现行标准中有关“粒度”概念的分析

Analysis on the concept of "grain size" in several standards in operation

颗粒的粒度与测量方法密切相关,我国现行磨料粒度检测标准采用不同的粒度检测方法,所得到的"粒度"概念不同。《GB/T 2481.1—1998》(或GB/T 2481.1—2009)、《GB/T 9258.2—2000》、《GB/T 6406—1996》采用筛分法测粒度,测得的"粒度"实际上是颗粒在筛面上的投影相距最远的两对边切线间的距离。《GB/T 2481.2—1998》、《GB/T 9258.3—2000》采用自然沉降法及光透沉降法测粒度,测出的"粒度"是用与颗粒有相同沉降速度的同质球体的直径来表征的,称为"斯托克斯当量直径"。《JB/T7990—1998》规定用图像分析仪或显微镜测量粒度,显微镜法测量的"粒度"是以颗粒投影的"最大宽度"来表征的,而用图像分析仪测量的"粒度"指的是"等面积圆直径",即,用与颗粒投影面积相等的圆的直径表征颗粒粒度。

The grain size of particles is related to testing method tightly. Different particle size testing methods are adopted in China＇ s current standards of abrasive in operation, so the concepts of ＂ grain size＂ are quite different. Screen analysis method is adopted in 《GB/T 2481.1--1998》 （or GB/T 2481.1--2009）, 《GB/T 9258.2--2000》 and 《GB/T 6406--1996》, according to which the ＂ grain size＂ means the longest distance between two opposite tangents of the grain projection on the screen. Gravity sedimentation analysis and photosedimentation technique are adopted in 《 GB/T 2481.2--1998》, 《 GB/T 9258.3--2000》, in which the grain size is expressed by the diameter of spherical particles with the same sedimentation velocity and of the same material, which is called ＂ Stokes equivalent diameter＂. Microscope and image analysis technique are adopted in 《JB/T 7990--1998》. The ＂grain size＂ tested by microscope is expressed by the ＂largest breadth＂ of the grain image. When the grain size is tested by image analysis instrument, the grain size is expressed by the diameter of a circle whose area equals the grain image＇ s.