Controlled crack propagation in alumina ceramic grinding wheel

Crack propagation has been controlled in alumina ceramic grinding wheel. A specific apparatus was designed in a tensile testing machine for step loading of notched abrasive samples. The initiated cracks were propagated progressively up to the final rupture of the sample. Step-by-step observations of the intersection of the crack with the surface of the sample as well as image analysis of the final crack surface were made. These experimental results were analyzed in view of the microstructure of the material (grit, bond, porosity). The main ‘scenarios’ of the crack propagation through the composite material were identified. Image analysis was then used to determine the most likely scenario. This analysis confirms the high cohesion between the grit and the bond.