Electroformed Nickel Alloy Precision Thin-wall Technology Research

The theory,characteristic,development,application of electroform technology were reviewed in this paper.Electroform technology have high precision of copy and better imitation,which can process parts super precision.It is mainly used for manufacturing various parts which is difficult or whose cost is high to be fabricated by machining.In recent years,with the development of industry, the needs of multifarious precision,complex superfine parts and the demands of correlative die are sharply increasing,electroform technology is highly recognized.The parts of Ni-Co alloys which are electroformed from sulfate electrolyte have many advantages such as,small density,thin wall,high rigidity,compact structure,slippery surface,et al.and have better application prospect.The influence of electrolyte component,current density,temperature,pH value,additive on the rigidity of electroforming layer,inner stress,electrodepositing speed and the effect of additive on cathode polarization were studied by condition experiment,in addition, Ni-Cu alloys deposition were tried.The results as follows:(1)The rigidity of plating layer rose with the increase of Co²⁺ concentration and declined with the increase of current density and temperature;(2)The inner stress of plating layer increased with the increase of Co²⁺ concentration,rose and then dropped with the current density,it reached maximum value 53.47MPa in 6A/dm²,it dropped with the rise of temperature,the influence of pH value on it are complicated,when pH≤3.0, it increased with the decline of pH,when pH≥4,it increased with the increase of pH,they are pull stress;(3)The electrodepositing speed rose with the increase of current density,increased and then declined with the increase of temperature,it reached maximum value in 50℃;(4)Electrochemistry experiment indicated that every additive in electrolyte both brought different extent effect on cathode polarization,in the light of need,we chose fit additive of strengthening rigidity and brightener to improve quality of electroforming layer;(5)The effects of Ni²⁺concentration on the current density in Ni-Cu codeposition is great,when Ni²⁺concentration is 0.6mol/L,the range of current is 3～5A/dm²,when Ni²⁺concentration is 0.8mol/L,the range of current is 7～12A/dm² or more.The SEM and XRD micrograph indicated that Co content percentage in electroforming layer increased,crystalline became thin and its growth became tropism with the increase of Co²⁺concentration in electrolyte,in addition,the additive brought effect on electroforming layer,in brief,the property of electroforming layer were influenced by various process condition.The cold-shield which were made by electroform technology is the key part in the second infrared imaging system Dewar subassembly.According to the study,the cold-shield that meet the demand can be successfully made if only the fit process flow is chosen and proper process parameter is controlled,it is important to develope new manufacture technology about exact thin wall part and accelerate development of military product infrared detector subassembly in home that the project is to be actualized.