Measuring the strength of irregularly-shaped fine particles in a microcompression tester

• Fracture strength and fracture energy of irregularly-shaped particles measured.
• Testing of 37–45 μm particles with a commercial microcompression machine.
• Mean strengths of particles correlated to breakage rates in a planetary ball mill.

Characterizing the response of individual particles to stresses is of great relevance in a number of fields. In the field of grinding, important advances in mill modeling by decoupling material from machine contributions to the outcome of the process have been made in recent years that require direct information on the distribution of strengths of particles being ground. Although a number of methods and experimental devices have been proposed to measure the breakage strength of individual particles, only recently alternatives have become commercially available for testing particles in the fine size range. The paper demonstrates that a micro compression testing machine allows measuring the distribution of strengths and fracture energies of non-spherical fine particles, although great care should be taken while doing the measurements. It then shows that the mean strength of particles contained in a narrow size range is closely related to the rate of breakage of particles in the same size range in a planetary ball mill, thus demonstrating the validity of the measurements.