The Failure Analysis Of Polycrystalline Diamond Compact (PDC) And Finite Element Simulation Analysis Of The Residual Stress

The polycrystalline diamond compact has been widely applied in oil and gas drill,mining,and nonferrous processing field,due to it owns extremely high wear resistance,hardness,favorable impact resistance,and weld ability.However,the thermal residual tensile stresses as a result of the difference of the coefficient of thermal expansion(CTE)between the PCD and substrate as well as diamond powder and Co element are generated in certain region.As the PDC cools down from sintering temperature to room temperature,it is possible to generate micro-crack in PCD,causing product failure.Hence the optimization of distribution and magnitude of residual stress is vital in manufacture PDC.This paper firstly probes into the cause of micro-crack in PCD edge of PDC1613,then conducts a systematic research on magnitude and distribution of residual stresses of PDC1913PCD via combining experiment with numerical simulation,at last propose relative optimization method by means of research of effect of geometry in interfacial configuration on magnitude and distribution of residual stress.In experiment,I carry on the characterization and test consisting of interfacial state、microstructure morphology.composition distribution.phase composition and Raman spectroscopy for PDC manufactured via the Sweep Through Catalyzed Recrystallization Method(STCR).Results show that the interface bonding between PCD and substrate is great;Sintering microstructure overall is relatively dense,does not appear the phenomenon of graphite;Cracks emergence at the edge of PDC1613A as a results of higher Co content at the PDC1613A edge crack than region without crack.In numerical simulation aspect,accomplishing establish of mathematical physics model on the temperature field and stress field during the cooling process of PDC.the residual stress of the PDC 1913 are studied via conducting a 3-D;"Heat-Structure"multi physics field sequential coupling simulation operating with the ABAQUS software.the experimental results corresponds with the simulation results,it confirm that the model conforms to the actual situation.Conducting further simulation analysis on influence layer of PCD thickness H,rib stiffener inclined angle γ,angle between two sides of stiffener θ,the depth H and width W of step in edge on residual stress of PCD surface.Results show that the radial compressive stress decreases of the central region,regional compressive stress of the edge transform into tensile stress as the increase of PCD layer thickness of H,then area of tensile stress expands;inclination angle γ of rib reinforcements smaller,the change of stress is the more stable,the maximum tensile stress shows slight increase;effect of angle θbetween two sides of stiffener on numerical changes of radial residual stress and circumferential stress are infinitesimal;Increase of step depth D and decrease the width W at the edge can reduce the value of maximum tensile stress,narrowing area size of tensile stress.In summary,through experimental analysis and finite element simulation,it is indicated that combining local high Co content with the radial tensile stress of the boundary cause the crack on the edge of the PCD surface.According to the result analysis,the production company properly lower the content of Co,the qualified rate of the product has been greatly improved.