Research On The Manufacturing Process Of Diffusion Bonding Of Copper Microchannel Heat Exchanger

Microchannel heat exchanger,as a closed and efficient heat dissipation device with precise microchannel heat dissipation structure,is one of the key components in the heat dissipation system of high thermal load equipment in the field of national defense industry.Conventional welding technology is difficult to manufacture closed hollow structural parts with many welding interfaces and complicated shapes,and the diffusion bonding can effectively break through the bottleneck of the above manufacturing technology.The diffusion bonding process is a key technology to realize the manufacture of microchannel heat exchangers,and it is necessary to precisely control the internal microchannel deformation under the premise of ensuring the quality of bonding.However,at present,there are few domestic studies on how to ensure both the bonding rate and deformation control of the micro-channel in the diffusion bonding process.For this reason,the paper takes the T2 red copper microchannel heat exchanger as the research object and conducts an in-depth and systematic study on its diffusion bonding manufacturing process.The main research contents and conclusions of this paper are as follows:1.With the bonding quality of temperature 780°C,pressure 5.5MPa and holding time 90 min as reference,the T2 copper diffusion bonding test is carried out by a single variable principle.When the temperature increases from 720°C to 780°C,the bonding rate increases 20.66%,the deformation increases 0.09mm;when the pressure increases from 5.5MPa to 8.5MPa,the bonding rate increases 28.29%,the deformation increases 0.175mm;when the holding time increases from 60 min to 150 min,the bonding rate increases 18.27%,and the deformation increases 0.099 mm.The effect of pressure on the bonding rate and deformation is most obvious.2.By keeping the bonding temperature and pressure as constant,and increasing the holding time by equal gradient,the bonding process of T2 copper diffusion interface is studied.The reason why the interface still has obvious boundary after diffusion bonding is analyzed: the coarseness of the copper crystal grains at high temperature and the oxide inclusions that may exist at the joint interface that hinder the transfer of the grain boundaries.3.Based on the orthogonal experiment,a nonlinear model between the T2 copper diffusion bonding process parameters and the bonding quality is constructed by BP neural network.The model prediction accuracy is 98.56% and the relative error is below 5%.Based on this model,the T2 copper diffusion bonding process parameters optimization model is constructed.The multi-objective optimization method is used to obtain the suitable process parameters: temperature 780°C,pressure 7.5 MPa,holding time 120 min.Under this condition,the bonding quality meets the requirements.The mechanical properties of shear strength and microhardness are tested.4.Based on the above researchs of T2 copper diffusion bonding,the manufacturing process of diffusion bonding of T2 copper microchannel heat exchanger is verified.The results show that the overall deformation size of the microchannel heat exchanger parts is small,and the ultrasonic C-scan shows that the interface is well connected.At the same time,the pressure and leakage resistance detection is satisfied,and the internal micro-channel deformation is small,which meets the heat exchanger design requirements.In this paper,the effects of diffusion bonding process parameters on bonding rate and deformation are studied by means of experimental research,theoretical analysis and experimental verification.The copper microchannel heat exchanger is manufactured with optimizational process parameters that can satisfy the requirement of related design,and successfully assemble to a type ships phased-array radar cooling system,which can provide reference for the welding fabrication of other types of micro-channel parts and internal precision parts with precision components.