Template-assisted growth is an important nanoelectrochemical deposition technique for synthesizing one-dimensional (1-D) nanostructures with uniformly well-controlled shapes and sizes. A good template with well-defined dimensions is imperative for realizing this task. Porous anodic alumina (PAA) has been a favorable candidate for this purpose as it can be tailor-made with precise pore geometries, such as pore length and diameter as well as inter-pore distances, via the anodisation of pure aluminium. This paper reports the fabrication of PAA templates and electrochemical synthesis of functional nanostructures in the form of nanowires using PAA templates as scaffolds. Axial heterostructured and homogeneous nanowires formed by engineering materials configuration via composition and/or layer thickness variations were fabricated for different functionalities. X-ray diffraction and imaging techniques were used to elucidate the microstructures, morphologies and chemical compositions of the nanowires produced. Due to their large surface area-to-volume ratios, and therefore high sensitivities, these functional nanostructures have useful applications as critical components in nanosensor devices and various areas of nanotechnology. Potential applications include as hydrogen gas sensors in nuclear power plant for monitoring structural integrity of reactor components and containment building, as well as environmental monitoring of air pollution and leakages of toxic gases and chemicals.
Thermoelectric nanostructures hold great promise for capturing and directly converting into electricity some vast amount of low-grade waste heats now being lost to the environment (e.g. from nuclear power plant, fossil fuel burning, automotives and household appliances). In this study, large-area vertically-aligned silicon nanowire (SiNW) arrays were synthesized in an aqueous solution containing AgN•i and HF on p-type Si (100) substrate by self-selective electroless etching process. The etching conditions were systematically varied in order to achieve different stages of nanowire formation. Diameters of the SiNWs obtained varied from approximately 50 to 200 nm and their lengths ranged from several to a few tens of um. Te/Bi2Tex.Si thermoelectric core-shell nanostructures were subsequently obtained via galvanic displacement of SiNWs in acidic HF electrolytes containing HTe02+ and 139' /HTe02+ ions. The reactions were basically a nano-electrochemical process due to the difference in redox potentials between the materials. The surface-modified SiNWs of core-shell structures had roughened surface morphologies and, therefore, higher surface-to-bulk ratios compared to unmodified SiNWs. They have potential applications in sensors, photovoltaic and thermoelectric nanodevices. Growth study on the SiNWs and core-shell nanostructures produced is presented using various microscopy, diffraction and probe-based techniques for microstructural, morphological and chemical characterizations.
Boundary element method (BEM) is a numerical technique that used for modeling infinite domain as is the case for galvanic corrosion analysis. The use of boundary element analysis system (BEASY) has allowed cathodic protection (CP) interference to be assessed in terms of the normal current density, which is directly proportional to the corrosion rate. This paper was present the analysis of the galvanic corrosion between Aluminium and Carbon Steel in natural sea water. The result of experimental was validated with computer simulation like BEASY program. Finally, it can conclude that the BEASY software is a very helpful tool for
future planning before installing any structure, where it gives the possible CP interference on any nearby unprotected metallic structure.