包覆工艺对微球形燃料相弥散燃料混合均匀性的影响

Influence of Coating Technology on Mixing Uniformity of Micro Spherical Fuel Phase in Dispersed Fuel Material

针对微球形燃料相颗粒与基体粉末的流动性相差较大、难于混合均匀,建立了一种微球的包覆工艺,并研究了包覆工艺对混合均匀性的影响。采用直径约为100μm的不锈钢微球代替燃料微球,研究结果表明,在微球表面物理包覆一层基体粉末,可增加颗粒表面粗糙度,降低两组元粉末的密度差及颗粒沉降的距离,包覆层还能使颗粒间保持一定的间距,微观上形成连续的基体网络,减少甚至避免发生偏聚,有效地改善了混合均匀性。包覆工艺的最佳参数为:保温温度,76℃;保温时间,6min;黏结剂添加量,1%;粉末粒径,小于25μm。该方法可用于改善(U-Mo)-Al、(U-Mo)-Zr等微球形燃料相弥散燃料的混合均匀性。

The difference of fluidity between spherical fuel phase particles and metalli‐cally matrix powders of dispersed fuel is significant ,so it is hard to mix uniformly . Aiming to solve this problem ,a coating technology for spherical fuel phase particles was established and the influence of the coating technology on mixing uniformity was studied .Stainless steel microspheres whose diameters are 100μm were chosen to replace fuel particles in experiment . The results show that by physically coating a layer of matrix pow der on the surface of microsphere ,its surface’ s roughness increases , the density difference between coated particles and matrix powder decreases ,and the sedi‐mentation distance is reduced as w ell .T he coating layer can also retain a definite space between particles ,and form continuous matrix network ,so particles’ assemble can be reduced or avoided ,at the same time mixing uniformity can be improved effectively . The optimum parameters of the coating technology are ：Keeping temperature is 76 ℃ , keeping time is 6 min ,the interpolative quantity of binder is 1% ,and size of coating layer’s powder is less than 25μm .The coating technology can be applied to improve the mixing uniformity of other dispersed fuel materials ,w hose particles are spherical ,such as （U‐Mo）‐Al and （U‐Mo）‐Zr .