Microstructure evolution of CMAS glass below melting temperature and its potential influence on thermal barrier coatings

CaO–MgO–Al₂O₃–SiO₂ (CMAS) deposition significantly degrades the performance of thermal barrier coatings (TBCs). In this study, the microstructure evolution of CMAS glass at temperatures below its melting point was investigated in order to study the potential influence of temperature on the applicability of CMAS glass in TBCs. The CMAS glass fabricated in this study had a melting point of 1240 °C, became opaque, and underwent self-crystallization when the temperature reached 1000 °C. After heat treatment at 1050 °C, diopside and anorthite phases precipitated from the glass; at a higher temperature (1150 °C), diopside, anorthite, and wollastonite were formed as the self-crystallization products. An increase in the dwelling time resulted in the transformation of diopside to wollastonite and anorthite. At 1250 °C, all products formed a eutectic microstructure and melted. The results indicate that even at low temperatures, CMAS glass underwent microstructure evolution, which could influence the coating surface and stress distribution when deposited on TBCs.     

空冷器用高压水清洗与雾化降温系统集成设计与开发

高压水清洗系统和喷淋降温系统分别是春季保持空冷器翅片表面清洁和夏季保证空冷器在高温下正常运行的2个重要辅助系统。针对喷淋系统的缺点研究了高压射流雾化技术,通过试验论证了高压水清洗与雾化降温系统集成的可行性和合理性。根据设计思路开发的集成系统已在山西某项目获得应用并取得了良好的使用效果,此高压水清洗与雾化降温集成系统中高压水发生装置及介质输送管路共用,产生的高压水射流雾化颗粒可达到60μm,夏季降温效果较传统喷淋降温效果大幅提升,水资源的利用率得到极大提高,系统性价比更高。     

基于改进SOA-VMD的磁声发射信号去噪算法

磁声发射（MAE）是铁磁性材料磁化过程中产生的声发射信号，在构件应力检测和微观损伤检测中有着广泛的应用。针对MAE信号非稳态、复杂性、衰减性等特点，提出海鸥算法结合变分模态分解（SOA-VMD）的去噪方法，为克服海鸥算法求解过程中易陷入局部最优解问题，利用柯西变异算子产生随机迭代过程，使改进算法即柯西变异海欧算法（CVSOA）跳出早熟收敛。采用以幅值谱熵为适应度函数，优化VMD算法中分解模态个数K和二次惩戒因子α两个参数，将含噪声的MAE信号进行VMD分解重构。经仿真信号和实际检测信号分析表明，改进后的CVSOA-VMD算法全局寻优能力和去噪性能优于传统的SOA-VMD算法，降噪后的MAE信号特征值对于不同应力下均方根、偏斜度特征值的重复性更好，可靠性更高。     

On the performance and failure mechanism of thermal barrier coating systems used in gas turbine blade applications: Influence of bond coat/superalloy combination

Surface engineering plays a major role in achieving the performance and design lives of gas turbine components such as the high pressure turbine aerofoils which operate under the most arduous conditions of temperature and stress leading to a wide range of thermal and mechanical loading during service. In this study, emphasis is placed upon the role of composite systems consisting of bond coat and superalloy substrate in determining the performance and useful life of thermal barrier coatings using yttria-stabilized zirconia as top coat processed by electron-beam physical vapor deposition. Three platinum-modified bond coats of the diffusion type and three nickel-based superalloys are included in the study. Thermal exposure tests at 1150 °C in air with a 24-hour cycling period to room temperature have been used to rank the performance of the coating systems. Various electron-optical techniques have been used to characterize the sequence of events leading to coating failure as marked by spallation of the top ceramic coat. It is shown that for a given superalloy substrate, the coating performance is dependent upon the type of bond coat. Conversely, for a given bond coat, the performance becomes a function of the superalloy composition used in the application. However, in both cases, coating failure is found to be predominated by loss of adhesion between the thermally grown oxide and bond coat indicating that the respective interface is the weakest link in the system. The results are interpreted in terms of the phase transformations which occur in the bond coats during exposure at elevated temperatures and the corresponding effects on their oxidation behavior.     

DD98合金重凝行为的研究

研究了第二代单晶高温合金DD98在标准固溶处理温度"0℃内,合金组织对热处理制度的响应.结果表明,合金的显微组织除与热处理温度和冷却速率密切相关外,还与晶体取向有关,<001>取向的单晶合金初熔温度比＜011>和<111>高约5℃C.当热处理温度较高时,单晶枝晶间区域发生初熔,重熔后在重凝区域中丫相以离异共晶方式规则析出,分布规律与母相一致.     

超音速火焰喷涂含氟化物的碳化铬/镍铬涂层结构及性能

采用超音速火焰喷涂技术制备用于航空发动机刷式封严系统的含氟化钙、氟化钡的碳化铬/镍铬自润滑耐磨涂层。对涂层各项性能进行了检测和分析:涂层显微组织结构均匀,结合强度大于60 MPa,硬度值86～90 HR15N,680～720 HV0.3,耐风冷热震循环次数1000次以上,最大摩擦因数不超过0.15。结果表明,超音速火焰喷涂含氟化钙、氟化钡的碳化铬/镍铬自润滑耐磨涂层综合性能优异,可以作为刷式封严系统的封严涂层。     

霍尔效应法在非铁磁性小直径无缝管壁厚测量中的应用

针对航空发动机用某非铁磁性小直径无缝管（ф3 mm×0.5 mm）的特点,分析当前无损测厚方法的可适用性,提出用霍尔效应法进行管材壁厚测量。试验证明其测量精度可以满足此类管材壁厚测量要求,有很好的应用前景。     

房屋建筑工业灰渣混凝土空心隔墙条板内隔墙的施工技术

系统阐述了房屋建筑工业灰渣混凝土空心隔墙条板内隔墙安装技术和施工操作方法,提出了条板隔墙抗震加固、竖向接板安装、门窗框板安装、板缝补强和条板固定等技术措施,使安装后的条板内隔墙做到牢固、垂直平整、无裂缝.     

温度和水分对3号喷气燃料电导率的影响

电导率是3号喷气燃料检验的一个重要指标,它直接反映了3号喷气燃料的绝缘程度、积聚静电荷及存在静电放电危害程度。在实际工作中经常会发生储存在油罐内的3号喷气燃料电导率发生降低的现象。针对这一现象,从电导率的主要影响因素之中的温度、水分着手进行试验,从而得出了其具体的影响数据,科学地分析了产生这些情况的原因。     

滑油系统管路铺设的计算机辅助设计

滑油系统是燃气轮机发电机组的一个重要组成部分,对燃气轮机轴承、减速齿轮箱轴瓦及传动齿轮齿面、发电机轴承进行润滑。来确保机组连续运行的润滑及散热需求。其合理使用和维护是确保机组连续运行的关键。根据滑油系统管路的铺设要求,运用计算机在三维软件下建立数字样机。实现一种经济高效地验证设计理念并加快设计产品的理想途径。介绍了Inventor2010中三维布管和二次开发在滑油系统设计中的实际应用。着重就Inventor2010三维管路软件设计平台进行了论述。