Automation of Technological Parameter Regulation in CCCM Manufacturing Based on Dielectric Characteristics Control

This article explores approaches to the automated control of technological parameters during the production of carbon–carbon composite materials (CCCM) through real-time monitoring of their dielectric properties. The influence of temperature, electromagnetic field frequency, porosity, and thermal processing rate on changes in the composite's complex dielectric permittivity has been investigated. The advantages and limitations of the parallel-plate capacitor method, which is based on measuring the capacitance of a sample placed between flat electrodes, are analyzed. It is noted that for complex heterogeneous materials such as CCCM, the use of effective medium models is appropriate. Analytical approaches based on the Maxwell-Wagner and Maxwell-Garnett models are employed. These models enable the consideration of multiphase structures, heterogeneities, defects, and interfacial polarization. It is demonstrated that both the real and imaginary components of the complex dielectric permittivity are sensitive to microstructural changes and can serve as informative parameters for assessing the degree of graphitization, uniformity of impregnation, phase transitions, and the content of residual volatile components. Characteristic frequency and temperature dependencies of the real and imaginary parts of the complex dielectric permittivity for CCCM, simulated using the Maxwell-Wagner model, are presented. The results of numerical modelling of effective dielectric permittivity accounting for porosity, based on the Maxwell-Garnett model, are also provided. It is shown that an increase in porosity from 0 to 2 % leads to an almost linear decrease in the effective dielectric permittivity, which is associated with a reduced ability of the material to polarize due to the replacement of the carbon matrix with air inclusions. The feasibility of using induction heating to achieve a stable temperature gradient during thermal processing is substantiated, along with the application of microwave probes for non-contact local monitoring of dielectric parameters. It is shown that integrating dielectric diagnostics data into digital control systems enables real-time adaptation of technological regimes, ensuring the accuracy, stability, and repeatability of the final material’s properties. The obtained results can be applied both within the framework of real-time process control and for validating numerical models used in the design of CCCM manufacturing processes. They may also be useful for applications across various industrial sectors.