粘结层预处理对PS-PVD沉积7YSZ热障涂层氧化行为的影响

目的提高PS-PVD沉积7YSZ热障涂层的抗高温氧化性能。方法采用等离子喷涂-物理气相沉积(PS-PVD)分别在未预处理和预处理(抛光+预氧化)的粘结层表面制备了柱状结构7YSZ热障涂层,并在大气环境下测试了柱状结构7YSZ热障涂层的950℃静态高温氧化性能。利用扫描电子显微镜、X射线衍射仪、能谱仪对高温氧化过程中的陶瓷层/粘结层界面形貌、TGO层结构演变进行表征。结果粘结层的抛光处理能够降低表面几何受力不均匀部位,抑制陶瓷层/TGO/粘结层界面处微裂纹的产生,同时粘结层的预氧化处理形成的薄而连续的TGO层能有效降低TGO的生长速度,抑制陶瓷层-粘结层之间的元素互扩散。柱状结构7YSZ涂层的高温氧化动力学曲线符合Wagner抛物线规律,粘结层未预处理和预处理的7YSZ热障涂层的氧化速率常数分别为0.101×10~(-12) cm~2/s和0.115×10~(-13) cm~2/s。结论粘结层预处理能有效改善等离子物理气相沉积7YSZ热障涂层的抗氧化性能。     

等离子喷涂热障涂层高温风洞热震行为

采用等离子喷涂工艺制备ZrO2-8%Y2O3(质量分数,下同)陶瓷层,冷喷涂制备CoNiCrAlY粘结层,在高温燃气风洞条件下测试热障涂层的热震性能,并研究了高温氧化处理对试样热震性能的影响.结果表明,等离子喷涂热障涂层具有较好的抗热震性能,经过100次热震循环后,涂层与基体结合良好,涂层较为完整,未出现大面积的剥落;经过氧化处理后的试样抗热震性较差.     

利用TGO建立独立坐标系的一种方法

首先分析了建立独立坐标系的常用方法,进而介绍了利用TGO建立独立坐标系的一种方法,最后通过实例,验证了该方法的可靠性。     

NiCoCrAlY粘结底层的高温氧化性能研究

采用增重法研究了NiCoCrAlY粘结底层的高温氧化性能,通过SEM、EDS等分析手段对高温氧化膜层TGO的显微形貌和组成进行了检测分析,初步探讨了TGO膜层的生长过程、生长机制以及热障涂层失效的影响因素。     

Oxidation behaviour of CoNiCrAlY bond coats produced by plasma, HVOF and cold gas dynamic spraying

This paper examines and compares the microstructure and oxidation behaviour of CoNiCrAlY coatings manufactured by the APS, HVOF and CGDS deposition techniques. The coatings microstructural features were characterized by means of SEM and XRD analyses. Coating samples were then subjected to isothermal heat treatments at 1000 °C. Oxide growth rates were obtained from a series of mass gain measurements while oxide scale compositions were determined from SEM, XRD and EDS analyses. Results obtained in this study show that the as-sprayed CGDS and HVOF coatings exhibit similar microstructures, whereas the APS coating features high levels of visible defects and oxide content. Oxidation experiments revealed low oxide growth rates for both the CGDS and HVOF coatings as a result of low porosity and oxide content. The oxide scale on the CGDS and HVOF coatings after 100 h of oxidation were composed mainly of alumina without the presence of detrimental fast-growing mixed oxides. The presence of Cr₂O₃ and dispersed NiO was however also observed for the HVOF coating. As expected, the APS coating featured the onset of mixed oxides in the early stages of oxidation. From these results, it appears that potential improvements to the bond coat oxidation behaviour can be achieved using low-temperature processing methods such as CGDS.     

Simultaneous synthesis by spark plasma sintering of a thermal barrier coating system with a NiCrAlY bond coat

As-fabricated thermal barrier coating (TBC) systems generally consist of a superalloy substrate, a MCrAlY bond coat (M = Ni, Co, Fe), and a ceramic (usually partially stabilized zirconia) top coat. The conventional methods for producing the two coating layers generally derive from thermal spray and physical vapor deposition techniques. Thermal exposure leads to the formation of an additional layer: the thermally grown oxide (TGO) between the bond coat and top coat. In the present work, a TBC system is synthesized through the application of spark plasma sintering (SPS), which provides not only the opportunity to synthesize all three layers at once, but the process is quite rapid and can produce dense layers. More specifically, this paper describes the application of this method to an yttria-stabilized ZrO₂ (YSZ) top coat and a NiCrAlY bond coat on a Ni-base Hastelloy X substrate. A one-micron thick Al₂O₃ TGO layer is also created from the reaction between an Al foil layer inserted in the stack prior to sintering and the ZrO₂ in the top coat. The effects of select process conditions are considered. The resulting multi-layer system is characterized with optical microscopy, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray analysis (EDAX) and X-ray diffraction (XRD). Differential thermal analysis (DTA) is used to investigate the reaction between the Al foil and the YSZ top coat.     

热障涂层高温氧化生长应力预测

基于Clark氧化生长应变率理论和Wagner氧化模型给出了涂层高温生长应力公式,计算预测了热障涂层中氧化生长应力随时间的演化规律;利用光致发光分析技术对氧化层的应力进行了实验测试,并对两种结果进行了比较和分析。结果表明,本文给出的热障涂层高温氧化生长应力模型预测与实验结果符合     

用TGO软件实现GPX、KML数据格式转换

TGO是一款随机数据处理软件,具有界面友好、操作简单的特点。本文通过对GPX、KML数据格式文件结构的分析和归类,探索了使用随机的GPS数据处理软件TGO生成GPX、KML数据格式文件的方法,介绍了进行数据格式转换的具体流程,应用于测量工作以及取得的实际效果。     

Heat treatment effect on coating shock resistance of thermal barrier coating system with different types of bond coat

The effect of heat treatment, growth of the TGO layer, oxidation of bond coat, and the impact of the presence of two bond coats on the TBC's thermal shock resistance has been investigated experimentally. TGO oxide layers were created with two-time heat treatment of 12 and 24 h at 1000. Then the thermal shock test was performed on the APS/APS and HVOF/APS/APS samples. The results show that the use of two BCs and the presence of a thin TGO layer has a good effect on TBC performance. The presence of two BC layers increased the shock resistance by an average of 37.2%. 12 h heat treatment caused a 14.0% and 17.4% shock resistance increase in samples with the HVOF/APS/APS layer and APS/APS layer, respectively. 24 h heat treatment decreased the samples' performance by 6.7% and 10.2% for samples with two BC and one BC, respectively.     

基于TGO系统的地方坐标系约束平差解决方案

在GPS控制测量中,若未知地方独立坐标系的相关定义参数时,便不能进行约束平差而只能用坐标转换的方法来求取未知点的地方坐标,在TGO系统中用点校正来解决问题。基于此,对点校正问题进行了理论和实例分析,结合笔者应用TGO的经验,得出了一些在工程测量中有益的结论和建议。