化学镀制备聚苯胺/金属复合导电织物

利用化学镀方法在聚苯胺复合织物表面均匀沉积金属铜,以改善复合织物的导电性能。探讨了化学镀条件(主盐硫酸酮、还原剂甲醛、络合剂、氢氧化钠用量、基质、时间和温度)对复合织物方阻、金属沉积速率及结合性能的影响。优化的化学镀工艺为:CuSO45g/L,酒石酸钾钠30g/L,NaOH6g/L,HCHO24mL/L,化学镀温度45℃,时间15min。     

玻璃纤维化学镀Ni-W-P工艺研究

研究硫酸镍浓度、钨酸钠浓度、次亚磷酸钠浓度、柠檬酸钠浓度及镀液温度和反应时间对玻璃纤维化学镀Ni-W-P工艺的增重率(镀层沉积速率的表征指标)的影响,然后结合单因素试验结果,并通过正交试验,确定了玻璃纤维化学镀Ni-W-P工艺的最优镀液配方和工艺参数。     

银/聚苯胺/锦纶导电织物的制备及性能

采用化学镀方法在聚苯胺/锦纶复合织物(PANI/PA)表面均匀沉积金属银(Ag),制备银/聚苯胺/锦纶导电织物(Ag/PANI/PA).采用正交试验方法,以沉积速率和织物方阻为评价指标,优化了化学镀工艺条件:硝酸银14 g/L,氨水100 mL/L,葡萄糖2.8 g/L,氢氧化钠9 g/L,温度30℃,时间50 min.制备的Ag/PANI/PA复合织物方阻达20～30 mΩ/□,导电性能优良.     

化学镀钴磷--氧化铝复合镀工艺与镀层性能

本文研究了化学镀钴磷一氧化铝复合镀工艺及氧化铝添加对复合镀层性能的影响，研究结果表明，氧化铝颗粒加入可提高化学镀沉积速度，使镀层硬度提高，高温磨损体积减小。     

铝锭翼表面镀Ni—P合金

本文研究了铝合金锭翼表面化学镀Ni—P合金,以提高耐磨性能。结果表明,Ni—P合金化学镀层硬度高,比铝合金具有更强的抗纤维磨损能力,经过175℃处理7小时后,效果更佳。     

聚酯/聚苯胺复合织物化学镀铜效果的影响因素

利用超声波辅助化学镀方法在聚酯/聚苯胺复合织物表面均匀沉积金属铜.探讨聚苯胺的沉积条件、化学镀工艺中敏化和活化条件以及超声波辅助等条件对复合织物方阻值、增重率及结合性能等方面的影响.通过浸泡法和阳极极化法比较聚酯/聚苯胺、聚酯/铜和聚酯/聚苯胺/铜3种复合织物的耐腐蚀性能.利用扫描电镜对不同织物的表观形貌进行表征,同时...     

镀银纺织品的制备与应用研究

简要介绍了镀银纺织品的制备方法及其相关应用,概述了磁控溅射、化学镀、物理气相沉积、化学气相沉积和超临界二氧化碳镀银方法,简述了镀银纺织品在抗菌除臭、防辐射及智能纺织品领域的发展状况。研究可为镀银纺织品在其他领域的应用提供参考。     

关于沉积速率与地层记录完备性的新看法

最近有几篇文章建议利用长期沉积速率与短期沉积速率之比估计地层剖面的完备性.我们证明这些文章中采用的短期沉积速率中值是错误的,大部分是非正常数据变换产生的人为数据.为了证实短期速率中值的人为性,我们绘制了一系列图解并取一具固定方差的稳定沉积速率及确定测量精度极限.这些图解证实,加大沉积沉积物所需时间的方差会造成短期沉积速率中值的伪升高.一种新的计算沉积速率中值的方法可解决伪速率中值问题,并用于改进期望完备性的估计.重新计算中值表明短期和长期时间间隔的深海沉积速率接近相同.将这一方法用于深海沉积速率的扩充编录证实典型深海沉积序列接近完备.这削弱了固有的时间不完备的论点,如对白垩系-第三系界线某些生物同时绝灭的解释.最后我们认为不能用短期沉积速率中值估计单个剖面的完备性.压实作用、生物扰动作用、岩心的污染、放射性年龄测定的不确定性及沉积速率固有的大方差表明,不管怎样计算,短期沉积速率是可疑的.沉积作用堆积图解在估计一给定沉积环境的期望完备性或将一沉积环境的完备性与另一环境的完备性比较方面很有用.     

钢领表面化学镀镍磷合金工艺的研究

为了提高钢领性能,延长使用寿命,针对纺纱钢领酸性化学镀镍磷的工艺进行了研究;着重研究了温度、pH值及络合剂对镀层沉积速率和表面形貌的影响,以及不同加热温度对钢领表面硬度的影响;以试验的方法得出最佳镀覆工艺为:化学镀温度应控制在80℃,pH控制为5.0时可获得最佳镀速和含磷量镀层;采用柠檬酸、乳酸、硼酸三种络合剂配合使用,可提高镀液的稳定性和钢领表面性能;镀镍磷合金钢钢领热处理温度最佳为350℃,不能超过400℃.     

动态微细胶黏物沉积实验新方法

介绍了用于监测浆水或白水中微细胶黏物沉积速率的新方法。并就实验室的OMG浆水,生产厂的TMP浆水和DIP-TMP混合浆水的微细胶黏物沉积速率进行了一系列的测试。结果表明该法较其他方法的主要优点是可以连续记录沉积速率,在低速和高速沉积条件下有较好的重现性和较高的灵敏性。     

Nonmonotonic variations in deposition rate coefficients of microspheres in porous media under unfavorable deposition conditions

The transport of carboxylate-modified polystyrene latex microspheres was examined in packed quartz sand under a variety of environmentally relevant ionic strength and flow conditions. The retained concentrations of microspheres in the sediment increased first, and then decreased with transport distance, indicating that the deposition rate coefficient changed nonmonotonically over the transport distance. This finding demonstrates the ubiquity of spatial variation in deposition rate coefficients under unfavorable deposition conditions, and in addition indicates that the previously recognized monotonic decrease with transport distance is not the sole form of spatial variations in deposition rate coefficients. In contrast, the deposition rate coefficients of similarly sized microspheres with different surface group densities were shown to decrease monotonically with transport distance in the same porous media, indicating that the form of spatial variation in deposition rate coefficient is highly sensitive to system conditions. The ubiquity and sensitivity of the spatial variation of deposition rate coefficients indicate that current practices that utilize log-linear extrapolation of discreet measurements of colloid attenuation to determine colloid removal with distance from source are not valid (for both biological and nonbiological colloids). The retained colloid profiles hold the promise to reveal processes governing colloid deposition under unfavorable conditions that are yet to be identified.     

Role of hydrodynamic drag on microsphere deposition and re-entrainment in porous media under unfavorable conditions

Deposition and re-entrainment of 1.1 microm microspheres were examined in packed glass beads and quartz sand under both favorable and unfavorable conditions for deposition. Experiments were performed at environmentally relevant ionic strengths and flow rates in the absence of solution chemistry and flow perturbations. Numerical simulations of experimental data were performed using kinetic rate coefficients to represent deposition and re-entrainment dynamics. Deposition rate coefficients increased with increasing flow rate under favorable deposition conditions (in the absence of colloid-grain surface electrostatic repulsion), consistent with expected trends from filtration theory. In contrast, under unfavorable deposition conditions (where significant colloid-grain surface electrostatic repulsion exists), the deposition rate coefficients decreased with increasing flow rate, suggesting a mitigating effect of hydrodynamic drag on deposition. Furthermore, the re-entrainment rate was negligible under favorable conditions but was significant under unfavorable conditions and increased with increasing flow rate, demonstrating that hydrodynamic drag drove re-entrainment under unfavorable conditions. The drag torque resulting from hydrodynamic drag was found to be 1 order of magnitude or more lower than the adhesive torque based on pull-off forces from atomic force microscopy measurements. This result indicates that hydrodynamic drag was insufficient to drive re-entrainment of microspheres that were associated with the grain surface via the primary energy minimum and suggests that hydrodynamic drag drove re-entrainment of secondary-minimum-associated microspheres.     

椰花汁多糖醇沉工艺的研究

研究椰花汁多糖的醇沉淀工艺。首先采用单因素试验研究粗多糖液浓缩度、乙醇体积数、沉淀时间和pH对多糖沉淀率的影响,然后采用正交优化试验探讨最佳工艺参数。结果表明,醇沉淀工艺的最佳条件为:粗多糖液浓缩度0.8,按1∶4加入85%乙醇溶液,pH7.0、4℃下沉淀18h,在该条件下,沉淀率达98.00%。     

Apparent decreases in colloid deposition rate coefficients with distance of transport under unfavorable deposition conditions: a general phenomenon

The transport of polystyrene microspheres was examined in packed glass beads under a variety of environmentally relevant ionic strength and flow conditions. The observed profiles of numbers of retained microspheres versus distance from the column entrance were much steeper than expected based on a constant rate coefficient of deposition acrossthe length of the column, indicating apparent decreases in deposition rate coefficients with transport distance. Deviation in the profile from log-linear decreases with distance was greatest under highly unfavorable conditions (low ionic strength), relatively reduced under mildly unfavorable conditions (high ionic strength), and was eliminated under favorable conditions. The generality of apparent decreases in deposition rate coefficients with distance of transport among microspheres, bacteria, and viruses leads to the conclusion that such effects reflect processes that are fundamental to filtration under unfavorable conditions. Numerical simulations of experiments that were performed under unfavorable conditions utilized a log-normal distribution of deposition rate coefficients among the colloid population in orderto simulate the effluent curves and retained profiles simultaneously. It is shown that while straining could be a significant contributor to the steep retained profiles at low ionic strength, where overall retention is low, distribution in interaction potentials among the population was a viable mechanism that can yield apparent decreases in deposition rate coefficients with distance of transport.     

织物表面涂层沉积过程模拟

通过对大气压等离子体液相沉积工艺过程作用机制的研究,围绕如何提高液相沉积效率问题,构建了织物表面微观薄膜沉积过程动力学模型。探讨了放电功率、超声频率、处理时间、单体流速、氦气流速对薄膜沉积速率及膜层性能的影响,数值模拟涂层表面形态的变化,得出不同工艺参数下织物表面的沉积率变化规律,揭示薄膜沉积过程中聚合粒子的生长、涂层密度和质量的产生规律。这些结果对于预测成膜结构和优化具体等离子体液相沉积的工艺参数,提高沉积率和沉积薄膜的均匀度及对实际生产中如何提高材料的利用率和节约成本等方面具有一定的指导作用。     

原子层沉积铝薄膜的研究

为了对原子层沉积金属薄膜进行研究,以三甲基铝为前驱体、氢气为还原剂,在微波电子回旋共振等离子体辅助原子层沉积装置中进行了铝薄膜的沉积。通过实验确定了三甲基铝和和H2进行饱和反应的参数。采用X射线衍射仪、原子力显微镜及四探针电阻仪对薄膜的结构和性能进行了测试。结果表明:用等离子体辅助原子层沉积技术可以成功制备金属铝薄膜,沉积速率和表面形貌受基底温度的影响,薄膜在H2氛围下退火处理后晶体结构可以得到有效改善,铝薄膜的表面电阻也有明显降低。     

Adhesion kinetics of viable Cryptosporidium parvum oocysts to quartz surfaces

The transport and deposition (adhesion) kinetics of viable Cryptosporidium parvum oocysts onto ultrapure quartz surfaces in a radial stagnation point flow system were investigated. Utilizing an optical microscope and an image-capturing device enabled real time observation of oocyst deposition behavior onto the quartz surface in solutions containing either monovalent (KCl) or divalent (CaCl2) salts. Results showed a significantly lower oocyst deposition rate in the presence of a monovalent salt compared to a divalent salt. With a monovalent salt, oocyst deposition rates and corresponding attachment efficiencies were relatively low, even at high KCl concentrations where Derjaguin-Landau-Verwey-Overbeek (DLVO) theory predicts the absence of an electrostatic energy barrier. On the other hand, in the presence of a divalent salt, oocyst deposition rates increased continuously as the salt concentration was increased over the entire range of ionic strengths investigated. The unusually low deposition rate in a monovalent salt solution is attributed to "electrosteric" repulsion between the Cryptosporidium oocyst and the quartz surface, most likely due to proteins on the oocyst surface that extend into the solution. It is further proposed that specific binding of calcium ions to the oocyst surface functional groups results in charge neutralization and conformational changes of surface proteins that significantly reduce electrosteric repulsion.     

Bacterial swimming motility enhances cell deposition and surface coverage

The influence of bacterial motility on cell transport and deposition was investigated in a well-characterized radial stagnation point flow (RSPF) chamber. Deposition experiments were conducted with nonmotile (PA01 deltafliC deltapilA) and motile (PA01 deltapilA) strains of Pseudomonas aeruginosa, and oppositely (positively) charged modified quartz surfaces. Deposition dynamics ofthe two bacterial strains were determined over a wide range of solution ionic strengths and at two flow velocities. The observed deposition dynamics were modeled using a modified expression of the random sequential adsorption (RSA) blocking function accounting for the impacts of hydrodynamic and electrostatic interactions on cell deposition. Results for the nonmotile bacteria indicated that the changes in blocking rate and surface coverage with ionic strength and flow rate were similar to those expected for nonbiological, "soft" particles, for which the coupling of hydrodynamic interactions and electrostatic repulsion governs the deposition dynamics. In contrast deposition dynamics of the motile bacterial cells reduced blocking rates and enhanced maximum coverages, approaching the jamming limit predicted for "hard" ellipsoids of 0.583. We hypothesized that cell motility allows the upstream swimming of bacteria and subsequent cell deposition on regions which are otherwise inaccessible to nonmotile cell deposition due to the "shadow effect".     

Influence of growth phase on bacterial deposition: interaction mechanisms in packed-bed column and radial stagnation point flow systems

The influence of bacterial growth stage on cell deposition kinetics has been examined using a mutant of Escherichia coli K12. Two experimental techniques--a packed-bed column and a radial stagnation point flow (RSPF) system--were employed to determine bacterial deposition rates onto quartz surfaces over a wide range of solution ionic strengths. Stationary-phase cells were found to be more adhesive than mid-exponential phase cells in both experimental systems. The divergence in deposition behavior was notably more pronounced in the RSPF than in the packed-bed system. For instance, in the RSPF system, the deposition rate of the stationary-phase cells at 0.03 M ionic strength was 14 times greater than that of the mid-exponential cells. The divergence in the packed-bed system was most significant at 0.01 M, where the deposition rate for the stationary-phase cells was nearly 4 times greater than for the mid-exponential cells. To explain the observed adhesion behavior, the stationary and mid-exponential bacterial cells were characterized for their size, surface charge density, electrophoretic mobility, viability, and hydrophobicity. On the basis of this analysis, it is suggested that the stationary cells have a more heterogeneous distribution of charged functional groups on the bacterial surface than the mid-exponential cells, which results in higher deposition kinetics. Furthermore, because the RSPF system enumerates only bacterial cells retained in primary minima, whereas the packed column captures mostly cells deposited in secondary minima, the difference in the stationary and mid-exponential cell deposition kinetics is much more pronounced in the RSPF system.     

Investigating the performance of thermonebulisation fungicide fogging system for loaded fruit storage room using CFD model

To study the operation of postharvest storage fungicide fogging systems, a CFD model was used. The modelling was based on an Eulerian-Lagrangian multiphase flow model. The effect of air circulation rate, circulation interval, bin design, stacking pattern and room design on deposition of fungicide was investigated. Air circulation rates of 0 m³ h⁻¹ (no circulation), 2100 and 6800 m³ h⁻¹ were used. Interval circulation of air was also investigated. The highest fungicide deposition was observed during fogging without circulation while the lowest deposition corresponded to fogging with the highest circulation rate. For the considered on/off combination times, the effect of circulation interval on overall average deposition and uniformity was not significantly different from the case of fogging with continuous air circulation. Bin with higher vent hole ratio and the presence of air deflector increased the amount and uniformity of deposition. Good agreement was found between measured and predicted results of deposition of fungicide particles.