喷涂涂层微结构协同调控体系及其微观缺陷抑制机制研究

With the constant pursuit for the coating performance in aerospace, nuclear industry, large vessels and other high-tech fields, it is a key problem to be solved urgently that the post treatment process which changes coating microstructure or adjusts properly the original organization is immature..Aimed at key performance - wear resistance of the spraying coating, as well as the major problems existing in the post treatment process, and the project utilizes the combination of laser remelting with different graphics trajectories and nano- technology to implement the cooperative regulation on micro-structure of coating, and explores further the new preparation method of high performance coating..Based on the theory of the rapid melting and solidification, the numerical models of collaborative control coating are created. According to this model, numerical simulation is carried out, the numerical simulation focus on coating’s deposition process and residual stress field, then the experiment investigation include influencing factors and formation reason of coating’s micro-defect, the effect of SiC nanoparticles and remelting technology parameters on collaborative control mechanism of coating’s microstructure and properties. Through data from what has been obtained above study. Some interesting findings may be detected, including the categories and formation mechanism and process of the microstructure evolution, the inhibition mechanism of coating’s micro-defect, evolution rule of tribological properties. By making a systematic analysis of these findings, the internal relation between the process elements and the tribological performances of remelting layer are revealed, the system architectures on remelting process - organizational structure - tribological properties are also established. Thus, the preparation technology of the remelted coating with little or no microscopic defects may be obtained, the study results can provide theoretical support and technical guidance for the project engineering practice.

随着航空航天、核工业和大型舰艇等高科技领域对涂层性能的不断追求，改变涂层组织或对组织进行适当调节的后处理工艺不成熟是亟待解决的关键问题。项目针对喷涂涂层关键使用性能—耐磨性以及后处理工艺中存在的主要问题，耦合不同图形轨迹激光重熔技术和纳米技术，对涂层微结构实施协同调控，进一步探索高性能涂层制备方法。以快速重熔和凝固理论为基础，建立协同调控涂层的数值模型，通过对涂层重熔和凝固过程分析以及残余应力场的数值模拟，特别是对涂层微观缺陷的形成原因及其影响因素以及纳米SiC与重熔工艺参数对涂层组织和性能的协同调控机制的试验研究，获得重熔层的形成机制和微观组织结构的演绎过程、涂层微观缺陷的种类和形成机制及其抑制机制以及涂层摩擦学性能的演变规律，揭示后处理工艺中相关要素与重熔层摩擦学性能的内在关联性，建立起重熔工艺—组织结构—摩擦学性能的系统体系，为制备少或无微观缺陷的高性能涂层提供理论支撑和技术指导。

随着航空航天、核工业和大型舰艇等高科技领域对涂层性能的不断追求，改变涂层组织或对组织进行适当调节的后处理工艺不成熟是亟待解决的关键问题。项目针对喷涂涂层关键使用性能—耐磨性以及后处理工艺中存在的主要问题，耦合不同图形轨迹激光重熔技术和纳米技术，对涂层微结构实施协同调控，进一步探索高性能涂层制备方法。以快速重熔和凝固理论为基础，建立了协同调控涂层的数值模型，通过对涂层重熔和凝固过程分析以及残余应力场的数值模拟，特别是对涂层微观缺陷的形成原因及其影响因素以及纳米SiC与重熔工艺参数对涂层组织和性能的协同调控机制的试验研究，获得了重熔层的形成机制和微观组织结构的演绎过程、涂层微观缺陷的种类和形成机制及其抑制机制以及涂层摩擦学性能的演变规律，研究表明：不同扫描速度激光重熔后，组织结构为发达的枝晶组织，涂层与基体均形成了冶金结合，其中扫描速度200mm/s表现最佳，微孔最少；而喷涂层除了[Fe,Ni]、Cr和WC相之外，还含有Cr7C3，Fe0.04Ni0.36等硬质相，经过不同扫描速度重熔后出现了Fe2Si 、Cr2Si等硬质中间相，且重熔层中的相组成几乎没有变化。喷涂涂层在激光重熔过程中生成了如M23C6型化合物、(Ni,Cr,Fe)7C3及(Cr,Ni)3Si等起到了弥散强化作用的强化相，阻止了磨损过程中激光重熔涂层磨损的进一步恶化。同时，重熔时加入纳米SiC可以使涂层的硬度较不加纳米SiC的重熔层更高。且随着纳米SiC含量的增加，涂层表面以及截面的显微硬度也随之增加。另外，显微硬度沿着重熔层表面向内部方向逐渐降低。涂层经激光重熔之后涂层表面的摩擦系数降低，磨损的失重量降低，且能改善等离子喷涂涂层的粘着磨损现象，耐磨性能提高。同时重熔时加入纳米SiC能够使重熔层的抗磨损能力更好。揭示了后处理工艺中相关要素与重熔层摩擦学性能的内在关联性，建立了重熔工艺—组织结构—摩擦学性能的系统体系，为制备少或无微观缺陷的高性能涂层提供理论支撑和技术指导。