Experimental Research On Electroforming Of Iron-nickel Alloy Based On The Vacuum And The Rotating Cathode

The low thermal expansion alloy which is represented by the Fe-Ni alloy has been widely used in a lot of fields such as the aerospace, the precision meter and the semiconductor package. Based on the principle of the electrodeposition, the Fe-Ni alloy electroforming process plays an incomparable role in the modern industry because of its fine grain, ease of regulating composition, less energy consumption and low temperature. In order to research the electroforming of Fe-Ni alloy in depth, the vacuum electroforming of Fe-Ni alloy and the Fe-Ni alloy electroforming of the rotating cathode have been proposed in the paper. The following works have been done:1. The traditional electroforming of the Fe-Ni alloy has been conducted and the problems have been summarized and analyzed such as peeling, cracking and the low Fe content.2. An experimental system of the vacuum electroforming of the Fe-Ni alloy has been structured, which is composed of the electrodeposition unit, the vacuum controlling unit, the anode unit, the cathode unit and the temperature controlling unit. The vacuum electroforming experiment of the Fe-Ni alloy was carried out and the composition, the microstructure and the properties of the Fe-Ni layer were tested by a series of physicochemical methods. The results showed that the vacuum electroforming technique can significantly increase the Fe content and diffraction peak intensity of the alloy deposits. Simultaneously the vacuum electroforming can usually improve the surface quality and the micro-hardness and decrease the thermal expansion coefficient of the Fe-Ni layer.3. The fundamental experimental study of the Fe-Ni alloy electroforming of the rotating cathode has been conducted and the thick Fe-Ni alloy electroforming examples which has an ideal Fe content were prepared. The influences of the process parameters e.g. the current density and the rotate speed of the cathode on the composition, the microstructure and the property of the electroforming layer have been analyzed. The results showed that the new process can improve the Fe content and change the microstructure of the Fe-Ni layer and the mechanical and thermal expansion properties of the Fe-Ni layer were influenced by the composition and the microstructure.