Effects of Zinc Addition on the Corrosion Behavior of Pre-Filmed Alloy 690 in Borated and Lithiated Water at 330 °C.

The purpose of this work is to quantify the effects of dissolved zinc cations on corrosion and release rates from a pre-filmed Alloy 690 steam generator tubing material that was subsequently exposed to water containing zinc. The corrosion tests were performed in circulating 2 ppm Li and 1000 ppm B water without and with 60 ppb zinc at 330 °C. Gravimetric analyses and oxide characterization revealed that the corrosion rates, release rates, and oxide thicknesses decreased by subsequent exposure of the pre-filmed Alloy 690 to zinc. These benefits are attributed to the formation of a chromium-rich inner oxide layer incorporating zinc.

Zeta Potentials of Magnetite Particles and Alloy 690 Surfaces in Alkaline Solutions.

Magnetite particles deposited on the secondary side of a steam generator (SG) can degrade the integrity and performance of pressurized water reactors. Therefore, it is necessary to produce the data of fundamental interfacial electrokinetic properties of magnetite particles and SG tube materials. This study investigated the zeta potentials of magnetite nanoparticles and Alloy 690 surfaces, which were dependent on the pH value, pH agent, and the presence of NaCl. The zeta potentials of the magnetite nanoparticles increased in the negative direction as the pH increased, regardless of the pH agent. At the same pH value, the absolute values of the zeta potentials with different pH agents were: ethanolamine < ammonia < morpholine. In the presence of NaCl, the zeta potentials of the particles further increased negatively. The meaning of the measured zeta potentials was discussed in terms of the dispersion stability and the agglomeration of the particles. Based on the relationship between the zeta potentials of the particles and Alloy 690 surfaces, the magnetite deposition on Alloy 690 was also discussed. Furthermore, the empirical formulas for the pH-dependent zeta potentials of magnetite particles in each alkaline solution were suggested.

Hydrothermal synthesis of ZnO nanorods in the presence of a surfactant.

Controlling the dimensions, positioning, and shapes of semiconductor nanowires, nanorods, and nanobelts lies in the synthesis and understanding of their growth mechanism. Controlled growth and synthesis is required in the fabrication of nanodevices and nanosensors. Among methods utilized for one-dimensional nanostructure synthesis, the hydrothermal process--a simple and cost-effective technique involving a low process temperature--has emerged as a powerful tool for the fabrication of anisotropic nanomaterials. Under hydrothermal conditions, many starting materials can undergo quite unexpected reactions, which are often accompanied by the formation of nanoscopic morphologies that are not accessible by classical routes. Synthesized ZnO nanostructures from aqueous solutions are usually poor in terms of morphology and size control. To improve the growth conditions and the controllability of the process, the use of surfactants or organic solvents has been attempted. In the present work, ZnO nanorods were grown on templates with a pre-sputtered ZnO seed layer over oxidized Si (100) substrates, and polyvinyl pyrrolidone (PVP) was used as a surfactant. By varying the PVP concentration in the growth solution, we can control the diameter and density of ZnO nanorods. The optical property of ZnO nanorods is highly improved by PVP addition.