Characterization of Superabrasives Using Dynamic Imaging Particle Analysis
Superabrasives, such as micronized diamonds and cubic boron nitride (CBN), are used extensively in applications for cutting, grinding and drilling of hard materials. Tools are coated with superabrasives so they can go through materials that standard tools cannot.
The effectiveness of a particular superabrasive material in a given application is determined by the particle size but, more importantly, the particle shape. While common particle analysis techniques such as sieving, Coulter Counters, and laser scatter instruments can provide particle size distribution, they cannot provide any shape information. In the past, manual microscopy was used to take a closer look at particle shape. However, microscopy is extremely time consuming, and does not allow for inspection of statistically significant amounts of sample.
FlowCAM® is ideally suited for the characterization of superabrasive materials because it can quickly determine particle shape and particle size. Using its VisualSpreadsheet® software, high-level image measurements such as roughness can be taken to characterize differences in particle shape that are not apparent using the older techniques. Plus it can do this at a much higher rate of speed and larger sample size than traditional microscopy methods, yielding higher statistical significance for the results.
The FlowCAM can characterize nearly 50,000 particles automatically in minutes allowing you to quickly determine whether you superabrasive material is in, or out, of spec.
Micronized Diamonds - Quality Control Using FlowCAM
A manufacturer of micronized diamonds used the FlowCAM to ensure a new batch met their desired specifications – at least 95% of the diamond particles needed to have a uniform, smooth perimeter.
The image above shows the FlowCAM results. The upper graphs are the frequency and volume distributions, which show a typical Gaussian size distribution with a mean Equivalent Spherical Diameter (ESD) of 21.54 µm. The aspect ratio (width/length) scattergram in the lower left, however, indicates that the particles are not uniform in shape.
Using VisualSpreadsheet it was easy to separate and display the particles of different shape. In the below image, both sets of particles have an ESD around the mean, but different degrees of smoothness around their perimeters. The set on the left have a relatively smooth perimeter with rounded edges, whereas the set on the right are more angular. However, the percentage of angular particles was automatically shown to be less than 5%, so this batch of diamonds met the set specification.
The manufacturer was quickly and easily able to evaluate the quality of this batch of micronized diamonds using the FlowCAM. To reach the same, statistically-significant conclusion using a microscope would have taken hours, if not days to complete.
Download the Characterization of Superabrasives Application Note >>