Comparison of nanocomposites based on nylon 6 and nylon 66

Nylon 6 and nylon 6,6 organoclay nanocomposites were prepared by melt processing using a twin screw extruder. The effects of polyamide type and processing temperature on the mechanical properties and the morphology of the nanocomposites were examined. Mechanical properties, transmission electron microscopy (TEM), wide-angle X-ray diffraction (WAXD), percentage crystallinity and isothermal thermo-gravimetric analysis (TGA) data are reported. A particle analysis was performed to quantitatively characterize the morphology; these results are later employed in modeling the modulus of these materials using composite theory. No significant difference was observed in the mechanical properties and morphology of PA-6 nanocomposites processed at two different temperatures. PA-6 nanocomposites had superior mechanical properties than those made from PA-66. The tensile strength of PA-66 nanocomposites deviated from linearity at high levels of MMT. WAXD and TEM results show that the PA-6 nanocomposites are better exfoliated than the PA-66 nanocomposites, which exhibit a mixture of intercalated and exfoliated structures. Mechanical properties were consistent with the morphology. DSC reveals a higher percentage of crystallinity in the PA-66 samples. Isothermal TGA shows only a 5% difference in the degradation of the organic modifier on the organoclay processed at 240 °C versus 270 °C. Particle analysis shows a higher average particle length and thickness, and a lower average particle density and aspect ratio in nanocomposites based on PA-66 versus PA-6. The Halpin-Tsai and Mori-Tanaka composite theories predict satisfactorily the behavior of the PA-6 nanocomposites, while the PA-66 nanocomposites were predicted acceptably up to a certain volume fraction where the non-linear behavior takes effect. All the results indicate that there is a lower degree of exfoliation in the nanocomposites produced with a PA-66 matrix apparently stemming from the chemical differences between PA-6 and PA-66.     

滚动轮胎温度场的有限元模拟计算

在轮胎热学稳态分析的基础上，利用有限元非线性分析功能，开发滚动轮胎温度场有限元模拟计算软件。该软件建立在以下4个假设基础上：①轮胎处于动态平衡时的稳态温度场；②将轮胎的形状看作以旋转轴轴对称；③导热系数和比热容等物性视为常数；④不计轮胎接地时以热传导形式发生的接触热量传递。实例验证表明，数值模拟计算结果与实际测试结果的变化趋势基本一致。     

硅化物-镍铁合金/碳化钛金属陶瓷的制备、组织结构与性能

研制了以熔融合金惰性气体雾化法制备的含有大量硅化物的镍铁合金粉末为烧结粘结相的硅化物-镍铁合金／碳化钛金属陶瓷。用SEM，EDS，XRD和热重天平等测试分析了金属陶瓷的组织结构与性能。结果表明：这种硅化物-镍铁合金／碳化钛金属陶瓷具有核／环形边缘结构，硅化物-镍铁合金对碳化钛粒子有较好的润湿烧结作用。研制的金属陶瓷的抗弯强度在1000～1200MPa，硬度HRA为80～90。由于合金中含有较高的对氧有较强亲和力的元素硅，在氧化过程中形成SiO2以及一系列复合氧化物构成的致密氧化膜，使合金具有高的抗高温氧化性能。     

特殊条件下的一段炉升降温方法

中原化肥厂合成氨装置由于修复过渡段保温材料，在过渡段降温及一段炉升温方法上采取了特殊措施，特别是一段炉升温采取了先点火的升温方法。     

Bi_4Ge_3O_(12):TR(TR=Pr,Eu,Ce)晶体的吸收和发光光谱

测量了Bi_4Ge_3O_(12)(BGO):Pr、Eu和Ce的吸收、激发和发光光谱。掺杂BGO吸收和激发带相应于pr~(3+)、Eu~(3+)和Ce~(3+)离子特征跃迁。Xe灯中不同波长激发所得到掺杂BGO的发光光谱可通过Bi~(3+)心和掺杂材料之间能量传输过程加以解释。Bi~(3+)心400—600mm发射强度因受到Ce杂质影响变弱,这现象在高Ce浓度晶体里更为显著。     

High temperature swelling of coal/tetralin mixtures in a high pressure microdilatometer

High pressure microdilatometer experiments were performed on a subbituminous (Wyodak) and a bituminous (Illinois no. 6) coal in helium and hydrogen atmospheres with and without added tetralin. Wyodak coal samples showed no swelling but contractions ranging between 24 and 40 vol% upon heating at 20 and 100 °C min^{− 1} under helium or hydrogen pressures between 150 and 1000 psig (˜1.0–6.9 MPa). Under the same conditions, Illinois no. 6 coals displayed contractions (25–60 vol%) prior to swelling up to 117 vol%. Upon tetralin addition (at 35–190 wt% of the coal), Wyodak coal samples did not swell but showed an increasing contraction with increasing helium or hydrogen pressure due to a slight softening and fusion of the coal particles. In contrast, addition of tetralin at much lower concentrations (5–35 wt%) had a marked effect on the contraction and swelling behaviour of Illinois no. 6. A maximum swelling of 200 vol% was obtained at a tetralin addition of 30 wt%. The increased swelling results from more extensive softening and fusion of coal particles in the presence of tetralin. Both coals showed a decreasing char yield with increasing tetralin concentration. The substantially lower extent of interaction observed between Wyodak coal samples and tetralin compared to Illinois no. 6 coal can be attributed to the differences in pore structure and/or chemical constitution of the two coal samples. Examination of the resultant solids by optical microscopy revealed the microstructural changes produced by thermal treatment in dilatometer experiments.     

基于WiFi无线通信的温湿度检测节点设计

基于AM2303温湿度传感器、STC15F104W单片机和WiFi模块设计了一种无线温湿度检测节点。介绍了AM2303及其通信协议、WiFi模块及其组网特性等,并且给出了读取AM2303数据的软件流程。经测试,该节点通信距离远,组网灵活,可很好地应用于粮库粮情检测等实际工作环境。     

合成氨装置中高温氢腐蚀问题探讨

探讨合成氨装置中的高温氢腐蚀问题,结合实际说明高温氢腐蚀的影响因素,提出预防高温氢腐蚀的措施.     

Heat Induced Structure Modifications in Polymer‐Layered Silicate Nanocomposites

Summary: The success of the use of layered silicates in polymer nanocomposites, to improve physical and chemical properties is strictly related to a deeper knowledge of the mechanistic aspects on which the final features are grounded. This work shows the temperature induced structural rearrangements of nanocomposites based on poly[ethylene‐co‐(vinyl acetate)] (EVA) intercalated‐organomodified clay (at 3–30 wt.‐% silicate addition) which occur in the range between 75 and 350 °C. In situ high temperature X‐ray diffraction (HT‐XRD) studies have been performed under both nitrogen and air to monitor the modifications of the nanocomposite structure at increasing temperatures under inert/oxidative atmosphere. Heating between 75 and 225 °C, under nitrogen or air, causes the layered silicate to migrate towards the nanocomposite surface and to increase its interlayer distance. The degradation of both the clay organomodifier and the VA units of the EVA polymer seems to play a key role in driving the evolution of the silicate phase in the low temperature range. The structural modifications of the nanocomposites in the high temperature range (250–350 °C), depended on the atmosphere, either inert or oxidizing, in which the samples were heated. Heating under nitrogen led to deintercalation and thus a decrease of the silicate interlayer space, whereas exfoliation was the main process under air leading to an increase of the silicate interlayer space.

Heat induced structural modification of EVA‐clay nanocomposite under nitrogen and air.     

酸性低温脉冲化学镀镍磷合金的性能

介绍了低温脉冲化学镀镍的研究工作。结果表明：由于电脉冲的催化作用，使得酸性化学镀镍的施镀温度降低至５０℃时，仍具有１１μｍ／ｈ的沉积速度，镀层磷含量达１０．４８ｗｔ％，结构组织仍为非晶态。其镀层的性能与８０℃施镀的化学镀镀层性能相当。