Cathodic electrosynthesis of alumina thin films and powders
01 Oct 2000-Journal of Materials Science Letters (Kluwer Academic Publishers)-Vol. 19, Iss: 19, pp 1715-1718
TL;DR: In this paper, the utility of cathodic electrosynthesis methodology in the preparation of alumina thin films and powders is explored, and the authors explore the utility and utility of electro-synthetic methods in the production of powders.
Abstract: The present work explores the utility of cathodic electrosynthesis methodology in the preparation of alumina
thin films and powders.
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TL;DR: In this paper, the authors investigated the electrosynthesis of cerium-containing films onto model Ni and both raw and aluminized nickel-based superalloy from concentrated aqueous solutions of the cerium nitrate at room temperature and established correlations between the electrochemical features and the microstructure of the resulting layers.
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References
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TL;DR: In this article, the multiplicity of the mechanical properties of alloys and compounds with particular emphasis on the mechanisms which are involved are discussed. But these properties can be varied significantly if one combines several elements, that is, by alloying.
Abstract: Pure materials have a number of inherent mechanical properties, as discussed in Chapter 3. These features, such as strength or ductility, can be altered only to a limited degree, for example, by work hardening. In contrast to this, the properties of materials can be varied significantly if one combines several elements, that is, by alloying. In this chapter, we shall unfold the multiplicity of the mechanical properties of alloys and compounds with particular emphasis on the mechanisms which are involved. Specifically, we shall discuss a number of techniques which increase the strength of materials. Among them are solid solution strengthening, precipitation hardening (age hardening), dispersion strengthening, and grain size strengthening. In order to understand these mechanisms, we need to study the fundamentals of phase diagrams.
1,300 citations
TL;DR: In this paper, a two-stage process was proposed for depositing nanocrystalline titanium dioxide thin films on electronically conducting glass was developed, where cathodic electrodeposition of titanium oxyhydroxide gel film from aqueous solution containing a Ti precursor and subsequent heat-treatment of this gel film results in the formation of titanium dioxide film.
Abstract: A new technique for depositing nanocrystalline titanium dioxide thin films on electronically conducting glass was developed. This technique is a two-stage process: (i) cathodic electrodeposition of titanium oxyhydroxide gel film from aqueous solution containing a Ti precursor and (ii) subsequent heat-treatment of this gel film results in the formation of titanium dioxide film. The deposition potential may have a considerable effect on the formation of nanocrystalline film. The nanocrystalline titanium dioxide film shows reversible electrochromism in lithium-ion-containing organic electrolyte. The coloration and bleaching throughout the visible and near-IR range can be switched on and off within a few seconds.
224 citations
Patent•
TL;DR: In this paper, a biased electrochemical cell is used to generate hydroxide ions that precipitate metallic or semimetallic ions to form insoluble solids that may be separated from the cell, then dried, calcined and sintered to form a ceramic composition.
Abstract: Ceramic precursor compositions, such as metal hydroxides and oxides, are electrochemically deposited in a biased electrochemical cell. The cell typically generates hydroxide ions that precipitate metallic or semimetallic ions to form insoluble solids that may be separated from the cell, then dried, calcined and sintered to form a ceramic composition.
186 citations
TL;DR: In this article, nanocrystalline CeO{sub 2} powders were prepared electrochemically by the cathodic electrogeneration of base, and their sintering behavior was investigated.
Abstract: Nanocrystalline CeO{sub 2} powders were prepared electrochemically by the cathodic electrogeneration of base, and their sintering behavior was investigated. X-ray diffraction and transmission electron microscopy revealed that the as-prepared powders were crystalline cerium(IV) oxide with the cubic fluorite structure. The lattice parameter of the electrogenerated material was 0.5419 nm. The powders consisted of nonaggregated, faceted particles. The average crystallite size was a function of the solution temperature. It increased from 10 nm at 29 C to 14 nm at 80 C. Consolidated powders were sintered in air at both a constant heating rate of 10 C/min and under isothermal conditions. The temperature at which sintering started (750 C) for nanocrystalline CeO{sub 2} powders was only about 100 C lower than that of coarser-grained powders (850 C). However, the sintering rate was enhanced. The temperature at which shrinkage stopped was 200--300 C lower with the nanoscale powder than with micrometer-sized powders. A sintered specimen with 99.8% of theoretical density and a grain size of about 350 nm was obtained by sintering at 1,300 C for 2 h.
169 citations
TL;DR: In this article, a two-step mechanism for the formation of hydroxyl ions (OH−) at the cathodic substrate by reduction of and dissolved, and then reaction of the hyroxyl ion with zirconyl ions present in the solution to form the hydroxide, which in turn decomposes on drying to yield Zirconia.
Abstract: coatings were deposited on graphite and titanium from an aqueous solution based on a water‐soluble precursor. A two‐step mechanism is suggested for the formation: generation of hydroxyl ions (OH−) at the cathodic substrate by reduction of and dissolved , and then reaction of the hydroxyl ions with zirconyl ions present in the solution to form the hydroxide , which in turn decomposes on drying to yield zirconia . Faradaic efficiencies of 20–50% were found, attributable to reduction reactions that do not produce hydroxyl ions, as well as to formation of the hydroxide at sites removed from the cathodic substrate due to diffusion of the hydroxyl ions. The effects of current density, time, and hydrodynamic conditions on coating weight, cell voltage, temperature, and pH of the solution were studied.
166 citations