直接还原碳化法制备超细WC-Ni-Fe合金粉的研究

Ultrafine Hard Alloy Powders of WC-Fe-Ni Prepared by the Direct Carbonization Process

采用超声喷雾热转换法制取的 (WO3-NiO -FeO)纳米级复合氧化物粉末为原料 ,按WO3+C→WC +CO的基本反应进行直接碳化 ,制备超细WC -Ni-Fe纳米级合金粉。在碳化过程中 ,用DSC、XRD、SEM等分析手段 ,研究了氢气与氮气对直接还原碳化反应温度、反应历程以及粉体物相和粒度的影响。结果表明 ,在氢气气氛下 ,直接还原碳化温度明显低于氮气气氛 (约低 170℃ ) ;无论在氮气或氢气气氛下 ,直接还原碳化过程均由前期的还原过程 (WO3→WO2 .72 →WO2 →W )和后期的碳化过程 (W +C→WC)组成 ;所制备的合金粉体粒度小于 2 0 0～ 30 0nm。

With the nano-scale composite oxide powders by the ultrasonic thermal spray transformation technique, we have prepared the ultrafine hard alloy powders of WC-Fe-Ni by the direct carbonization process based on the reaction of WO 3 +C→WC+CO. The effects of atmosphere of H 2 or N 2 on the carbonization temperature, reaction process, phase compositions and particle sizes of the powders were studied. The results show that the reaction temperature in the atmosphere of H 2 is lower about 170℃ than that in N 2 . In the direct carbonization process, the reduction of WO 3 to W occurs first, followed by the carbonization reaction of W+C→WC in the atmosphere of H 2 or N 2 . The particle sizes of the alloy powders are smaller than 200～300nm.