Preparation and characterization of multilayer Gd2O2S:Tb phosphor screen for X-ray detection application

Gd2O2S:Tb (GOS) phosphor screen, generally with a multilayer structure, has been widely used in digital X-ray imaging. GOS phosphor screen is fabricated via a slip casting route, which is an effective method to obtain multilayer composites with good strength. The GOS slurry was prepared using the menhaden oil, polyvinyl butyral and PEG-400 as dispersant, binder and plasticizer, respectively, and slip casted on a support layer. After the GOS scintillation layer is formed, a transparent polyethylene terephthalate film is covered on it as a protective layer. The X-ray excited emission spectra of the obtained GOS phosphor screen is well match to the spectral response of a-Si:H photodiode, and the spatial resolution was close to 3.7 LP/mm, which could meet the request of the commercial application.     

焦化废水膜法组合深度处理工艺设计与应用

针对煤化工企业焦化废水的二级生化出水可生化性差、含盐量与COD高,以及废水中包含多环芳香族化合物、脂肪族化合物等难生物降解污染物的特点,采用Fenton氧化+电渗析+超滤+反渗透膜法组合深度处理工艺对废水进行处理。运行结果表明,产水水质达到并优于《工业循环冷却水处理设计规范》(GB 50050—2007)中再生水水质要求,产水可作为厂区生产补充新水使用,废水回收率稳定达到75%。采用Fenton氧化与电渗析粗脱盐技术相结合的强化预处理设施,可以有效缓解反渗透装置的膜污染,延长反渗透膜的清洗周期至3个月。     

Preparation,ablation behavior and mechanism of C/C-ZrC-SiC and C/C-SiC composites

ZrC precursor was synthesized by a solution approach using ZrOCl₂·8H₂O, acetylacetonate, glycerol and boron-modified phenolic resin. A ZrC yield of ~ 40.56 wt% was obtained at 1500 °C in the C/Zr molar ratio of 1:1. C/C-ZrC-SiC composites were fabricated by a combined processes of chemical vapor infiltration (CVI) and precursor infiltration and pyrolysis (PIP) using the synthesized ZrC precursor. For comparison, C/C-SiC composites were prepared by CVI. Thermogravimetric analysis showed that C/C-ZrC-SiC composites exhibited better oxidation resistance than C/C-SiC composites. After oxyacetylene torch ablation, the mass ablation rate of C/C-ZrC-SiC composites was 9.23% lower than that of C/C-SiC composites. The porous ZrO₂ skeleton in the ablation center was prone to be peeled off by the flame flow, resulting in the higher linear ablation rate of C/C-ZrC-SiC composites. The oxide layers of ZrO₂ and SiO₂ were formed on the transition and brim region of C/C-ZrC-SiC composites and acted as effective heat and oxygen barriers. For C/C-SiC composites, the C-SiC matrix was severely depleted in the ablation center and the formed SiO₂ layer in the brim region could protect the matrix against further ablation.     

污泥减量化技术研究进展

面对近年来污水处理行业污泥产量大、处理处置成本高而环境要求日趋严格的严峻形势,该文综合国内外近年来的学术研究和实践成果,系统介绍了污泥减量的理论基础,即污泥隐性增长、解偶联代谢、生物捕食和维持代谢。并详细探讨了基于4种减量原理的污泥减量新技术。     

接结纱经向间距对EP/CFSF复合材料性能的影响

基于不同接结纱经向间距的设计,研究了不同接结纱经向间距对环氧树脂(EP)/碳纤维间隔织物(CFSF)复合材料的力学性能、电学性能的影响规律,结合扫描电子显微镜,分析经向间距对复合材料性能的影响机制。结果表明,随着接结纱经向间距的增加,EP/CFSF复合材料的冲击强度和弯曲强度减小,韧性减弱,电阻率增大。当接结纱经向间距为4 mm时,复合材料具有较佳的综合性能,其冲击强度为13.5 k J/m~2,弯曲强度为121.30 MPa,导电性能最好,电阻率为0.077Ω·m。     

Microstructural modeling approach applied to rock material

The importance of the microstructural parameters in rock mechanical behavior has been investigated by several authors. Moreover, the Weibull statistical model has been used to characterize the heterogeneity of several materials on the basis of the concept that the microscopic defects within the material determine their mechanical strength. The modeling of different rocks is a topic that is fundamental for the prediction of rock fragmentation. In this article, the analysis of rock microstructure is performed using the microstructural modeling approach, which consists of the simplification, quantification, and modeling of the main properties of rock microstructure. The grain size, grain shape, and microcracks are modeled by means of statistical density functions, namely, Cauchy, chi-squared, exponential, extreme value, gamma, Laplace, normal, uniform, and Weibull. It is found that the Weibull distribution is the most appropriate statistical model of the grain size and grain shape, when compared with the other eight statistical models. Regarding microcracks, the results show that the gamma distribution is the most appropriate model. The Weibull and gamma distributions are then used to analyze the heterogeneity of the microstructure. This is done by comparison of the statistical models of each microstructural property evaluated in several thin sections of the same rock. It is found that with respect to grain size and grain shape, the rock is homogeneous, while the size distribution of the microcracks shows a clear trend toward less homogeneity. The microstructural modeling approach is important for modeling, characterizing, and analyzing the microstructure of rock material. Among other applications, it can be used to explain differences in the mechanical behavior obtained in testing several specimens.     

真空自耗电弧熔炼TC4铸锭的凝固组织和缩松缩孔的模拟

建立三维轴对称有限元模型,采用移动边界法模拟了真空自耗电弧熔炼( VAR)TC4合金铸锭凝固过程的温度场分布,并基于元胞自动机和有限元耦合法(CAFE法)计算了VAR过程中TC4铸锭的凝固组织、缩松和缩孔的形成.结果表明,模拟结果与试验观察在晶粒结构、柱状晶生长方向,柱状晶-等轴晶转变及缩松和缩孔等方面相符合.     

鹤壁电厂除灰系统改造中的问题及处理措施

介绍鹤壁电厂 2× 2 0 0 MW机组由原水力除灰系统改造为正压气力除灰系统的设备配置、输灰方式、系统控制与调试以及生产中存在的主要问题 ,并就存在的问题提出了改进意见 ,为相同类型干除灰系统的优化设计、完善改造及提高除灰系统运行可靠性和经济性提供参考。     

AlCoCrFeNiTi0.5高熵合金的组织控制和腐蚀性能

研究冷坩埚悬浮熔炼AlCoCrFeNiTi0.5多组元高熵合金的微观组织及回火工艺对合金组织、硬度和电化学性能的影响规律。结果发现,冷坩埚悬浮熔炼AlCoCrFeNiTi0.5高熵合金铸锭中晶粒呈树枝晶长大并析出少量ω相。随回火温度的升高,晶粒长大,共晶组织增多,BCC相强度呈先下降后升高趋势。800 ℃时,合金树枝晶晶粒变得细小,之后随着温度的升高,枝晶间的元素偏析减弱。合金具有较强的抗回火软化能力。在3.5%NaCl溶液中,孔蚀主要集中在树枝晶与共晶组织α相的交接处,回火后合金的耐蚀性均优于铸态合金,700 ℃回火后合金的耐腐蚀性能比铸态及其它合金更强。     

锆基金属玻璃中离子减薄诱导的微结构变化

用电化学双喷、凹坑法和离子减薄制备了4组Zr52.5Cu17.9Ni14.6Al10Ti5金属玻璃的透射电子显微镜样品。透射电镜观测表明,电子透明区域的微结构随采用的离子减薄条件变化敏感。通过对比选区电子衍射花样和相同成分样品等温退火的X衍射花样发现,在一些严重依赖于离子减薄制备的电镜样品中存在显著的加热效应,导致在离子减薄区域形成了不同的有序结构。在那些特意使用长时间减薄的样品中,可达到约780 K的局域峰值温度,远远超过了该成分的玻璃转变温度。这个结果表明,在用离子减薄获得非晶合金的电镜样品时,必须注意减薄过程所诱导的潜在的微结构变化,以避免得到错误的判断