紫钨喷雾干燥-直接碳化法制备纳米WC-Co复合粉

Preparing WC-Co Composite Powder by Spray Drying Direct Calcination Using Violet Tungsten Oxide as Raw Materials

以WC-6%Co为基本成分，计算原料紫钨、醋酸钴、有机碳及超纯炭黑配料量，称量后加入装有适量纯水的可倾斜式滚动球磨机，湿磨混匀12 h，形成复合盐料浆，然后充分搅拌，进行喷雾干燥后制备的前驱体粉末粒度在10～100μm，平均粒度为50μm。将喷雾干燥好的粉末装舟（200 g），推入高温钼丝炉中，通入氢气，还原碳化温度950℃，时间30 min制备的纳米WC-Co复合粉，粉末粒度分布窄，颗粒粒度在5-45μm，平均粒度为23.38μm。SEM、BET结果表明WC晶粒度在300 nm左右，由扫描电镜（SEM）、X光微区分析（EDS）及元素面分布图得到，W、Co、C分布均匀、Co相均匀包覆在WC晶粒周围，不存在成分偏析。 XRD的半高宽窄，晶粒细小；物相纯净，无η相。

Using WC-6 % Co as raw materials, the ingredients of violet tungsten oxide, cobalt acetate, organic carbon and ultrapure carbon are calculated. Then these ingredients are mixed wet with pure water in the inclinable rolling mill for 12 h. The complex salt slurry formed is sufficiently stirred with spray drying at 230 ℃inlet temperature and 125 ℃outlet temperature with 60 mL/min feeding rate and 12 000 r/min spinner speed. Then precursor powder is prepared. Its size is about 10～100μm with the average particle size 50 μm. The spray dried powders are loaded in boat （200 g）, then pushed into the heated molybdenum wire furnace. Hydrogen gas is then charged, carburizedreduced at 950℃ for 30 min. In this way, nano WC-Co composite powder was prepared with a narrow particle size distribution（particle size 5～45μm, an average particle size of 23.38μm）. SEM and BET data indicate the grain size of WC is about 300 nm. SEM, X ray microanalysis （EDS） and the element distribution images shows that W, Co, C distribute uniformly with uniform Co phase coating around WC grain without segregation. The half height width of XRD shows fine grain size, pure phase withoutηphase.