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1.
介绍了在软X-射线显微术研究领域中有重要应用的Si_3N_4薄膜窗口的实验室制作方法,并形成一套独特制备工艺,Si_3N_4薄膜窗口的研制成功推动了我国软X射线显微术研究的发展。  相似文献   

2.
聚硅氮烷的热分解特性研究   总被引:4,自引:0,他引:4  
研究了由有机氯硅烷氨解制得的聚硅氮烷(PSZ)在N2与NH3气氛中的热分解特性.结果表明,在N2气氛中,PSZ经三个阶段转化为无定形陶瓷,在更高温度下则得到α-Si3N4结晶与β-SiC微晶的复合体.β-SiC的形成来源于Si-CH3基团的热分解,降低PSZ中Si—CH3,含量能提高产物中Si3N4的含量.在NH3气氛中热分解时产生脱碳反应,导致形成无定形态的无机物,它在1500℃转化为几乎为纯的α-SiN4.  相似文献   

3.
应用BET、气相色谱、红外光谱、竞争加氢反应和XPS等方法,在以前工作的基础上继续考察了Y2O3、Sm2O3、Eu2O3、Gd2O3、Tb4O7、Dy2O3、Er2O3、Tm2O3、Yb2O3作为添加剂,对镍在γ-Al2O3表面的分散度、甲烷化活性、CO在镍上的吸附态及表面镍原子的电子状态的影响.结果表明,稀土氧化物添加剂不仅明显地提高了金属镍的分散度和甲烷化活性,还直接地影响表面镍原子的电子状态.对不同稀土氧化物,这些效应各异.作者认为,利用稀土氧化物添加剂调节表面镍原子的电子状态,可能成为改进甲烷化催化剂活性的一个有效途径.  相似文献   

4.
超细氮碳化物中吸附氧和化合氧的测定   总被引:5,自引:0,他引:5  
陈名浩  沈汝美 《分析化学》1994,22(7):698-701
用跟踪式程序升温、红外检测和微机解卷技术,测定氮碳化物超细粉的吸附氧和化合氧,探讨了超细Si3N4,AIN,TiCN和SiC中不同状态氧量与其制备方法,颗粒度及放置时间的关系。  相似文献   

5.
沈汝美  陈名浩 《分析化学》1996,24(10):1208-1211
利用游离硅和游离铝与碱溶液作用产生氢气,使它们与SiC、Si3N4、AlN,SiO2以及Al2O3等多种硅(铝)化合物分离。  相似文献   

6.
氮化磷化合物的合成德国Postfach大学的W.Schnick博士最近利用PCl5或(PNCl2)3和NH4Cl在低于800℃的温度下进行氨解,首次制出了纯态的P2N5。同样令人惊奇的是,他发现了以前被认为是化学惰性的化合物BN和Si3N4可作为制备...  相似文献   

7.
La2O3—Y2O3自增韧氮化硅的相转变与晶体生长   总被引:2,自引:0,他引:2  
研究了高La2O3Y2O3含量自增韧Si3N4在热压预烧结及高温气压处理过程中的相转变和晶体生长。采用热压烧结方法制备了几种具有较高相对密度,不同α相含量的Si3N4预烧体,并在1900℃、09MPaN2压力中进行气压处理。结果表明,预烧体中α相量越高,预烧体及高温处理后烧结体的显微结构就越细,预烧体的晶粒尺寸分布就越窄;经高温气压处理后,提高了材料的组织均匀性,相转变完全的预烧体均匀性提高最为显著  相似文献   

8.
本文报道在机械驱动下力,通过机械合金化途径使氮或氨直接在室温下的逐步细化的,新鲜的,高反应活性的硅界面上充分扩散,形成亚稳态系统,在800℃真空炉处理后得到纳米α-Si3N4粉末。发现气氛对合成Si3N4纳米粉末有很大影响。在氮气中,高能球磨前硅粉表面形成的氧化膜在高能球磨过程中与氮反应生成Si2N2O保护层,阻止氮的进一步扩散,使反应产物含有大量未反应的游离硅。在氨气中可以避免生成了Si2N2o  相似文献   

9.
描述了以镍单核配合物NiCp2和簇合物Ni3Cp3N-t-C4H9为前体的SiO2载镍催化剂的制备,通过元素分析、TRR、TPDE、XPS,CO吸附和苯加氢反应对以镍配合物和簇合物为前体制备的催化剂的性能及其制备过程了研究和表征。结果表明,镍与合物和簇合物在担载过程中同载体SiO2表面发生了相互作用,其化学组成发生了变化,在苯加氢反应中,此催化剂的活性比以Ni(NO3)2为前体制备的催化剂高得多,  相似文献   

10.
在Ni系ABO3和A2BO4型复合氧化物催化剂上NO吸附性能的研究   总被引:4,自引:1,他引:4  
合成了具有钙钛石和类钙钛石结构的复合氧化物LaNiO3,La0.1Sr0.9NiO3,La2NiO4和LaSrNiO4。考察了它们对NO的吸附和NO直接分解反应的催化性能,结合比表面测定,化学分析,XRD和NO-TPD对催化剂的表征结果,探讨了该系列复合氧化物对NO的吸附规律。  相似文献   

11.
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.  相似文献   

12.
非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。  相似文献   

13.

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

  相似文献   

14.
Two vanilloids, (5E)-8-(4-hydroxy-3-methoxyphenyl)oct-5-en-4-one (1) and 4-[3-hydroxydecyl]-2-methoxyphenol (2), isolated from the dried seeds of Grains of Paradise (Aframomum melegueta), were synthesized; the latter compound was made as the S-enantiomer and the material derived from the seeds was found to be a 1:1.7 mixture of the R and S isomers. The synthetic route used should allow the preparation of analogs having extended alkyl chains and consequently different lipophilicity, and 3, a homolog of 2, was also prepared.  相似文献   

15.
In this review, the research of the author in the field of colloidal systems is summarized. The factors influencing colloidal stability are systematized and analyzed. Examples are presented to illustrate the practical utilization of the theory of stability of colloids and thin films.This review was prepared on the basis of the works of the author, which were awarded the State Premium for 1991 in the field of science and technology, chemistry section.Institute of Physical Chemistry, Russian Academy of Sciences, 117915 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1708–1717, August, 1992.  相似文献   

16.
Main hydration products of two cement pastes, i.e. CSH-gel, portlandite (P) (and specific surface S) were studied by static heating, and by SEM, TEM and XRD, as a function of cement strength (C-33 and C-43) hydration time (th) and subsequent hydration in water vapour.Total change in mass on hydration and air drying, Mo, increased with strength of cement paste and with hydration time. Content of water escaping at 110 to 220°C, defined as water bound with low energy, mainly interlayer and hydrate water, was independent on cement strength but its content increased with (th). Content of chemically bound (zeolitic) water in CSH-gel, escaping at 220-400°C, was slightly dependent on strength and increased with (th). It was possibly derived from the dehydroxylation of CSH-gel and AFm phase. Portlandite water, escaping at 400-500°C, was independent on cement strength and was higher on longer hydration. Large P crystals were formed in the weaker cement paste C-33. Smaller crystals were formed in C-43 but they increased with (th). Carbonate formated on contact with air (calcite, vaterite and aragonite), decomposed in cement at 600-700oC. It was high in pastes C-33(1 month) and C-43(1 month), i.e. 5.7 and 3.3%, respectively; it was less than 1% after 6 hydration months (low sensitivity to carbonation) in agreement with the XRD study showing carbonates in the air dry paste (1month), and its absence on prolonged hydration (6 months) and on acetone treatment. Water vapour treatment of (6 months) pastes or wetting-drying increased this sensitivity.Nanosized P-crystals, detected by TEM, could contribute to the cement strength; carbonate was observed on the rims of gel clusters.This revised version was published online in November 2005 with corrections to the Cover Date.  相似文献   

17.
翟宗玺  刘树深  夏树屏 《化学学报》1990,48(10):946-950
用氧化镁氯化镁水溶液制备了8水合氯氧化镁[nMg(OH)2·MgCl2·8H2O], 并测定了其在盐酸中的溶解热, 实验结果表明, 氯氧化镁溶解热与n值呈线性关系, 根据溶解热求出5Mg(OH)2·MgCl2·8H2O和3Mg(OH)2·MgCl2·8H2O的生成热分别为-7727.1和5888.1kJ·mol^1^-。  相似文献   

18.
19.
The enthalpies of solution of several oxosulfides of rare-earth elements and the high-temperature enthalpies of oxosulfides and oxosulfates of lanthanum and yttrium were measured using solution calorimetry and high-temperature microcalorimetry techniques. Standard enthalpies of formation and some thermodynamic properties of oxosulfides and oxosulfates were calculated. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2 pp. 294–297, February, 1997.  相似文献   

20.
设计了铁的锈蚀实验,说明了铁钉的处理方法,增加了温度、酸、碱的影响条件,实现了铁跟蒸馏水及空气中氧气快速反应而生锈,使实验在5 min左右就能够得到准确的结果。  相似文献   

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