A Pyrolysis Cycle Optimization Framework for Evaluation of Novel Carbon Precursors

Over the past twenty years, Materials Research & Design, Inc. (MR&D) has been involved on many programs focused on the simulation, development, and study of various pyrolysis processes. The initial pyrolysis of polymer-derived high-temperature composites is a process step during carbon-carbon (C/C) and ceramic matrix composite (CMC) fabrication that poses a significant challenge to the material system, particularly ones utilizing 2D continuous fiber reinforcement. The decomposition induced stresses which result from pore pressure generation and conversion of the matrix from a cured polymer to a porous carbonaceous char can be severe enough to induce delaminations in a component. To combat this, many fabricators utilize conservative, lengthy pyrolysis cycles which are applied to components agnostic of geometry or layup architecture. As domestic manufacturers of C/C and CMCs transition from prototyping operations to production, there exists a need not only to accelerate the rate at which components are produced, but to ensure that the existing processes are not being changed in a way that is deleterious to the manufacturability or structural capability of the resulting material. MR&D and their program partners propose an effort to develop a computational framework for the optimization of C/C pyrolysis cycles. Despite being focused on C/C, the approach will be equally applicable to CMC manufacturers utilizing similar process routes. The Phase II STTR program proposed herein will focus on several carbon precursors. MR&D will work closely with the National Institute for Aviation Research (NIAR) at Wichita State University (WSU) – the Phase II Research Institute (RI) – to characterize various thermo-poro-elastic properties through initial pyrolysis. The measured material properties through decomposition will serve as critical inputs to the computational analyses performed by MR&D. A feasibility demonstration of the proposed pyrolysis cycle optimization methodology would be incomplete without preliminary validation. To this end, MR&D has enlisted the support of Kratos SRE (KSRE) (Birmingham, AL) to perform pyrolysis trials on flat panel materials. These trials will employ the cycles defined by MR&D and the resulting materials will be assessed thermo-mechanically and microstructurally. By these metrics, the Phase II team will assess the degree of material improvement over a baseline pyrolysis cycle, and establish a path forward for transition and commercialization.