FORMATION OF PHYSICAL AND MECHANICAL CHARACTERISTICS OF CARBON-CARBON MATERIALS IN ISO-STATIC TECHNOLOGY FOR PRODUCING CARBON MATRIX

At certain stages of the "High Pressure-High Temperature" technology of obtaining carbon matrixes, studies were conducted to determine the level of properties of carbon-carbon structural materials during stretching, compression, and bending. The values of the modulus of elasticity were calculated from the deformation curves. The advantages of this technology are shown in the paper: constant porosity preservation in an open form, accessible for the subsequent stage of impregnation of the precursor of the carbon matrix. As a result, technically, the most efficient filling of all levels of the pore structure of carbon fibers and multidimensional structures with sizes ranging from fractions to thousands of microns is achieved. Dependences of the change in physical and mechanical properties on the porosity of the carbon matrix qualitatively changed for the three states of the composite: highly porous (lack of monolithic material); dense material (100% realization of the elastic modulus of the reinforcement); high-density material (~ 100% realization of reinforcement strength). It is shown that the strength of the composite corresponds to the notion of a "bound" and "unbound" fiber bundle according to Weibull. According to these models, the tensile strength of the carbon-carbon composite material was calculated and the results were obtained in good agreement with the experimental ones. It is established that the porosity level of ~ 0.14 and the corresponding density level of ~ 1.8 g / cm3 is the boundary for the formation of carbon-carbon composite materials with this type of carbon matrix, with the qualities of the structural material. With the provision of hydrostatic pressure in the carbonization process, there are no physical reasons for the separation of the technological scheme into "preliminary" and "finish" processes with a different set of equipment.