Analytical Laboratory Services
The Institute of Materials Processing uses many different methods and types of equipment to determine the size and shape of a particle. Listed below are some of the methods used and a description of the mechanism for determining either particle size or shape.
Definition: One of the most fundamental methods for determining particle size is a sieve analysis. This method involves passing the material being sized through openings of a particular standard size in a screen. The particle-size distribution is then reported as the weight percentage retained on each of a series of standard sieves of decreasing size and the percentage passed of the finest size.
Equipment: Large assortment of screens available for sieving. Have Ro-tap for doing large (up to 100 kg) sample size as well as Sonic Sifter for small (2g) samples.
Particle Size Analysis
Definition: The lineal dimension of a particle as determined by various analytical methods.
Equipment: Leeds & Northrup Microtrac - laser based method for determining particle size. Sample is put into solution in an aqueous fluid. Laser intensity through the turbidity is used to determine material and particle size. The range of particle size is from 700 to 1 µFm.
Equipment: Micromeretics Sedigraph 5000ET - x-ray based method for determining particle size. Sample is mixed with a viscosity specific fluid which allows the particles to go into solution while being stirred with a magnetic stirrer. X-ray intensity is used to determine the settling rate and to calculate the particle size distribution. Normally used for characterization of spherical particles between 100 and 0.3 µFm in size.
Surface Area Analysis
Definition: Measurement of the exposed external area of a particle.
Equipment: Micromeretics FlowsorbII 2300 - the measurement of surface area of a material is made by detecting the amount of nitrogen given off after absorption, considering one atomic layer of nitrogen adsorbed. Normally used for characterization of non-spherical and porous particles.
Definition: Particle shape.
Equipment: SEM and image analysis can be used to define particle shape. Particle shape can be documented with a microphotograph. Particle shape can be quantified by using image analysis in conjunction with SEM. The image analysis unit has the capability to generate an array of chords across the particle to arithmetically define the shape of the particle