In-situ synthesis of TiO2 nanostructures on Ti foil for enhanced and stable photocatalytic performance

TiO_2 nanostructures with strong interfacial adhesion and diverse morphologies have been in-situ grown on Ti foil substrate through a multiple-step method based on conventional plasma electrolytic oxidation(PEO) technology, hydrothermal reaction and ion exchange process. The PEO process is critical to the formation of TiO_2 seeding layer for the nucleation of Na_2Ti_3O_7 and H_2Ti_3O_7 mediates that are strongly attached to the Ti foil. An ion exchange reaction can finally lead to the formation of H_2Ti_3O_7 nanostructures with diverse morphologies and the calcination process can turn the H_2Ti_3O_7 nanostructures into TiO_2 nanostructures with enhanced crystallinity. The morphology of the TiO_2 nanostructures including nanoparticles(NP), nanowhiskers(NWK), nanowires(NW) and nanosheets(NS) can be easily tailored by controlling the NaOH concentration and reaction time during hydrothermal process. The morphology, composition and optical properties of TiO_2 photocatalysts were analyzed using scanning electron microscope(SEM), X-ray diffraction(XRD), photoluminescence(PL) spectroscopy and UV–vis absorption spectrum. Photocatalytic tests indicate that the TiO_2 nanosheets calcined at 500?C show good crystallization and the best capability of decomposing organic pollutants. The decoration of Ag cocatalyst can further improve the photocatalytic performance of the TiO_2 nanosheets as a result of the enhanced charger separation efficiency. Cyclic photocatalytic test using TiO_2 nanostructures grown on Ti foil substrate demonstrates the superior stability in the photodegradation of organic pollutant, suggesting the promising potential of in-situ growth technology for industrial application.     

Comparison of in-situ measurement techniques of solder joint reliability under thermo-mechanical stresses

Thermo Mechanical Cycle Lifetime (TMCL) test is a widely used test methodology for evaluating the reliability of solder joints in the microelectronics industry. The commonly used measurement techniques to monitor solder joint failures during the TMCL test are either event detector or data logger. In this study, TMCL test has been carried out on the same devices in parallel with both measurement techniques. The pros and cons of both techniques are compared. It is observed that the solder joint reliability results on the investigated samples by both techniques are comparable. The event detector can catch short intermittent events, while the data logger is able to capture the details of the solder joint degradation process. In applications for which performance is dependent on the transmission of signals with a frequency of several hundred megahertz or more, the event detector technique shall be used. In such cases the data logger technique may overestimate product lifetime. On the other hand, for some applications where the performance is less susceptible to intermittent solder joint interconnect interruption but more to the increase of the solder joint resistance, the data logger shall be used. In such cases the event detector technique may underestimate product lifetime. In conclusion depending on the end application of the device, the most suitable technique can be selected.     

Copper wire interconnect reliability evaluation using in-situ High Temperature Storage Life (HTSL) tests

This paper describes the use of in-situ High Temperature Storage Life (HTSL) tests based on a four point resistance method to evaluate Cu wire interconnect reliability. Although the same set up was used in the past to monitor Au–Al ball bond degradation, a different approach was needed for this system. Using conventional statistical methods of failure probability distributions and a fixed failure criterion were found to be unsuitable in this case. Besides this, tests usually take very long until a sufficient percentage of the population have failed according to that criterion. A simple physical model was used to electrically quantify ball bond degradation due to the prevailing failure mechanism in a substantially smaller amount of test time. The method enabled the determination of activation energies for a number of moulding compounds and is extremely useful for a fast screening of such materials regarding their suitability for Cu wire.     

Insight from in situ microscopy into which precipitate morphology can enable high strength in magnesium alloys

Magnesium alloys, while boasting light weight, suffer from a major drawback in their relatively low strength. Identifying the microstructural features that are most effective in strengthening is therefore a pressing challenge. Deformation twinning often mediates plastic yielding in magnesium alloys. Unfortunately, due to the complexity involved in the twinning mechanism and twin-precipitate interactions, the optimal precipitate morphology that can best impede twinning has yet to be singled out. Based on the understanding of twinning mechanism in magnesium alloys, here we propose that the lamellar precipitates or the network of plate-shaped precipitates are most effective in suppressing deformation twinning. This has been verified through quantitative in situ tests inside a transmission electron microscope on a series of magnesium alloys containing precipitates with different morphology. The insight gained is expected to have general implications for strengthening strategies and alloy design.     

用原位X射线衍射法对电化学插层过程的研究

采用原位X射线衍射技术研究了石墨在65％HNO3中的电化学插（脱）层过程,提出了一套处理XRD图谱的数据处理方法。     

Si－C－O－N系统相稳定性及反应烧结制备原位SiC（p）复合ZAS材料

给制了Ｓｉ－Ｃ－Ｏ－Ｎ系统平衡状态下相稳定性与Ｎ２分压和Ｏ２分压以及相稳定性与Ｎ２分压和ＳｉＯ分压的关系图；以此为指导，将原位复合引入到反应烧结锆莫来石（ＺＡＳ）材料中，制备了含原位（ｉｎ－ｓｉｔｕ）ＳｉＣ（ｐ）的ＺｒＯ２ＳｉＣ（ｐ）、ＺｒＯ２－３Ａｌ２Ｏ３·ＺＳｉＯ２－ＳｉＣ（ｐ）－ＳｉＣ（ｐ）复合材料。研究了烧结温度、时间、碳添加量、成型压力等工艺因素对烧结ＺｒＳｉＯ４－Ｃ体系中原位ＳｉＣ生成量的影响，并观察了试样的显微结构。     

高强度、高导电性Cu-Ag合金的研究进展

近来,通过原位复合技术制备出了高强度、高导电性的Cu-Nb、Cu-Ag线材,并开始用于高脉冲磁场实验。本文对多相结构铜合金原位复合技术以及Cu-Ag合金的组织结构、物理性能、电学性能和稳定性进行综述,并指出尚存在的不足。     

自韧Si3N4陶瓷的高温性能特征

研究了自韧Si_3N_4的高温力学性能、氧化行为和抗热震性能。结果表明,晶界玻璃相对高温性能有重要影响,在室温～1350℃的范围内,自韧Si_3N_4的抗弯强度随温度的升高而降低,断裂韧性随温度的升高而增加;在1300～1350℃的温度范围内,自韧Si_3N_4的氧化符合抛物线规律,氧化过程主要由晶界处添加剂离子和杂质离子的扩散过程控制。由于热应力导致裂纹的产生和扩展,使得热震后材料的性能降低。     

环氧油一步合成的反应机理和动力学研究

研究了环氧油一步合成的反应机理和动力学；结合实验结果和理论分析动力学模型，首次提出：在适当的反应条件下，油脂的一步环氧化反应动力学模型可以表示为过氧酸生成反应动力学模型；其实验动力学模型方程为：ｒ０＝ｋ［Ｈ２Ｏ２］（０．９９）［ＨＯＡｃ］（０．９７），其中ｋ与催化剂用量有关。     

以纳米球形聚电解质刷为载体原位还原制备贵金属纳米粒子的研究

以具有核壳结构的纳米球形聚电解质刷为载体,通过吸附不同种类的贵金属离子并将其原位还原,得到分布和粒径不同的贵金属纳米粒子。采用动态光散射(DLS)研究了金属离子浓度和pH对壳层聚电解质链长的影响,使用透射电镜(TEM)观察了贵金属粒子在纳米球形聚电解质刷中的分布,并测量了金属粒子的尺寸。结果表明:金属离子浓度增大,聚电解质链长减小;pH>5时,负载金属粒子之后的聚电解质链长度均大于负载前的长度。不同金属粒子的负载情况相差较大:相同温度下,纳米金属粒子的尺寸符合Ni>Ag>Co的顺序;较高温下制得的金属粒子尺寸要高于低温下制得的金属粒子尺寸;三种纳米金属粒子中,Co纳米粒子具有最好的分布和最小的尺寸。