| The clean energy using and the development elevation of temperature enables the fuel cell automobile to become various countries attention gradually the hot spot. Proton exchange membrane fuel cell (PEMFC) because of its low temperature (60-120℃) run,to start fast, high-power density, to demand power change response well and so on, enjoy the favor well. Bipolar plate is one of the core components in PEMFC. Stainless steel sheet is the best candidate for bipolar plate manufacturing materials, the use of stainless steel bipolar plate can be possible to raise the quality power density and the volume power density of fuel cell enormously.The main task is to the bipolar plate anode plate, coolant flow field box and cathode plates welded together, and to guarantee that the formation of bipolar plate is not deformed. The main contents of the study is to determine the solder of stainless steel vacuum soldering, the soldering technological parameter choice to joint shearing strength influence and the solder choice to joint corrosion property influence. At last ,design the corresponding fixture and use the optimized parameters to solder the stainless steel bipolar plate.The results indicated that the Sn-Ag solder must surpass the Sn-Pb solder in the wetting effect of stainless steel. when the silver compound is from 2% to 4%, with the increase in the amount of silver, wetting area has been the increase. When the silver compound reached 4%, the maximum wetting area.When the silver compound is between 4% and 6%, with the increase in the amount of silver, gradually reduce the size of wetting; For TS- 2AgSn, the best soldering temperature is 230℃, for TS-4AgSn, the best soldering temperature at 250℃,for TS-6AgSn, the best soldering temperature at 260℃.The parent metal surface roughness is advantageous to solder moistness. Used the vacuum soldering method to solder stainless steel bipolar plate, in three kinds of solders, uses the TS-4AgSn solder the attachment intensity to be highest, the TS-6AgSn solder next best, the TS-2AgSn solder is the smallest. Used vacuum soft brazing method to braze stainless steel bipolar plate, the joint gap to 0.15mm, the holding time to 15min, the highest joint strength. In the electrolyte 0.5mol/L H2SO4 and 5ppm F- solution ,the brazed joints of the interface have had a galvanic corrosion, the use of TS-4AgSn solder has been the head of the brazing stainless steel corrosion current density value of the minimum 1.67μA·cm-2. Compared with laser welding, vacuum soldering techniques is more effective control of the welding of the stainless steel bipolar plate deformation. |
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