Status of aqueous surfactant phase science

Recent phase studies of several surfactant-water systems, using new or refined methods, have revealed significant errors in earlier phase diagrams. These diagrams had been determined largely using methods based on the isoplethal phase studies principle. This principle has inherent limitations which do not exist in isothermal methods. Isothermal nuclear magnetic resonance and refined calorimetric methods have been extensively used in recent surfactant phase studies. Methods based on the new lyotrope gradient (swelling) principle show great promise as a means of improving the efficiency and quality of surfactant phase studies.     

丙烯酸接枝线形低密度聚乙烯的热学行为及结晶形态

利用差示扫描量热仪研究了丙烯酸接枝线形低密度聚乙烯（PE-LLD-g-AA）的热学行为，结果表明，与纯线形低密度聚乙烯（PE—LLD）相比，PE-LLD-g-AA的熔融温度（Tm）略有增加，结晶温度（Tc）增加大约4℃，熔融焓（AHm）随AA含量的增加而降低。还利用差示扫描量热仪研究了PE—LLD和PE—LLD-g—AA的等温结晶动力学，用扫描电子显微镜观察了PE—LLD-g—AA等温结晶形态。结果表明，PE-LLD-g-AA的结晶速率大于纯PE—LLD的，随着接枝率的增加，PE-LLD的球晶半径减小，接枝到PE—LLD分子链上的AA分子起到了成核剂的作用。     

煤焦水蒸气气化特性及动力学研究

运用等温热重法，对三种不同的煤焦，在反应温度900℃～1200℃之间进行水蒸气气化实验。分别考察了常压下反应温度、水蒸气分压和煤种对反应的影响；并且对不同煤焦的反应进行动力学计算，求取动力学参数，研究发现，煤焦水蒸气的反应与煤焦—CO2的反应相比速率要快得多，并且随反应温度升高，反应速率急剧增大。     

Studies on crystal morphology and crystallization kinetics of polypropylene filled with CaCO3 of different size and size distribution

Changes in the crystal morphology, crystallinity, and the melting temperature of thermoplastics resulted in significant changes in the mechanical behavior of composites containing them. For this reason, the research of crystal morphology and crystallization kinetics in thermoplastic composites became an important requirement. The thermoplastic filled with the filler of different size gradation was a new method for improving processability of thermoplastic composites. We have previously reported that the melt viscosity of polypropylene (PP) composites, which were filled with 30 wt % CaCO₃ of effective size gradation, could be evidently declined. In this study, two sizes of CaCO₃, 325 meshes and 1500 meshes, were blended by different proportions and filled into PP matrix with 30 wt %. Crystal morphology and isothermal crystallization kinetics of a series of composites were characterized by differential scanning calorimeter (DSC) and polarizing microscope. The results showed that composites filled with CaCO₃ of effective size gradation leaded to a well‐crystalline order and a large crystal size, while their isothermal crystallization kinetics and crystallization rate constant (k) were declined, and their Avrami exponents (n) and crystallization half‐life (t_1/2) were increased compared with the composites filled with single size CaCO₃. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2437–2444, 2006     

Influence of isothermal aging onσprecipitation in super duplex stainless steel

The time-temperature-transformation (TTT) curve of the 00Cr25Ni7Mo4N duplex stainless steel was obtained with a Formastot-digital thermal dilatometer,and the influence of isothermal aging on σ precipitation was studied by metallographic observation,X-ray diffraction (XRD),and transmission electron microscopy (TEM).The results show that the decomposition of ferrite phase is accompanied by the formation of σ phase at 750-1000℃,especially in the range of 800-900℃.The longer the aging time,the higher the amount of σ precipitation.The area fraction of various phases remains at a certain value upon the completion of ferrite deformation.The temperature of 850℃ is the most sensitive transaction temperature,the incubation time for the formation of o precipitation is less than 1 min,and aging for 20 min leads to the complete transformation of ferrite.The o phase is formed preferentially at the α/α/γ junction,and then grows along the α/α boundary in the matrix.     

Electrical conductivity changes of bulk tin and Sn-3.0Ag-0.5Cu in bulk and in joints during isothermal aging

The changes of electrical conductivity(resistance) between Sn-3.0Ag-0.5Cu solder joints and printed circuit board(PCB) assembly during aging at 125℃were investigated by the four-point probe technique.The microstructural characterizations of interfacial layers between the solder matrix and the substrate were examined by optical microscopy and scanning electronic microscopy.Different types of specimens were designed to consider several factors.The experimental results indicate that electrical conductivitie...     

Cycling hardening and serration yielding of Fe-Ni-Cr alloy at high temperature under out-phase TMF

Behaviour of hardening and serration yield of a Fe-Ni-Cr alloy under isothermal cycling (ISC) and out-phase TMF was studied on the basis of varied hysteresis loops. Cycling hardening and serrated yielding for ISC depend on the temperature and the total strain range, stronger hardening with serrated yielding at higher strain range under ISC at 600 °C, but no hardening and serrated yielding occurred under ISC at 800 °C. Stronger hardening with stress serration occurred at the thermal path going to the lowest temperature, no stress serration occurred at the highest temperature under the out-phase. The hardening also depends on the total strain range, higher total strain range with lower cycling temperature resulted in a stronger hardening and remarkable serration yielding behavior. Weaker hardening without serrated yielding occurred at near 800 °C may due to an obvious cycling stress drop under out-phase TMF. Change in the shape of the hysteresis loops also expresses the degree of the damage of the tested alloy under out-phase and ISC.     

Dy-Fe-Sb三元合金相图400℃等温截面中的物相分析

利用X射线衍射分析等技术测定了Dy-Fe-Sb三元系合金相图400℃等温截面,该等温截面由12个单相区、22个两相区、11个三相区组成.实验结果表明,在400℃下,FeSb有一固溶范围,约从44at%Sb延伸到46at%Sb,Dy在FeSb相中的最大固溶度约为1at%Dy,Sb在Fe相中的最大固溶度约为3at%Sb.在此等温截面中观察到8个二元化合物和1个三元化合物.     

杯形件等温压扭复合成形模具失效分析及改进

为解决7A60铝合金杯形件等温压扭复合成形实验中凹模的早期失效问题,借助DEFORM有限元软件,从工艺特点、应力分布及模具结构等方面详细探讨和分析失效原因,应力集中、冷热循环热应力以及高温模具氧化是导致凹模转角处发生早期破裂的主要原因.基于"未裂先分"的方法对凹模结构进行改进,结果表明:模具改进效果较好,等效应力极值降低30%,有效避免了凹模的应力集中;杯形件成形效果较好,宏观上无明显缺陷,表层金属流线清晰可见.     

65Mn钢圆锯片等温处理工艺的探讨

比较了６５Ｍｎ等温处理和淬火回火处理后的硬度、韧性、抗弯性能和耐磨性。６５Ｍｎ钢圆锯片用等温处理取代现行的淬火回火处理，将会在提高锯片的内在质量和节能方面取得明显效益。