Precision machining and grinding of brittle materials requires good surface finish and no fracture damage in the workpiece. Considering grinding as a multi-scratch process, the response of a single cutting grain and the damage transitions produced by the cutting action as the load on the grain is varied, will be of primary interest. The present work addresses fracture initiation issues during microcutting tests using a single cutting grain.; Glass (soda-lime and borosilicate), semiconductor silicon, and SiC thin films were used as the test materials. A controlled loading system consisting of a PZT actuator, motorized stage, and an acoustic emission sensor, was used for the tests here. The PZT actuator was used to achieve force controlled loading profiles and the motorized micrometer stage was used for providing the translation during microcutting tests. Acoustic emission was used as the tool for detecting the cracking threshold during the tests. The fracture damage morphologies were determined by scanning electron microscopy. A Vickers diamond indenter was used as the tool.; In the case of borosilicate glass, optimal tool geometry to produce minimal fracture damage was established. Detailed investigations of sub-surface damage were undertaken. An interesting triggering effect due to residual stress was observed. This was well supported by stress models. In addition, detailed investigations of indentation fracture were undertaken using soda-lime glass. In the case of SiC coatings, the fracture damage morphologies and adhesion studies were conducted. These are of wide importance considering their potential use in engineering components to minimize erosion and wear damage. In the case of silicon, crystallographic directions and indenter orientations to produce minimal fracture damage were established. Microcutting tests showed the formation of ductile chips and the presence of an amorphous phase. The latter was attributed to the formation of a high-pressure metallic phase. Interesting periodic features were observed consistently and uniquely in the microcutting grooves for silicon. The loading rate effects and the features in the grooves prompted tests using a diamond turning machine (DTM) and a force sensing system, since much higher cutting speeds can be employed in this case with a much stiffer setup. The force sensor yielded similar results, and also was proven useful to detect crack-initiation thresholds in the case of thicker soda-lime glass samples, since acoustics could not be used in the case of soda-lime glass.
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