Measurement of the impurity gas pressure during combustion of a “gasless” system in a long cylindrical shell

A method for estimating the maximum impurity gas pressure averaged over the specimen cross section in the combustion wave for different cross sections of a long specimen is proposed. The impurity gas pressure in a given specimen cross section is understood as the gas pressure that induces cross-sectional fracture of the specimen enclosed into a shell and certain displacement along the shell of the pressed matter portion located ahead of the combustion wave front at the instant of fracture initiation. Special composite specimens are used to ensure constant conditions of impurity gas removal from the volume and to model the SHS process and associated impurity degassing in the case of long $(L/d\ll1)$ cylindrical specimens under the condition $L=\operatorname{const}$. The model mixtures are chosen to be typical compositions for SHS: Ti+C and Ti + 2B.