氮化钛的制备及表征

以金红石为原料 ,金属铝作还原剂合成氮化钛 ,以X射线衍射、热分析等方法进行测定 ,结果表明该法合成得到的氮化钛纯度较高 ,经济可行。     

利用康普顿散射分析碳化硅陶瓷在高温下使用氧化后组成的变化

用波长色散X射线荧光光谱仪,通过测量散射体(样品)对铑的康普顿散射线(RhKα-C)强度的变化,实现了碳化硅陶瓷在高温下使用时氧化情况的监控。用一套8只碳化硅校准样品建立了康普顿散射强度与样品平均原子序数之间关系的数学模型。利用此模型计算了碳化硅氧化后组成含量的变化。结果表明:用此方法测得的样品中碳、硅及氧的相对含量与X射线光电子能谱法所测结果相符,两者间的相对偏差均小于1%。据此认为,此方法所测得的数据是可以接受的。     

低磷化学镀镍层性能的研究

低磷镀层（ＬＰ）在碱性和中性盐水条件下的耐蚀性较高磷镀层好，当ＬＰ镀层在３５０℃下热处理１ｈ后，镀层在显微硬度从４５４Ｈｖ增加到８９０Ｈｖ。差热分析研究发现，在３４１．６℃和４０６．２℃有两个放热峰，分别对应于新相Ｎｉ５Ｐ２和Ｎｉ３Ｐ的形成，利用Ｘ射线衍射对镀层的结构进行分析，发现该镀层由非常细的微晶构成。     

掺铁碳化硅陶瓷的制备及其吸波性能

将羰基铁和液态聚碳硅烷(LPCS)反应生成的铁(Fe)溶胶与固态聚碳硅烷(PCS)混合,合成出不同Fe质量分数的PCS先驱体,然后经氧化交联和高温热解制备了不同Fe质量分数的磁性碳化硅陶瓷(Fe/SiC),系统地研究了Fe元素的引入对SiC陶瓷的组成、结构、磁性能和介电性能的影响规律。 研究发现,当Fe质量分数小于8.94%时,在热解过程中,Fe元素可以显著促进SiC_xO_y的分解,生成β-SiC,且随着Fe质量分数的增加,β-SiC的结晶峰越来越强;但随着Fe质量分数继续增加,达11.78%时,则主要生成Fe₃Si;Fe/SiC陶瓷均呈铁磁性,其饱和磁化强度随着Fe质量分数的增加而呈指数形式增加;当Fe质量分数为4.19%时Fe/SiC陶瓷在12.4 GHz具有最小的反射损耗,为-9.4 dB,同时低于-5 dB的带宽为2.4 GHz,Fe质量分数为8.94%时,低于-5 dB的带宽则为3.7 GHz,可用作良好的微波吸收材料。     

先驱体聚合物粘结法制备SiC纳米多孔陶瓷

采用SiC纳米粉体与聚碳硅烷(PCS)为原料低压成型低温烧结制备SiC纳米多孔陶瓷,研究了PCS含量对烧成纳米多孔陶瓷性能的影响。SEM和AFM微观形貌分析表明,PCS裂解产物将SiC纳米颗粒粘结起来,烧成陶瓷内部有大量的纳米孔存在。烧成SiC纳米多孔陶瓷孔径分布呈单峰分布、孔径分布范围窄,随着PCS含量的增大烧成多孔陶瓷强度增大,但孔隙率降低、烧结过程中坯体尺寸线收缩率增大。PCS含量为20wt%时三点弯折强度为36.8MPa,孔隙率为39.5%,平均孔径为49.3 nm。     

具有Dawson结构的钼钒磷杂多酸的制备和性质研究

本文报道用改良的分步处理合成方法, 直接制备了五种未见报道的2:18系列钼钒磷杂多酸, 详细考察了它们的生成条件. 经元素分析、电位滴定和差热热重分析确定阴离子的组成分别为[P2Mo17VO62]^7^-,[P2Mo16V2O62]^8^-,[P2Mo15V3O62]^9^-, [P2Mo14V4O62H2]^8^-, [P2Mo13V5O62H2]^9^-. 对五种杂多酸的热化学性质和碱度进行了讨论. 根据紫外、红外及X射线衍射结果讨论了它们的结构, 表明都属于具有Dawson结构的杂多化合物.     

添加稀土和重金属氧化物玻璃陶瓷的制备和烧结及性能研究

通过分别添加稀土氧化物和重金属氧化物作为烧结助剂 ,采用电子陶瓷工艺制备了具有非化学计量组成的堇青石基玻璃陶瓷。为了评价玻璃粉末的烧结特性 ,对烧结热处理后试样的密度和显气孔率进行了测定。结果表明 ,两种烧结助剂能促进玻璃的烧结致密化和降低 μ 堇青石向α 堇青石转变的温度并影响玻璃陶瓷的介电性能。玻璃陶瓷的完全致密化温度可以低到 90 0℃。该材料具有低的介电常数 (≈ 5 )和低的介质损耗因子 (≤ 0 2 % )以及合适的热膨胀系数 ((2 80～ 3 5 2 )× 10 - 6 ℃ - 1) ,能够在低于 95 0℃与高导电率的金属如金、铜和银 /钯共烧 ,是一种潜在的低温共烧陶瓷基板材料。     

用热分析技术测定碳化硅粉体对聚乙二醇的吸附量

用热分析技术TG-DTA(thermal gravimetric and differential thermal analysis)测定浆料中碳化硅粉体对分散剂聚乙二醇PEG(polyethylene glycol)的吸附量. 结果显示PEG在Ar气氛中411.5 ℃时完全分解; 碳化硅表面分散剂PEG的吸附量随着pH的增大而下降, 在较高pH下大多数分散剂仍存在于溶液中; 分散剂PEG的吸附量通过公式(1)进行计算. 该方法简单方便, 可以应用于测量氧化物或非氧化物吸附紫外-可见分光光度法不能测定的一些有机聚合物分子.     

EuI2—KI二元系相图

用差热分析和Ｘ射线衍射的方法研究了ＥｕＩ２－ＫＩ二元体系在３＊１０＾－４Ｐａ压强下的低压相图。实测相图显示，该二元体系存在一个同份熔化化合物ＫＥｕ２Ｉ５和一个异份熔化化合物Ｋ４ＥｕＩ６，两个在相共晶点的温度和成分分别为７３７Ｋ，２０％ＫＩ和７１３Ｋ，６０％ＫＩ。Ｘ射线粉末衍射的结果表明，ＫＥｕ２Ｉ５的晶体结构参数与文献数据十分吻合。本文还讨论了实测相图的误差来源，并由相图计算出ＥｕＩ２的熔化热为２１０１２Ｊ．ｍｏｌ＾－１。     

铕掺杂BaPbO3的EXAFS研究

采用扩展Ｘ射线吸收精细结构方法，研究了铕掺杂ＢａＰｂＯ３多晶粉末中Ｅｕ，Ｐｂ两种原子的近邻结构。Ｅｕ的掺杂，导致八面体中金属Ｐｇ，Ｅｕ的配位数降低。     

Spectroscopic Characterization of Dental Ceramics Composed of Yttrium-Stabilized Zirconium

Yttria–zirconia ceramics in various compositions of Y₂O₃ and SiO₂ were synthesized by a high temperature solid state reaction process in alumina crucibles at 1400°C for 2?h. The obtained samples were characterized by X-ray diffraction, infrared spectroscopy and X-ray absorption near edge structure analysis. Combining all of the structural characterizations, we conclude that the addition of lower Y₂O₃ and SiO₂ contents induces structural changes in the host matrix without partially or/and fully stabilizing the lattice of the zirconia crystalline phase.     

具有高机械强度的双孔硅胶的制备

0IntroductionPorous materials are useful for a variety of appli-cations,for example,heterogeneous catalysis,adsorp-tion and molecular separation[1￣3].In addition tocon-ventional mesoporous and microporous materials,multi-modal such as bi-or trimodal porous materials have at-tractedimmenseinterests,andanumberofmethodshavebeen used to create such pore structures in silica[4￣6].Nakanishi et al.[7,8]prepared a bimodal porous silicawith interconnected macropores and mesopores by fix-ing transitio…     

Physicochemical properties of new cellulosic fibers from the bark of Acacia arabica

With the growing environmental consciousness toward carbon emissions, natural fibers are the best alternative and act as a substitute for synthetic fibers due to their potential properties. New cellulosic fibers were identified from Acacia arabica bark. This study aimed at understanding the characteristics of Acacia arabica fibers (AAFs) extracted from the bark of the A. arabica, and its physicochemical properties were examined by thermal stability analyses, X-ray diffraction, chemical constitutions, and Fourier transform infrared spectroscopy analysis. Cellulose content (68.1 wt%), density (1028 kg m^?3), and crystallinity index (51.72%) properties were identified.     

Physicochemical and tensile properties of alkaline-treated new natural cellulosic Gossypium arboreum fiber

This article describes the characterization of novel natural lignocellulosic bark fibers extracted from the stem of the Gossypium arboreum (cotton) plant. The G. arboreum stem fibers were treated with 5% (w/v) aqueous NaOH solution for different soaking times, and the Fourier transform infrared spectroscopy analysis was conducted to examine the chemical compounds of the raw and treated fibers. The cellulose content improved from 70.06 to 83.91% after the treatment. The X-ray diffraction results indicate that the crystalline index and size were enhanced. Thermogravimetric analysis was performed to study the thermal properties and found that the thermal stability was higher for the treated fibers. The tensile strength and modulus were increased for the alkaline-treated fibers compared to the untreated fibers.     

多孔碳材料的制备

多孔碳材料不仅具有碳材料化学稳定高、导电性好等优点,由于多孔结构的引入,还具有比表面积高、孔道结构丰富、孔径可调等特点,在催化、吸附和电化学储能等方面都得到了广泛的应用。本文综述了微孔、介孔、大孔及多级孔碳等多孔碳材料的最新研究进展,重点介绍了多孔碳孔道结构的调控,并对多孔碳材料的应用进行了展望。     

Physico-chemical properties of new cellulosic fibers from the bark of Acacia planifrons

Identification of new natural fibers is growing due to their superior properties and the impetus for researchers to develop high-performance composites. This investigation was aimed at understanding the physico-chemical properties of Acacia planifrons fibers (APFs). The crystalline structure of APFs was analyzed by X-ray diffraction, and the crystallinity index (65.38%) was calculated. The chemical functional group of APFs was confirmed by Fourier transform-infrared spectroscopy, the thermal stability measured by thermogravimetric analysis, and surface characterization established by atomic force microscopy. Taken together, all the properties of APFs can play a vital role in establishing APFs as new reinforcement in polymer composites.     

Porous alumina as a support for catalysts and membranes. Preparation and study

Porous alumina as single tubes and as a multihole structure with controlled properties has been prepared. It is shown that the porous structure of these supports can be controlled without burning out additives but by a variation of the ratio between the main alumina component (α-Al₂O₃) and aluminium hydroxide (binder) in the extrusion masses and thermal treatment conditions. Gas permeability measurements have been used for the characterization of the supports. The properties of the ceramics are shown to satisfy the requirements of membrane supports.     

多孔β－TCP生物降解陶瓷的拉曼光谱

求文研究了多孔Ｂ－ＴＣＰ生物降解陶瓷及其粘结剂的拉王光谱。参照各种磷酸盐及磷酸盐玻璃的拉曼光谱，对生物降解陶瓷的拉曼特征频率进行了经验式的归属和指认。实验结果表明，生物降解陶瓷以β－Ｃａ３（ＰＯ４）２（β－ＴＣＰ）为主晶相，当粘结剂含量增加时，生物降解陶瓷中出现明显的Ｃａ４Ｐ２Ｏ９９和Ｃａ２Ｐ２Ｏ７，晶相和其他非晶相，其含量随粘结剂量增加而增加，并呈现一种多孔的网络结构。