Ultra-High Temperature Ceramics (UHTCs) such as silicon carbide (SiC) typically oxidize in extreme environments, which can result in swelling deformations and internal stresses that cause fracture. In this paper, we present two approaches to computationally model this class of technical ceramic failures, and we apply them to SiC. First, a thermodynamically-consistent continuum theory of thermo-chemo-mechanics is specialized to describe thermally-activated oxidation-induced swelling in UHTCs. In transport-limited cases, the specialized model is shown to capture the molecular diffusion of oxidant through the reaction product layer using only fundamental transport properties, i.e. without the need for calibration to reaction experiments. Second, a phenomenological model is presented that can be calibrated to passive oxidation experiments or alternatively to the fundamental model. We use this second approach to analyze oxidation-induced swelling, delamination and fracture in SiC. We implement both models in a computational discontinuous Galerkin (DG) interfacial multiphysics framework, which enables the analysis of enhanced oxidation along fractured surfaces as well as oxidation-driven fracture. We conduct simulations that provide a full description of the progression of the delamination front. Among the important new insights obtained from the analyses, we infer a direct functional dependence between the temperature-dependent oxidant diffusivity and the delamination rate.

中文翻译：

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超高温陶瓷中氧化驱动断裂的多保真度分析

碳化硅 （SiC） 等超高温陶瓷 （UHTC） 通常在极端环境中会氧化，这可能导致膨胀变形和内应力，从而导致断裂。在本文中，我们提出了两种对这类技术陶瓷失效进行计算建模的方法，并将它们应用于 SiC。首先，热化学力学的热力学一致连续体理论专门用于描述 UHTC 中热激活氧化诱导的溶胀。在传输受限的情况下，专用模型显示仅使用基本传输特性即可捕获氧化剂通过反应产物层的分子扩散，即无需校准反应实验。其次，提出了一个现象学模型，该模型可以校准为被动氧化实验或基本模型。我们使用第二种方法来分析 SiC 中氧化诱导的膨胀、分层和断裂。我们在计算间断伽辽金 （DG） 界面多物理场框架中实现了这两个模型，从而能够分析沿断裂表面的增强氧化以及氧化驱动的断裂。我们进行模拟，提供分层前沿进展的完整描述。在从分析中获得的重要新见解中，我们推断出与温度相关的氧化剂扩散率和分层速率之间存在直接的功能依赖性。