"Kinetics of Liquid-Solid Displacement Reaction" 

Glenn Peterson, MSE PhD Candidate 

Advisor: Professor Michael Sangid and Professor Kenneth Sandhage

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Abstract:

Defense, aerospace, and nuclear applications rely heavily on materials able to withstand extreme environments. Of potential solutions, ceramic-metal (cermet) composites can address several fundamental concerns such as temperature, mechanical behavior, and oxidation/corrosion resistance. Forming refractory metal/ultra-high temperature ceramic composites is not intuitive. A novel method of processing these materials is through reactive melt infiltration. In general terms, this is a process where a liquid fills a porous perform, and a displacement reaction occurs. A thermodynamic analysis is presented, and several models for reaction rate are developed for evaluating various controls of solid-liquid displacement reactions. Two common rate limiting steps are chemical reaction or diffusion controlled. Knowledge of reaction constants-necessary data points-must be experimentally determined and can be subsequently used to derive activation energies. These activation energies are one of the tools used to identify the rate limiting step for a given reaction. Fundamentally, determining the reaction rate for a system enables the capability to scale up a process and make usable engineering components.