Synthesis and thermophysical properties of RETa3O9 (RE = Ce,Nd, Sm,Eu, Gd,Dy, Er) as promising thermal barrier coatings

Thermal barrier coatings (TBCs) are one of the most important materials in gas turbine to protect the high temperature components. RETa₃O₉ compounds have a defect‐perovskite structure, indicating that they have low thermal conductivity, which is the critical property of TBCs. Herein, dense RETa₃O₉ bulk ceramics were fabricated via solid‐state reaction. The crystal structure was characterized by X‐ray diffraction (XRD) and Raman Spectroscope. Scanning electron microscope (SEM) was used to observe the microstructure. The thermophysical properties of RETa₃O₉ were studied systematically, including specific heat, thermal diffusivity, thermal conductivity, thermal expansion coefficients, and high‐temperature phase stability. The thermal conductivities of RETa₃O₉ are very low (1.33‐2.37 W/m·K, 373‐1073 K), which are much lower than YSZ and La₂Zr₂O₇; and the thermal expansion coefficients range from 4.0 × 10^?6 K^?1 to 10.2×10^?6 K^?1 (1273 K), which is close to La₂Zr₂O₇ and YSZ. According to the differential scanning calorimetry (DSC) curve there is not phase transition at the test temperature. Due to the high melting point and excellent high‐temperature phase stability with these oxides, RETa₃O₉ ceramics were promising candidate materials for TBCs.     

镁铝钆合金在空气中的氧化与燃烧

研究了在镁铝质量比为20:80的镁铝合金中加入稀土金属钆后,合金在空气中的氧化与燃烧特性。借助TG-DSC,SEM,XRD,EDS以及高速摄像仪等仪器对Mg-Al-Gd合金的氧化、燃烧过程及产物进行分析。结果表明:相对于不含钆的Mg-Al合金,Mg-Al-Gd合金在空气中的点火温度较低,约为487.6℃。在TG-DSC实验中,镁铝钆合金的氧化分为2个阶段,第1个阶段为镁的氧化反应,第2个阶段为氧化镁、铝以及氧气的反应,反应生成MgAl_2O_4。当Mg-Al-Gd合金在空气中燃烧时,合金粒子表面会形成一层薄的致密的氧化层,氧化层限制了合金粒子固相或液相的氧化,促进其气相燃烧,同时也导致燃烧出现喷射现象。燃烧没有生成MgAl_2O_4,而是形成了一种新的产物AlN。     

石灰石/石膏湿法烟气脱硫装置湿式球磨制浆系统的运行调整

石灰石制浆系统被广泛应用于燃煤电厂石灰石/石膏湿法烟气脱硫装置中。以典型的湿式球磨制浆系统为研究对象,根据其特性,围绕提高石灰石浆液品质及降低制浆能耗,提出合理的运行调整方法。     

Al-Ni-Co微细球形粉末的制备及SLM成形研究

采用气雾化(IGA)制备了Al-Ni-Co粉末,初筛后的最大粉末粒径小于150μm。分别采用霍尔流速计、XRD、SEM、VSM等测试方法研究了不同粒径范围Al-Ni-Co微粉的微观形貌、相成分、磁性能等。研究表明：微粉的球化率在95%左右;50～80μm范围微粉的流动性相对最好;20μm以下微粉因为粒径偏小,成分偏析较为严重;80～150μm微粉因为粒径过大,表面吸附卫星小颗粒,粗糙度较差;Al-Ni-Co微粉的磁性为软磁,相组成为AlNi和FeCo相。综合比较微观结构、相成分及粉末占比量,选取20～80μm的Al-Ni-Co微粉采用SLM法制备了6组Al-Ni-Co圆柱形磁体,热处理后磁体的密度、磁性等综合性能达到铸造Al-Ni-Co磁体的性能水平。     

Semantic language and multi-language MT approach based on SL

Any natural language is regarded as a representation of semantic language.The translation between two languages (I,J) is regarded as a transformation between two representations.A natural language-Ⅰ is translated into another natural language-J only by two steps.One is semantic-analysis of language-Ⅰ based on “semantic-element-representation-base of language-I“,the other is deploying into the representation of language-J based on “semantic-element-representation-base of language-J‘.For translating in N natural languages,it is needed to develop N translation systems only,rather than N（N-1）/2,or 2N systems.     

浅析涂料经营的"品牌策略"

品牌对于涂料企业来说最有价值，同时涂料企业如何经营品牌，让它发挥最大效益。品牌策略就成为品牌经营的关键。文章通过对品牌不同策略探讨，为中国国内涂料品牌运作提供建议。     

Single event transient characterization of SiGe HBT by SPA experiment and 3-D process simulation

Science China Technological Sciences - The single-photon absorption induced single event transient in the silicon-germanium heterojunction bipolar transistor is investigated. The laser wavelength...     

喷钙脱硫成套技术炉内流场数值模拟计算

用k-ε湍流模型对全炉膛冷态流场进行了数值模拟计算,模型的求解采用压力修正的SIMPLLE算法,计算流场时采用交错网格系统,对差分方程组采用TDMA逐线、逐面迭代,为使迭代稳定的收敛,计算中采用了低松弛方法。     

某发电厂吸风机叶片断裂原因分析

针对某发电有限责任公司4B吸风机叶片短期内频繁发生的断裂事故,从化学成分、金相组织及力学性能等方面进行试验分析,根据试验结果认为4B吸风机叶片断裂为疲劳断裂,其主要原因是：叶片运行中存在交变应力源,增加叶片的附加循环应力,导致叶片的疲劳失效断裂。     

伊敏露天矿卡车优化调度系统监控方法研究

介绍了伊敏露天矿卡车优化调度系统的二维显示方法、三维显示方法、系统显示范围扩展方法,提出了示意停车场的概念,以图文并茂、形象直观的方式将露天矿卡车优化调度系统采集的信息全面、快速、准确地显示出来,将设备完全置于调度人员的监视之下,并将监控范围扩展到调度室以外的有关部门,显著提高了系统的监控作用,取得了满意的效果。