Phase-Field Model of the Silicon Carbide System

Abstract

Silicon carbide (SiC) is a versatile material that is a semiconductor with many highly suitable properties for various applications. It is a part of a group of materials, ceramic matrix composites (CMCs) which have gained notoriety presently for their valuable properties in fields such as aerospace, automotives and aviation. Though SiC is a multi-faceted material, there is still much to learn and there exists an opportunity to exploit it for further gains. Computational simulations have been instrumental in identifying information that is difficult to obtain experimentally. Recent literature has shown that phase-field modeling is a valuable tool in the simulation community to examine a variety of materials, interfaces, and/or physical phenomena. By utilizing computational methods in concert with experimental validation, we can seek ways to improve the properties and performance of CMCs. Knowledge of the microstructure of a material is the key to not only controlling the properties of a material but also predicting properties as well. Computer modeling and simulations are in high demand and have become a more integral part of materials science and engineering. The presented work details a computational phase-field methodology for the modeling of the microstructure evolution of the binary Si and C system. In short, the preliminary model based on phase-field methodology is used to investigate the evolution of the microstructure of SiC that is modeled as a result of green bodies created using reactive melt infiltration (RMI) by molten sil-icon. This project seeks to develop a phase-field model (PFM) by which the interaction of the available processing parameters of these materials influences the kinetic and microstructure evolution of the composite. We use CALPHAD descriptions as well as the SGTE (Scientific Group Thermodata Europe) data for pure elemental database for the thermodynamics of the bulk phases (C, Si, and SiC) [1]. We begin with the growth of the silicon carbide layer at the initial stage and analyze the consumption of residual silicon that is present in the melt and measure the growth of SiC at the interface. In addition, we will describe the parameterization of the model in which we will compare a variety of parameters that are vital to the evolution of the simulation which will affect not only the interfaces but affect the composite that is created and the behavior of SiC as the simulation progresses. This will serve as an introduction to the optimization of properties for future CMCs as well. The simulations can then be compared to experimental values as we seek to bring together experimental and computational experiments for analysis. Planned work seeks to use this methodology to explore various changes in the initial model such as thickness of SiC growth over time, which properties have a greater impact on the evolution of the interface and the microstructure in the simulations and how they compare to experimental results. Also, the opportunity to run a design of experiments is suggested to aid in the parameterization of the model for a broader temperature and property range. We are also interested in identify-ing experimental information that is scarce for this reaction such as diffusivity values, interfacial energies, and mobilities.