Reaction-diffusion model for the reaction bonding of alumina-zirconia composites using the intermetallic compound ZrAl3

This paper describes a reaction-diffusion model for the reaction of a gaseous oxidant (O2) and a reactive solid (ZrAl3), which allows for the consumption of the solid and the oxidant. The experimentally determined “kinetic triplet” (i.e. Arrhenius parameters Ea and A and the reaction model f(α)) for the oxidation of ZrAl3 powders is incorporated in the model, which consists of simultaneous mass and energy balances. The resulting system of partial differential equations is solved with the numerical method of lines for the 1D case. The influence of different processing parameters is studied and the numerical results are compared with experimental thermogravimetric data. The model is used to find optimal heating cycles for the production of defect-free reaction bonded alumina-zirconia composites of different sizes and to avoid uncontrollable thermal runaway reactions.