Effect of Ultrasonic Cleaning of Titanium Turning Scraps Immersed in Alkaline Solution and Subsequent Preparation of Ferrotitanium Ingots

Ti has excellent properties but is more expensive than other materials due to its high melting point, high reactivity and difficult processability. One way to lower the production cost of Ti products is to recycle Ti scraps. Before recycling Ti scraps, pretreatment to remove contamination is essential. Ti scraps can be pretreated in an alkaline solution, thus eliminating the use of acidic solutions. However, a pretreatment only involving immersion in alkaline solution requires a high concentration solution, and has low efficiency. Therefore, in this study, an optimized ultrasonic cleaning process is introduced to pretreat Ti scraps in a lowconcentration alkaline solution. The carbon content of Ti scraps before pretreatment was 6,800 ppm, and showed a sharp decrease with pretreatment. Using this pretreatment process, C, O, and N impurities were removed by 97.6%, 58.8%, and 29.2%, respectively. Ferrotitanium ingots were then produced by vacuum arc melting (VAM) and plasma arc melting (PAM) using the pretreated Ti scraps and electrolytic iron. Differences in ingots melted by VAM and PAM were investigated. As the time was increased, the content of impurities decreased. Subsequently, a ferrotitanium ingot prepared using the pretreated Ti scraps showed that the carbon concentration in the ingot was less than 200 ppm.

Concentration Polarization of High Concentration Solution in Sub-nm Nanopore

The behavior of ion transport through the sub-nm nanopores on the film is is different from the behavior of bulk behavior. Many intriguing phenomena in ionic transport are the key to the design and fabrication of solid-state nanofluidic devices. However, ion transport through the sub-nm nanopores is not yet clearly understood. We investigate ionic transport of sub-nm nanopore from the perspective of conductance by the method of MD. The results show that the ion concentration polarization phenomenon is heavily dependent on the external electric field and the size constraints of nanopores. At the same time, ion concentration polarization also has a profound effect on ion conductance. These conclusions indicate that ion concentration polarization has an important influence on ion transport, and help a new understanding of the design of nanofluidic devices.

Kinetics of in situ desorption of dye molecules on sensitized TiO2 nanoparticles in a high concentration solution: ion parasitic adsorption process and mass reference

This paper applies a method to study the in situ mass change responses on dye-sensitized TiO2 films in different potential ranges, and explore the dye desorption process in depth and in detail.

Bundle Size Engineering of Single-Walled Carbon Nanotubes on Silica Nanoparticles

Small and large single-walled carbon nanotubes (SWCNTs) bundles from different-sized cobalt catalyst clusters have been synthesized and prepared through chemical vapor deposition (CVD) method by using Co-acetate ethanol solution with silica nanoparticles. By controlling concentration of Co-acetate ethanol solution (0.2 wt% and 0.4 wt%), various sizes and types of bundle of SWCNTs are grown on the silica nanoparticle substrates. Synthesized SWCNT’s diameter ranged from 0.92 nm to 1.63 nm, and chirality of SWCNTs and their electronic property from high concentration solution show diverse characteristics. In high concentration solution, the large number of cobalt clusters is induced to merge on the surface of silica nanoparticles and then lots of nucleation points are provided by cobalt clusters for growth of SWNTs. These results give us a promising path to selectively synthesize various types of SWCNTs with different shapes of merged cobalt catalyst. Engineering bundle sizes of SWCNTs can be promising key for diverse applications of carbon nanotubes.

In Situ Observation of Diamagnetic Fluid Flow in High Magnetic Fields

The effect of high magnetic field on diamagnetic fluid flow has been studied by in-situ optical observation. The Schlieren optics utilizable under high magnetic fields was developed to carry out in-situ observation of the behavior of feeble magnetic fluids. Using a crystal of the diamagnetic aluminum potassium sulfate dodecahydrate, the behavior of the downward flow of high concentration solution in the sample dissolution process was observed. It was found that the direction of diamagnetic fluid flow was changed under spatially varied magnetic field. This phenomenon was understood qualitatively by considering the magnetic force acting on the high concentration solution and the surrounding solution.