A passive oxidation, finite element kinetics model of an Ultra-High Temperature Ceramic composite

Abstract A finite element analysis of an Ultra-High Temperature Ceramic (UHTC) composite was conducted to observe the self-healing property of such a class of materials during damage propagation. In this work, a constitutive relation is presented to the composite that couples oxygen kinetics in from UHTCs additives with quasi-brittle damage propagation. The model is solved in a finite element framework, with polycrystalline multiscale material calculations obtained through a Representative Volume Element (RVE) calculation. The self-healing was obtained from self-healing time population and strength recovery during fracture for passive oxidation conditions, while accounting for loading beyond fracture limits and reloading past such limits. The oxidative model set by an Arrhenius relation is used to show the passive oxidative reaction role in changing the constitutive relation through change of a damage parameter for a quasi-brittle constitutive model. A single element study has been introduced to illustrate both the constitutive behavior and the self-healing population with time during passive oxidation at multiple temperatures. Also, a model was set to obtain the flexural strength of a Zirconium Diboride-30% Silicon Carbide ceramic composite to observe the strength recovery from oxidative additives for loading and reloading. The model captured the flexural strength recovery during reloading past the fracture limits and concurrent passive oxidation, where the strength has increased from 675 MPa to 746 MPa.