等离子喷涂纳米结构Al2O3-YSZ热障涂层组织与性能研究

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摘要

本文利用辊压振动磨对商用微米 α-Al2O3和7wt%Y2O3-ZrO2粉体研磨合成

6wt%Al2O3-YSZ 复合粉体。通过大气等离子喷涂方法在高温合金基体上制备了

双层结构热障涂层，粘结层为 NiCrCoAlY，陶瓷层由研磨处理后的 AYSZ 粉体

喷涂而成，此外在相同粘结层上喷涂商用微米 YSZ 粉体制备陶瓷层作为常规

YSZ 对比涂层。利用 SEM、XRD、BET 和Nanoindenter 等测试手段，对比分析

两种涂层的显微结构、力学性能、高温抗氧化和抗热震性能，并研究了微观组织

与相组成对涂层抗氧化和抗热震性能的影响规律。

研究结果表明，振动研磨过程中 Al2O3粉末与 ZrO2粉末粘结成具有包覆结

构的复合质点，反复碰撞和粘结作用达到平衡后形成固溶体。AYSZ 复合粉体平

均粒径约为 67μm，其中 ZrO2以T相和 C相存在，没有发现 M相。通过 AYSZ

复合粉体高温煅烧实验，粉体中 T相ZrO2没有发生转变，有微量 α-Al2O3偏析，

说明 AYSZ 复合粉体适合作为等离子喷涂热障涂层原料。

振动研磨的 AYSZ 复合粉体经过等离子高温场，晶格间存储的大量层错能、

应变能被释放，形成含有 AlxZr1-xO2-0.5x

（0.1<x<0.5）固溶体的纳米结构涂层，利

用谢乐公式计算 AYSZ 涂层平均晶粒度约为 52nm，而 YSZ 对比涂层经 SEM 观

察晶粒度大于 250nm。AYSZ 涂层中 ZrO2主要为 T′相，而 YSZ 涂层中 ZrO2

主要为 T相。AYSZ 涂层的孔隙率、弹性模量和硬度都比 YSZ 涂层大。

从恒温氧化动力学曲线可以看出，纳米结构 AYSZ 涂层的抗氧化性能与常

规YSZ 微米涂层基本相同。AYSZ 纳米涂层孔隙细小规则，微裂纹均匀分布，

无明显的方向性，这有利于降低涂层的热导率，从而提高隔热性能，但这些微裂

纹扩展成孔洞后，会加速 NiCrCoAlY 粘结层氧化，并产生巨大的应力导致涂层

失效。随着氧化温度提高，AYSZ 纳米涂层中 T′相 ZrO2分解为 T相和 C相，

AYSZ 纳米涂层使用温度应小于 1100℃。

AYSZ 纳米涂层高温下热震性能好于常规 YSZ 微米涂层。热震实验中 AYSZ

纳米涂层微裂纹扩展方向以沿晶为主，而常规 YSZ 微米涂层表面裂纹呈直线扩

展，表现为穿晶断裂。AYSZ 纳米涂层中，Al3+扩散进入 ZrO2的晶格中，使其结

构更加稳定，提高了 T′相 ZrO2高温稳定性。

以振动研磨的微米级粉体等离子喷涂制备纳米结构热障涂层，简化了传统纳

米涂层的制备方法，且表现较好的力学和抗热震性能，具有潜在的工程应用价值。

关键词：纳米结构涂层等离子喷涂 Al2O3-YSZ 涂层组织抗热震

ABSTRACT

In this dissertation, 6wt%Al2O3-YSZ composite was prepared by roller vibration

mill using commercial micro α-Al2O3 and 7wt%Y2O3-ZrO2 powders. Two-layer

structured thermal barrier coatings were prepared on super alloy by air plasma spray

of which the bond layer materials were NiCrCoAlY and the surface layer materials

were as-prepared AYSZ composite. In addition another suface layer was sprayed by

commercial micro YSZ powder on bond layer of same materials to prepare

comparative conventional YSZ coating. Comparison of both coatings microstructure,

mechanical properties, oxidation and thermal shock resistance was analyzed by SEM,

XRD, BET, Nanoindenter and other testing methods. The effect of microstructure and

phase composition on oxidation and thermal shock resistance was also investigated.

The results revealed that the bonding of Al2O3 and ZrO2 occurred in the process

of milling and formed composite particle of core-shell structure. The solid solution

was produced after the equilibrium of collision and bonding happened. The mean

diameter of AYSZ powder was 67μm. The main phase of ZrO2 were tetragonal and

cubic and the monoclinic phase was not introduced. The tetragonal phase in AYSZ

composite did not transform to monoclinic after calcination test, and traces of

α-Al2O3 were segregated, which indicated that AYSZ composite adapted to plasma

spraying thermal barrier coating.

High strain energy and stacking fault energy stored in vibration milled AYSZ

composite were released under high temperature of plasma and the nanostructured

coating which contained AlxZr1-xO2-0.5x(0.1<x<0.5) solid solution was formed. The

average grain size of AYSZ coating was 52nm estimated by Scherrer equation, while

that of YSZ coating was over 250nm observed by SEM. The main phase of AYSZ

coating was nontransformable tetragonal, while that of YSZ coating was tetragonal.

AYSZ coating had higher porosity, elastic modulus and hardness compared with YSZ

coating.

Oxidation kinetics exhibited that nanostructured AYSZ coating had same

oxidation resistance as conventional microstructured YSZ coating. Small pores and

non directional micro cracks were distributed homogeneously in AYSZ coating. This

resulted in lower thermal conductivity and higher heat isolation. However when these

micro cracks spread and became large pores, the rate of NiCrCoAlY bond layer

oxidation would accelerate and the following tremendous stress lead to coating failure.

The nontransformable tetragonal ZrO2 would decompose to tetragonal phase and

cubic phase with the increase of temperature, therefore the operating temperature of

AYSZ coating should be less than 1100℃.

Nanostructured AYSZ coating exhibited better resistance to thermal shock than

that of conventional microstructured YSZ coating in high temperature. The micro

crack of AYSZ coating propagated along grain boundary, while that of YSZ coating

spread straightly and presented transgranular fracture. Al3+ diffused in ZrO2 lattice in

AYSZ coating stabilized structure and improve the phase stability against high

temperature.

Preparation of nanostructured thermal barrier coating by plasma spraying

vibration milled micro powder simplifies conventional preparation method and the

coating has good mechanical properties and thermal shock resistance. Thus this

method possesses significant application potential.

Key Words: nanostructured coating, plasma spray, Al2O3-YSZ,

microstructure of coating, thermal shock resistance

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目录

摘要

ABSTRACT

第一章绪论.............................................................................................................. 1

§1.1 课题的研究意义.......................................................................................... 1

§1.2 热障涂层系统概述...................................................................................... 2

§1.2.1 热障涂层结构...................................................................................... 3

§1.2.2 热障涂层材料...................................................................................... 4

§1.2.3 热障涂层制备技术.............................................................................. 6

§1.2.4 热障涂层测试技术.............................................................................. 7

§1.3 等离子喷涂热障涂层.................................................................................. 9

§1.3.1 等离子喷涂原理及特点...................................................................... 9

§1.3.2 等离子喷涂热障涂层结构与性质...................................................... 9

§1.3.3 等离子喷涂热障涂层的性能与设计................................................ 10

§1.3.4 等离子喷涂工艺对热障涂层性能的影响........................................ 11

§1.4 氧化锆基热障涂层.................................................................................... 12

§1.4.1 氧化锆基热障涂层晶体结构和相变................................................ 12

§1.4.2 氧化锆基热障涂层物理性质............................................................ 13

§1.4.3 氧化锆基热障涂层失效机理............................................................ 14

§1.4.4 氧化锆基热障涂层研究方向............................................................ 15

§1.5 本课题研究内容........................................................................................ 17

第二章等离子喷涂用 Al2O3-YSZ 复合粉体的制备及热稳定性研究 ................. 19

§2.1 引言............................................................................................................ 19

§2.2 机械化学法................................................................................................ 19

§2.2.1 机械化学法概述................................................................................ 19

§2.2.2 机械振动磨概述................................................................................ 20

§2.2.3 实验所用振动磨及其操作................................................................ 21

§2.3 材料及研磨过程........................................................................................ 23

§2.3.1 实验仪器及选材................................................................................ 23

§2.3.2 粉体研磨过程.................................................................................... 23

§2.3.3 试验结果与分析................................................................................ 24

§2.4 热稳定性实验............................................................................................ 28

§2.4.1 实验方法............................................................................................ 28

§2.4.2 相组成分析........................................................................................ 28

§2.4.3 显微结构分析.................................................................................... 29

§2.5 本章小结.................................................................................................... 30

第三章等离子喷涂 AYSZ 涂层显微结构及力学性能 ......................................... 31

§3.1 引言............................................................................................................ 31

§3.2 喷涂材料及设备........................................................................................ 31

§3.2.1 基体材料............................................................................................ 31

§3.2.2 涂层材料............................................................................................ 31

§3.2.3 等离子喷涂设备................................................................................ 32

§3.2.4 等离子喷涂预处理............................................................................ 33

§3.3 涂层制备及测试方法................................................................................ 33

§3.3.1 等离子喷涂工艺................................................................................ 33

§3.3.2 涂层表征仪器与测试设备................................................................ 33

§3.3.3 测试方法与数据计算........................................................................ 34

§3.4 结果与讨论................................................................................................ 35

§3.4.1 涂层相组成分析................................................................................ 35

§3.4.2 显微结构分析.................................................................................... 36

§3.4.3 孔隙率的分析.................................................................................... 38

§3.4.4 涂层力学性能的分析........................................................................ 39

§3.5 本章小结.................................................................................................... 40

第四章等离子喷涂 AYSZ 涂层抗氧化和抗热震性能 ......................................... 41

§4.1 引言............................................................................................................ 41

§4.2 试验方法和仪器........................................................................................ 41

§4.2.1 实验仪器设备.................................................................................... 41

§4.2.2 氧化实验............................................................................................ 41

§4.2.3 热震实验............................................................................................ 42

§4.3 等离子喷涂 AYSZ 涂层抗氧化性能 ....................................................... 42

§4.3.1 氧化动力曲线.................................................................................... 42

§4.3.2 组织结构对抗氧化性能影响............................................................ 43

§4.3.3 相组成对抗氧化性能影响................................................................ 46

§4.4 等离子喷涂 AYSZ 涂层抗热震性能 ....................................................... 48

§4.4.1 纳米与微米涂层抗热震性能比较.................................................... 48

§4.4.2 组织结构对抗热震性能影响............................................................ 48

§4.4.3 相组成对抗热震性能影响................................................................ 51

§4.5 本章小结.................................................................................................... 52

第五章结论............................................................................................................ 53

参考文献...................................................................................................................... 55

在读期间公开发表的论文和承担科研项目及取得成果.......................................... 61

致谢.......................................................................................................................... 62

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第一章绪论

§1.1 课题的研究意义

燃气轮机（Gas Turbine）是以连续流动的气体为介质带动叶轮高速旋转，将

燃料的化学能转变为动能的内燃式动力机械，是一种旋转叶轮式热力发动机，其

结构如图 1.1 所示。随着高温结构材料到的不断发展以及叶轮冷却技术的不断提

高，燃气温度逐步提高，使燃气轮机效率不断上升。

图1.1 航空燃气轮机结构简图

Fig.1.1 A sketch of an aircraft gas turbine.

燃气轮机上使用多种无机涂层，无机涂层是将陶瓷或金属粉末喷涂或沉积在

金属或陶瓷表面，这些涂层的主要功能如：润滑，抗腐蚀，耐磨，隔热，与润滑

油的相容性好，与金属结合强度大，较高的性价比。实际应用在航空航天领域的

有热障涂层，抗氧化涂层，温控涂层，耐酸碱涂层等。

热障涂层（Thermal Barrier Coating，简称 TBC）是无机涂层中的一个重要分

支，起源于 20 世纪 40 年代末[1]。涡轮叶片是有镍基高温合金构成，其软化温度提

高到了 1589K，已慢慢接近其熔点即 1672K。在过去的 20 多年里，已经发展了几

代高温合金，燃气轮机涡轮前进气温度得到提高。但由于高温合金熔点、应力断

裂和表面腐蚀等不足，进一步提升涡轮前进气温度难以实现，而且用于高性能发

动机冷却的空气量是有限的。在表面制备一层保护性陶瓷涂层即 TBC，可以隔离

叶片与高温火焰直接接触，从而降低叶片温度、保护叶片、提高发动机效率。

目前使用最广泛的热障涂层材料是 Y2O3部分稳定的 ZrO2（Yttrium Stabilized

Zirconia,简称 YSZ）。但是这种材料在高温下（>1200℃）会发生相变而导致涂层

的体积增加，使喷涂所具有的微裂纹扩大，同时 Y2O3易与工作介质中的酸碱杂质

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摘要：

摘要本文利用辊压振动磨对商用微米α-Al2O3和7wt%Y2O3-ZrO2粉体研磨合成6wt%Al2O3-YSZ复合粉体。通过大气等离子喷涂方法在高温合金基体上制备了双层结构热障涂层，粘结层为NiCrCoAlY，陶瓷层由研磨处理后的AYSZ粉体喷涂而成，此外在相同粘结层上喷涂商用微米YSZ粉体制备陶瓷层作为常规YSZ对比涂层。利用SEM、XRD、BET和Nanoindenter等测试手段，对比分析两种涂层的显微结构、力学性能、高温抗氧化和抗热震性能，并研究了微观组织与相组成对涂层抗氧化和抗热震性能的影响规律。研究结果表明，振动研磨过程中Al2O3粉末与ZrO2粉末粘结成具有包覆结构的复合质点，...

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