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Description
The efficiency of the fuel cell largely depends on the minimization of ohmic losses. This is determined by such factors as the choice of material, as well as the constructive assembly. The developed functional coatings for current collectors/bipolar plates molten carbonate fuel cells will allow to increase their electrical conductivity and oxidation resistance compared to traditionally used ones. Existing mathematical models require additional parameters that can only be obtained by experimental methods. The obtained correlation dependencies of area surface resistance on temperature, clamping
Summary of the results
A coating based on chromium nitride on a steel substrate was obtained by the physical vapour deposition (PVD) method. According to the results of chemical analysis, the phase composition corresponds to stoichiometry. X-ray phase analysis showed that the coatings contain a chromium nitride phase. The technological parameters of obtaining such a coating have been determined, namely, a nitrogen pressure of 2 Pa and a bias voltage of 150 V. The obtained coatings have a high characteristic of oxidation resistance. The textured coating with a thickness of 16.6 microns has the best oxidation resistance at 600°C. Chemical analysis showed that in such coating after long-term oxidation, the share of oxygen is the smallest, and X-ray analysis did not record the presence of chromium oxide. It was established that after exposure for more than 500 hours, oxygen saturation of the coating material occurs and phase stabilization occurs. It is shown that after waiting for 2...3 hours, the value of the contact resistance stabilizes and reaches a plateau, so it can be stated that for mathematical calculations it is enough to take the value of the contact resistance after 2-3 hours. All coatings based on chromium nitride have 7 times lower ASR values at 650°C compared to uncoated steel. This allows us to propose this type of coating for current collectors/bipolar plates molten carbonate fuel cells.