Failure modes chemical degradation mechanism

Much recent ongoing work has focused on the chemical degradation mechanisms and revealed that radical attack is the root cause of the membrane decomposition. However, there is still a lack of fundamental understanding of the mechanisms for the degradation of mechanical strength, which is related to the membrane failure mode responsible for the sudden death behavior of fuel cells. 

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. 

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

The primary failure mode for membranes is hole formation, which can be caused by chemical degradation, material fatigue due to mechanical stresses, or a combination... 

There are various improvements that can be made to the presented model, some improvements could be accomphshed. Foremost among these possible future-work directions is the inclusion of nonisothermal effects. Such effects as ohmic heating could be very important, especially with resistive membranes or under low-humidity conditions. Also, as mentioned, a consensus needs to be reached as to how to model in detail Schroder s paradox and the mode transition region experiments are currently underway to examine this effect. Further detail is also required for understanding the membrane in relation to its properties and role in the catalyst layers. This includes water transport into and out of the membrane, as well as water production and electrochemical reaction. The membrane model can also be adapted to multiple dimensions for use in full 2-D and 3-D models. Finally, the membrane model can be altered to allow for the study of membrane degradation, such as pinhole formation and related failure mechanisms due to membrane mechanical effects, as well as chemical attack due to peroxide formation and gas crossover. 

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