Experimental Study On Internal Stress In Ni-SiC Composite Electroforming

As the core part of UV-LIGA technology,Micro-electroforming technology is widely used in micro-nano manufacturing,especially used in the production of precision,fine structure with high processing costs or which is difficult to achieve with traditional processing.However,the layer obtained by the micro-electroforming process have the disadvantage of large internal stress,which leads to problems such as deformation and shedding of the layer,and even affect the fatigue properties of the electroformed layer,which increases the difficulty and cost of micro-fabrication.In this paper,the Ni-SiC composite electroforming method is used to study the effect of SiC particles and the process parameters on the stress in the electroformed layer by means of the comparative experiment and the orthogonal experiment.Finally,the optimum process parameters of Ni-SiC composite electroforming layer for internal stress are obtained.The internal stress of Ni-SiC composite electroformed layer was measured by X-ray diffraction method according to experimental conditions and sample conditions.Based on the study of the composite electroforming process and the Ni-based composite electroforming materials,SiC particles were selected as the second phase particles of composite electroforming.Then,based on the characteristics of SiC particles,the particle size of SiC suitable for the experiment was selected by preliminary experimental study,and the SiC particles were pretreated by the appropriate method.The electroforming system was selected,and the composite electroforming equipment was set up.The influence of Si C particles on the stress in the layer was studied by experiment and theoretical analysis.It is found that the internal stress of Ni-SiC composite electroformed layer is smaller than that of pure nickel electroformed layer,and the average internal stress value is reduced from-350 MPa to-241.8MPa and the internal stress reduction rate is30.9%.Based on the analysis of the metal polycrystalline growth,the mechanism of the compressive stress of the cast is analyzed from the aspects of the adsorption of organic matter.The effect of SiC particles on the growth of the electroformed layer is briefly analyzed.The SiC particles doped in the electroformed layer increase the friction of the cathode surface,so that the Ni layer is more uniform.Moreover,the embedding of SiC particles increases the probability of lattice micro-plastic deformation,and then release the internal stress.In order to further study the influence of different process parameters on the stress in Ni-SiC composite electroformed layer,orthogonal experiment was carried out.The result shows that the maximum reduction of internal stress is 34%.and the effects of the current density and the SiC concentration are greater than that of the magnetic stirring speed and the electroforming temperature on reducing the internal stress.The optimum process parameters of the composite electroforming layer are: the concentration of SiC is 20 g / L,the current density is 1A / dm2,the magnetic stirring speed is 600 rpm and the electroforming temperature is 50 ?.