Evaluation And Research On The Mechanical Properties Of Diamond Tool Based On The Simulation Of The Discrete Dislocation Plasticity

The failure mechanism of many devices in the micro/nano-scale compared tomacro state a fundamental change has occurred, it showed significant size effect.The failure of materials is not only related to atomic structure, but also with thematerial of the micro defects, such as defects(holes), line defects(dislocations),planar defects(grain boundary), etc. Since the size of micro diamond tool decreasesharply, so that the crystal defects of the actual tool material itself andmicro-structural defects (such as micro-cracks, voids, impurities) generated duringthe preparation become important factors to determine their cutting property.Therefore, the study of the micro-scale effect of diamond material andmicro-structural defects on the mechanical properties is significant.Firstly, on the basis of access to lots of literature, the finite element model ofindentation of diamond film is established to study stress distribution in the cloud inthe process of the indentation on diamond film and to predict crack growth trends inthe film. followed by the displacement curve obtained from the simulation tocalculate the elastic modulus, hardness of the film and other parameters, to facilitatecomparison with the experimental data.Secondly, based on the two-dimensional and three-dimensional modelpreviously established, dislocation in the mimic diagram in the process ofindentation through discrete dislocation plasticity coupled with finite element modelis obtained. To analyze the micro-scale effect of hardness parameters and so on inthe process of indentation of the film and then through the picture of dislocationdistribution to analysis the film cracks extended trend as well.Finally, the verification experiments of nano-indentation are conducted. Byusing nano-indentation experiments, polycrystalline diamond was pressed in variousindentation points used the same maximum load and various maximum loads.According to the indentation hardness value of these points and draw a diamondmaterial hardness depth curve to analysis the material size effect of hardness.According to the indentation points of load displacement data, the load displacementcurve was drawn to compare with the simulation results and verify the rightness ofthe simulation model. Then the indentation morphology and of polycrystallinediamond materials is observed using the atomic force microscope.