基于Marangoni效应的光学元件化学抛光工艺研究

介绍了Marangoni界面效应及化学抛光反应机理,进行了数控抛光刻蚀实验研究,包括刻蚀稳定性实验、刻蚀量与刻蚀头速率的关系以及初步的面形修复加工.通过对实验结果进行分析,得到稳定可控刻蚀抛光的上限刻蚀速率和刻蚀效率与刻蚀头走速的函数关系.     

聚磷酸铵的改性及其对聚丙烯阻燃特性的研究

探讨了三聚氰胺(MEL)改性聚磷酸铵(APP)过程中APP本身的化学及物理变化。发现在改性反应条件下,APP聚合度略有增加,晶型由I型变为Ⅰ、Ⅱ型混合物,导致改性产物(MAPP)的热稳定性大大提高,其失重特征更符合阻燃要求。将其与季戊四醇组成膨胀型阻燃剂(IFR)用于聚丙烯阻燃特性研究,结果表明添加25%时即具有良好的阻燃效果。同时热分析还证明,与简单掺混型相比,其失重速率峰值更小,500℃时的残余量更高。     

PbO-Yb2O3催化苯酚与碳酸二甲酯的酯交换反应

制备了一系列固体催化剂用于苯酚(PhOH)与碳酸二甲酯(DMC)酯交换合成碳酸二苯酯(DPC).其中,铅镱复合氧化物催化剂活性较高,能多次回收使用.用正交实验方法详细研究了该催化剂焙烧温度、催化剂组成及反应温度等影响因素.实验结果表明:选择铅镱物质的量比为2∶1,700℃下焙烧的催化剂,在n(PhOH)∶n(DMC)=2∶1,反应温度170℃,反应16 h时,得DMC转化率56.87%,DPC产率17.10%.碳酸甲苯酯(MPC)产率33.24%.该催化剂多次回收使用后仍有较好的活性.     

6-氟-3,4-二氢-2H-1-苯并吡喃-2-甲酸的合成

6-氟-3,4-二氢-2H-1-苯并吡喃-2-甲酸是制备新型抗高血压药奈必洛尔的关键中间体.今以4-氟苯酚为起始原料,经酯化、Fries重排、环化、氢化等6个步骤得到目标产物,总收率27%.4-氟苯酚Ⅰ与乙酸酐酯化得4-氟苯基乙酸酯Ⅱ,Ⅱ在AlCl3催化下Fries重排得4-氟-2-乙酰基苯酚Ⅲ,比从4-氟苯酚的Friedel-Crafts酰化收率更高,二步总收率58%;Ⅲ与酰化试剂乙二酸二乙酯经酯化、环合及碱性水解得到6-氟-4-氧代-4H-1-苯并吡喃-2-甲酸Ⅵ,用一种试剂完成了酰化、环化并引入羧基;Ⅵ在乙酸介质中,以10%Pd/C催化加氢得外消旋6-氟-3,4-二氢-2H-1-苯并吡喃-2-甲酸Ⅶ.以上所述的方法具有条件温和、试剂常见易得、易于工业化的优点,并首次给出了关键中间体及目标产物的光谱图,表明产物结构正确.     

γ-氯丙基三甲氧基硅烷季铵化反应中的溶剂效应研究

研究了不同类型的溶剂对γ-氯丙基三甲氧基硅烷与十八烷基二甲基叔胺季铵化反应的影响.实验发现:在不同类型的溶剂中季铵化反应速率有显著差别,相同温度下在DMSO(二甲基亚砜)中的反应速率高于在其它类型溶剂中的反应速率;在大多数溶剂中该季铵化反应符合二级反应速率方程,作者通过线性拟合得到了不同溶剂中季铵化反应速率常数,并以80℃下季铵化反应速率常数对溶剂的介电常数和偶极矩作图,发现反应速率随着溶剂极性的增加而增大,但是苄醇显著偏离此规律.实验发现:季铵化反应速率随着温度的升高而增大,其中醇类溶剂中的反应速率对温度的依赖性远大于其它类型的溶剂,120℃下在丙二醇单甲醚溶剂中反应速率是80℃下的113倍,这表明高温破坏了叔胺和醇类溶剂形成的氢键,造成了反应速率显著升高.作者根据过渡态理论计算了季铵化反应中的热力学参数,表明随着反应速率的增加,季铵化反应的过渡态Gibbs自由能降低,熵值增加、焓值降低.     

Preisach逆补偿的GMA精密轨迹跟踪与实验优化

针对超磁致伸缩执行器(GMA)的非线性迟滞,研究了开环条件下采用Preisach逆模型对参考轨迹实现精密跟踪的补偿方法。简要介绍了经典Preisach迟滞数值模型,详细推导了Preisach逆模型及其数值实现方法。采用FFT数字滤波方法对一阶回转下降曲线 (FOD)实验数据进行优化处理,同时结合拉各朗日双线性插值方法,提高了在同等离散水平下Preisach模型对GMA非线性迟滞的预测精度。在精密预测的基础上,通过Preisach逆模型实现了GMA对参考轨迹的精密跟踪。实验结果表明:在0~34 μm,跟踪误差由补偿前的-14.7%~+11.2%减小到-2.9%~+2.7%。此外,FFT滤波和双线性插值算法可以明显提高Preisach模型对GMA非线性迟滞的预测精度,基于Preisach数值逆模型的补偿算法可以有效消除由于GMA非线性迟滞造成的跟踪误差。实验同时指出,如果要进一步提高跟踪精度,还须结合反馈实现闭环控制。     

锰锑酸铅-锌铌酸铅-锆钛酸铅陶瓷的铁电性能

通过电滞回线测试,探讨了xPb(Mn1/3Sb2/3)0.05(Zr1/2Ti1/2)0.95O3(1-x)Pb(Zn1/3Nb2/3)0.28(Zr1/2Ti1/2)0.72O3[xPMnS-(1-x)PZN]陶瓷的铁电性能及铁电相变特性.同时研究了Ba2 取代Pb2 对材料铁电性能的影响.结果表明;三方相含量较高的0.2PMnS-0.8PZN陶瓷具有较高的矫顽场和较大的剩余极化强度;四方相含量较高的0.5PMnS-0.5PZN和0.6PMnS-0.4PZN陶瓷具有较低的矫顽场和较小的剩余极化强度,Ba2 取代使三方相含量增加,铁电性能明显提高.     

Nouveaux materiaux cathodiques pour generateurs a anode de lithium: Les oxydes mixtes de bismuth et de plomb 2ième partie: Etude électrochimique et radiocristallographique du processus de réduction: New cathode materials for lithium batteries: lead bismuth mixed oxides

The different phases observed during reduction of various Li/(1−n) Bi₂O₃, n PbO cells have been investigated using X Ray analysis and cyclic voltammetry. The results imply a pseudo single-phased behaviour. Comparisons between definite compounds and solid solutions occuring at the same compositions seem to indicate that the discharge kinetics is influenced by the degree of ordering of the ionic network. The existence of a large voltage plateau at 1,5 volt, the high energy density and the very good stability of the initial capacity during long time storage make Li, Bi Pb Oxyde cells specially suitable for watch supply applications.     

Mechanochemical preparation and thermal stability of γ-Fe2O3 derived from γ-FeOOH

The dehydration process of lepidocrocite, γ-FeOOH, induced by wet grinding procedures has been studied. Microcrystals of maghemite, γ-Fe₂O₃, are found in the product of ball-milling in hexane and cyclohexane media. In contrast, grinding in air leads to hematite α-Fe₂O₃. This change is accompanied by the development of a characteristic texture in which a slit-shaped porous system is present. On the other hand, mechanochemically prepared maghemite increases in its thermal stability. This fact has been attributed to the higher crystallinity of ground microcrystals as revealed by the values of crystallite size and microstrains.     

Synthesis and properties of thin film polymorphs of molybdenum trioxide

Thin film polymorphs of molybdenum trioxide have been synthesized by reactive r.f. sputtering in an atmosphere of argon plus oxygen. Films deposited on thermally insulated substrates are polycrystalline and exhibit preferred orientation. Depending on the oxygen partial pressure P_O2 during sputtering, the films crystallize in either the thermodynamically stable α-MoO₃ form (P_O2 ≈ 50%) (unique two-dimensional layered structure) or the newly discovered, metastable monoclinic β-MoO₃ phase (P_O2 ≈ 10%) (three-dimensional ReO₃-related structure). Metastable β films convert thermally to the α phase and the transformation appears topotactic. In contrast, films deposited on cooled substrates are amorphous. A correlation between the particular phase formed and adatom mobility is noted.