Analysis of aluminum oxynitride AlON (Abral®) abrasive grains during the brittle fracture process using stress-wave emission techniques

Abstract

This article presents the properties of a new generation of abrasive grains made from aluminum oxynitride AlON (Abral®), as well as the methodology and application of acoustic emissions as a measurement analysis method for those stress waves generated during the brittle fracture process. The methodology of evaluation of grain properties presented in the article mostly consists of examining the resistance to fracture as a result of the force applied and analyzing the registered acoustic emission signals. The applied solution involves using a tension machine and conducting compression tests upon AlON grains and, as a point of comparison, white fused alumina 99A grains, microcrystalline sintered corundum SG™, and green silicon carbide 99C. What was analyzed were the registered compression force values and acoustic emission signals within the time and frequency domains. The characteristics within the time function involve determination of the event and ring-down parameters for single acoustic emission impulses. In the case of the frequency analysis, the signal amplitude and phase characteristics were determined. The research results indicate that stress fractures appear during grain compression tests, which generate elastic waves of various characteristics. The recording and analysis of these waves, in the form of an acoustic emission signal, turned out to be an efficient tool for analyzing the process of abrasive grain cracking and made it possible to differentiate their structure. The research results obtained point to the necessity for further analyses into stress-wave emission, especially with reference to the selection of the most effective methods for analyzing the signal frequency spectrum.