Formation and characterization of electroformed nickel based structures

Date

2024-1-25

Author

Başkan, Mertcan

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Nickel electroforming process has been used for critical applications such as erosion shields or combustion chambers in liquid propellant rocket engines. Although there are many studies based on electroforming in the industry and academic environment, most of them focus on the MEMS applications. On the other hand, this thesis was based on the utilization of the electroforming process for structural parts rather than electronic applications. In this thesis, the nickel sulfamate based electrolyte composition and other deposition parameters were determined by experimental methods. Then, the Ni-Co platings, which were obtained by the addition of cobalt sulfate, were studied and compared with the pure nickel platings. Finally, Ni-Co functionally graded alloy platings were obtained by changing the electrolyte composition and current density to combine the advantages of each plating type. For electroforming studies, a channeled structure was selected as a case study and pretreatment and electrodeposition steps were discussed in detail. A new method, which yields quantitative information about the adhesion strength between the substrate and the electroformed layer, was developed. Also, the developed method vi was applied to AISI 304L stainless steel substrate and nickel electroformed layer and the effects of surface roughness and heat treatment on the adhesion strength were investigated. The adhesion strength changed in the range of 91 to 170 MPa depending on the surface roughness and heat treatment operations. Finally, the nickel electroforming process was simulated via Comsol Multiphysics software and different electroforming configurations which aimed to have homogeneous thickness distribution throughout the part were run. Among these, the use of a dummy cathode was the most effective method for preventing localized thickness increase due to the edge effect.

Subject Keywords

Electroforming, Electroplating, Alloy plating

URI

https://hdl.handle.net/11511/108496

Collections

Graduate School of Natural and Applied Sciences, Thesis