Properties of Thermal Barrier Coatings Made of Different Shapes of ZrO2-7wt%Y2O3 Powders

大气等离子喷涂ZrO2-7%Y2O3 (7YSZ, Y2O3为质量分数)热障涂层广泛用于航空发动机热端部件以提高金属基体的抗腐蚀、耐高温、抗冲蚀等性能。采用超音速火焰喷涂(HVOF)以NiCoCrAlYTa粉为原料在高温合金K4169基体上制备了粘结层,通过大气等离子喷涂(APS)分别以团聚、空心7YSZ粉为原料在粘结层上制备了陶瓷面层。使用扫描电镜(SEM)和工业电子计算机X射线断层扫描技术 (ICT)对团聚、空心粉热障涂层的微观结构进行观察分析,然后再对以上 2 种热障涂层的抗氧化、热震、结合、隔热等热物性能进行对比分析。研究结果表明：空心粉热障涂层陶瓷层中存在大量的微孔和裂纹;热障涂层陶瓷层中不同孔隙率对粘结层高温抗氧化性能没有明显的影响,但它有助于提高热障涂层的热震性能和隔热性能;此外,高的涂层孔隙率会导致空心粉热障涂层的结合强度低于团聚粉热障涂层     

未来航空发动机热障涂层材料及制备技术

概述了未来航空发动机热障涂层最有前景的新材料、结构和制备工艺。新材料主要有改进型氧化钇稳定的氧化锆、A2B2O7型材料;新结构主要有双陶瓷层;新工艺主要为制备含垂直裂纹的热障涂层的改进大气等离子体喷涂、等离子喷涂-物理气相沉积、悬浮液等离子喷涂、电子束直接气相沉积。这些相互结合,必将促进高性能热障涂层的快速发展和应用,使其在未来航空发动机中发挥重要作用。     

团聚及空心ZrO_2-7%Y_2O_3热障涂层性能（英文）

大气等离子喷涂ZrO2-7%Y2O3(7YSZ,Y2O3为质量分数)热障涂层广泛用于航空发动机热端部件以提高金属基体的抗腐蚀、耐高温、抗冲蚀等性能。采用超音速火焰喷涂(HVOF)以NiCoCrAlYTa粉为原料在高温合金K4169基体上制备了粘结层,通过大气等离子喷涂(APS)分别以团聚、空心7YSZ粉为原料在粘结层上制备了陶瓷面层。使用扫描电镜(SEM)和工业电子计算机X射线断层扫描技术(ICT)对团聚、空心粉热障涂层的微观结构进行观察分析,然后再对以上2种热障涂层的抗氧化、热震、结合、隔热等热物性能进行对比分析。研究结果表明:空心粉热障涂层陶瓷层中存在大量的微孔和裂纹;热障涂层陶瓷层中不同孔隙率对粘结层高温抗氧化性能没有明显的影响,但它有助于提高热障涂层的热震性能和隔热性能;此外,高的涂层孔隙率会导致空心粉热障涂层的结合强度低于团聚粉热障涂层。     

单晶高温合金热障涂层的循环氧化行为

在Ni基单晶高温合金基体上，采用磁控溅射沉积Ni30Cr12Al0.3Y粘结层，电子束物理气相沉积（EB－PVD）氧化锆陶瓷面层，制备了热障涂层。粘结层的晶粒尺寸小于100nm，为纳米结构，具有优异的抗氧化性能；陶瓷面层为柱状结构，有较好的应变允许度。XRD分析表明，沉积态的陶瓷层存在大量的非平衡正方相（t′），还有少量的立方相（c)和单斜相（m),t′相在冷却时不会转变为m，对陶瓷的高温稳定性有重要的作用。在1050℃下，对单晶合金基体和热障涂层进行了循环氧化实验。结果表明，单晶合金经过几次循环后氧化膜发生剥落，100次循环氧化后，表面氧化物主要由NiO和少量的Al2O3以及由于Kirkendell效应造成的孔洞组成；而热障涂层经过100次循环后，表面没有剥落，但有微裂纹出现，粘结层与陶瓷层之间的热氧化产物（TGO）为Al2O3。300次循环氧化后，TGO与粘结层之间有裂纹产生。     

表面处理对热障涂层寿命及失效机理的影响研究

采用真空电弧离子镀和电子束物理气相沉积技术在高温合金DZ125上沉积NiCrAlYSi金属粘结层和YSZ陶瓷面层。研究了抛光、振动光饰、砂纸打磨及吹砂四种不同的表面处理方法对金属粘结层表面微观结构和界面状态的影响。实验结果表明,四种表面处理方法都改善了金属粘结层表面结构,降低了表面粗糙度。进一步探讨了表面处理对涂层结合强度的作用,结果表明经过表面处理后的样品结合强度都得到了提高。并分析了不同表面处理方法对涂层寿命的影响,最终明确了热障涂层失效机理。     

多层结构热障涂层抗热震性能的研究

本文采用电子束物理气相沉积技术(EB-PVD)在镍基单晶合金N5基体上制备了双层热障涂层(粘结层+陶瓷层)和三层热障涂层(粘结层+混合层+陶瓷层),并对两组涂层体系的热循环性能进行1100℃保温5min 水冷的热震实验,对其微观组织结构采用扫描电镜、能谱仪以及X射线衍射进行了分析。研究发现,在粘结层和陶瓷层之间添加的混合层(NiCrAlY+YSZ)能够延缓TGO层的生长,并具有缓解内应力的作用,两者的共同作用使得三层结构的热障涂层表现出更为优异的热匹配性。     

高性能纳米氧化锆热障涂层性能研究

采用HVOF 技术喷涂金属粘结层NiCrAlY 作为底层,采用APS 技术喷涂纳米氧化锆陶瓷层作为面层,制备高性能热障涂层。设计正交试验优化HVOF 和APS 工艺,分析了优化工艺制得的热障涂层的微观形貌及性能。分析表明,NiCrAlY 涂层孔隙率小于2%,纳米氧化锆涂层孔隙率为15%。通过胶膜法测得纳米氧化锆热障涂层喷涂态的结合强度为30.4 MPa,且涂层经1100 益水淬50 次后表面无宏观裂纹,热生长氧化层为致密的Al2O3。     

粘结层真空退火处理对热障涂层热循环寿命的影响研究

目的研究粘结层真空退火处理对热障涂层热循环条件下服役性能的影响。方法在某二代镍基单晶高温合金上涂覆铂铝粘结层,然后采用电子束物理气相沉积法沉积氧化钇稳定的氧化锆陶瓷层,构建热障涂层体系,在1100℃下可自动升降的循环氧化炉中进行热循环测试,通过高精度电子天平对涂层样品进行称量并绘制质量变化曲线,采用拍摄宏观照片的方式观察样品表面陶瓷层剥落情况,利用扫描电子显微镜观察沉积态及热循环后的样品截面微观组织结构形貌。结果与沉积态粘结层相比,在高真空中进行退火处理后,热障涂层的热循环寿命几乎增加一倍,且陶瓷层与热生长氧化膜结合良好。未经过真空处理的铂铝涂层表面陶瓷层发生明显剥落,且热生长氧化膜质量较差,出现了明显裂纹。结论真空退火处理可使铂铝涂层表面更加平整,在高温氧化过程中生成的低缺陷氧化膜有更好的质量,陶瓷层与粘结层的结合力更强,热障涂层体系的服役性能和寿命得到有效提升。     

功能金属/陶瓷梯度热障涂层的材料体系及制备方法

介绍了功能金属/陶瓷梯度热障涂层各组成层材料的选择,以及梯度过渡层的设计原则和方法,讨论了制备梯度热障涂层常用的方法。最后展望了过渡层设计方法的发展方向,提出了制备功能金属/陶瓷梯度热障涂层方法的选择原则。     

航空发动机浮动瓦片热障涂层脱落分析

航空发动机火焰筒浮动瓦片采用等离子喷涂Y₂O₃-ZrO₂热障涂层进行防护,发动机试车后部分浮动瓦片的热障涂层局部区域发生脱落。利用体视显微镜、扫描电子显微镜、能谱仪、X射线衍射仪等对发生涂层脱落的浮动瓦片表面形貌、显微组织、微区成分和相组成进行分析。结果表明：热障涂层主要发生Y₂O₃-ZrO₂面层剥落,裂纹萌生于NiCoCrAlY底层未熔颗粒突起部位所形成的热生长氧化层(TGO)附近,并沿平行于界面的方向扩展。陶瓷面层脱落的原因与金属底层厚度偏薄,金属底层含有超量的未熔颗粒及孔隙,陶瓷面层中含有单斜晶系m相有关,从而导致高温下陶瓷面层中应力过大而开裂、剥离。加强涂层组织结构检验并采用纳米结构团聚型面层喷涂粉末,能够改善热障涂层的工作可靠性。     

Improved Thermal Cycling Durability of Thermal Barrier Coatings Manufactured by PS-PVD

The plasma spray-physical vapor deposition (PS-PVD) process is a promising method to manufacture thermal barrier coatings (TBCs). It fills the gap between traditional thermal spray processes and electron beam physical vapor deposition (EB-PVD). The durability of PS-PVD manufactured columnar TBCs is strongly influenced by the compatibility of the metallic bondcoat (BC) and the ceramic TBC. Earlier investigations have shown that a smooth BC surface is beneficial for the durability during thermal cycling. Further improvements of the bonding between BC and TBC could be achieved by optimizing the formation of the thermally grown oxide (TGO) layer. In the present study, the parameters of pre-heating and deposition of the first coating layer were investigated in order to adjust the growth of the TGO. Finally, the durability of the PS-PVD coatings was improved while the main advantage of PS-PVD, i.e., much higher deposition rate in comparison to EB-PVD, could be maintained. For such coatings, improved thermal cycling lifetimes more than two times higher than conventionally sprayed TBCs, were measured in burner rigs at ~1250 °C/1050 °C surface/substrate exposure temperatures.     

Effect of surface preparation on the durability of NiCoCrAlY coatings for oxidation protection and bond coats for thermal barrier coatings

A principal concern with alumina‐forming coatings for high‐temperature oxidation protection and bond coats (BCs) for ceramic thermal barrier coatings (TBCs) used in gas turbines is the spalling of the alumina scales during service. This paper describes the effects of BC surface preparation on the durability of NiCoCrAlY coatings exposed under thermal cycling conditions. State‐of‐the‐art TBC systems deposited by electron beam physical vapor deposition (EBPVD) with NiCoCrAlY overlay BCs were found to fail as the result of defects which included transient oxides, defects in the BC surface, defects in the as‐deposited microstructure of the TBC, and excessive oxidation of reactive element additions. In some instances, the TBC life was greatly extended by surface treatments, such as fine polishing. The oxidation behavior of NiCoCrAlY coatings, absent a TBC, was found to be sensitive to Y content and to surface preparation. This paper describes how a variety of surface treatments affected coating lives and failure mechanisms.     

Ceramic Top Coats of Plasma-Sprayed Thermal Barrier Coatings: Materials,Processes, and Properties

The ceramic top coat has a major influence on the performance of the thermal barrier coating systems (TBCs). Yttria-partially-stabilized zirconia (YSZ) is the top coat material frequently used, and the major deposition processes of the YSZ top coat are atmospheric plasma spraying and electron beam physical vapor deposition. Recently, also new thermal spray processes such as suspension plasma spraying or plasma spray-physical vapor deposition have been intensively investigated for TBC top coat deposition. These new processes and particularly the different coating microstructures that can be deposited with them will be reviewed in this article. Furthermore, the properties and the intrinsic–extrinsic degradation mechanisms of the YSZ will be discussed. Following the TBC deposition processes and standard YSZ material, alternative ceramic materials such as perovskites and hexaaluminates will be summarized, while properties of pyrochlores with regard to their crystal structure will be discussed more in detail. The merits of the pyrochlores such as good CMAS resistance as well as their weaknesses, e.g., low fracture toughness, processability issues, will be outlined.     

热障涂层脱粘裂纹缺陷的高温表征方法与演变规律EI北大核心CSCD

热障涂层在服役过程中相邻区域脱粘裂纹的扩展合并是造成陶瓷层最终剥落的重要原因,然而缺乏简单有效的无损测试方法。提出利用空腔高热阻在陶瓷层表面局部热积累,形成表面亮斑的特点,通过亮斑反向跟踪脱粘缺陷的新方法。结果表明,在界面处制备水溶性盐斑,继续喷涂陶瓷层后用水浴溶解的方式可在YSZ与金属粘结层界面有效预制特定外形与尺寸的人造脱粘裂纹缺陷;预制脱粘裂纹与表面高温亮斑尺寸呈正相关,且近似呈现为比例系数为1.031的线性关系,当预制裂纹直径大于0.4 mm时,可在涂层表面观测到亮斑,当预制裂纹直径大于0.7 mm时,用亮斑尺寸预测裂纹尺寸的相对误差低于15%;在梯度热冲击循环下,热障涂层随热冲击次数的增加,表面首先出现亮斑,随后亮斑长大、合并,在2500次左右热循环时合并速度加快,最终陶瓷层在亮斑处局部剥落。基于脱粘裂纹对于纵向热流的阻碍作用,提出一种人造脱粘裂纹缺陷的预制方法,并确立一种通过测量表面亮斑尺寸估计内部裂纹尺寸的热障涂层无损测量方法。解决了热障涂层高温缺陷难以实时观测的问题,并进一步研究了其高温演变规律,可为热障涂层的寿命预测提供数据支持。     

氧化锆粉体的制备及其在热障涂层中的应用

分别描述了纳米氧化锆粉体与空心球氧化锆粉体的制备工艺，分析了不同工艺影响氧化锆产物形态、结构、粒度等方面的因素，并将2种粉末制备的涂层分别与传统微结构涂层进行性能对比。在分析由不同氧化锆粉末制备而成的涂层性能时，除了工艺参数外，更多的是考虑初始氧化锆粉末对涂层性能所带来的影响。期待在未来的研究中，能够优化现有或者探索出更优异的制粉工艺，研究出性能更加优良的新型粉末，以期能够提高热障涂层的性能，满足高精尖领域在未来的使用需求。最后，针对不同制粉工艺及不同粉末制备涂层的发展方向进行了展望。     

Formation and behavior of thermal barrier coatings on nickel-base superalloys

Plasma-sprayed thermal barrier coatings (TBCs) have been used to extend the life of combustors. Electron beam physical vapor deposited (EB-PVD) ceramic coating has been developed for more demanding rotating as well as stationary turbine components. Here 3 kW RF magnetron sputtering equipment was used to gain zirconia ceramic coatings on hollow turbine blades and vanes, which had been deposited NiCrAIY by cathodic arc deposition. NiCrAlY coating surface was treated by shot peening; the effects of shot peening on the residual stress are presented. The results show that RF sputtered TBCs are columnar ceramics, strongly bonded to metal substrates. NiCrAlY bond coat is made of β, γ‘ and Cr phases, ZrO2 ceramic layer consists of t‘ and c phases. No degradation occurs to RF ceramic coatings after 100 h high temperature oxidation at 1150℃ and 500 thermal cycles at 1150℃ for 2 min, air-cooling.     

热障涂层失效机理、改进方法及未来发展方向

热障涂层(Thermal Barrier Coatings,TBCs)是用于航空发动机及燃气轮机的一种高效功能性隔热涂层,常用材料为氧化钇(质量分数6％～8％)部分稳定氧化锆(YSZ).首先,从TGO生长、高温烧结、CMAS腐蚀、盐雾腐蚀和热膨胀失配等方面介绍了YSZ的失效机理,以上因素会从不同程度上造成涂层分层、开裂...     

Thermal barrier coating experience in gas turbine engines at Pratt & Whitney

Pratt & Whitney has accumulated more than three decades of experience with thermal barrier coatings (TBCs). These coatings were originally developed to reduce surface temperatures of combustors of JT8D gas turbine engines to increase the thermal fatigue life of the components. Continual improvements in de-sign, processing, and properties of TBCs have extended their applications to other turbine components, such as vanes, vane platforms, and blades, with attendant increases in performance and component du-rability. Plasma-spray-based generation I (Gen I) combustor TBCs with 7 wt % yttria partially stabilized zirconia deposited by air plasma spray (APS) on an APS NiCoCrAlY bond coat continues to perform ex-tremely well in all product line engines. Durability of this TBC has been further improved in Gen II TBCs for vanes by incorporating low-pressure chamber plasma-sprayed NiCoCrAl Y as a bond coat. The modi-fication has improved TBC durability by a factor of 2.5 and altered the failure mode from a “black fail-ure” within the bond coat to a “white failure” within the ceramic. Further improvements have been accomplished by instituting a more strain-tolerant ceramic top layer with electron beam/physical vapor deposition (EB-PVD) processing. This Gen III TBC has demonstrated exceptional performance on rotating airfoils in high-thrust-rated engines, improving blade durability by three times through elimination of blade creep, fracture, and rumpling of metallic coatings used for oxi-dation protection of the airfoil surfaces. A TBC durability model for plasma-sprayed as well as EB-PVD systems is proposed that involves the accumulation of compressive stresses during cyclic thermal expo-sure. The model attempts to correlate failure of the various TBCs with elements of their structure and its degradation with thermocyclic exposure.     

地面重型燃气轮机及其热障涂层的研究进展与发展趋势

国际公认的重型燃气轮机制造尖端技术之一—热障涂层技术,高温下通常面临CMAS(CaO-MgO-Al₂O₃-SiO₂)腐蚀、氧化、相变与烧结等问题,其抗CMAS腐蚀性等关键性能极大地影响涂层寿命,提高热障涂层的性能刻不容缓。对重型燃气轮机用热障涂层的研究进展与发展趋势进行全面总结与分析。首先介绍国内外重型燃气轮机的现状及发展趋势、热障涂层的系统结构、材料和几种典型的制备工艺,然后针对高温下燃气轮机热障涂层遇到的一些问题,对其隔热性、抗氧化性及抗热震性等关键性能的研究进展进行综述,最后分类详述热障涂层的CMAS腐蚀机理及其防护研究进展。综述热障涂层的几种关键性能,提出热障涂层的性能与其材料、结构及制备工艺密切相关,据此总结归纳提高热障涂层性能的方法,为热障涂层性能的提高提供参考依据,以弥补燃气轮机热障涂层领域目前缺乏这类综述文章的不足。