Microstructured benchmarking

Bipolar plates in PEMFCs were conventionally made of graphite with excellent corrosion resistance, chemical stability, and high thermal conductivity. However, graphite has a high cost, poor mechanical properties, and very little formability due to its microstructural nature. This limits its further applications as plate material and forces a search for alternative solutions. Nevertheless, the performance, durabilify, and cosf of fhe graphite plate (e.g., POCO graphite and graphite plates) have been taken as benchmark references to compare with those of alternative materials. 

Figure 1.111 Flow rate dependence of the Dushman mixing quality of the interdigital concentric consecutive microstructured mixers of the StarLam series and other micro mixers taken for benchmarking [130].

Figure 1.2 Benchmarking of microstructured reactors. (Adapted from Ref. [11). Copyright <...

The superiority of microreactors for reduced deactivation due to less thermal load on the catalyst has been proven several times (e.g. [47]), even benchmarked to a fixed bed [18] or to a foam [19]. However, one should be careful when operating the catalyst in a microreactor at its kinetic limit. The deactivation behavior of a specific catalyst could be more visible than in a conventional fixed bed or even coated foam. The mass of thin wall-coated catalysts operated free from mass transfer limitations could be much less for reaching 100% conversion. However, there is no backup catalyst mass. Hence additional catalyst mass has to be considered for process layout [20]. Also, leaks and the parallelizing of microstructures (concerning their feed distribution and heat distribution) are a challenge that can influence the catalyst stability and thus the operation of a microreactor [40]. 

Both alloy composition and processing influence the microstructure and phase formation. Composition and microstmcture are the important features that determine the property profile. A major part of the work in the development of an implant is based on research and development, followed by the optimization of the process to achieve a defined property profile. As long as the benchmarks of the previously selected application are not reached, this work has to be revised as often as necessary. 

For this purpose, several oxides were tested and benchmarked as described in [4]. The benchmarking process mainly dealt with experimental work consisting of repeated redox cycling tests and microstructural analysis of pressed samples as well as subsequent XRD measurements to estimate phase composition after various redox cycles. In this study especially the system Fc203-Ca0 was found to be a promising candidate because of apparent low degradation. Possibly, the reversible formation of mixed oxides leads to better... 

---