Study On High Temperature Mechanical Properties Of C/SiC Composites

C/SiC composites still have strong load-bearing capacity in high temperature environments,and have broad application prospects in the fields of aviation and aerospace.C/SiC composites will be mainly used in aircraft thermal protection layers and hot end components,and their high-temperature mechanical properties are very important.The high-temperature performance prediction of materials is an important guarantee for the reliability design of aircraft.The research on C/SiC composites at home and abroad mainly focuses on the test pieces prepared in the furnace,while the research on C/SiC materials intercepted in-situ from large structural parts is less,and there is currently no suitable method for aircraft The high-temperature performance of the C/SiC parts on the above is accurately predicted.In response to the abovementioned shortcomings,this paper conducts microscopic observations on the C/SiC structure specimens,simultaneously measures its porosity and density,and conducts vacuum high-temperature mechanical performance tests based on radiant heating,and finally establishes the two characteristic quantities of material porosity and density and high temperature The relationship between mechanical strength provides a reference for the prediction of mechanical properties of C/SiC composite parts on aircraft.Use the stereo microscope and scanning electron microscope to observe the microscopic morphology of the C/SiC structure sample,and use the Micro-CT system to obtain the structural feature information inside the material,and carry out the mercury intrusion experiment to determine the diameter range distribution of the pores inside the material.The microstructure image of the material estimates the size of the holes inside the material.The tensile strength of the C/SiC structure specimens is tested,focusing on the high-temperature compression performance and high-temperature interlayer shear performance,and the porosity and density of the specimens are measured at room temperature,500℃,800℃,1000℃,and 1300℃.Carry out vacuum high-temperature compression and interlaminar shear experiments at several temperature points of1300℃,analyze the failure mechanism with the microscopic image of the fracture of the specimen,summarize the law of the high-temperature strength with temperature and make a reasonable explanation.While ensuring that other functions and parameters remain unchanged,establish different structures of BP neural networks,take the porosity and density of the C/SiC composites as input,and high-temperature mechanical strength as output,comprehensively compare the network with three evaluation indicators Finally,a BP neural network that can accurately predict the high-temperature compressive strength and high-temperature interlayer shear strength of C/SiC composites is selected.Realized the theoretical prediction of the high temperature mechanical properties of C/SiC composites based on the material microstructure characteristics.