A study of the crystallization kinetics of Ge-Te amorphous systems

The glass-forming ability of binary GexTe100-x (x=15, 20, 30) alloys was investigated. The crystallization mechanism of these amorphous bulks was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and differential scanning calo- rimetry (DSC). The temperature of glass transition, the temperature of crystallization, the activation energy for glass transition and crystallization, and the order of the crystallization mechanism were calculated from the different heating-rates.     

Accurate electrical resistance measurement of the crystallization kinetics of amorphous alloys

An accurate four-line ac electrical resistance measurement (ERM) apparatus was developed. By using the ERM the crystallization kinetics of amorphous Ni80P20, FeZr2, Fe86B14 alloys were investigated. The experimental results show that the ERM can identify the early stage of crystallization in amorphous alloys. The ERM detects a crystallization temperature range obviously wider than the DSC does, indicating that the ERM is more sensitive to the structure evolution in crystallization. For the eutectic or polymorphic crystallization, three distinct processes can be identified from the measured resistance variation: (i) crystal nucleation, (ii) subsequent growth of crystal nuclei, and (iii) coarsening of the crystallites. In the early stage of the primary crystallization, the ERM results reflect the nucleation information as well.     

草甘膦结晶动力学研究

结晶动力学研究可以为结晶器设计、结晶过程放大和优化以及结晶过程控制提供重要的基础数据。测量了草甘膦在工业溶液中的溶解度与温度的关系;使用连续的混合悬浮、混合产品排出(mixed suspension mixed product remove, MSMPR) 理想结晶器,用外推法得到了草甘膦结晶粒度无关生长动力学模型以及粒度相关的生长动力学模型,并得到了成核速率模型。 实验表明:草甘膦的溶解度随温度的变化较快,使用冷却结晶的方法可以实现草甘膦的生产;草甘膦的晶体生长速率与晶体的粒径相关;在实验条件下,悬浮密度和能力输入对成核速率的影响不大。     

Non-isothermal crystallization kinetics of kaolin modified polyester

Fiber-class modified kaolin and PET have been blended in the twin-screw and granulated to chips containing 4 wt% of kaolin.Non-isothermal crystallization process of kaolin modified polyester was investigated using a differential scanning calorimetry (DSC),and the addition of kaolin enhances either the melting temperature (Tm) or the crystallization temperature (Tc).The morphology of kaolin modified polyester,the melt of which is cooled at different cooling rate,was observed by scanning electron microscope (SEM).The relationship between Tc and cooling rate F was studied.Semi-crystalline phase t1/2 makes an exponential decline with increasing F,and the higher the cooling rate,the shorter the time of crystallization completion.Non-isothermal crystallization kinetics parameters and the activation energy were calculated,indicating that the higher rate of cooling needs the higher relative crystallinity in the unit crystallization time,the crystallization rate increased while speeding up the temperature reduction,and the activation energy ΔE was calculated to be-204.1566 kJ/mol for the non-isothermal crystallization processes by the Kissinger’s methods.     

Non-isothermal melt crystallization kinetics of anhydrite-filled polypropylene composites

The non-isothermal crystallization kinetics of polypropylene (PP), PP/anhydrite composites were investigated by differential scanning calorimetry (DSC) with various cooling rates. The Avrami analysis modified by Jeziorny and a method developed by Mo were employed to describe the non-isothermal crystallization process of these samples. The difference in the exponent n between PP and PP/anhydrite composites indicated that non-isothermal kinetic crystallization corresponded to tri-dimensional growth with heterogeneous nucleation. The values of half-time, Z _c and F(T) showed that the crystallization rate increased with the increasing of cooling rates for PP and PP/anhydrite composites, but the crystallization rate of PP/anhydrite composites was faster than that of PP at a given cooling rate. The method developed by Ozawa did not describe the non-isothermal crystallization process of PP very well. Moreover, the method proposed by Kissinger was used to evaluate the activation energy of the mentioned samples. The result showed that the activation energy of PP/anhydrite was greatly larger than that of PP.     

Al-induced Lateral Crystallization of Amorphous Si Thin Films by Microwave Annealing

Al-induced lateral crystallization of amorphous silicon thin films by micr owave annealing is investigated,The erystallized Si films are examined by optical microscopy,Raman spectroscopy ,transimission electron microscopy and transmission electron diffraction micrography.After microwave annealing at 480 ℃ for 50min the amorphous Si is completely cystallized with lagrge grains of main (111) orientation,The rate of lateral crystallization is 0.04μm/min,This process,labeled MILC-MA ,not only lowers the temperature but also reduces the time of crystallization.The crystallization.mechanism during microwave annealing and the electrical properies of polycrystalline Si thin films are analyzed.This MILC-MA process has potentila application in large area electronics.     

透闪石／尼龙1010复合材料等温结晶动力学研究

将经过表面修饰的透闪石与尼龙1010按一定比例共混制成复合材料,采用差示扫描量热法（DSC）研究了该复合材料的等温结晶行为,并应用Avrami方程对其进行了等温结晶动力学分析。结果表明：透闪石对尼龙1010结晶起到了异相成核的作用,尼龙1010的结晶速率随透闪石的含量的增加而提高,Avrami指数n略有降低。对尼龙1010及其复合材料样品结晶活化能的计算表明,后者高于前者,结晶速度对温度的敏感性增加。     

过滤动力学浅析

通过对过滤机理的理论分析，尤其是迁移机理中公认的五大作用：拦截作用，沉淀作用，惯性作用，扩散作用，水运输,并通过合理假设，得出过滤动力学的模型及方程。     

透闪石/尼龙1010复合材料等温结晶动力学研究

将经过表面修饰的透闪石与尼龙1010按一定比例共混制成复合材料,采用差示扫描量热法(DSC)研究了该复合材料的等温结晶行为,并应用Avrami方程对其进行了等温结晶动力学分析。结果表明:透闪石对尼龙1010结晶起到了异相成核的作用,尼龙1010的结晶速率随透闪石的含量的增加而提高,Avrami指数n略有降低。对尼龙1010及其复合材料样品结晶活化能的计算表明,后者高于前者,结晶速度对温度的敏感性增加。     

体积收缩对高聚物等温结晶动力学过程的影响

采用Monte Carlo法，模拟了在预先成核条件下，体积收缩对高聚物等温结晶动力学过程的影响，用模拟结果对Avrami方程和Price方程的有效性进行了评价，得到了体积收缩对结晶动力学参数影响的定量数据。结果表明，体积收缩导致结晶初期Avrami指数n值减小，复合结晶速率常数Z值和由Z返算的线生长速率常数G值增加；与Avrami方程相比，Price方程仍不能较准确地描述高聚物后期结晶行为。     

丙烯酸等离子体改性纳米TiO2/PET复合体非等温结晶动力学

为提高纳米颗粒在聚合物中的分散性,使用丙烯酸(AA)等离子体聚合技术,在TiO2纳米粉体表面包覆均匀的有机聚合物薄膜.将AA等离子体改性纳米TiO2分散在乙二醇溶液中,与对苯二甲酸聚和获得了包含丙烯酸等离子体改性纳米TiO2的PET复合体.使用DSC法研究了AA等离子体表面改性纳米TiO2粉体对PET复合体结晶性能的影...     

Limitation of the Johnson-Mehl-Avrami equation for the kinetic analysis of crystallization in a Ti-based amorphous alloy

The primary crystallization of the Ti40Zr25Ni8Cu9Be18 amorphous alloy was studied by isochronal differential scanning calorimetry (DSC). The activation energy was determined by the Kissinger-Akahira-Sunose method. Trying to analyze the crystallization kinetics of the Ti40Zr25Ni8Cu9Bei8 amorphous alloy by two different methods, it was found that the crystallization kinetics did not obey the John-son-Meh1-Avrami equation. A modified method in consideration of the impingement effect was proposed to perform kinetic analysis of the isochronal crystallization of this alloy. The kinetic parameters were then obtained by the linear fitting method based on the modified kinetic equation. The results show that the isochronal crystallization kinetics of the amorphous Ti40Zr25Ni8Cu9Be18 alloy is heating rate dependent, and the discrepancy between the Johnson-Meh1-Avrami method and the modified method increases with the increase of heating rate.     

L-亮氨酸分批发酵动力学研究

通过检测发酵过程的基质浓度、菌体量和产物浓度，建立了一组反映TQ9806菌株L-亮氨酸分批发酵的动力学模型，结果显示该动力学模型可以很好的拟合发酵过程。     

Influence of small Cu addition on the crystallization of amorphous alloy Fe-Zr-B

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CBT/PA6共混物等温及非等温结晶动力学

利用溶液共混法制备了尼龙6(PA6)/对苯二甲酸丁二醇酯(CBT)的共混物,研究了PA6和CBT/PA6体系粘度随温度的变化、结晶形态以及等温和非等温结晶动力学。流变结果表明,CBT的加入可以明显降低PA6的粘度。DSC结果表明:等温结晶时,加入CBT后,PA6的Avrami指数n、t1/2、tmax均降低,结晶速率G提高;非等温结晶时,共混物的Jeziorny指数n有所降低,相比于PA6,结晶速率加快。POM结果表明:CBT的加入能有效地增加PA6的成核密度。可见CBT有望成为PA6结晶过程促进剂。     

电子束辐照交联超高分子量聚乙烯等温结晶动力学

研究了电子束辐照交联超高分子量聚乙烯的等温结晶行为与辐照剂量、交联度和结晶温度的关系.首先,用差示扫描量热技术(DSC)研究了以0,50,100 kGy电子束辐照的超高分子量聚乙烯分别在不同的温度下等温结晶过程,发现半结晶时间(t1/2)和Avrami指数(n值)与结晶温度有关.与未交联超高分子量聚乙烯相比,交联聚乙烯等温结晶动力学的t1/2和n值较小,证明交联网络可加速聚乙烯成核,且抑制晶体生长.在此基础上,采用阶梯式温度"跃变"方法,诱导交联聚乙烯分子链在不同温度下分别结晶,得到具有多个熔融温度的交联聚乙烯结晶,而未交联的超高分子量聚乙烯则只显示单一熔融温度,证实了在交联聚乙烯中存在的不均匀交联网络结构导致分子链结晶能力不同.     

Effects of heat-treatment on crystallization and wear property of plasma sprayed Fe-based amorphous coatings

The Fe-based amorphous coatings were produced by air plasma spraying. The as-sprayed coatings were heat-treated at the temperature of 573, 873, and 1 023 K, respectively. The crystallization and wear behavior of the heat-treated amorphous coatings were investigated. It was found that the amorphous-nanocrystalline transformation appeared when the as-sprayed coatings were treated at 853 K. The crystallization process had completed and a coating with microcrystallines was formed when the treatment temperature reached 1 023 K. The resultant amorphous and nanocrystalline composite coatings exhibited superior wear resistance compared to crystalline coating. It is attributed to fine grain strengthening of formed nanocrystallines.     

控制系统数学模型的统一性研究

采用一种等价的δ算子代替离散时间系统中的平移算子，使连续时间系统与离散时间系统的数学模型得到统一；并讨论了离散时间系统与其对应的连续时间系统之间的某些内在关系．     

Al88Ce8Ni4非晶合金的热稳定性和晶化行为的研究

采用单辊甩带技术制备出的铝基非晶合金Al88Ce8Ni4,利用XRD、TEM和DSC对非晶热稳定性和晶化行为进行了分析,结果表明,该所制备的铝合金属于完全非晶态,开始晶化温度达到（Tx）530K,其稳定性良好.晶化过程分两步进行,且晶化产物除了初生相α-Al,大多以Al-Ce和Al-Ni原子簇组成.     

硬-软件系统冗余结构最优化研究

基于硬件系统和软件系统中的容错冗余技术,提出了在一定约束条件下,使得硬-软件系统可靠度达到最大的最优系统冗余结构模型,并给出了模型的求解方法．