Particle Size Analysis and Distribution

Abstract

Scanning Electron Microscope (SEM) is a instrument used for examining samples at magnifications from 32 X to 500,000 X (for our instrument). The SEM is attached with an electron gun and is directed onto the sample. The sample then produces an image where it is read on the monitor. The electron gun is positioned at the top because it needs to shoot at the sample that is being tested. The electrons are then shot in a downward motion traveling through several lenses, such as the condenser lens for a more precise reading. Once the samples have been read by the instrument, it will show a picture that has a certain number of particles. Particle size distribution have many uses that are essential to life habits (health) or even conventional use for example construction. Here are just a few examples of how particle size analysis and distribution are being used even today. This Standard Reference Material (SRM) is primarily intended for use in the calibration of equipment used to measure particle size distributions (PSD) in the 9 μm to 30 μm range. A unit of SRM 1984 consists of a single bottle containing approximately 14 g of tungsten carbide/cobalt powder. Certified values: The PSD values at five mass percentiles were measured by scanning electron microscopy (SEM) and laser light scattering (LLS). The NIST certified PSD values by SEM are listed. These certified values were determined by the measurement of over 10 000 individual particles from three bottles. Comparing the certified NIST SRM 1984 tungsten carbide/cobalt powder with our results are almost identical. This is great because more accurate work can be done and proves that our laboratory is able to reproduce NIST results. In conclusion, the scanning electron microscope is used to capture the sampled element and display it to be counted. Without the use of particle distribution, it would be a difficult time to get necessities such as medicine, asthma pumps, constructing materials, or as simple as ink. Overall, our study is an experimental comparison of the techniques we have in house, which are LLS and SEM (combined with the NIH ImageJ software) using the NIST SRM-1984 as a common, well characterized sample so that we have an idea of how the results from the techniques compare.