Study Of Low Stress Ni Electroforming Technology And Engineering Application

The X-ray focusing telescope for the Enhanced X-ray Time Varying and Polarization Space Observatory(e XTP)project consists of multiple sets of coaxial confocal lenses nested and assembled.In order to increase the effective area and reduce the weight,it is required that the lens should be as thin as possible on the basis of ensuring the mechanical properties.And the traditional machining methods can no longer meet the accuracy requirements,so it is necessary to use the electroforming technology for manufacturing.The internal stress of electroformed lenses tends to be 0 MPa,to prevent stress from causing deformation,and the thickness of electroformed lenses should be uniform.In order to achieve the above purpose,this paper studies the law of the influence of various factors on the internal stress of electroformed nickel,and simulates the current density and thickness distribution to guide the engineering application of electroformed X-ray focusing mirror lenses.In this paper,the influence of concentration of main salt and additive,temperature,p H value and current density on the internal stress of electroformed nickel was studied by using sulfamate nickel electroforming system.The results of measurement by bending cathode method show that the internal stress of electroformed nickel will change from tensile stress to compressive stress if the temperature is increased.And it will change from compressive stress to tensile stress with the increase of current density.The internal stress of electroformed nickel is the lowest when the plating solution p H is 4.0.The optimized process conditions are: nickel sulfamate 350 ? 400 g / L,boric acid 30 g / L,nickel chloride 10 g / L,additive 2 ml / L,sodium dodecyl sulfate 14.3 ml / L.The p H range of the electroforming solution is 3.8?4.0,the electroforming temperature is 50?,and the current density range is 1.5?2.5 A/dm~2.When the current density is in the range of 1.5 to 2.5 A / dm~2 and the temperature is in the range of 40 to 55 ?,the hardness of electroformed nickel will gradually decrease if the current density increases,and it will gradually increases with the increase of temperature.In order to improve the uniformity of x-ray focusing lens,the current density and thickness distribution in the electroforming process were simulated by Using the secondary current distribution corresponding to the electroplating module in the software.The results show that the anode configuration has a significant effect on the current density distribution.The current density in the middle of the core mold appears a maximum value.Reduce the distance between the lower end of the mandrel and the anode,the current density in the middle of the mandrel will be at its maximum;The distribution uniformity of current density can be improved by installing the auxiliary cathode on the top and bottom of the spindle,and the thickness deviation of the electroformed lens can be reduced.Moreover,the higher the auxiliary cathode is,the more uniform the current density and the thickness of the deposition layer will be.According to the requirement that the thickness deviation of 540 ?m for x-ray focusing lens electroforming is less than 10%,the anode configuration and auxiliary cathode are designed by simulation.The simulation results shou that when the top center of the core mould is 500 mm away from the anode,the bottom center is 400 mm away from the anode,and the upper and lower ends are installed with 200 mm auxiliary cathode,the deviation of the average thickness of 544.3 ?m lens electroforming is 9.3%.According to the simulation of current density distribution and the results of stress experiment,the bath fabrication,anode configuration and electroforming solution configuration were carried out.30 different types of x-ray focusing lenses were obtained by electroforming.