Research On Removal Mechanism Of SiC_f/SiC Ceramic Matrix Composite

SiC_f/SiC ceramic matrix composite is a typical hard and brittle material,which has many excellent mechanical properties,such as high temperature resistance and corrosion resistance.So it is widely used in extreme conditions,such as nuclear reactors,aircraft engine combustion chambers,etc.Due to its high hardness and high brittleness,it is prone to chipping and cracking during processing.However,there is still a lack of research on the deformation damage mechanism of SiC_f/SiC ceramic matrix composites.Therefore,in order to improve the processing efficiency and production application of SiC_f/SiC ceramic matrix composites,it is of great significance to study the deformation damage mechanism of SiC_f/SiC ceramic matrix composites.Scratch test technology is a test method currently used to study the mechanical properties and damage mechanism of materials.This method has the advantages of simple test and convenient operation.Therefore,this paper uses finite element simulation to simulate the stress character istics of SiC_f/SiC ceramic matrix composites in the scratch test process,and analyzes the removal mechanism of SiC_f/SiC ceramic matrix composites with the morphology of the scratch test.The finite element analysis software ABAQUS is used to establish a s imulation model of SiC_f/SiC ceramic matrix composites.Cohesive bonding elements are used to simulate the interface properties of SiC_f/SiC ceramic matrix composites using the maximum principal stress criterion.The simulation results of ordinary silicon ca rbide and SiC_f/SiC ceramic matrix composites were compared,and the effects of different scratch speed,scratch depth and other parameters on the scratch results were studied.The results show that although the increase in scratch speed and scratch depth w ill lead to an increase in the force of the two materials,the force of the SiC_f/SiC silicon ceramic matrix composite is smaller than that of ordinary silicon carbide.It can be seen that the addition of silicon carbide fibers can significantly improve the processing stress state of the silicon carbide matrix.Then the influence of fiber orientation on scratch simulation is studied.Based on the above research,it is concluded that in the grinding process of SiC_f/SiC ceramic matrix composites,the grinding linear speed and grinding depth should not be too large;and it is believed that the grinding wheel grinding linear speed direction is perpendicular to the fiber direction can significantly improve the processing force status.Scratch tests of SiC_f/SiC ceramic matrix composites were carried out.Under two loading methods,linear progressive loading and constant load loading,a tapered indenter with a diameter of 100 microns was used to carry out scratch tests and simulations along the transverse and lon gitudinal directions of the fiber.The theoretical research is verified.The results show that the mechanism analysis results of the above simulation research are applicable regardless of whether it is progressive loading or constant loading.In addition,by observing the acoustic emission signal,it is concluded that the grinding force is about 8 to 27N,which can make the material in a relatively stable state of processing stress.