主虹虹带分布的模拟研究

本文对主虹虹带分布进行数学模拟分析,提供各种色光的出射光范围的对比分析,实现对主虹自然现象的剖析。     

铸铁滑动摩擦副边界润滑表面膜的考察

在铸铁材料油润滑与线接触滑动磨损机制基础上，对这种材料在边界润滑状态下表面膜的形成、识别、结构组成和导致膜破裂脱落的因素作了试验研究与考察，摩擦磨损过程中，摩擦表面在摩擦热的作用下，缺陷增多，塑性变形加剧，润滑油和空气中的氧通过扩散流动进入变形层，从而形成较厚的扩散反应膜，其主要成分是Ｆｅ３Ｏ４氧化膜。     

铸造锌-石墨复合材料的摩擦学特性

作者以高铝锌基合金ZA-27为基体,使之与石墨在熔融状态下复合成为均匀浆料,经过挤压铸造成型,得到了几种石墨含量不同的锌-石墨复合材料。微观结构分析结果表明,金属-石墨界面结合状态良好,石墨分布均匀。这种材料在石墨含量低于5％(wt,下同)时的承载能力比青铜ZQSn6-6-3的高。其线膨胀系数随着石墨含量的增加而下降。在本试验条件下,随着石墨含量的增加,复合材料进入稳定磨损阶段所需要的时间缩短,滑动过程的平稳性增大,摩擦表面温度降低,摩擦系数明显下降,磨损率减小;在石墨含量达到6.2％时,锌-石墨复合材料的减摩性。耐磨性和相对抗咬合性都远比基体合金ZA-27的好,表明锌-石墨复合材科是一种新型的具有良好开发应用前景的减摩耐磨材料。     

真空浇铸聚苯乙烯薄膜的拉伸力学行为

高分子溶液的浓度从极稀到极浓的转变过程是高分子链从单链体系转变成相互穿透的多链体系的分子凝聚过程 .在极稀溶液中高分子链以无规线团状态孤立地存在于溶剂介质中 ;在良溶剂中是溶涨的无规线团 ,可以设想溶液浓度逐渐增大时 ,有一高分子线团开始相互接触的所谓接触浓度 ;随着浓度进一步增加高分子线团之间就发生交叠而相互穿透 ,这时溶液就转变成物理交联结构的浓溶液 .分子链的互穿程度会随浓度的继续增加而增加 .如果能用一些特殊的实验方法将高分子在不同浓度的溶液中的凝聚状态尽量全部或部分的保留到高分子固体中 ,则所得到的具有…     

Studies on the thermal properties of caprolactam/long chain lactam copolymer

The thermal properties of caprolactam/long chain lactam copolymer were studied with a Perkin-Elmer DSC 7. The melting point (T _m), heat of fusion (δH _m), crystalline degree (X _c), crystallization temperature (T _c) and glass transition temperature (T _g) of the copolymers increase with decrease of the content of the log chain lactam. From the changes in the mechanical properties with corresponding changes in the thermal properties, it is clear that the copolymers are thermal plastic and elastic. In addition, it is found that the results at a heating rate of 10 deg·min^?1 are almost the same as that at 20 deg·min^?1 after thermal history is erased.     

Effect of Material Structure and Additives on the Optical Properties of PP Cast Films

Summary. Polypropylene homopolymer and ethylene/propylene-random-copolymer cast films formulated with slip, anti-blocking, and acid scavenger aids were analyzed as to material structure and optical properties. The structural and topographical characterization was done by atomic force microscopy and by spectroscopic methods. Optical properties were determined using a hazemeter and an UV/VIS/NIR spectrophotometer. As to the effect of additives it was established that slip and anti-blocking aids migrate to and accumulate on the surface, resulting in increased surface roughness and larger scattering identities close to the surface. Acid scavenger additives were shown to contribute to less significant slip aid domains and hence to lower haze. In general, films without additives showed much better optical properties. The separation of haze into its bulk and surface components revealed that the total haze is dominated by surface haze.     

Oxidative Degradation of trans‐1,4‐Polyisoprene Cast Films and Single Crystals by Enzyme‐Mediator Systems

Depolymerization and morphological changes of cast films and single crystals of trans‐1,4‐polyisoprene with three enzyme‐mediator systems, lipoxygenase/linoleic acid (LPO/LH), horseradish peroxidase/1‐hydroxybenzotriazole (HRP/1‐HBT) and laccase/1‐hydroxybenzotriazole/linoleic acid (laccase/1‐HBT/LH), were investigated by scanning electron microscopy and gel permeation chromatography. Treatment of cast film with a LPO/LH system involving radical generation via lipid peroxidation led to a marked decrease in the molecular weight of polymers. LPO/LH system resulted in the morphological damage of single crystals of trans‐1,4‐polyisoprene. Laccase/1‐HBT/LH also destroyed the single crystals and depolymerized emulsified trans‐1,4‐polyisoprene. On the contrary, spherulites appeared on the surface of cast films and the molecular weight slightly decreased after treatment with HRP/1‐HBT, indicating that the amorphous region was predominantly degraded and the crystal region remained unchanged. The morphology of single crystals remained unchanged during the treatment of HRP/1‐HBT system for 6 d. In addition, Fenton reagent/linoleic acid was used as a chemical initiator of lipid peroxidation for degradation of trans‐1,4‐polyisoprene cast films. This system reduced molecular weight of the cast films, as well as LPO/LH system.

Scanning electron micrographs of trans‐1,4‐polyisoprene single crystals before (A) and after (B) treatment with the lipoxygenase/linoleic acid system.     

稀土对高镍铬合金铸铁热疲劳性能的影响

研究了高镍铬合金铸铁热轧辊用材料的裂纹形成和在热循环４０和７０周次后裂纹的扩展过程。结果表明：稀土元素的加入，能明显提高高镍铬合金铸铁热轧辊用材料的抗疲劳性能，使裂纹出现时冷热循环次数提高４２％－１６３％，同时给出稀土加入量以０．０５ｗｔ％－０．１５ｗｔ％为宜。     

Considerations on the Thermal Behaviour and Oxidation Resistance of Cast Iron

Thermal analysis was used to characterize the thermal behaviour and oxidation resistance of some nodular cast irons. Samples of nodular cast iron in various stages of elaboration, with different chemical compositions, were studied. The samples were heated in air, in the temperature range 291-1273 K, and the thermal (TG, DTG and DTA) curves were recorded. A group of samples with low silicon content exhibit similar behaviour: a continuous increase in mass and an exothermic effect up to 1123 K. The thermal effects correspond to iron oxide (Fe3O4, FeO, Fe2O3) formation. At high temperatures (T>1123 K), there is a decrease in mass and an endothermic effect. A decrease in the superficial carbon content by combustion (‘decarburization’ effect) occurs in the range of high temperatures. The two effects of oxidation and decarburization depend on the structural changes which occur in cast iron at high temperatures. The decarburization process was modelled and the kinetic parameters were determined (reaction order n=0.76; activation energy E=141 kJ mol-1; pre-exponential factor A=2·102s-1). The oxidation process was studied by non-isothermal methods with regard to two mechanisms: two-dimensional transport for low temperatures, and three-dimensional transport through a sphere for high temperatures. The activation energies were calculated: 68 kJ mol-1 for low temperatures and 122 kJ mol-1 for high temperatures. This revised version was published online in July 2006 with corrections to the Cover Date.     

位错及掺杂对球铁冲击韧性影响的电子机理

在球墨铸铁金属基体中建立α-Fe[100](010)刃型位错原子模型,利用基于密度泛函理论的CASTEP目的 计算C原子在位错芯区的埋置能、亲和能、电荷布居数等电子参数.结果表明:α-Fe[100](010)刃型位错芯区局域效应集中范围较小并具有C_2v点群对称性.位错芯区的能量低谷吸引轻质杂质C原子偏聚,C原子的2p轨道与刃型位错尖端Fe原子的4s价轨道之间发生电荷转移,具有较强的相互作用,使位错运动受阻.Fe-C原子间布居数较大、原子间距离较小表明,Fe-C原子间有生成渗碳体化合物的倾向.Si原子掺杂渗碳体的结合能及各原子轨道分波态密度表明,Si原子能够促使渗碳体分解,析出碳硅化合物成为石墨球化的核心,从而改善球墨铸铁的冲击韧性.