ايجاد پوشش نانو الكترولس نيكل بر روي فولاد AISI316 به عنوان صفحات دوقطبي در پيلهاي سوختي با غشاي الكتروليت پليمري

چكيده انگليسي :

Electroless Nano Structured Nickel Coating on the AISI316 Steel as a Bipolar Plate in Proton Exchange Membrane PEM Fuel Cell Behrang Bazoo bazoo behrang@yahoo comEmail address Date of submission July 30 2011 Department College of Material Engineering Isfahan University of TechnologyDegree M Sc Language FarsiSupervisor s Name and Email address A Saatchi asaatchi@cc iut ac irS M Moonirvaghefi mah vagh@ma iut ac irAbstractThin sheets of stainless steel are low cost material for fuel cell components that can be easily formed to yieldcompact volume Stainless steel satisfies many of the requirements for proton exchange membrane PEM fuelcell bipolar plates except its corrosion behavior under the fuel cell operating conditions Contact resistance as aresult of metal oxide formation and metal dissolution can cause contamination of the membrane electrolyteassembly MEA These problems can be solved by coating stainless steel plates with corrosion resistant andconductive layers This process should be able to make significant improvement on the corrosion resistance andthe electrical resistance at a reasonable cost In this study AISI 316 stainless steel was coated with theelectroless Ni P alloy deposits After 45 minutes 150 minutes and 5 hours deposition thickness of coating wereabout 10 30 and 60 microns respectively and these coatings done in deferent pH as 4 2 4 7 and 5 2 Depositionrate in lower pH is lower than higher pH X ray diffraction analysis showed that the low pH coatings had semi amorphous structures and the high pH coatings had semi crystalline structures The structures were mixture ofamorphous phase and nano crystalline phase Low pH coating contained Ni 111 middle pH coating containedNi 111 Ni3P 200 Ni3P 211 Ni3P 311 Ni3P 411 Ni3P 640 Ni3P 431 and high pH coating containedNi 111 Ni 220 Ni3P 200 Ni3P 211 Ni3P 311 Ni3P 411 Ni3P 640 Ni3P 431 To evaluate the corrosionresistance of the coated plates polarization and electrochemical impedance spectroscopic EIS studies of theplates were performed in a simulated proton exchange membrane fuel cells PEMFCs environment withsolutions of 0 5M H2SO4 2 ppm F Tafel polarization testing showed corrosion rate in coating with lower pHis better than corrosion rate in coating with higher pH in samples with 4 2 4 7 and 5 2 pH coating corrosionrate were 0 12 0 20 and 0 71 A cm2 and in AISI316 is 0 63 A cm2 Tafel polarization testing showedCorrosion potential in coating with lower pH is better than corrosion rate in coating with higher pH in sampleswith 4 2 4 7 and 5 2 pH coating corrosion potential were 294 360 and 398 mV Electrochemical impedancespectroscopy testing after 1 hours immersion of samples in simulated solution showed resistance pittingcorrosion Rpore increase with decrease pH Electrochemical impedance spectroscopy testing after 38 daysimmersion of samples in simulated solution showed the solution could diffuse through coating The electricalproperty was also evaluated by performing an interfacial contact resistance ICR measurement Interfacialcontact resistance ICR measurement shown in coating with higher pH interfacial contact resistance is lowerthan interfacial contact resistance in coating with lower pH but after corrosion testing Interfacial ICR increased The polarization and electrochemical impedance spectroscopic EIS studies endorsed improvedcorrosion resistance of the coated plates The interfacial contact resistance ICR tests have also shownacceptable contact resistance However the Ni P deposited AISI316 bipolar plates showed a better performancethan the uncoated AISI316 bipolar plates more study is highly required for the development of metallic bipolarplates of proton exchange membrane fuel cells PEMFCs Keywords metallic bipolar plates proton exchange membrane fuel cell electroless Ni P corrosion resistance interfacial contact resistance

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ايجاد پوشش نانو الكترولس نيكل بر روي فولاد AISI316 به عنوان صفحات دوقطبي در پيلهاي سوختي با غشاي الكتروليت پليمري

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