5　平均晶粒度的测定　　许多固体物质经常以小颗粒状态存在 ,小颗粒往往由许多细小的单晶体聚集而成。这些小单晶称为物质的一次聚集态。小颗粒为二次聚集态。通常所说的平均晶粒度是指物质一次聚集态晶粒的平均大小。晶粒度直接关系到相关材料的物理与化学性能 ,在催化材料以 5 Determination of the average grain size Many solid materials often exist in the form of small particles, small particles often assembled from many small single crystals. These small crystals are called primary aggregation of matter. Small particles are secondary aggregation. Commonly referred to as the average grain size refers to the average size of the material aggregated state grains. Grain size is directly related to the physical and chemical properties of the relevant material, in the catalytic material