Failure modes thermal degradation

PEMFC chemical, thermal and mechanical degradation. These overarching failure categories can contain numerous individual failure modes that a PEMFC can experience. 

Failure mode XIII Seal embrittlement. Its causes are idle periods between use, contaminants, thermal degradation, and fluid/seal incompatibility. 

Oxide spallation is one of the modes of failure in TBCs, usually observed when the substrate is a Ni-based superalloy containing active elements like Hf. Driving force for spallation is provided by the continued buildup of thermal stresses during cooling, particularly at regions of the oxide-BC interface where internal oxidation of Hf has occurred. Degradation of thermal stability of the BC... 

Membrane degradation can result in loss of the electrolyte, loss of separator functionality, and severe fuel cell failure. In following sections, three membrane degradation modes—chemical, mechanical, and thermal—are introduced. 

Failure too is nebulous. Various degradation modes can occm, including a shift in transformation temperature, a reduction in the available strain, walking (or ratcheting), and fi-acture itself. Thermal cycling with no applied load can even result in some degradation. See Ref 40 to 43 for further information. 

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