Study On Service Performance Of Asynchronous Rolling Pure Titanium And Its Soft Die Forming Process Of PEMFC Bipolar Plate

Bipolar plate plays an important role in distributing reactant gas,collecting current,mechanical support,hydrothermal management and separating anode and cathode reactant gas in Proton Exchange Membrane Fuel Cell（PEMFC）.It has attracted extensive research at home and abroad.At present,the key problem is how to achieve high corrosion resistance and ensure the service life of the whole system on the premise of ensuring reasonable conductivity.In view of the above problems,in this paper,on the premise of the existing surface modification technology,the corrosion resistance of the metal after surface modification is improved by increasing the corrosion resistance of the matrix itself.To improve the corrosion resistance of titanium plate,high-ratio differential speed rolling（HRDSR）is used to control the microstructure of titanium matrix,such as grain size,texture strength and grain boundary type.The asynchronous rolling process was simulated by ABAQUS,and the influence of the process parameters of asynchronous rolling on the deformation of titanium plate was analyzed.The mechanical properties and corrosion resistance of titanium plate after asynchronous rolling were tested,the sample with different speed ratio of 2 had the best comprehensive performance.The tensile strength is about 477 MPa,the hardness is 168.5 HV,the corrosion potential is-359.61 m V,and the corrosion current density is 428.85 n A·cm^-2,which meets the corrosion resistance index of bipolar plate(corrosion current density<10³ n A·cm^-2).Based on the above experiment and finite element simulation results,the optimum technological parameters are listed as follows:different speed ratio is 2,and the annealing temperature is 400℃.The titanium plate made by this process was punched with soft film,and the influence of cylinder pressure on the forming quality of bipolar plate channel was analyzed.The optimal cylinder pressure range was 6.8-7.0 k N by testing the fitting degree between the channel and the mold accompanied with calculating the thick Ness uniformity of the channel spine.Finally,pure titanium bipolar plates with excellent corrosion resistance,mechanical properties,good filling and high surface quality were successfully prepared.