混合稀土对共晶Al-2％Fe合金组织形态的影响

研究了富La混合稀土对共晶Al-2％Fe合金组织形态的影响。当混合稀土加入量较少时，合金中的α—Al相为明显的胞状枝晶；随着混合稀土加入量的增加，α-Al枝晶优先形核生长得到抑制，共晶Al3Fe相得到细化；当稀土加入量增至0．6％(质量分数)共晶Al3Fe相尺寸逐渐增大。并对混合稀土对共晶Al-2％Fe合金组织形态的影响机制进行了探讨。     

富铈混合稀土对AZ81合金组织与性能的影响

研究了富铈混合稀土对挤压铸造AZ81合金的显微组织和力学性能的影响。结果表明:加入不同含量富铈混合稀土的合金中都出现了一种新相Al11(Ce,La)3相,Al11(Ce,La)3相数量增多而Mg17Al12相则减少,能细化合金的组织晶粒,其细化作用在添加了1.5%富铈混合稀土的镁合金中尤为明显,但是当富铈混合稀土加入量大于2.0%时,合金中Al11(Ce,La)3相开始长大以粗大长杆状存在;在富铈混合稀土含量为1.5%时,AZ81合金的室温和150℃的综合力学性能达到最佳效果,超过2.0%时合金的室温和150℃综合力学性能开始下降;合金试样的拉伸断口带有局部韧窝的解理断裂和韧性断裂的混合特征。     

P+Sr+Ce复合变质对高硅耐热铝合金组织与性能的影响

采用正交实验设计方法研究了Al-21Si-1.5Cu-1.5Ni-2.5Fe-0.5Mg合金P Sr Ce复合变质。正交实验表明变质剂的最佳加入量(质量分数)为:2%(CaH2PO4 2CaSO4) 0.2%Sr 0.2?,可一次细化初晶硅与共晶硅,并改善富铁相形态。X射线衍射分析与能谱分析表明,未变质合金中的针状富铁相为Al9FeSi3,复合变质使粗大针状富铁相消失,生成鱼骨状富铈富铁相Al8CeFe4。在最佳变质条件下,室温抗拉强度与300℃瞬时抗拉强度均比未变质合金提高约30%,扫描电镜观察发现拉伸断口由脆性的沿晶断裂变为混合断口,断口中有大量韧窝存在。     

混合稀土对共晶Al-2%Fe合金组织形态的影响

研究了富La混合稀土对共晶Al-2?合金组织形态的影响. 当混合稀土加入量较少时, 合金中的α-Al相为明显的胞状枝晶;随着混合稀土加入量的增加, α-Al枝晶优先形核生长得到抑制, 共晶Al3Fe相得到细化;当稀土加入量增至0.6% (质量分数)共晶Al3Fe相尺寸逐渐增大. 并对混合稀土对共晶Al-2?合金组织形态的影响机制进行了探讨.     

单一稀土Ce, La和混合稀土在工业纯铝中的作用

通过对比实验的方法，研究了稀土Ce，La和混合稀土对工业纯铝组织、电性能和机械性能的影响。结果表明：单一稀土La，Ce可降低工业纯铝的电阻率，提高工业纯铝的导电性，其中La的效果优于Ce．而混合稀土对电阻率几乎无影响；La，Ce和混合稀土均能减小工业纯铝的晶粒度，在其加入量为0．1％后细化效果明显，当其含量大于0．5％后细化效果趋于平缓，其中Ce的效果最佳，La次之，混合稀土最弱；单一稀土La，Ce在一定含量时可提高工业纯铝的σb6和δ，Ce的作用强于La，混合稀土对σb和δ的影响不明显。     

钕对Mg7Zn2Al镁合金显微组织及力学性能的影响

采用光学显微镜、XRD、SEM和万能实验机等手段研究了稀土Nd(0.3%,0.6%,0.9%)对Mg7Zn2Al镁合金显微组织和力学性能的影响。结果表明:Mg7Zn2Al镁合金中添加Nd后,显微组织中有针状或棒状的Al2Nd和AlNd等稀土相生成,合金中的共晶组织(α-Mg+Mg32(Al,Zn)49+Mg7Zn3)得到了明显细化;但是α-Mg有粗化趋势,呈现发达的树枝状或胞状,共晶相由粗大连续的网状变为细小的块状或颗粒状分布在树枝晶的一次枝晶臂或二次枝晶臂的间隙。随着Nd含量的增加,合金的抗拉强度和延伸率呈逐渐下降趋势,显微组织的粗化是造成合金拉伸性能降低的主要原因,而硬度没有明显的变化。     

铝钛硼稀土中间合金的微观组织及其细化纯铝机制研究

采用氟盐与稀土铝水反应法制取Al5Ti4RE1B中间合金,对其进行物相、微观组织和细化效果分析,通过深入观察细化处理后晶粒形貌和微区成分分析对细化机制进行了研究。XRD及EDS分析显示RE和TiAl3结合生成了Ti2Al20RE相,细化试验表明Al5Ti4RE1B比Al5Ti1B具有更强的细化能力。微观组织及面扫描结果显示细化后的晶粒呈菊花状,在花瓣的不同位置存在RE和Ti分布的不均匀性,热处理后晶粒花瓣减少,成分也趋于均匀。这是由于Ti2Al20RE相在铝液中逐渐溶解并释放出RE和Ti原子,而-αAl晶体以枝晶的方式生长,同时将稀土原子排到枝晶间,最终形成了菊花状组织及元素分布的不均匀性。     

钪变质处理对A356合金凝固组织和性能的影响

采用稀土Sc对A356合金进行变质处理,研究了Sc对A356合金的初生α相和共晶硅形态及其力学性能的影响。结果表明:加入Sc在铝熔体中生成Al3Sc可以作为α-Al的非自发形核的核心,显著细化A356合金中的初生α相,由粗大的树枝晶形态变为细小的短枝晶和圆整的颗粒状形态,同时,Sc对共晶硅也具有显著的变质作用,使其由粗大的针片状变为细小的纤维状和蠕点状。当Sc的加入量为0.2%(质量分数)时,对A356合金中初生α相的细化作用和对共晶硅的变质作用即可达到最佳的效果,合金的铸态抗拉强度和伸长率分别提高23.7%和58.1%,在此基础上,继续增加Sc的加入量,对进一步改善合金微观组织和力学性能的作用不显著。     

钇对ZA-27锌合金老化性能的影响

采用金相、扫描电镜、 X射线衍射、电子探针及盐水浸蚀、热蒸汽浸蚀等方法, 对不同钇含量的ZA-27锌合金进行了显微组织及抗老化性能的研究.研究结果表明, 在ZA-27合金中添加适量的稀土钇, 钇可与铝生成细小的YAl3相, 为α相提供凝结核, 使α相形核量增加, 在结晶过程中, α相枝晶不能充分发育, 从而起到细化晶粒、减少偏析的作用; 同时, 还可与锌生成弥散、细小的钇锌相, 从而改变晶界状况, 提高合金的抗老化性能.当钇稀土含量较高时, 由于在晶界与晶内均有大块钇锌相生成, 破坏了合金晶界的致密度, 并增加了相界面, 从而使合金的抗腐蚀性能有所下降.     

微量稀土对工业纯铝中杂质相的变质行为

采用SE,EDAX,TEM他稀土对工业纯铝中富Fe(Si)杂质相的变质作用及机制,结果表明：富铈混合稀土（RE）是一种有效变质剂,可使铝中杂质相由粗大长针（条）状或骨骼变细小的团球状或短棒状,且分布均均匀,提高了材料的力学性能（尤其是塑性）,其变质机制主要是因稀土在固／液界面前前沿的富集,导致了稀土进入杂质相形成（AlFeSiRE)的复杂化合物,或吸附在杂质相表面阻碍其长大,但过量稀土易导致第二相数量增多,降低材料塑性,其加入量应小于 0．07％（质量分数）。     

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.     

非那雄胺合成工艺改进

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。     

Acid hydrolysis of carboxymethylcellulose of low degree of substitution

Cotton cellulose was swollen in a sodium hydroxide solution and carboxymethylated by a two-bath method for different periods of time for each process. The kinetics of acid hydrolysis and the crystallinity of the swollen and carboxymethylated samples were measured. The proportion of broken bonds, rate constants for hydrolysis, and permeability of cellulose to hydrolyzing agents were calculated. The susceptibility of glycosidic linkages to acid hydrolysis was improved by carboxymethylation more than by swelling in alkali. The increased accessibility of carboxymethylcellulose to acid was regarded as a consequence of increased intra-and intercrystalline swelling and of the glycosidic bonds' weakness caused by the electron-attracting carboxymethyl group on the C-6 position.     

氯氧化镁生成热的研究

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^-。     

Determination of heats of detonation and influence of components of composite explosives on heats of detonation of high explosives

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.

     

Estimation of Kinetic Parameters of Thermal Oxidation of Ilmenite

The aim of the presented work was the investigation of thermal oxidation of ilmenite in static air atmosphere. The investigations were carried out by use of a derivatograph (MOM, Hungary). The changes of crystallographic structure of investigated samples were identified by X-ray diffractometry on Philips PW-1710 diffractometer. In temperature above 500°C appears structure of hematite Fe₂O₃. On the basis of the thermogravimetric measurements, the contracting area and contracting volume models were found as the best fitting experimental data. This revised version was published online in August 2006 with corrections to the Cover Date.     

Mechanism of action of base-catalyzed oxygenation of phenol derivatives

Cyclopropyl derivative of 2,6-di-tert-butylphenol is synthesized as a probe to investigate the mechanism of base-catalyzed autooxidation of phenol derivatives. Our study indicates that one electron reduction of molecular oxygen from phenolate gives phenoxyl radical 3, a key intermediate of autooxidation. The coupling of phenoxyl radical and superoxide radical gives peroxylate anion 4 and produces the final epoxy alcohol adduct 6.     

Synthesis of phenolic components of Grains of Paradise

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.     

化学计量中不确定度评定研究进展

测量不确定度是表征合理地赋予被测量之值的分散性的参数。本文针对化学计量不确定度评定基础模型仅适用于线性模型、概率分布为正态分布或缩放位移t分布等局限,介绍了近年来不确定度评定的研究热点:蒙特卡罗方法(Monte Carlo Method,MCM),不确定度评定的来源、评定概念、评估方法及其发展过程,扩大了测量不确定度评定与表示的适用范围。     

微量钙的测定方法研究进展

介绍了1995-2006年期间测定微量和痕量钙的方法,如电感耦合等离子体-原子发射光谱法、原子吸收光谱法以及离子色谱法等的工作原理和特点,并说明了其测定微量钙的应用领域。并对微量钙的测定技术进行了展望(引用文献55篇)。