气液固多相状态下PS-PVD准柱状结构涂层微观结构调控机制研究

Plasma spray-physical vapor deposition (PS-PVD) has exhibited potential capacity to shape the coating microstructures by controlling the co-deposition of vapor phase, liquid droplets and solid phase. Therefore, PS-PVD represents the development direction of the future preparation of thermal barrier coatings (TBC). In particular, the quasi-column structured coatings, which mainly deposited out of vapor phase, show a promising application in the thermal barrier coatings field due to its low thermal conductivity and good thermal shock resistance. However, unlike EB-PVD columnar crystals formed by pure gas phase, the formation of PS-PVD quasi-columnar structures is the co-deposition of gas/liquid/solid multiphase particles. The growth process is complicated, and the related formation mechanism and microstructure control mechanisms remained to be studied thoroughly. In this work, the plasma-powders interaction was studied. And the control methods of gas/liquid/solid multiphase state for spray powders were concluded. On this basis, the effect of solid/liquid phases on the nucleation and growth process during vapor deposition was investigated. Besides, the influence of the deposition conditions on the microstructure of the quasi-columnar coating was also discussed. Based on the above results, the growth mechanism of the quasi-columnar coating deposition was proposed. In addition, the influence between the microstructure and properties of the coating were also studied, and finally microstructure control mechanisms of PS-PVD quasi-columnar coatings were concluded, which would provide scientific guidance for development of thermal barrier coatings with long lifetime and good thermal insulation property.

等离子物理气相沉积（PS-PVD）可通过气相、液相与固相的共沉积，实现不同组织结构的复合设计，代表了未来高性能TBC制备技术的发展方向。尤其是气相沉积为主时制得的准柱状结构涂层兼具低热导率和良好抗热冲击性能，在热障涂层领域表现出很好的应用潜力。然而，不同于EB-PVD柱状晶由纯气相粒子生长形成，PS-PVD准柱状结构的形成是气/液/固多相粒子共同沉积长大，其生长过程复杂，相关形成机理、微观结构调控机制等缺乏深入探讨。本项目在明确高能等离子射流与喷涂粉末交互作用规律和掌握喷涂粒子气/液/固多相状态控制方法的基础上，通过研究固相/液相的存在对气相沉积过程中晶粒形核和长大过程的影响以及基体温度等沉积条件对准柱状结构涂层微观结构的影响规律，揭示涂层沉积生长机理，并对涂层组织结构与性能的影响规律开展研究，最终实现PS-PVD准柱状结构涂层微观组织结构调控，为长寿命高隔热热障涂层研制提供科学指导。

等离子物理气相沉积（PS-PVD）可通过气相、液相与固相的共沉积，实现不同组织结构的复合设计，代表了未来高性能热障涂层制备技术的发展方向。尤其是当以气相沉积为主时制得的准柱状结构涂层兼具低热导率和良好抗热冲击性能，在热障涂层领域表现出很好的应用潜力。然而，与电子束物理气相沉积（EB-PVD）柱状晶的纯气相形成机制不同，PS-PVD准柱状结构由气/液/固多相粒子共同沉积形成，其生长过程复杂，相关形成机理、微观结构调控机制等缺乏深入探讨。本项目采用检测计算与实验验证的方法明确了超低压环境下高能等离子射流与喷涂粉末交互作用规律并掌握了喷涂粒子气/液/固多相状态控制方法；在此基础上，通过研究固相/液相的存在对气相沉积过程中柱状晶形成和长大过程的影响以及基体温度等沉积条件对准柱状结构涂层微观结构的影响规律，提出了气/固和气/液/固两种状态下准柱状结构涂层形成机理，阐明了准柱状结构涂层微观结构调控机制；制备了具有不同微观形貌特征准柱状结构YSZ/Gd2Zr2O7(GZO)热障涂层，通过考核对比其孔隙率、结合强度及抗热冲击等性能，揭示了涂层微观组织结构对性能的影响规律，最终实现了PS-PVD准柱状结构涂层微观组织结构调控，为长寿命高隔热热障涂层研制提供科学指导。