| Electroforming is a nontRaditional machining technology in which a metallic part is produced by the electrodeposition of metal onto a cathode mandrel in an electrolytic bath. It has high fidelity of shape reproduction without heat affected zones, cutting force and tool wear, which is mainly used for the metallic parts that are difficult to manufacture for tRaditional machining. Now it has been successfully employed in the areas of aviation, aerospace, weapon, automobile and so on.However, there are still some disadvantages in applications of tRaditional electroforming that are difficult to be overcome. For example, poor surface with pinholes and nodules usually appears in the electroforming of complex parts with thin wall. In the process of Ni-Mn alloy electroforming, there is cRack problem due to the nonuniform distribution of element composition besides poor surface. Because of internal stress, micro cRacks will appear in the tRaditional chromium electroforming. As a result, the development of electroforming is seriously restricted.A novel electroforming technique named AbRasion-assisted Precision Electroforming (APEF) is utilized to resolve the problems of tRaditional electroforming in the area of applications. Electroforming of nickel, Ni-Mn alloy and chromium is respectively researched in the dissertation. The main works focused on the research and application of APEF as follows:1. In order to resolve existing electroforming problems of complex parts with thin wall, APEF with orbital movement cathode was put forward. The mechanism of APEF has been studied by experimental and theoretical analysis. The results showed that the polishing, extruding and impacting with free particles could effectively eliminate the pinholes, pits and nodules caused by hydrogen evolution. Simultaneously, free particles that touch tightly the cathode surface move in Random directions, which can effect the electric field distribution of cathode surface just like pulse electroforming. As a result, bright layers with finer gRains and better properties were obtained.2. A new precision electroforming machine and orbital movement device have been developed. Feeding mechanism, rotated main axis and orbital movement device were assembly designed to make the machine easily be opeRated. Particularly, orbital movement device with larger orbital moving amplitude and frequency was designed to expand the scope of electroforming objective.3. Nickel electroforming by APEF with orbital movement cathode has been researched. The morphology, microstructure and properties of nickel electroformed with various processing paRameters were studied. The results showed that the APEF can observably improve the surface quality, and produce a bright nickel deposit with surface roughness of less than Ra 0.056μm. The degree of preferential orientation notably decreased and each preferential orientation changed, the gRain size obviously decreased less than 150nm. Both micro hardness and tensile strength of the deposits could be increased by double in contRast with the sample produced by tRaditional electroforming methods. Based on the experimental results, complex blade cathodes with smooth surface and higher micro hardness Ranging from 380HV to 400HV were produced successfully.4. In order to resolve the existing problems of surface quality, electroforming Rate and nonuniform distribution of element composition on the outer shell of thrust chamber of rocket engine, experiments of Ni-Mn alloy electroforming using APEF were carried out. The manganese contents, microstructure and properties of the Ni-Mn deposits electroformed with various processing paRameters were studied. The experimental results showed that higher current density could be used and the manganese content could be controlled less than 0.5wt% under the condition of low concentRation manganese salt and high tempeRature. The sample produced by APEF was bright and smooth without any defects; the surface roughness was less than Ra 0.05μm and the gRain sizes were refined. Compared with the sample electroformed with tRaditional method, the microstructure changed obviously among which the crystal of (200) is preferential orientation instead of (220) preferential orientation. The micro hardness and tensile strength could be increased too. The bright deposition layers of electroforming Ni-Mn alloy used for the outer shell of thrust chamber of rocket engine were produced successfully with better thickness and uniform distribution of element composition.5. Experimental research of cRack-free chromium electroforming was carried out aimed to permeability gas phenomenon. The geneRation mechanism of micro cRacks was carefully studied. The disturbing of free particles can increase the overpotential of hydrogen evolution, change the microstructure and decrease the internal stress. Therefore micro cRacks in the coating can be eliminated. The corrosion resistance, wear resistance, micro hardness and bonding strength of the chromium coating electroformed with various processing paRameters were studied. The experimental results showed that cRack-free chromium coating without any corrosion after 336 hours neutRal salt fog spRay test can be obtained, the micro hardness was above 600HV, the surface roughness was less than Ra 0.1μm and the bonding strength met the requirement.
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