PPESK／SiO2杂化材料的制备及动态力学性能研究

以含二氮杂萘酮结构聚芳醚砜酮（PPESK）为基体，正硅酸乙酯（TEOS）为原料，N-甲基吡咯烷酮（NMP）为共溶剂，采用溶胶-凝胶方法制备出不同二氧化硅质量百分含量的PPESK／SiO2杂化材料。利用动态热机械分析仪（DMA）对PPESK／SiO2杂化均质薄膜进行动态力学性能测试和表征。结果表明，杂化材料中SiO2组分含量及扫描频率对PPESK／SiO2杂化材料的动态力学性能及玻璃化转变过程都有一定程度影响。SiO2含量的增加，杂化材料的力学损耗峰温度移向高温区，并且峰值升高；随着扫描频率的增加，杂化材料的损耗因子峰移向高温。同时采用Arrhenius方程计算PPESK／SiO2杂化材料在α转变时分子运动活化能。另外，还考察了SiO2粒子含量对PPESK／SiO2杂化材料的力学性能的影响。     

粉状乳化炸药热分解动力学研究

利用热重法（TG）研究了粉状乳化炸药的热分解过程和非等温反应动力学,采用Ozawa法和非线性等转化率积分法获得了其热分解动力学参数和机理函数。结果表明,粉状乳化炸药初始分解温度稍高于乳化炸药基质,分解活化能为97kJ／mool,是热稳定性良好的工业炸药。粉状乳化炸药的热分解机理属随机成核和随后成长,热分解动力学方程为dα/dt=1×10^10×（1-α）exp（-1．2×10^4／T）。     

Pd/SiO2有机-无机薄膜的制备及其在N2气氛中的热稳定性

采用溶胶-凝胶法,在甲基化改性SiO2溶胶中掺杂PdCl2,制备Pd/SiO2有机-无机薄膜.通过XRD、红外光谱、TG-DTG分析、接触角以及SEM测试,考察该样品在N2气氛中的热稳定性.结果表明,Pd/SiO2膜材料经200℃以上温度焙烧后,样品中即出现了少量纳米金属Pd粒子,这些金属Pd为PdCl2还原所得.随着焙烧温度的升高,金属Pd粒子的衍射峰强度增加,膜材料中的Si-CH3吸收峰和Si-OH吸收峰减弱.样品中的Si-CH3吸收峰在750℃时完全消失.金属Pd的掺杂对SiO2膜材料的化学结构基本没影响.保持Pd/SiO2有机-无机薄膜及分离膜疏水性的最适宜焙烧温度为350℃.     

PHPMA/SiO2有机无机杂化材料的研究

以甲基丙烯酸p羟丙酯(HPMA)、正硅酸乙酯(TEOS)为原料，基于溶胶凝胶技术合成出聚甲基丙烯酸B羟丙酯PHPMA／SiO2均质透明有机无机杂化材料。采用气相色谱(GC)技术、紫外可见分光度技术研究TEOS与HPMA杂化机理。利用FT—IR和DSC技术对杂化材料进行表征。实验结果表明，HP—MA的活性羟基与TEOS的乙氧基间能够发生杂化反应，形成以Si—O--C链结合的有机无机杂化网络，这些有机无机杂化网络赋予了材料优异的力学性能和热学性能。根据实验结果预测了PHPMA／SiO2杂化材料网络模型。     

聚醋酸乙烯酯／二氧化硅杂化材料的制备与性能研究

以硅酸钠在HCL溶液中的水解，经四氢呋喃（THF）萃取，制备聚硅酸溶胶，再与聚醋酸乙烯酯（PVAC）的THF溶液混合，经溶胶-凝胶过程制备了PCAC/SiO2有机/无机杂化材料。用扫描是镜（SEM），红外光谱（IR），X射线衍射，热失重及透光率等的分析测试，对制备的PVAC/SiO2杂化材料进行了结构与性能的研究。结果表明：本法制备的杂化材料中SiO2在PVAC的基体中分布均匀，SiO2在非晶态的PVAC中亦呈无定形态，杂化材料的硬度、软化温度和热分解温度都比纯PVAC有较大的提高；SiO2含量少于40%的杂化材料其断裂伸长率、屈服强度和断裂强度也比纯PVAC提高；另外，还发现在制备过程中加入少许偶联剂KH-570后，杂化材料中的有机-无机相间的相容性增加，不易发生相分离，材料的透光性能也大为改善。     

聚酰亚胺/纳米SiO2杂化膜的制备和表征

以均苯四酸二酐、4,4＇-二氨基二苯基甲烷和正硅酸乙酯为原料,采用溶胶-凝胶法制备聚酰亚胺／纳米SiO2杂化膜,利用FT—IR、XPS、AFM对杂化膜的制备过程及杂化膜的结构进行了表征．证实聚酰胺酸加热亚胺化较为完全,杂化膜中有SiO2粒子生成,并以纳米尺度均匀地分布于聚酰亚胺中．采用综合热分析仪对杂化膜的热性能进行了分析,结果表明杂化膜的热性能优于聚酰亚胺膜,其热分解温度比聚酰亚胺膜提高了17．8℃．     

纳米SiO2-Al2O3/聚酰亚胺杂化薄膜的制备及表征

用溶胶-凝胶法制得二氧化硅(SiO2)及三氧化二铝(Al2O3)溶胶,将其掺入到聚酰胺酸基体中,得到SiO2-Al2O3/聚酰亚胺杂化薄膜,并对其结构性能进行了研究.结果表明,薄膜材料中SiO2和Al2O3粒子分散均匀,与有机相存在键合;材料热分解温度有所提高.     

PMMA/SiO2纳米杂化材料的制备及作为润滑油添加剂的摩擦学性能

用无皂乳液聚合法，一步制备了聚甲基丙烯酸甲酯，表面有机化二氧化硅（PMMA／SiO2）纳米杂化材料，采用了红外光谱（FT-IR）、透射电子显微镜（TEM）以及热分析（TGA-DSC）等仪器对材料的核一壳结构进行表征，利用四球机考察了添加剂在AN10全损耗系统用油中的摩擦学性能。结果表明，合成的PMMA／SiO，纳米杂化材料能提高润滑油的抗磨性能及承载能力，并能降低摩擦系数，其最佳用量为1．5％，同时，PMMA／SiO2纳米杂化材料能极大地提高润滑油的极压性能。     

溶胶-凝胶法制备无机纳米/聚酰亚胺杂化膜及其表征

采用溶胶-凝胶法制备了SiO2及A12O3溶胶,并将其掺入到聚酰胺酸基体中,得到无机纳米SiO2-Al2O3/聚酰亚胺杂化膜,并对其结构性能进行了研究.实验表明,薄膜材料中无机纳米SiO2和Al2O3粒子分散均匀,与有机相存在键合;材料热分解温度有所提高.     

一种无卤阻燃聚丙烯的热分解动力学

利用Kissinger、Flynn-Wall-Ozawa(FWO)及Coast-Redfern方法研究了聚丙烯(PP)和IFR/SiO2/PP体系的热分解动力学。结果表明,IFR/SiO2添加提高了PP的主分解阶段活化能,增强了PP阻燃性能。PP热分解机理函数g(α)=-ln(1-α),反应级数n=1,为随机成核和随后增长反应;IFR/SiO2/PP体系热分解机理函数为g(α)=1-(1-α)1/4,反应级数n=1/4。     

Thermal stability of metal-silicide nanocrystal nonvolatile memory with barrier engineered tunnel layers

WSi2 nanocrystal nonvolatile memory devices were fabricated with a silicon oxide-nitride-oxide (SiO2: 2 nm/Si3N4:2 nm/SiO2:3 nm) tunnel layer. WSi2 nanocrystals of 2.5 nm diameters and a density of 3.6 x 10(12) cm(-2) were formed using radio frequency magnetron sputtering and annealing processes. The WSi2 nanocrystal nonvolatile memory device exhibited strong thermal stability during writing/erasing operations at temperatures up to 125 degrees C. When the writing/erasing voltages were applied at +10 V/-10 V for 500 ms, the memory window of the initial approximately 2.6 V decreased by approximately 1.1 V at 25 degrees C and 0.4 V at 125 degrees C after 10(4) sec, respectively. These results show that WSi2 nanocrystals with barrier-engineered tunnel layers are possible for application in nonvolatile memory devices.     

晶须补强增韧熔石英材料的热学性能

用热压烧结方法制得致密的SiCw/SiO,Si3N4w/SiO2复合材料,研究了材料的热膨胀,抗热震,抗烧蚀等性能,探讨了晶须补强增韧熔石英材料用于航天防热材料的可行性。     

Thermal behavior of freestanding microstructures fabricated by silicon frontside processing using porous silicon as sacrificial layer

Freestanding microstructures are essential elements in thermal and mechanical microsensors. In this paper, microbridges were fabricated by silicon surface micromachining using porous silicon as sacrificial layer. Two different approaches were considered. In first approach, n-Si was used as anodization masking material and n-Si/SiO/sub 2/ as microstructure material. In the second approach, silicon nitride and SiO/sub 2/ /Si/sub 3/ N/sub 4/ bilayer has constituted masking and microstructure materials, respectively. In order to characterize their thermal behavior, platinum heating elements were defined on developed microbridges. Microstructures fabrication process was described, insisting specially on silicon anodization step. The process parameters (HF-electrolyte concentration, current density, and process duration) were established for both approaches. Thermal behavior of developed microbridges was studied in relation to anodization masking materials and freestanding microstructure materials. Microbridge temperature versus applied power to heating element was analyzed. Additionally, entire sample thermal behavior and microbridge dynamic thermal behavior was characterized. The obtained results suggest developing a third approach where n-Si will be used as masking material and SiO/sub 2/ / Si/sub 3/ N/sub 4/ bilayer as freestanding microstructure material.     

Solid-State Thermal Reaction of a Molecular Material and Solventless Synthesis of Iron Oxide

Solid-state thermal decomposition reaction of a molecular material \(\{\hbox {As}(\hbox {C}_{6}\hbox {H}_{5})_{4}[\hbox {Fe}^{\mathrm{II}}\hbox {Fe}^{\mathrm{III}} (\hbox {C}_{2}\hbox {O}_{4})_{3}]\}_{\mathrm{n}}\) has been studied using non-isothermal thermogravimetry (TG) in an inert atmosphere. By analyzing the TG data collected at multiple heating rates in 300 K–1300 K range, the kinetic parameters (activation energy, most probable reaction mechanism function and frequency factor) are determined using different multi-heating rate analysis programs. Activation energy and the frequency factor are found to be strongly dependent on the extent of decomposition. The decomposed material has been characterized to be hematite using physical techniques (FT-IR and powder XRD). Particle morphology has been checked by TEM. A solid-state reaction pathway leading the molecular precursor to hematite has been proposed illustrating an example of solventless synthesis of iron oxides utilizing thermal decomposition as a technique using innocuous materials.     

氯磺化聚乙烯的热行为和热降解过程

用TG、DTG和DSC研究了氯磺化聚乙烯(CSM)的热行为和热降解过程。结果表明:CSM的热降解温度和失重50％的温度均随升温速率升高而增高;在氮气氛和空气中,CSM分别为三步和四步降解。     

Thermal expansion of rhodium,iridium, and palladium at low temperatures

Coefficients (α) of linear thermal expansion of Rh, Ir, and Pd are reported to be respectively 8.45, 6.65, and 11.78×10^?6 ° K^?1 at 238°K, and 3.50, 3.43, and 6.21×10^?6 °K^?1 at 75°K. At temperatures below 10°K, α may be represented by $$\begin{gathered} 10^{10} \alpha = 20{\rm T} + 0.052{\rm T}^3 (Rh) \hfill \\ 10^{10} \alpha = 9{\rm T} + 0.070{\rm T}^3 (Ir) \hfill \\ 10^{10} \alpha = 40.5{\rm T} + 0.435{\rm T}^3 (Pd) \hfill \\ \end{gathered} $$ TheT andT ³terms are identifiable with electron and lattice vibrational components, respectively. Corresponding Grüneisen parameters are γ (electron)≈2.8, 2.7, and 2.22 for Rh, Ir, and Pd, and γ ₀ (lattice)≈2.0, 2.3, and 2.25.     

Thermal Decomposition of Molecular Materials {\{{\rm N}(n{-}{\rm C}_{4}{\rm H}_{9})_{4}[{\rm M}^{\rm II} {\rm Fe}^{\rm III}({\rm C}_{2} {\rm O}_{4})_{3}]\}_{\infty},\,{\rm M}^{\rm II} = {\rm Zn},\, {\rm Co},\, {\rm Fe}}

Thermal decomposition of oxalate-based molecular precursors, namely ${\{{\rm N}(n{-} {\rm C}_{4} {\rm H}_{9})_{4}[{\rm Zn}^{\rm II}{\rm Fe}^{\rm III}({\rm C}_{2} {\rm O}_{4})_{3}]\}_{\infty}, \{{\rm N}(n{-}{\rm C}_{4}{\rm H}_{9})_{4}[{\rm Co}^{\rm II}{\rm Fe}^{\rm III}({\rm C}_{2}{\rm O}_{4})_{3}]\}_{\infty}}$ , and ${\{{\rm N}(n{-}{\rm C}_{4} {\rm H}_{9})_{4}[{\rm Fe}^{\rm II}{\rm Fe}^{\rm III}({\rm C}_{2}{\rm O}_{4})_{3}]\}_{\infty}}$ , abbreviated as BuZnFe, BuCoFe, and BuFeFe, respectively, are studied using thermogravimetry (TG) in the temperature range from ~300?K to ~675?K at multiple heating rates. This study also deals with how the thermal decomposition of the complexes proceed stepwise through a series of intermediate reactions. The effect of the divalent metal M^II on the nature of thermal decomposition of the complexes, reflected in their TG profiles in terms of number of steps involved, is reported in this study. The temperature range of thermal decomposition steps for BuZnFe, BuCoFe, and BuFeFe with the same heating rates are studied systematically. Two different isoconversional methods, namely an improved iterative method and a model-free method are employed to calculate the kinetic parameters, and thus the most probable reaction mechanism of thermal decomposition is determined. Based on kinetic parameters, the important thermodynamic parameters such as the changes of entropy, enthalpy, and Gibbs free energy are estimated for the activated complex formation from the precursors. Considering the mass loss during the different thermal decomposition steps of BuZnFe, BuCoFe, and BuFeFe, observed in the thermogravimetry profiles, the overall reactions of the thermal decompositions are demonstrated.     

SiO_2-AIN 复合材料的介电性能

热压烧结制备了ＳｉＯ２－ＡＩＮ复合材料,研究了烧结温度、第二相颗粒ＡＩＮ的引入量对ＡＩＮ颗粒补强ＳｉＯ２基复合材料介电性能的影响．结果说明：随着热压温度的提高,复合材料的介电常数增加,介电损耗减少;在一定的热压温度下,复合材料的介电常数和介电损耗随第二相颗粒ＡＩＮ的引入量的增加而增加。１ＭＨｚ时１０ｖｏｌ％ＡＩＮ－ＳｉＯ２复合材料的介电常数和介电损耗分别为４．１和９．０ｘ１０－４。从复合材料的组成和结构角度对以上结果予以解释。     

SiO2-Si3N4复合材料的力学性能及其增韧机理

采用热压工艺制备了ＳｉＯ２－Ｓｉ３Ｎ４复合材料，其抗弯强度和断裂韧性达到１４３ＭＰａ和１．７ＭＰａ．ｍ＾１／２，比基体ＳｉＯ２材料分别提高１０７％和７０％，复合材料改善是由于高弹性模量的Ｓｉ３Ｎ４引入以及ＳｉＯ２和Ｓｉ３Ｎ４热膨胀系数不匹配导致的残余应力。     

Transient interferometric technique for measuring thermal expansion at high temperatures: Thermal expansion of tantalum in the range 1500–3200 K

The design and operational characteristics of an interferometric technique for measuring thermal expansion of metals between room temperature and temperatures in the range 1500 K to their melting points are described. The basic method involves rapidly heating the specimen from room temperature to temperatures above 1500 K in less than 1 s by the passage of an electrical current pulse through it, and simultaneously measuring the specimen expansion by the shift in the fringe pattern produced by a Michelson-type polarized beam interferometer and the specimen temperature by means of a high-speed photoelectric pyrometer. Measurements of linear thermal expansion of tantalum in the temperature range 1500–3200 K are also described. The results are expressed by the relation: $$\begin{gathered} (l - l_0 )/l_0 = 5.141{\text{ x 10}}^{ - {\text{4}}} + 1.445{\text{ x 10}}^{ - {\text{6}}} T + 4.160{\text{ x 10}}^{ - {\text{9}}} T^2 \hfill \\ {\text{ }} - 1.309{\text{ x 10}}^{ - {\text{12}}} T^3 + 1.901{\text{ x 10}}^{ - {\text{16}}} T^4 \hfill \\ \end{gathered}$$ where T is in K and l₀ is the specimen length at 20°C. The maximum error in the reported values of thermal expansion is estimated to be about 1% at 2000 K and not more than 2% at 3000 K.