颗粒形状对粒度测量的影响

粒度分析是几乎所有行业中具有Myriad应用的有效工具。有多种自动化技术可用于测量粒度分布。

Particle size is typically reported in units of equivalent spherical diameter owing to the ambiguity of defining the diameter of non-spherical particles and limitations intrinsic in the instrument detection system.

对于非理想配偶的粒度分布cles reported in equivalent spherical diameter differ between different measurement techniques for a number of reasons. The selection of an appropriate particle sizing technique for a specific sample or application is based on:

• Understanding what each technique actually quantifies
• How each technique carries out the measurement
• How each technique converts the measured value into equivalent spherical diameters

本文讨论了使用不同分析技术的石榴石，硅灰石和玻璃珠样品的分析，包括动态图像分析，X射线沉淀，电感区（Coulter原理）和静态激光散射，以证明效果粒子尺寸测量粒子形状。

Dynamic Image Analysis

In dynamic image analysis, images of particles are acquired while they are passing through the detection zone. Many different shape parameters are employed to analyze linear dimensions of the cross-sectional shape for each image. This technique reports the particle size in terms of these linear dimensions.

X-Ray Sedimentation

X-ray Sedimentation determines particle size by determining the terminal velocities of particles that settle in a fluid medium. This method reports the粒子尺寸就与相同的终端速度相同的终端速度的球体的直径作为相同流体的感兴趣的颗粒，并且在相同的力的效果下。

电气传感区

在电感区域技术中，分散在电解质中并通过电流的孔电流抽出的颗粒产生与穿过孔口的颗粒的体积欧洲杯猜球平台成比例的阻抗的变化。该变化来自颗粒的电解质的位移并产生电信号。

Measurement of the signal determines the electrolyte volume displaced by the particle and therefore the particle volume. This technique reports the particle size in terms of the diameter of a sphere displacing the same amount of electrolyte as the non-conducting particle.

激光散射

The laser light scattering technique is based on the assumption that light is scattered by spherical particles of different size in patterns of intensity as a function of scattering angle. These scattering patterns are specific to the particle diameter, and are cumulative with respect to particles of different size.

This technique reports particle sizes in terms of the diameters of spheres in a group of spherical particles producing the same, or virtually the same, scattering pattern as that determined by the instrument.

分析技术性质

The following table summarizes the analytical techniques, basic measurement performed by the techniques, particle variables that are affecting the measurement, and the corresponding Micromeritics analyzers that were employed to collect the data to demonstrate the effect of particle shape on particle size measurement.

分析技术	基本测量	影响测量的粒子变量	Micromeritics分析仪
Laser light scattering	光强度与散射角度	折射率，形状，方向	土星®DigiSizer II
电气传感区	Change in electrical signal across a conducting orifice	孔隙度，电导率	Elzone.®II
沉降	安乐速度	Density, shape	SediGraph®III
Dynamic image analysis	Linear dimensions of projected cross-section of particle	粒子方向	Particle Insight

实验结果

石榴石晶体

Garnet crystals have approximately cubic shapes. When compared to a sphere of the same volume, a cube has a roughly 30% longer diagonal. As a result, techniques that consider orientation such asdynamic image analysis and laser light scatteringreport larger particle size (Figure 1).

Figure 1.Test results for garnet crystals

Wollastonite Particles

硅灰石有棒状颗粒。欧洲杯猜球平台由于粒子取向可以大大地影响棒状颗粒的表观尺寸，因此将粒子取向的检测技术考虑到帐户产生更宽的峰和更大的粒度测量（图2）。欧洲杯猜球平台

Figure 2.硅灰石粒子的测试结果欧洲杯猜球平台

Glass Spheres

As anticipated, the most consistent results were obtained for glass spheres for the different techniques. The particle orientation does not affect the particle size measurement for glass spheres as they are spherical in shape.

Microscopy of the sample revealed the presence of air bubbles of different sizes in some of the glass spheres, lowering their density to some extent. As a result, some of the spheres are detected as undersized by the SediGraph, thus widening the distribution and shifting it to a somewhat finer size (Figure 3).

Figure 3.玻璃球体的测试结果

This information has been sourced, reviewed and adapted from materials provided by Micromeritics Instrument Corporation.

有关此来源的更多信息，请访问Micromeritics仪器公司