SiC composites at elevated temperatures are prone to oxidation, prompting the use of environmental barrier coatings to limit or prevent the ingress of oxidants. Cracks in such coatings can provide fast diffusion pathways that can lead to accelerated local oxide growth. The localized oxide confined at the tip of such features generates significant stress due to the large molar volume change associated with converting SiC to SiO₂. In this work, a multi-physics computational framework is used to simulate the evolution of such internal oxide domains; the framework integrates analyses of oxidant transport, oxide growth (domain evolution) in dry air environments and stress evolution mitigated by creep. Significant insights regarding oxidation-driven damage are obtained from a broad parametric study involving the crack opening, the effective diffusivity of the coating, the crack spacing and the magnitude of applied loads. (i) Oxide growth at the tip of the crack is comparable to that of a bare surface; even very narrow open channels lead to rapid, localized oxidation. (ii) Coatings with low diffusivity produce highly confined oxide ‘bubbles’ at the tip of the crack; confinement produces high compressive stresses in the oxide and significant tensile stresses in the surrounding material. Stresses along the coating/substrate interface and in the substrate beneath the bubble can be 2–7 times those arising from mechanical loading alone, promoting coating decohesion and substrate cracking. (iii) Significant applied stress reduces high hydrostatic stresses in the oxide and mitigate the stress elevation associated with local oxidation. The paper concludes with a brief discussion of the implications of these observations for damage mechanisms occurring at elevated temperature, and indicate the importance of further study of the impact of wet environments and different oxide compositions.

碳化硅复合材料在高温下容易氧化，促使使用环境屏障涂层来限制或防止氧化剂的进入。这种涂层中的裂纹可以提供快速扩散通道，从而加速局部氧化物的生长。_{由于与将 SiC 转化为 SiO 2}相关的大摩尔体积变化，限制在此类特征尖端的局部氧化物会产生显着应力. 在这项工作中，使用多物理计算框架来模拟此类内部氧化物域的演变；该框架整合了对氧化剂传输、干燥空气环境中的氧化物生长（域演化）和蠕变缓解的应力演化的分析。从涉及裂纹开口、涂层的有效扩散率、裂纹间距和施加载荷大小的广泛参数研究中获得了关于氧化驱动损伤的重要见解。(i)裂纹尖端的氧化物生长与裸露表面相当；即使是非常狭窄的开放通道也会导致快速的局部氧化。(二)扩散率低的涂层会在裂纹尖端产生高度封闭的氧化物“气泡”；限制在氧化物中产生高压应力，在周围材料中产生显着的拉应力。沿涂层/基材界面和气泡下方基材的应力可能是单独机械载荷产生的应力的 2-7 倍，从而促进涂层剥离和基材开裂。(三)施加的显着应力降低了氧化物中的高静水压力，并减轻了与局部氧化相关的应力升高。本文最后简要讨论了这些观察结果对高温下发生的损伤机制的影响，并指出进一步研究潮湿环境和不同氧化物成分的影响的重要性。