Stainless steel dual-polar plate welding method

Abstract

A method of welding a stainless two-polar plate comprises following steps: low-melting alloy solder is coated on a compressed positive plate that is provide with a flow field, a channel for pass-in-and-out gas and a channel for refrigerant and one side of the refrigerant of the negative plate which needs to be welded; the coated surface is cleaned; two surfaces of the positive plate and the negative plate coated with the solder that contact with each other are overlapped and put into the flat-bed press to have hot press for 1 to 8 minutes under the temperature of 150 to 180 DEG C and the pressures of 0.5 to 1 MPa; and then the radiating medium is added into the radiating channel of the flat-bed press; the temperature of the flat-bed press is reduced to 20 to 25 DEG C; the two-polar plate is taken out to be cooled until the temperature of the two-polar plate reaches the room temperature; after being welded, air tightness of the two-polar plate is tested to ensure that the finished two-polar plate does not have water or gas leakage. The invention has an advantage that the two-polar plate has simple welding technology and the manufactured twp-polar plate that has good planeness, high strength and uniform performance does not become deformed.

Description

technical field [0001] The invention belongs to fuel cell technology, in particular to the manufacturing technology of proton exchange membrane fuel cell bipolar plates. Background technique [0002] A fuel cell (FC) is an electrochemical power generation device that converts chemical energy stored in fuel and oxidant isothermally directly into electrical energy according to electrochemical principles. With the advantages of high energy conversion efficiency, environmental friendliness, quietness, and high reliability, it is considered to be the preferred clean and efficient power generation technology in the 21st century. [0003] In addition to the general characteristics of fuel cells, proton exchange membrane fuel cells (PEMFC) also have outstanding features such as rapid startup at room temperature, no electrolyte loss, easy water discharge, long life, and high specific power and specific energy. Therefore, it is not only suitable for ground power stations, but also es...

AI Technical Summary

Problems solved by technology

Its shortcomings are: due to the low mechanical strength and poor flexibility of graphite, the graphite bipolar plate is relatively thick, and the machining of the flow field takes a long time and the cost is too high, which cannot meet the commercial requirements of the proton exchange membrane fuel cell (PEMFC). Requirements for cheap production at scale

The disadvantage of the prior art is that when the bonding method is adopted, the adhesive is usually a polymer material, which will swell in solvents such as ethylene glycol and lose its bonding effect, so that the coolant cannot use organic solvents, which limits Low temperature applications for fuel cells; when welding methods are used, typically laser welding, resistance welding or brazing

The high temperature of laser welding or resistance welding can easily lead to deformation of the bipolar plate, and the laser solder joints are easy to corrode; the corrosive material in the brazing solder remains in the coolant cavity of the bipolar plate, which is difficult to clean, causing the bipolar plate corrosion