Research On Thermal Shock Characteristics And Milling Performance Of SiC/C-SiC Composite

SiC/C-SiC composite is a new type of high temperature structural material and functional material.It has the performance advantages of low density,high hardness,high temperature resistance,good toughness,good oxidation resistance and low coefficient of expansion.It is used in aerospace vehicles.Fields such as hot-end components and nuclear fusion shields have great application prospects.When SiC/C-SiC composites are used in hot-end components such as aero engines,they need to withstand harsh service environments,especially thermal stresses caused by rapid heating and cooling.Thermal shock resistance can comprehensively reflect the mechanical and physical properties of materials,and is an important assessment item for the application of high-temperature structural materials.Therefore,the research on the thermal shock characteristics of 3D SiC/C-SiC composites is of great significance to the engineering application of this material.SiC/C-SiC composite components usually use near-net-shape technology.In order to meet the requirements of shape and dimensional accuracy in actual engineering applications,secondary processing of components is required.At present,there are few researches on machining methods for SiC/C-SiC composites.To this end,carry out research on the material removal mechanism and milling performance of SiC/C-SiC composite material cutting,and provide technical support for realizing high-efficiency and high-quality processing of SiC/C-SiC composite material.This paper takes the self-developed 3D SiC/C-SiC composite material as the research object,and expounds the basic structure and phase of the material.Based on X-ray tomography(XCT)technology,the material composition and pore distribution trends of 3D SiC/C-SiC are obtained.Carry out physical and mechanical performance testing of 3D SiC/C-SiC composite materials.Provide analysis basis for subsequent research on thermal shock behavior of materials and cutting removal mechanism.Aiming at the actual engineering application environment of SiC/C-SiC composites,based on the thermal shock experiment method of high temperature and low temperature water quenching,the 3D SiC is revealed by analyzing the changes in the mass,pore distribution and mechanical properties of the sample before and after thermal shock SiC/C-SiC composite thermal shock behavior.Based on the single particle scratch test method of the gradual depth method,the change trend of the scratch force of different processed surfaces is analyzed,and it is concluded that the fiber orientation and pore distribution will have a great influence on the scratch force.The scratch profile curve,aspect ratio change trend and micro morphology of different machined surfaces are discussed,and the material removal mechanism and damage form of 3D SiC/C-SiC composites are obtained.The performance test of SiC/C-SiC composites with brazed diamond tools was carried out,the transient images of the material removal process were analyzed,the trend of milling force changes under different process parameters were compared,and the chips,surface macro-defects and micro-surfaces after milling were discussed Morphology,the influence of process parameters on surface roughness was studied,and it was concluded that brazed diamond tools have good processing performance in the surface processing of 3D SiC/C-SiC composites.