Study On Improving Reflective Performance Of Nickel Casting Layers By Ultrasonic Pulse Microelectroforming

Glass micro bead reflective film is often used in previous years. However, a new type of micro prism reflective film with reflecting higher brightness and lower manufacturing cost was born with the rapid development of science and technology, and it is used in the fields of airport, wharf, billboards, photography and manufacturing of traffic signs in recent years widely.The making process of micro prism reflective film, including unit array structure designed, master maked and replicatied, substrate determinated and thermal imprint processing. Master replicating is achieved with making nonreflective micro prism nickel plate of convex into copied by microelectroforming process to formating layer of concave. In order to obtaining reflective film of high reflective performance, controlling microelectroforming process strictly has becomed a very important link.There are many factors affecting the process of microelectroforming including current density, ultrasonic power and frequency, solution temperature, solution stirring method, plate spacing, electroforming solution composition and p H values of the solution. Therefore, it is important to studying the effect of process parameters on obtaining nickel casting layers with high reflective performance. In this paper, the main research contents are presented as follows:(1) The basic characteristics and application fields of micro prism reflective material are described first, and reflective principle and manufacturing process of which is also stuied. The principle and process characteristic of microelectroforming is studied by theoretical analysis, and research direction of microelectroforming with ultrasound and pulse is discussed, respectively.(2) The electrochemical basic principle in the process of microelectroforming is studied. The mechanism of ultrasonic vibration and pulse power affecting significantly in the process of microelectroforming is analyzed, thus microelectroforming experiment principles of ultrasonic direct current, bidirectional pulse and ultrasonic+pulse are obtained. The experimental platform is built for the reasons mentioned above, thus influence laws of ultrasonic frequency, ultrasonic power, current density, pulse duty ratio and plate spacing affecting on the process of microelectroforming are studied.(3) The experimental materials and electroforming solution are prepared. According to the microelectroforming experiment principle of ultrasonic direct current, bidirectional pulse and ultrasonic+pulse, the experiments of orthogonal and single factor are carried with taking reflective coefficient and micro hardness of nickel casting layers to be as index on the experimental platform.(4) The reflective coefficient, surface morphology and micro hardness of nickel casting layers obtained through experiments are measured by detective methods of Inverse Reflection Coefficient, Field Emission Scanning Electron Microscopy, Confocal Laser Scanning Electron Microscopy, X Ray Diffraction and Micro Hardness, and the experiment results are also be analyzed.Comprehensiving analysis with the experimental results obtained, conclusions are shown below: A trend of increasing first and then decreasing with the increased of ultrasonic power, current density, duty ratio and plate spacing is presented by reflective coefficient of nickel casting layers changed in the range of this paper. The excellent performance of nickel casting layers can be obtained by pulse current density of 8A/dm2, and for ultrasonic power of 210 W, pulse duty ratio of 20% be also exerted.