氧化物与稀土磷酸盐复合陶瓷的切削加工性评价

应用模糊综合评判原理, 评价可加工陶瓷材料的切削加工性, 判断材料的切削加工性等级.通过Ce-ZrO2/CePO4复合陶瓷的材料制备、性能测试、模糊综合评判和加工实验, 研究了氧化物与稀土磷酸盐复合陶瓷的材料切削加工性.根据模糊数学提出一种可加工陶瓷材料切削加工性的综合评判方法.以陶瓷材料的力学性能参数为因素集, 选择5种切削加工性等级, 根据隶属函数计算模糊矩阵, 通过模糊变换确定出氧化物与稀土磷酸盐复合陶瓷的切削加工性.综合评判结果将所制备的几种Ce-ZrO2/CePO4复合陶瓷材料分为3个切削加工性等级, 材料的切削加工性等级随CePO4含量的增加而提高, 评判结果与钻削实验的材料去除率结果相符.Ce-ZrO2/CePO4复合陶瓷材料的钻削加工表面具有明显的塑性变形加工痕迹.还分析了含LaPO4的其它氧化物复合陶瓷材料的切削加工性等级.材料切削加工性的评价方法建立了材料性能与加工技术之间的关系, 可提供一种新的材料设计方法.     

中间层组成对坯体连接CePO4-ZrO2陶瓷强度和界面结构的影响

用含CePO4和ZrO2的中间层将25％CeP04／ZrO2和ZrO2陶瓷坯体在无压条件下连接起来后，经1450℃保温2h烧结成一整体，分析了CePO4／(ZrO2 CePO4)比例对连接结合强度的影响，并发现在实现条件下，连接面处的颗粒基体小，显微结构比基体更均匀、致密，没有明显的裂纹、气孔和其他缺陷。     

CePO_4/Ce-ZrO_2可加工陶瓷性能与断裂机制研究

以Ce ZrO2为基体,通过复合不同加入量的第二相CePO4颗粒,研究了陶瓷材料力学性能的变化,并借助加载能谱仪(EDS)的扫描电子显微镜(SEM)对材料弯曲断口及压痕裂纹扩展方式进行分析。当CePO4加入量为25%时,虽然材料力学性能有一定下降,但已经能用WC刀具进行加工。材料的弯曲断口显示,CePO4在两相体系中的断裂呈层片状形式;加入CePO4后,由于两相之间弱结合界面的存在,压痕裂纹扩展形式发生明显变化,由连续扩展机制过渡为不连续扩展。由这两种机制形成的材料断裂过程是阶段性的,在实际中可以用作材料最终破坏前的预报。     

CePO4／Ce—ZrO2可加工陶瓷性能与断裂机制研究

以Ce-ZrO2为基体，通过复合不同加入量的第二相CePO4颗粒，研究了陶瓷材料力学性能的变化，并借助加载能谱仪(EDS)的扫描电子显微镜(SEM)对材料弯曲断口及压痕裂纹扩展方式进行分析。当CePO4加入量为25％时，虽然材料力学性能有一定下降，但已经能用WC刀具进行加工。材料的弯曲断口显示，CePO4在两相体系中的断裂呈层片状形式；加入CePO4后，由于两相之间弱结合界面的存在，压痕裂纹扩展形式发生明显变化，由连续扩展机制过渡为不连续扩展。由这两种机制形成的材料断裂过程是阶段性的，在实际中可以用作材料最终破坏前的预报。     

ZrO2/CePO4可加工陶瓷的性能与压痕裂纹形貌

研究了CePO4加入量对ZrO2/CePO4陶瓷材料的力学性能和压痕裂纹形貌的影响.结果表明, 在ZrO2组成中加入适量的CePO4可形成强弱界面相互分布的网络结构, 在弱界面处裂纹可发生偏转、分支、桥联等形式, 从而在保证该材料具有可加工性的同时仍可维持较高的力学性能.     

Hydrothermal Synthesis and Characterization of Nd Doped One-dimensional Hexagonal CePO_4 Nanowires

One-dimensional Nd doped CePO4 hexagonal nanowires have been synthesized for the first time at 140 ℃ for 24 hours via a hydrothermal method using P123 surfactant as the template.The products were characterized by X-ray diffraction,transmission electron microscopy,photoluminescence and high-resolution transmission electron microscopy.Compared with CePO4,one-dimensional nanomaterials we have synthesized,Nd doped CePO4 nanomaterials remain their hexagonal one-dimensional morphology and smooth surface.However,their photoluminescence emissions are greatly enhanced at the wavelength of 348 nm.With their novel fluorescence-emission property,the Nd doped CePO4 nanomaterials are potential in many fields such as optics and electronics.     

CePO4纳米线的热稳定性及光学性能

以铈盐和磷酸为前驱体, 经水热合成获得了高长径比的具有六方晶型和单斜晶型独居石结构的CePO4纳米线, 采用XRD、HRTEM、SEM和荧光光度计对其晶相组成、形貌及发光性能进行了表征. 结果表明, 六方晶型CePO4纳米线直径约为40 nm, 长度约为3 μm; 单斜晶型独居石结构CePO4纳米线直径约为50 nm, 长度可达10 μm, 产物均为高纯且结晶良好的CePO4晶体. 可通过控制水热反应时间达到控制CePO4纳米线晶型的目的. 随水热反应时间的延长, 磷酸铈纳米线从六方晶型转变为单斜晶型(独居石结构). 随煅烧温度的升高, 磷酸铈纳米线直径增大, 但经1000 ℃煅烧仍具有一维线性结构, 其热稳定性高. 磷酸铈纳米线在紫外光激发下具有可见光区蓝紫发射区, 但随煅烧温度的升高, 磷酸铈纳米线的发光强度明显降低.     

不同晶型磷酸铈纳米材料的水热法合成及荧光性能

纳米材料;水热合成;晶体结构;荧光;CePO4     

磷酸铈共沉淀分离富集硫酸钴中痕量铅及铅的原子吸收光谱测定

提出了用磷酸铈(CePO4)作为共沉淀捕集剂分离富集CoSO4溶液中的痕量Pb2+,用火焰原子吸收光谱(FAAS)测定的方法。共沉淀效率受pH、Ce(NO3)3和H3PO4溶液用量的影响。结果显示,在溶液pH3.0～4.0时,CePO4能够定量共沉淀CoSO4溶液中的Pb2+,对于20mL的样品溶液,方法的检出限为5.59×10-2mg/L,铅的标准加入回收率为98.32%,排除了基体干扰,取得了较为满意的结果。     

Tb3+掺杂CePO4核壳微球的水热合成及其发光性能

在pH=1无模板条件下水热合成出直径为2~3 μm的CePO4∶Tb核壳微球结构。 其核壳表面由直径为20~30 nm、长度为200~300 nm的纳米棒组成。 产物生长过程实验表明,首先形成球状团聚产物,然后一些颗粒在表面生长,由于奥斯瓦尔德熟化效应产物尺寸变大,最后表面上的部分颗粒消耗内部的核而外延生成一维纳米棒。 CePO4∶Tb核壳微球的荧光性质和荧光寿命测试表明,当Tb3+摩尔分数为10%时,发射强度达到最大值,Tb3+浓度再增加其荧光发射强度由于浓度淬灭作用而迅速降低。     

Neutral diterpenoids of oleoresins of five species of conifers of Transcarpathia

The compositions of the neutral diterpenoids of the oleoresins of five species of conifers growing in the Transcarpathia have been studied. It has been found that the oleoresins ofAbies alba M.,Larix decidua M., andPicea excelsa L. contain more than 50% of neutral diterpenoids. The group and qualitative compositions of the oxygen-containing diterpenoids have been determined. In the oleoresins ofAbies alba,Picea excelsa, andPicea abies tertiary alcohols — cis-abienol and isocembrol — predominate, while inLarix decidua the main component is the hydroxy ester larixyl acetate. Primary alcohols related to the resin acids have been found in all the oleoresins investigated. Features of the distribution of diterpenoids according to the species of conifers have been revealed. The results obtained are necessary for the chemotaxonomy of conifers of the family Pinceae.Novosibirsk Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR. Translated from Khimiya Prirodynkh Soedinenii, No. 6, pp. 812–816, November–December, 1988.     

利用手持技术改进测定乙醇分子结构实验

利用压强传感器代替排水集气法,改进测定乙醇分子结构实验的仪器装置,并探索最佳反应条件。另外,设计两个空白实验,结合压强变化曲线对实验误差进行相关讨论。     

光谱仪测试范围的扩展

由于石化行业的生产需要，其材质的使用具有多样性和广泛性，经常会出现顾客委托的测试样品的一个或几个元素跨越光谱仪现有测试程序测量范围的情况。本法通过对光谱仪测试原理的认识，根据光谱仪的测试能力及标样的采集，实现了一个或几个元素测量范围的扩展，并对其测量的影响因素进行了研究。     

Effect of the Method of Modification of Zeolite X on Selectivity of Catalytic Methylation of Toluene

Theoretical and Experimental Chemistry - The effect of the method of modification of catalysts based on zeolite X by cesium and magnesium cations (ion exchange and impregnation) on the selectivity...     

Dichroism of absorption and polarization of phosphorescence of molecules of the closed form of nitrobenzospirothiopyran

The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.     

Influence of viscosity of medium on processes of oxygen quenching of excited states of mesoporphyrin

The oxygen quenching rate constants for singlet and triplet excited states of the dimethyl ester of mesoporphyrin IX increase with decreasing viscosity of the medium and reach a maximum at a viscosity of approximately 0.4 mPa·sec, after which the rate constants begin to decrease. The drop in rate constant with increasing fluidity of the medium may be related to a nonequilibrium character of the elementary act in the interaction of the reactants in the solvent cage. In viscous media such as isopropyl alcohol, isobutyl alcohol, and isoamyl alcohol, the reaction radius is greater than the sum of the radii of the reacting particles. The long-range character of these processes is due to the relatively weak dependence of the quenching probability on distance.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 2, pp. 161–167, March–April, 1989.     

Synthesis of tetrabenzoporphins of the basis of isoindoline

Chemistry of Heterocyclic Compounds -