喷雾造粒-H_2还原制备WC-Co热喷涂粉末

Preparation of WC-Co Thermal Spraying Powder by Spray Granulation-H_2 Reduction Process

以水溶性醋酸钴代替金属钴粉与WC粉、纯水、微量炭黑和有机碳球磨混匀,经喷雾造粒,H2还原制备WC-Co热喷涂粉。结果表明：当进风温度260℃、出风温度140℃、转速10000r/min所制备的粉末粒度在10-80μm,平均粒度为35μm。在1250℃下,H2还原WC-Co粉末接近共晶温度,产生大量液相,粉末合金化。中空球形颗粒,在重力作用下生成的液相开始流动,填充孔隙,使粉末颗粒密实、颗粒收缩、薄壁变厚,松装密度增大,粉末粒度在10-50μm、平均粒度为25μm,Co相均匀包覆球形WC颗粒。

Thermal spray feeder powder of WC-Co was prepared by H2 reduction of the perform by spray drying granulating of ball milled mixture started from water soluble cobalt acetate, WC powder, pure water, solid carbon powder and liquid organic carbon. It was shown that during spraying drying granulating process, particle size range is from 10 μm to 80μm, with mean particle size around 35 μm, when inlet air temperature is 260℃,outlet temperature is 140℃ and when revolving speed of the spray drying nozzle is 10000 r/min. It was also shown that during H2 reduction process, when powder was heated up to 1250 ℃, which is near the eutectic temperature, liquid phase was formed in the powder, leading to alloy of elements, shrink of the particle and increase of bulk density. Powder obtained had particle size from 10 μm to 50 μm, with mean particle size around 25 μm. SEM shown that cobalt phase was uniformly distributed in the particle.