| Electroforming technology has been widely used in the precision manufacturing industry due to its extremely high electrodeposition sample preparation accuracy.The capillary metal needle tube has always been a difficult point in the material preparation process due to its small size,high surface and physical and chemical performance requirements.The process can be optimized by computer simulation of the electroforming reaction process.The Comsol Multiphysics software can couple multiple physical fields for analysis and solution.The simulation results of the flow field changes and mass transfer process during the electroforming process are in line with reality.In this paper,combined with the theory of electrodeposition,the electric field equation and boundary conditions of the electroforming are analyzed,and the electrode polarization curve and reaction conditions are obtained through electrochemical experiments.Secondly,according to the polarization characteristics of each electrode,Sn-Pb low melting point alloy and carbon fiber core molds are selected,and the Butler-Volmer model is used to simulate the electrodeposition characteristics of single metal layer and bimetal layer of Au and Cu under different current densities.The simulated cathodic current density distribution is obtained and the time required for deposition of specified casting layer thickness is predicted.Finally,the experimental samples were electroforming experi-ments with the same current density.The surface morphology and roughness of the samples in the actual preparation process were studied by SEM and white light interferometer,and the simulated electroforming process was compared and analyzed.The conclusions are as follows:Comsol software simulates the process of electrodepositing copper castings on Sn-Pb alloy core molds.The results show that when the current density is I=3.5 A/dm~2,the current density distribution is the most uniform.When the predicted thickness of the casting layer reaches 90μm,the thickness error and reaction time error of the casting layer during the electroforming process are the smallest,which are 0.56%and 5.00%respectively;In the gold deposition model of C fiber core mold,the experimental results show that when the predicted thickness reaches 10μm,the minimum error of layer thickness in the electroforming process of I=2.0 A/dm~2 is 6%;In the copper layer depo-sition model of C fiber core mold,the experimental results show that when the predicted thickness reaches 60μm,the minimum error of the casting thickness during the electroforming process of I=3.0 A/dm~2 is 2.8%;In the copper layer deposition model of C fiber core mold,the experimental results show that when the predicted thickness reaches60μm,the thickness error of the casting layer during the electroforming process of I taking 3.0 and 3.5 A/dm~2 does not exceed 3.8%.In the actual electroforming experiment,under the pyrophosphate electroforming copper system,when the system temperature is 35℃,pH=8.6(±0.1),Sn-Pb alloy core mold electrodeposition copper layer,the current density is 3.5 A/dm~2,while the C fiber core mold deposition copper,the current density is 3.0 A/dm~2,the experimental process electroforming process grain size is fine,the surface roughness is the lowest,the surface of the copper layer is smooth and uniform,and the microhardness is up to 1905 MPa.In the cyanide-free gold electrodeposition system,chloroauric acid is the main salt.When the system temperature T=25℃,pH=3.0(±0.1),the C fiber core mold deposits Au,and the current density I=2.0 A/dm~2,the experimental process During the electroforming deposition process,the crystal grains are fine,the surface roughness is the lowest,the surface of the gold casting layer is flat and uniform.In summary,the simulation results of capillary double-layer metal tubes prepared based on electroforming technology have good consistency and economic efficiency.It is feasible to use Comsol Multiphysics to simulate the electroforming process to prepare capillaries. |
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