Papers by Keyword: Surface Morphology

Abstract: The surface morphologies, chemical composition, phase composition, compactness, thickness and the corrosion resistance of porous anodic films prepared in the sulfuric electrolyte with different additives at 35°C were investigated by XRD, FESEM, EDS, drop method in this paper. The additives are including organic acids, polyhydric alcohols and rare earth (REE) salts. It is indicated that a porously anodic film with about 20 nm holes in diameter can be obtained by additives into the sulfuric electrolyte. The main chemical compositions of the anodic films are Al, O elements, and a small amount of S. The film after boiling water sealing is composed of boehmite phase (Al₂O₃·H₂O) and alumina (Al₂O₃). The corrosion resistance of the anodic film can be improved by the coupling effect of the additives. The mechanism is discussed.

Abstract: The effects of micro-arc oxidation (MAO) voltage (370V, 400V, 420V) on the surface morphology, adhesion of film/substrate, corrosion resistance and fretting friction and wear properties after micro-arc oxidation and heat-treatment for 48h of TiNi alloy were investigated. The results show that, as the voltage gradually increases: (1) micro-arc oxidation coatings form, when the voltage increase to 420V, the coating shows a significant micro-arc oxidized porous characteristics; (2) the Ca/P ratio in the coatings also increases, so the Ca/P ratio can be controlled by adjusting the voltage of micro-arc oxidation; (3) the corrosion resistance of MAO coatings can be significantly improved by increasing the output voltage, the corrosion rate and the corrosion potential of 420V are smaller two magnitude than 370V’s; (4) the coating of 420V shows lower friction coefficient with higher resistance, narrower wear scar width; (5) the MAO coatings have formed different types of hydroxyapatite crystals (HA) after immersed in high temperature and pressure reactor for 48h, and the phase composition of the coating are mainly apatite.

Abstract: An attempt is made here to analyze the effect of the process parameter and shoulder of tool on the surface topography of FSJ (friction stir joining) joint. It is found that, it is a linear relationship between the feed speed and arc lines spacing, and the slope decreases as feed speed increasing. As the rotational speed increasing, the arc line spacing reduces. While FSJ processes completed at different parameters contain the same ratio between the feed speed and the rotation speed, the arc line spacing of the joint surfaces is the same. The shoulder of tool can increase the width of joint lines, refine arc lines structure, reduce the flash in the retreating side, but increase the flash in the advancing side.

Abstract: The study presents the contribution in engineering of surfaces particularly in surface morphology of Austenitic Stainless Steels. The objective of the investigation was to determine the surface morphology of austenitic stainless steel after turning with coated carbide tool point. The investigation included geometrical parameters of SI for different cutting parameters in dry turning process of austenitic stainless steel. The study has been performed within a production facility during the production of electric motor parts and deep-well pumps.

Abstract: Conventional characterization methods of grinding surface using surface roughness parameters, e.g., Ra, depend on either the resolution of the measuring instrument or the length of the sample. But fractal dimension (FD) as a scale-independent fractal parameter is effective to evaluate the ground surface at any length scale and represent lots of surface phenomenon at its relevant length scales. In this paper, a three-dimensional (3D) box-counting fractal analysis method is used to investigate ground surface morphology of monocrystal sapphire by calculating 3D fractal dimension of the ground surface. The results obtained show that fractal dimension decreases with the increasing surface roughness. For the ground surface with higher fractal dimension, its microtopography is more exquisite with minor defects. Once the fractal dimension become smaller, deep cracks and pronounced defects are exhibited in ground surface. Moreover, the ground surface obtained in ductile mode has much higher fractal dimension than that in brittle mode. Therefore, the fractal analysis method has the potential to reveal the ground surface characteristics of monocrystal sapphire.

Abstract: A novel microforming process - Micro Cross Wedge Rolling (MCWR) has been developed, which is promising for fabricating micro stepped components used in micro electro-mechanical systems. Numerical simulations have been established and the effect of geometrical and process parameters such as forming angle α, stretching angle β and reduction ΔA have been studied. Micro stepped components have been fabricated successfully on a MCWR testing rig by adopting flat wedge tools. The effects of initial surface roughness of tool, grain size and cross section area reduction on surface morphology have been assessed quantitatively.

Abstract: In order to improve the non-cyanide electroless gold plating deposition performance, the effects of the kinds of additives as well as its concentration on the deposition performance were investigated. The appearance inspection, deposition rate, adhesive force, surface morphology and corrosion resistance were evaluated. The results showed that the introduction of appropriate additives did improve the coating properties. The optimal concentration of polyethylene glycol and polycrylamide were 0.6~1.0 g·L^-1 and 1.0~1.5 g·L^-1, respectively. The corrosion resistance of the coating deposited in baths containing polyacrylamide was best.

Abstract: Extensive research data were published in the last decade on synthesis, characterization and application of AuNP for drug delivery and protein conjugation. Gold nanoparticles were synthesized by the well-known citrate reduction (Turkevitch) method. Precursor concentrations were measured by UV-Vis spectroscopy and iodometric estimation methods. During reaction surface plasmon resonance (SPR) peaks of the reaction medium decreased from 556.5 nm to 527.2 nm in about 300s. Experimental data on time-concentration profiles of the precursor in the reaction medium were used to calculate pseudo-first order rate constant (0.0178± 0.002 s^-1). Atomic Force Microscopy (AFM) was used for morphological characterization of the nanoparticles.

Abstract: To study the relation between surface morphology and deformation mechanism of the target material under the shock, a flexible boundary loading, in laser shock peening (LSP), the macroscopic and microscopic surface morphology of a single crystal copper treated by LSP was investigated. The optical profilometer shows a 200-μm-deep pit forms on the shocked surface under LSP. The optical microscopy shows a set of parallel slip bands appear at the center of the shocked region and many vertical cross slip bands appear at the edge of shocked region. This indicates a large plastic deformation occurs by means of slip for the single crystal copper under LSP and the distributing features of slip bands correspond to the spatial distribution of the shock pressure. The results confirm that the surface morphology of materials under LSP can reflect the deformation mechanism and it can be a new method of studying the deformation mechanism of materials under LSP.

Abstract: The direct laser drilling could bring the recast layer and micro cracks, here introduced a new method named low-pressure water jet assisted laser drilling.It mainly studied some factors influence on the surface and inwall morphologies of Al2O3 ceramic when using low-pressure water jet, such as auxiliary gas pressure、pulse energy、repeated frequency.By optimizing the parameters, it can get the better surface and inwall morphologies. The results show that, taking advantage of the erosion of water jet, the composite drilling can obviously lessen molten slags, in order to reduce the recast layer and micro cracks, the processing quality can be improved much.