微粒射流复合电沉积抑制枝状晶的机理及工艺研究

The remaufacturing engineering (RE) has become a hot issue in the field of energy conservation and emission reduction. Electrodeposition of reparative coating on the scrap metal part surface has been a key technology in RE and has shown important values as function of prolonging machine service life and strenthening the sustainable development. Aiming at electrodeposition's inherent deficiency, edge effect, dendrite and non-uniformity, in remedying process, this project uses jet electrodeposition as core process and allows the insulate particles to co-inject with electrolyte onto cathode.By controling particles' friction and disturbance and using electric-field distribution and electrocrystallization as entry-point, this reserch enables flexible restraining dendrites deposit and provides a good finish at one step. As a new exploration to tackle the inherent barrier of electrodeposition , this research includes such aspects as follows:①study electric, flow field in particles-jet compound electrodoposition and explore particle mechanism of action under muti-field condition;②construct particle-jet compound electrodeposition electrocrystallization model, explore the nucleation and growth mechanism under the disturbance of particles and realize process control of the coated metal electrocrystallization;③study the influence law of controllable parameters on the sedimentary surface morphology especially uniformity and performance, set up the dynamic coupling mathematical model ④summarize technological parameters and complete a set of technological process, realize size recovery and performance recovery of scrap parts.

再制造工程是节能减排领域的热点。在废旧机械零部件表面电沉积修复性涂层是再制造工程中的关键技术，对于延长机械使用寿命，实现可持续发展具有重要意义。针对电沉积修复加工中存在的边缘效应（枝状晶、沉积不均匀）的问题，本课题以射流电沉积为核心工艺，将绝缘微粒随同电解液一同喷射到阴极（工件）表面，通过控制微粒的扰动和摩擦，以改善电场分布和电结晶过程为切入点，柔性抑制枝状晶等沉积物，实现制备光整沉积表面的目的，对解决现存电沉积技术障碍是一次新颖的探索。拟开展以下工作：①微粒射流复合电沉积电场、流场分布研究，探索多场耦合条件下的粒子作用机理；②建立微粒射流复合电沉积零件沉积电结晶模型，了解粒子扰动下形核长大机制与长大过程，实现涂层金属电结晶过程的控制；③研究工艺参数对沉积层表面形貌特别是整平性及机械性能的影响规律，建立加工动态耦合数学模型；④形成整套加工工艺，实现废旧零件的尺寸恢复和性能修复。

本项目基于对微粒射流电沉积加工特点的分析以及面向再制造应用的背景，进行了以下研究内容：微粒射流复合电沉积系统设计，微粒射流电沉积对沉积形貌影响的工艺优化，微粒射流电沉积电场、流场分布，微粒射流电沉积在零件再制造方面的应用研究。取得了以下进展：1. 设计并研制出微粒射流复合电沉积加工实验平台，具有加工精确简单实用的特点，总结和制定了一套科学、系统的操作程序和工艺经验以及实验中出现问题的解决方案；2. 开展了微粒射流电沉积过程中影响电沉积表面形貌参数优化，实验发现在加工参数为电流密度150-300A/dm2扫描速度10-15mm/s喷射速度10m/s时沉积颗粒减小表面平整，具有较好的表面沉积质量。添加适量三氧化二铝微米级颗粒（15-30g/L）在电解液中循环可抑制枝晶形成，亦可提升沉积表面质量；3. 开展了射流电沉积涂层与基体结合强度表征手段的探索，利用纳米压痕法和刮削法对涂层与基体结合强度进行探索，尝试采用能量的角度来分析结合效果；4.采用仿真软件COMSOL和fluent初步建立了射流电沉积的电场流场模型。.该项目探索了制约射流电沉积加工方法在应用中表面质量的基础问题，提出了解决方案，为进一步技术推广奠定了基础。