高频脉冲电镀电源设计 毕业论文.doc

LANZHOU UNIVERSITY OF TECHNOLOGY 毕业设计(论文) 题 目 学生姓名 学 号 专业班级 指导教师 学 院 答辩日期 摘 要 电镀，即采用电化学的方法使金属离子还原为金属，并在金属或非金属制品表面形成符合要求的平滑、致密的金属覆盖层。电镀后的镀层性能在很大程度上取代了原来基体的性能，起装饰和防护作用，随着科学技术与生产的发展，电镀工艺已遍布各个领域。但目前电镀技术仍存在某些缺陷，诸如加工时间长、镀层厚度均匀性差、镀层容易出现缺陷以及存在较大内应力等。这些缺陷大大限制了电镀技术的应用和发展，不能适应当前的生产，尤其是精密制造的需要。 脉冲电镀实际上是一种通断直流电镀。脉冲电镀过程中，当电流导通时，脉冲(峰值)电流相当于普通直流电流的几倍甚至几十倍，正是这个瞬时高电流密度使金属离子在极高的过电位下还原，从而使沉积层晶粒变细;当电流关断时，阴极区附近放电离子又恢复到初始浓度，浓差极化消除，这利于下一个脉冲周期继续使用高的脉冲(峰值)电流密度，同时关断期内还伴有对沉积层有利的重结晶、吸脱附等现象。这样的过程同期性地贯穿整个电镀过程的始末，其中所包含的机理构成了脉冲电镀的最基本原理。 本设计采用pic单片机对脉冲进行控制，实践证明，脉冲电镀在细化结晶、改善镀层物理化学性能、节约贵金属等方面比传统的直流电镀有着不可比拟的优越性。 关键词：电镀；脉冲电源；pic单片机 Abstract Electroplating, namely by electrochemical method to make the metal ion to metal, and formed with smooth, dense requirements of the metal coating on the surface of metal or non-metal products. The performance of plating plating after replacing the original matrix to a great extent, play a role of decoration and protection, with the development of science and technology and production, electroplating process across the field. But the electroplating technology still has some defects, such as long processing time, coating thickness uniformity of coating, prone to defects and the presence of larger internal stress. These defects greatly limits the application and development of electroplating technology, cannot adapt to the current production, especially the need of precision manufacturing. Pulse electroplating is actually an on-off DC plating. Pulse electroplating process, when the current is switched on, the pulse (peak) several times the current equivalent to an ordinary DC current or even several times, it is the instantaneous high current density of metal ions reduction in potential high, so the grain became fine; when the current is turned off, the cathode area near the disch