避光储存3个月后黏度几乎没有变化,对于复材加工的工艺适应性良好。在酚醛用量3.25 wt%(以PHT质量分数100%计算)、煅烧温度为1450℃、保温时间为1.5 h的合成条件下,可以得到纯相的Ta4HfC5粉体,晶粒尺寸为25~50 nm,粒径分布在100~200 nm之间,Dv(50)=136 nm。

Tantalum hafnium carbide(Ta4HfC5)ultra pure and fine powders were fabricated by the pyrolysis of ceramic precursor.By co-hydrolysis with tantalum alkoxide and hafnium alkoxide as starting materials,blending phenolic resin(PF)as carbon source,the precursor PHT was successfully prepared as transparent stable light brown solution in xylene solvent.After the precursor was cured and mineralized,ceramic products were obtained at various pyrolysis conditions.Crystalline phase of the ceramic products was studied by XRD and SEM.Pure Ta4HfC5 solid solution was obtained when 3.25 wt%PF(weight ratio 100%PHT supposed)was used and the sample was calcinated at 1450℃for 1.5 h.Morphology,element and particle size analysis were conducted by SEM,TEM,ICP and laser particle analyzer.Particle size of the powder was 25 to 50 nm,and uniform fine particles were obtained with narrow size distribution,100-200 nm with Dv(50)=136 nm.Viscosity of the PHT samples changed little after 3 months duration at atmospheric temperature with light avoided,which is favorable for the precursor impregnation pyrolysis manufacturing process.