Study on Etching Technology and Diffusion Bonding Process in Manufacturing Stainless Steel Heat Exchangers with Internal Microchannels
摘要
The microchannel heat exchanger is of great importance in industrial fields due to its advantages of miniaturization, large surface area to volume ratio and high heat transfer rate. The manufacturing process mainly involves chemical etching of the laminates and diffusion bonding between the laminates. In this work, 304 stainless steel sheet was selected as the laminate material, the influence of the etchant composition and etching parameters (etching temperature and spray pressure) on the accuracy and surface roughness of the stainless steel surface microchannel was systematically investigated. The optimal process parameters for chemical etching of microchannels were determined (etchant composition: 10% H2O2 + 8-9% HCl, etching temperature 20-25 °C and spray pressure 0.5-0.6 MPa). The vacuum diffusion bonding method was used to achieve interface bonding of stainless steel. With the optimized bonding parameters, an excellent stainless steel bonding interface was achieved. The influence of the bonding parameters on the bonding ratio and deformation of the joint was investigated. The hardness and thermal conductivity of the bonding interface were characterized. The optimal bonding parameters were 950 °C-30 min-5 MPa. The interface bonding ratio can reach more than 98%, and the corresponding joint strength can reach 539.6 MPa at room temperature. The above research results are of great importance for realizing a low-cost, high-efficiency and controllable manufacturing process for internal microchannel heat exchangers.