Influence of high temperature treatment on the mechanical characteristics of carbon-carbon composite materials withpyrocarbon matrix

Pyrolytic compaction of porous substrates is one of the methods for obtaining carbon-carbon composite materials. When using such materials at high temperatures, for example, as elements of heaters, it is necessary to take into account the effect of high temperatures on their mechanical characteristics. In this work, the influence of high-temperature treatment on mechanical characteristics was studied and the mechanism of destruction of samples of the material "Argolon GR" produced by JSC "Composite" was considered. It is shown that with an increase in the processing temperature from 1800 to 2400 °C, the open porosity of the samples increases in proportion to the increase in the number and size of cracks in the samples. The compressive failure stress depends very weakly on temperature, however, the graph of the corresponding dependence clearly shows its slight decrease with an increase in the processing temperature from 2000 to 2400 °C, which corresponds to the accumulation of damage in the material matrix that reduces its strength. Attention is drawn to a significant increase in the tensile strength of the material after high-temperature treatment, which is not typical for carbon-carbon composite materials. The dependence of the breaking stress in tension with an increase in the processing temperature for material samples has a pronounced maximum at 2000 °C. The analysis of the change in impact strength, the roughness parameter of the fracture surface of the samples, and the breaking stress in tension showed that the dominant mechanism during fracture is the mechanism of strength increase associated with the violation of the compatibility condition of deformations in the components of the material, while the effect of thermal stress relaxation is very small.