基于液相放电铝表面减磨催化陶瓷层制备的基础科学问题

In order to resolve the demands of energy-saving and emission-reduction in automotive engines, composite functional ceramic coatings with the function of anti-friction resistance reduction and catalytic combustion on the aluminum alloy cylinder wall will be prepared, which will break through the manufacturing bottleneck of lightweight engine. The key scientific problems in the preparation of new multiple functional ceramic coatings are developed which mainly includes: the morphology and size of discharge channel as well as motion state of curing discharge fused product within the aluminum matrix ceramic coating are determined according to the particle tracer method, and the breakdown pattern of plasma discharge in liquid and the influence on the holes will be feed back to establish the transient fused physical model; and the influence of the electrolyte composition (including solvent and solid powder) on the discharge breakdown and transient fused will be determined. With the coating of Al2O3 as a barrier layer, arc discharge in liquid phase carried out in micro-region, according with the temperature field distribution calculated through simulating ceramic coatings, concentrate on the study of the heterogeneous interface microstructure, as well as the emergence, evolution of micro-defects and the internal-stress during the process of liquid phase plasma discharg, and to discover the connection among control parameter, discharge in liquid and transient fused. The method of structure control of CuO-Al2O3-graphite ternary composite ceramic coatings is established to prepare ceramic coatings with functions of anti-friction resistance reduction and catalytic effect. The study will provide scientific foundations for the preparation and quality control of composite function ceramic layer on aluminum alloy, and the developing process acceleration of lightweight engine of energy-saving and emission-reduction functions.

针对汽车发动机节能减排的需求，对铝合金缸体内壁涂覆减摩降阻和催化燃烧的复合功能陶瓷涂层，将突破轻量化发动机的制造瓶颈。开展新型多元功能陶瓷涂层制备的关键科学问题研究，主要包括：以粒子示踪的方法，确定铝基陶瓷涂层放电通道形态、尺寸，固化放电熔融中产物的运动状态，反馈液相等离子体放电击穿模式及对孔洞的影响特征，建立瞬态熔凝物理模型；确定电解液组成，包括溶剂和固态粉末，对放电击穿和瞬态熔凝的影响机制。以Al2O3做阻挡层，实现微区域液相弧光放电，结合实验模拟计算陶瓷涂层形成中温度场分布，侧重研究液相等离子体放电过程异相界面微结构、微缺陷及内应力的产生与演化，发现控制参量—液相放电—瞬态熔凝的关联。建立CuO-Al2O3-石墨三元复合陶瓷涂层的结构调控方法，制备具有减摩降阻和催化效果的陶瓷层。本研究将为铝复合功能陶瓷层的制备与质量精确控制奠定科学基础，加速我国轻量化节能减排发动机的研制进程。

本项目针对目前汽车行业对发动机技术提出的高效低能耗的要求，依托等离子体微弧氧化（PEO）涂层技术，以内燃机铝合金缸体、活塞等关键部件为研究对象，从液相等离子体放电机制、催化燃烧涂层微观结构设计以及内燃机环境下涂层服役性能三个角度出发，研发拥有减磨降阻、催化燃烧并兼备优良的内燃机环境服役可靠性的节能减排功能涂层，开展新型多元功能PEO陶瓷涂层制备的关键科学问题研究。主要研究内容包括：以内燃机的主流材质铝硅合金为基体，采用PVD技术预制Al2O3阻挡层，探究预制阻挡层对液相等离子体放电的影响机制，结合液相等离子体温度模拟计算，探究液相等离子体状态、放电参数、涂层生长机制三者之间的内在关联；采用PVD-Ti粒子示踪的方法，分析了铝基陶瓷涂层的放电机制，探究液相等离子体放电击穿模式及对孔洞的影响特征，探究陶瓷层微观结构形态的演变机制；分析电解液成分及放电关键参数对涂层微观孔洞结构及热物理性能的影响规律及机制，探究润滑和催化组元对涂层生长的作用机理，建立复合陶瓷涂层的结构调控方法，制备具有减摩降阻和催化效果的陶瓷层。探究了电解液对放电击穿和瞬态熔凝的影响机制；针对减磨催化层功能特征进行表征分析，探究涂层微观结构对热物理性能、催化减磨性能的影响机制，形成适合发动机燃烧室工作环境的催化减磨陶瓷涂层调控机制。