纳米氧化铝包覆氧化锆热障涂层材料的制备及其性能研究

In the present project Al2O3-ZrO2（Y2O3） thermal barrier coating materials with excellent properties were fabricated by plasma spraying and thermal spraying methods using Al2O3-ZrO2(Y2O3) as ceramic layers, NiCoCrAlY as transition layers. The surface modification and coating mechanisms of silane coupling agent in as-prepared powders will be discussed from the viewpoint of chemistry theory. Several basic issues will be systematically investigated including the composition of transition and ceramic layers, the matching between ceramic layers and alloy matrix, interfacial bonding, interlayer stress, failure mechanism and preparation technology. The powder composition, structure, coating effect as well as the internal stress of transition layers and ceramic layers and interface bonding will be characterized by XRD, TEM, SEM, FT-IR and EDS. The heat-insulating property of the prepared thermal barrier coating will be tested by means of heat insulation experiments at high temperatures, and then compared with that of ZrO2(Y2O3) based coating. Several novel design strategies will be demonstrated in the present project: the continuous gradient structure system formed by nano-particle self-permeability, the preparation of nano composite powders with silane coupling agent modification and the combination of the plasma spraying and thermal spraying methods to prepare thermal barrier coating. Such strategies can be further extended to the fabrication of other composite powders, functional coatings and the development of new products. In addition, this research will also provide some basic data and key technology for the preparation and application of nano-structure thermal barrier coating materials.

本项目选用Al2O3-ZrO2(Y2O3)作陶瓷层，NiCoCrAlY作过渡层，采用等离子喷涂和热喷涂相结合制备性能优异的Al2O3-ZrO2(Y2O3)热障涂层材料。从化学理论出发探讨自制粉体中硅烷偶联剂的表面改性机制和包覆机理；研究过渡层、陶瓷层的组成配比、与合金基体之间的匹配问题、界面结合、层间应力、失效机理及制备技术等基本问题。采用XRD、TEM、SEM 、FT-IR、EDS等测试粉体组成、结构及包覆效果，分析过渡层、陶瓷层的内部应力、界面结合情况；通过高温隔热试验，检测此热障涂层的隔热性能，并与ZrO2(Y2O3)基热障涂层作对比。本研究提出的采用硅烷偶联剂改性制备纳米复合粉的方法和等离子喷涂和热喷涂相结合制备热障涂层及纳米粒子自渗形成连续梯度结构体系的设计思路，可以拓展到其它复合粉体、功能涂层的制备和产品研发上，并为纳米结构热障涂层材料的制备和应用提供一定的基础数据和关键技术。

随着科学技术的发展，热障涂层作为一类高温防护涂层，已在航空航天、汽车制造、化工和冶金等领域得到了广泛应用。氧化钇部分稳定的氧化锆涂层由于具有隔热效果好、保护基体免遭氧化、耐磨损等优点，在某些高温应用领域发挥独特的优势。为满足现代高温防护涂层对热障涂层的发展需求，进一步降低热导率，改善高温隔热和腐蚀性能等，本项目系统研究了纳米氧化铝包覆氧化锆复合粉体的制备、表面改性机制和包覆机理，以及涂层的界面结合强度、隔热性能和高温抗氧化性能。.其中比较突出、具有代表性的成果包括：(1)通过在氧化锆颗粒表面包覆一层氧化铝前驱体的形式，制备得到具有核壳结构和包覆效果较好的氧化铝包覆氧化锆（8mol.%Y2O3）复合陶瓷粉体。当反应条件为pH=5，AlCl3浓度为0.1 mol•L-1，A质量分数为1.0%时，所得粉体的分散性较好。(2)复合粉体的性能对涂层的结合强度有一定的影响，Al2O3包覆ZrO2/Y2O3粉体制备的热障涂层比未包覆ZrO2/Y2O3粉体制备的热障涂层结合强度高，并且随着涂层厚度的增加，涂层整体结合强度下降。(3)在相同加热温度下, 增大涂层厚度能够提高热障涂层的隔热性能，并且加热温度越高涂层隔热效果随涂层厚度增大优势越明显。(4) NiCrAlY 粘结层明显提高了K304不锈钢合金的高温抗氧化性能，高温形成的氧化膜对氧向基体内部的扩散有一定阻挡作用，能够有效保护基体。且涂层的抗氧化性能随着涂层厚度的增大而增强。项目执行以来，在本领域国内外学术期刊上已发表和接收SCI/EI收录的文章29篇，申请并授权国家发明专利1项。上述研究工作所取得的研究结果可以拓展到其它复合粉体、功能涂层的制备和产品研发上，并能为纳米结构热障涂层材料的制备和应用提供一定的基础数据和关键技术，具有一定的科学意义和实际应用价值。