Papers by Keyword: Growth Process

Abstract: Micro-arc oxidation technique was studied on the surface of 2A12 aluminum alloy using AC power in this paper. The micro-arc oxidation process was divided into several periods to investigate the changes of thickness and surface morphology of oxide film that forms in different periods and record the voltage change between oxide film. The following conclusions have been found: The growth of oxide film can be divided into three stages, the first stage is the formation and disruptive discharge of amorphous oxide film, producing the ceramic oxide granules; the second stage is the formation of ceramic oxide film, the ceramic oxide granules turns into porous structure oxide film in this stage; the third stage is the growth of ceramic oxide film, the gas film forms in the oxide film’s porous structure is electric broken-down, leading higher energy discharged by micro-arc, which becomes a significant reason for promoting the growth of ceramic film.

Abstract: Elecrodeposited Ni-P alloy thin films have been the subject of extended investigations, since the pioneering works of Brenner et al, in the late 1940s. It is well known, that the physical and chemical properties of the Ni-P deposit composition are strongly influenced by the preparation conditions. In our experimental procedure, we have used a Parstat 2253 potensiostat equipped with Power-Suite software. All the electrochemical experiments were performed in a three electrode cell in which the volume of the bath was 150ml, in this experimental technique, we can measure one or more of three parameters: the potential (V), current (i), and time (t). The aim of our work consists to study the nucleation and growth process and given morphology and composition of electrodeposited Ni_x-P_100-x thin films on Copper substrates. For this purpose, cyclic voltametry and chnonoamperomaty have been used in order to determine the previous cited properties of thin films Ni-P, [0.10 of NaPH₂O₂ solutions. The chrnoamperogramms can be interpreted by the use of one of three models called: Growth mode (Me layer by layer formation); Franck Van der Merwe, FM model, Growth mode 3D (Me island formation on the top of predeposited), 2D Meads overlayers on substrat and Stranski-Krastanov; (SK model).

Abstract: In this paper, plasma electrolytic carburizing has been applied on the commercially pure titanium substrates in an organic based electrolyte with presence of some hard tungsten carbide nanoparticulates in suspension state. Pulsed current with variable duty cycle has been used for fabrication of functionally gradient nanocomposite coating. As a result, a hard nanocomposite layer has been formed on the surface of the samples with complex titanium carbide as its matrix and tungsten carbide nanoparticulates as its reinforced phase. In addition of used SEM, TEM and AFM for evaluation of coating nature, the presence of tungsten in different depths of formed layer has been followed by means of EDS. The effects of rate of variable duty cycle of applied pulsed current or treatment time have been described. Hardness profiles showed that the higher rates for variable duty cycles will cause lower hardness and sharper profilesThis document explains and demonstrates how to prepare your camera-ready manuscript for Trans Tech Publications. The best is to read these instructions and follow the outline of this text. The text area for your manuscript must be 17 cm wide and 25 cm high (6.7 and 9.8 inches, resp.). Do not place any text outside this area. Use good quality, white paper of approximately 21 x 29 cm or 8 x 11 inches (please do not change the document setting from A4 to letter). Your manuscript will be reduced by approximately 20% by the publisher. Please keep this in mind when designing your figures and tables etc.

Abstract: In order to get a clear picture for describing the growth process of plasma electrolytic oxidation coatings under escalating voltage waveform, the composition, the concentration of the dissolved Mg2+ of PEO coatings formed at different reaction stages were investigated. The voltage-current characteristics during the PEO process were also discussed.

Abstract: Hexagonal prismatic hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂, HAP) was successfully prepared by a homogeneous precipitation method. The products were characterized by X-ray diffraction, Fourier transform infrared spectrum, and scanning electron microscope. The growth process of the hexagonal prism was surveyed in detail based on the effects of the reaction time on the phase composition and the crystal morphology.

Abstract: Hairball-like bismuth trisulphide microcrystallines has been successfully prepared via one step solvothermal process and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM) techniques. The morphologies of the Bi₂S₃ microcrystallines were influenced by reaction time, temperature, the mole ratio of the reactants and concentration of starting materials, and the growth process has been proposed. The electrochemical behavior of Bi₂S₃ was investigated using the cyclic voltammetry.

Abstract: This work describes atomic-scale, crystalline structure and size distribution for noble metal nanoparticles produced by water-based, environmental friendly technologies. The process was developed and implemented to produce noble metal nanoparticles to be used in water filters, sensors and cosmetics. The particles were investigated by TEM methods and particle size analysis. Growth process of the crystallites in sols made by chemical reduction in aqueous solutions is discussed. Comparison with growth models for vacuum deposited thin films is also identified.

Abstract: The growth of ultrananocrystalline diamond (UNCD) by pulsed laser deposition necessitates hydrogen atmospheres during the deposition. Optical emission spectroscopy was used to study the roles of the hydrogen atmosphere on the UNCD growth. Time-resolved images of a plume that expanded from a laser-irradiation spot toward a substrate were taken using a high-speed ICCD camera equipped with narrow-bandpass filters. While the plume disappeared at the longest within 1 s in vacuum, the emission from C+ lasted above the substrate surface for approximately 7 microseconds at a hydrogen pressure of 53.3 Pa. Since emission lifetimes of species are approximately 10 nanoseconds, this implies that C+ ions collided actively for such a long time. The hydrogen atmosphere has a role of forming a high number density of C+ ions. In addition, we believe that atomic hydrogen that might be generated by the collisions with carbon species contributes to the UNCD crystallite formation by their terminating the dangling bonds of carbon clusters as theoretically predicted in previous reports.