Papers by Keyword: Surface Morphology

Abstract: Sr_2-x(Li_2/3, Ce_1/3)_x Nb₂O₇ (x = 0, 0.05, 0.1, 0.2, 0.3, 0.5) (SLCN) ceramics were prepared by solid-state reaction method. The microstructure, dielectric and ferroelectric properties were investigated. The results show that all ceramics have high relative densities. Li⁺ and Ce⁴⁺ co-doping can promote the grains growing, and improve the dielectric and ferroelectric properties of strontium niobate ceramics. The dielectric constant decreases firstly, and then increases with the increasing of x in Sr_2-x(Li_2/3, Ce_1/3)_x Nb₂O₇, and the sample with x = 0.5 exhibits enhanced dielectric properties (ε_r ≈ 250, tanδ ≈ 0.02). The remnant polarization (P_r) and coercive electric field (Ec) of SLCN ceramics increase firstly, and then decrease with the increasing of Li⁺ and Ce⁴⁺ content, finally reach the maximum value of remnant polarization (P_r ≈ 0.058μC/cm², Ec ≈ 6.87 kV/cm ) for x = 0.2.

Abstract: Abstract: The Interface of sisal fiber which was treated by using alkali, potassium permanganate, atmospheric plasma and silane reinforced polypropylene composites were investigated by single fiber pull-out testes and surface morphology were studied. The results indicated that the morphological changes observed on the sisal fiber surface were obviously evident. Untreated, permanganate and plasma treated sisal fiber reinforced PP show a stable debonding process. Silane treated sisal fiber reinforced PP show an unstable debonding process. Single fiber pull-out tests indicated that the IFSS value was in the order of FIB < FIBKMnO₄ < FIBP < FIBKH-550 < FIBKH-570. As can be seen from surface morphology of pull-out fiber, a little of PP resin was adhered to the pull-out FIB, FIBKMnO₄, FIBP of sisal fiber. In contrast, PP resin at the surface of pull-out fiber was flaked off and sisal fibril was drawn out from sisal fiber were observed from pull-out fibers of FIBKH-550 and FIBKH-570.

Abstract: This paper reports on the effects of gold (Au) catalyst on the growth of zinc oxide (ZnO) nanostructures by thermal chemical vapor deposition (TCVD). The thickness of Au catalyst was varied from 5 to 15 nm. The Au catalyst was annealed at 500 °C prior to the deposition of ZnO nanostructures by thermal chemical vapor deposition (TCVD). The morphology of the Au catalyst at different thickness and also ZnO nanostructures were characterized by field emission scanning electron microscopy (FESEM). The material component and crystalline properties of ZnO nanostructures were determined using Energy Dispersive X-ray spectroscopy (EDX) and also Raman Spectroscopy respectively. We found that the shape of the deposited ZnO nanostructures were different on different thickness of Au catalyst. There was no growth of ZnO on the 5 nm thick Au observed by FESEM and supported by EDX due to very small amount of Zn. On the 10 and 15 nm thick Au, growth of ZnO nanostructures were clearly observed.

Abstract: Micro-arc oxidation (MAO) coating was prepared in different electrolyte compositions on 6063 alloy and its characterizations were detected by X-ray diffractometer (XRD), scanning electric microscope (SEM), energy dispersive X-ray spectrometer (EDX) and Vickers hardness tester. Friction and wear behaviors of the coatings were tested without lubrication and the abrasion loss was measured after the friction test. The results showed that the MAO coatings, presenting rough and porous surface and high hardness, mainly consisted of α-Al₂O₃ and γ-Al₂O₃ phases. The composition of electrolytic solution had great influence on the coating morphology and its mechanical performance. Compared with the coating prepared in silicate and borate solutions, the coating prepared in aluminate solution had not only denser and smoother surface but also higher micro-hardness value and better abrasion resistance.

Abstract: We systematically study the componential and morphological characteristics of Cu₃N films induced by femtosecond laser irradiation on glass substrate. The experimental results demonstrate that with increase of laser power, significant changes on surface morphology can be observed, and coarse ripples structures present dominantly on film surfaces after irradiated by femtosecond laser. By XRD analysis of the treated sample area, componential evolutional process from the Cu₃N to Cu can be revealed at with increase of laser power, which provides an attracting application prospect in the field of utilizing microelectronic devices.

Abstract: Gadolinium doped barium titanate (Gd-BaTiO₃) thin films with the molar ratio of 70:30 have been fabricated on SiO₂/Si substrates using sol-gel technique. The effect of number of deposited layers on the grain size and surface morphology has been investigated using an atomic force microscope in contact mode. AFM micro-images show that the films have well distributed grains, dense and crack free surface. In general, the results show that the grain size increases from ~170 nm to ~189 nm as the number of deposited layers increase from one to four layers which attributed to the grain growth mechanism during heating and annealing processes. However, the surface of the films is analysed through amplitude parameters to find out that the films surface is smooth with a predominant for peaks and relatively low number of high peaks and low valleys.

Abstract: By analyzing the geometry of craters in a single pulse, the model of surface roughness in EDM was established and the main factors impacting on surface roughness were analyzed. On the base of establishment of the roughness model, the effect of discharge parameters on surface roughness was investigated by the process test method during the process of aluminum alloy 2A12 in EDM. At the same time, surface morphology obtained by different discharge parameters was comparatively analyzed. The results show that the effect of peak current and pulse width on the surface roughness is more significant, the crater on the machined surface has larger size while using higher peak current and pulse width, but the number of discharge craters is reduced.

Abstract: The study investigated the variation of friction coefficient of a vertical assembly of flank lock type precision locknut at the different tightening speed by a torque and axial force test machine. The tightening speed is set at 4rpm, 6rpm and 8rpm, respectively. The lubricant is a type of 2TML. Surface morphology was observed before and after the test via an optical microscope. The experiment proceeded to five preloads to test and took the sixth as the experimental setting through the ISO 2320 specification. The study observed the variation of friction coefficient at the different tightening speed under a preload. The results show that the friction coefficient tends to be smaller when the tightening speed becomes faster. The increase of friction coefficient associates with the increase of anti-loosening ratio. For the surface morphology, it was found that the seat surface and the thread surface of the locknut generates the reaming, scraping and fatigue damage after the repeated tightening and loosening test.

Abstract: This paper investigates the morphological modifications of the nanocrystalline diamond (NCD) film surface under reciprocating sliding test conditions. The surface morphology was characterized by atomic force microscopy (AFM). We observed longitudinal grooves and transverse ripples which were formed during the sliding tests on the NCD film surface. The primary goal of the study was to understand the influence of frequency, sliding distance and load variations on the formation of ripple patterns on the wear scars surface. The morphological alteration from continuous to broken ripple shapes was observed. Our study suggests that the geometrical shape of ripples is affected by the formation of the periodic array of grooves.

Abstract: High thermal conductivity and dense SiC coating were fabricated by chemical vapor deposition (CVD) on surface of different graphite at temperature of 1100°C. The results indicated that the thickness of the coating influences the quality of coating. There was no crack in coating when thickness of the coating is less than 0.3mm. The structure of graphite affected the reaction badly. When the graphite is coarse and porous the reaction is chemical vapor infiltration (CVI) and the interface of coating and substrate isnt obvious. When the graphite is dense and smooth, the coating is covered in surface of graphite, the interface is found between the coating and substrate. Optical microscope and SEM were used to observe the surface and cross-section morphology and microstructure of coatings. It shown coating and substrate had a good combination and the deposited grains mainly showed equiaxed form with the crystallite size of 30 nm at 1100°C.