Evaluation of grinding strategy for bioceramic material through a single grit scratch test using force and acoustic emission signals

A specified geometry of diamond indenter with different rake angles such as 0 degrees, - 2 degrees and - 4 degrees were used in single scratch experiments to study the mode of material removal on both the sintered and pre-sintered yttria-stabilized tetragonal zirconia (Y-TZP). To evaluate these features during the scratch experiment, the generated forces and the acoustic emission signals were correlated with the surface morphology of scratches. The results indicated that the forces generated by the higher negative rake angle ( - 4 degrees) increase with reduced chipping in comparison with other rake angles.The material removal above 5 mu m scratch depth for sintered zirconia resulted in a brittle fracture, whereas a quasi-plastic behavior was observed with microcracks leading to a clumsy chip in pre-sintered zirconia. This was analyzed from the morphology of the chips and the scratches produced. The formation of chipping was reduced with the increase in negative rake angle, indicated by the changes in the features of the acoustic emission signal. The major frequency peaks were formed at a lower level below 250 kHz denoted the predominant brittle fracture. The acoustic emission burst occurred in the sintered component, which indicated the cracking and chipping formation was more compared to the pre-sintered block.