scholarly journals Influence of silicon on growth mechanism of micro-arc oxidation coating on cast Al–Si alloy

2018 ◽  
Vol 5 (7) ◽  
pp. 172428 ◽  
Author(s):  
Huijun Yu ◽  
Qing Dong ◽  
Yang Chen ◽  
Chuanzhong Chen
Keyword(s):  
Surface Morphology ◽  
Adhesive Strength ◽  
Growth Process ◽  
Substrate Surface ◽  
Ceramic Coatings ◽  
Al Alloy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Alloy Substrate ◽  
Micro Arc Oxidation

Micro-arc oxidation (MAO) is a plasma-assisted electrochemistry method to prepare protective ceramic coatings on aluminium alloys. Alloy elements of the Al-alloy substrate, such as Si, Cu, Mg and Li, have effects on the microstructure and composition of the MAO coatings. Usually, silicon distributes in the cast Al–Si alloy substrate as small laths and they cover approximately 10% of the substrate surface. Therefore, their effects on the growth process and microstructure of the MAO coatings are worthy of notice. In the present study, oxide coatings with a thickness of 15–18 µm were prepared on the ZL109 Al–Si alloy by MAO. The phase content, surface morphology and element distribution of the coatings were investigated by X-ray diffraction, grazing incidence X-ray diffraction, scanning electron microscope, and electron probe micro-analysis respectively. The average hardness of the coatings was 622.3 ± 10.2 HV 0.05 . The adhesive strength of the coatings is 40.55 ± 2.55 N, and the adhesion of the coatings could be rated as 5B by tape test according to ASTM D3359-17 standard test methods, which indicated a high adhesive strength between the MAO coating and substrate. The effects of silicon laths on surface morphology and composition of the coatings were discussed, and a model was put forward to describe the growth process of the MAO coatings on cast Al–Si alloys. The authors believe that the high silicon content of the substrate has no adverse influence on the structure and properties of the MAO coating on the ZL109 alloy.

A Comparative Study of GaN Films Grown on Different Faces of Sapphire by ECR-Assisted MBE

1992 ◽  
Vol 242 ◽  
Author(s):  
T. D. Moustakas ◽  
R. J. Molnar ◽  
T. Lei ◽  
G. Menon ◽  
C. R. Eddy
Keyword(s):  
Surface Morphology ◽  
Low Temperatures ◽  
Smooth Surface ◽  
Growth Process ◽  
X Ray Diffraction ◽  
Epitaxial Relationship ◽  
X Ray ◽  
Sapphire Substrates ◽  
Growth Method ◽  
Step Growth

ABSTRACTGaN films were grown on c-plane (0001), a-plane (1120) and r-plane (1102) sapphire substrates by the ECR-assisted MBE method. The films were grown using a two-step growth process, in which a GaN buffer is grown first at relatively low temperatures and the rest of the film is grown at higher temperatures. RHEED studies indicate that this growth method promotes lateral growth and leads to films with smooth surface morphology. The epitaxial relationship to the substrate, the crystalline quality and the surface morphology were investigated by RHEED, X-ray diffraction and SEM studies.

Ceramic Coatings of Magnesium Alloy for Biomaterial Applications

2010 ◽  
Vol 434-435 ◽  
pp. 634-637 ◽  
Author(s):  
Pu Liang Zhang ◽  
Bin Liu ◽  
Dong Zhang ◽  
Yong Wei Tao ◽  
Sheng Rong Yang ◽  
...  
Keyword(s):  
Body Fluid ◽  
Ceramic Coatings ◽  
Alkaline Treatment ◽  
Mg Alloy ◽  
X Ray Diffraction ◽  
Electrodeposition Technique ◽  
Corrosion Properties ◽  
X Ray ◽  
Micro Arc Oxidation ◽  
Porous Oxide

Ceramic coatings were produced on magnesium (Mg) alloy of AZ91D for biomaterial applications by micro-arc oxidation (MAO) and electrodeposition methods. The morphology, microstructure, phase composition and corrosion properties of the prepared coatings were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and potentiodynamic polarization tester, etc. The results indicated that a porous oxide layer was grown on the Mg alloy sheets after MAO process and the compositions of oxides were mainly Mg2SiO4 and MgO. After further electrodeposition and alkaline treatment, a flake-like structure diverging from centre to periphery was grown on the MAO coating and the coating was mainly made up of hydroxyapatite (HA). Moreover, the corrosion resistance of the Mg alloy after being treated with MAO and electrodeposition technique increases obviously, which was evaluated in stimulated body fluid (SBF).

Effects of graphene on the microstructure and properties of MAO coatings formed on AA7050

2020 ◽  
Vol 111 (6) ◽  
pp. 463-468
Author(s):  
Bo Xu ◽  
Yafeng He ◽  
Xiangzhi Wang ◽  
Weimin Gan
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Corrosion Resistance ◽  
Aluminum Alloy ◽  
Composite Coatings ◽  
Ceramic Coatings ◽  
X Ray Diffraction ◽  
X Ray ◽  
Micro Arc Oxidation ◽  
Scanning Electron

Abstract Ceramic coatings were prepared on the surface of 7050 highstrength aluminum alloy using micro-arc oxidation in an aluminate electrolyte with added graphene. To analyze the surface morphology, roughness, phase composition, and corrosion resistance, scanning electron microscopy, X-ray diffraction, X-ray photoelectron, and electrochemical measurements were used, respectively. The addition of 9 g · L-1 of graphene to the electrolyte decreased the micro-pore size of the composite coatings and improved the density. In addition, with the addition of graphene, the roughness was the lowest, and the corrosion resistance was significantly improved.

Microstructure and properties of rare earth CeO2-doped graphene composite coatings prepared by MAO on AA7050

2020 ◽  
Vol 111 (11) ◽  
pp. 923-930
Author(s):  
Yu Zong ◽  
Renguo Song ◽  
Tianshun Hua ◽  
Siwei Cai
Keyword(s):  
Corrosion Resistance ◽  
Rare Earth ◽  
Composite Coatings ◽  
High Strength ◽  
Ceramic Coatings ◽  
X Ray Diffraction ◽  
X Ray ◽  
Micro Arc Oxidation ◽  
Doped Graphene ◽  
Micropore Size

Abstract In this paper, ceramic coatings were prepared on the surface of 7050 high strength aluminum alloy using a micro-arc oxidation process in a silicate electrolyte combined with the rare earth element cerium or graphene. To analyze the surface morphology, roughness, phase composition, and corrosion resistance, scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectrometry, and electrochemical measurements were used, respectively. It was shown that the micropore size of the composite coatings, which mainly consisted of α-Al2O3 and γ-Al2O3, decreases and the density improved with the simultaneous addition of 4 g · L-1 of CeO2 and 10 g · L-1 of graphene to the electrolyte. In addition, with the addition of CeO2 and graphene, the roughness was the lowest and the corrosion resistance was significantly improved.

scholarly journals Grain Structure and Growth of Dispersed Phase BN-AlN Coatings Grown via Chemical Vapor Deposition

1990 ◽  
Vol 202 ◽  
Author(s):  
Garth B. Freeman ◽  
Woo Y. Lee ◽  
W. J. Lackey ◽  
John A. Hanigofsky ◽  
Karren More
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Substrate Surface ◽  
Chemical Vapor ◽  
Ceramic Coatings ◽  
Grain Structure ◽  
Dispersed Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron

ABSTRACTThis paper discusses the variation in microstructures encountered during the separate depositions of boron nitride (BN) and aluminum nitride (A1N) as well as during the codeposition of BNߝA1N dispersed phase ceramic coatings. This combination was chosen in order to take advantage of the self lubricating properties of hexagonal BN along with the hard, erosion resistance of A1N. Films were characterized using scanning and transmission electron microscopy (SEM and TEM), x-ray photoelectron spectroscopy (XPS), and x-ray diffraction (XRD).A range of coating microstructures are possible depending on the conditions of deposition. The best films produced, in terms of hardness, density, and tenacity, were a fine mixture of turbostratic BN and preferentially oriented A1N whiskers aligned with the whisker axis perpendicular to the substrate surface as seen by both electron microscopy and x-ray diffraction.

Research on Properties and Formation Mechanism of Ceramic Coatings Prepared by Micro-Arc Oxidation on 2024 Aluminum Alloy Surface

2006 ◽  
Vol 315-316 ◽  
pp. 259-263 ◽  
Author(s):  
Wan Sheng Zhao ◽  
T.Z. Xin ◽  
Zhen Long Wang ◽  
J.C. Liu
Keyword(s):  
Phase Composition ◽  
Ceramic Coatings ◽  
High Energy ◽  
High Energy Density ◽  
Alloy Surface ◽  
Al Alloy ◽  
X Ray Diffraction ◽  
2024 Aluminum Alloy ◽  
Micro Arc Oxidation ◽  
Coating Formation

In this paper, ceramic coatings prepared on 2024 Al alloy surface in electrolyte by micro-arc oxidation are studied. The parameter of discharge and rate of ceramic coating formation are investigated. We analyzed microstructure and phase composition of the coatings by scanning electronic microscopy (SEM) and X-ray diffraction (XRD), and studied the tribological performance of the coatings. The reactions on the electrode surface are deduced and the mechanism of coating formation has been analyzed. The results show that the relation between the thickness and reaction time is not linear. The ceramic coatings contain phase γ-Al2O3 andα-Al2O3; there is a big difference in contents of phase composition between inner coating and outer coating due to the different cooling rates of them. In MAO process, the coating undergoes a course of melting, solidifying and cooling. The coating can be divided into three layers, namely, transition layer, compact layer, and loose layer. The coating and substrate adheres firmly by a metallurgical process. Not only the elements of electrolyte (K, Si) and substrate (Cu) are found in the coatings but also the element of cathode (Fe). The Si-Al-O complex compound is formed in the discharge channels under high energy density condition.

EFFECT OF KOH ON MICRO-ARC OXIDATION COATINGS OF 2A12 ALUMINUM ALLOYS IN CH3COONa–Na2WO4 ELECTROLYTE

2014 ◽  
Vol 21 (02) ◽  
pp. 1450026
Author(s):  
ZHAO QING LIN ◽  
HUI JUN YU ◽  
SI YU HE ◽  
YI NING HE ◽  
CHUAN ZHONG CHEN
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Current Density ◽  
Corrosion Current ◽  
Scratch Test ◽  
Ceramic Coatings ◽  
X Ray Diffraction ◽  
Electrolyte System ◽  
X Ray ◽  
Micro Arc Oxidation ◽  
Scanning Electron

The ceramic coatings were prepared on 2A12 alloy by micro-arc oxidation in CH 3 COONa – Na 2 WO 4 electrolyte system with different concentration of KOH added. The effects of KOH in this electrolyte on micromorphology, phase compositions, adhesion and corrosion resistance of the coatings were investigated by scanning electron microscope (SEM), X-ray diffraction (XRD), scratch test and electrochemistry workstation. The results show that KOH has a significant influence on the surface morphology, which can make the surface smoother. The adhesion of the coating becomes stronger with the increase of KOH in the electrolyte. The corrosion resistance of the coated specimen increases a lot compared with that of the substrate. And the lowest corrosion current density (I corr ) of the coating prepared in the electrolyte with KOH is about three orders of magnitude lower than that of the substrate.

The Synthesis and Characterization of Ba0.5Sr0.5TiO3 Film Fabricated by Micro Arc Oxidation

2012 ◽  
Vol 151 ◽  
pp. 266-270
Author(s):  
Ming Wang ◽  
Hui Yong Guo ◽  
Wen Bo Huang ◽  
Wen Fang Li
Keyword(s):  
Surface Morphology ◽  
High Dielectric Constant ◽  
Energy Dispersive Spectrometer ◽  
X Ray Diffraction ◽  
Titanium Plate ◽  
X Ray ◽  
Low Dielectric ◽  
Micro Arc Oxidation ◽  
High Dielectric

Ba0.5Sr0.5TiO3film was successfully fabricated by micro arc oxidation of titanium plate in aqueous solution containing Sr(OH)2and Ba(OH)2for 25 minutes. X-ray diffraction , energy dispersive spectrometer and scanning electron microscopy were used to characterize the crystalline structure, elements composition and surface morphology and HP4284 capacitance prober was used to analyze the dielectric properties of the film. The micro arc oxidation film is mainly composed of tetragonal Ba0.5Sr0.5TiO3 phases and possesses both high dielectric constant of 454.2 and low dielectric loss of 0.052 at the frequency of 100Hz.The surface morphology appeares smooth and homogeneous except that some holes are uniformly distributed outwardly.

scholarly journals Laser-Induced Deposition of Plasmonic Ag and Pt Nanoparticles, and Periodic Arrays

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 10
Author(s):  
Daria V. Mamonova ◽  
Anna A. Vasileva ◽  
Yuri V. Petrov ◽  
Denis V. Danilov ◽  
Ilya E. Kolesnikov ◽  
...  
Keyword(s):  
Substrate Surface ◽  
Pt Nanoparticles ◽  
Single Step ◽  
X Ray Diffraction ◽  
Ag Nps ◽  
X Ray ◽  
Periodic Arrays ◽  
Potential Applications ◽  
Surface Decoration ◽  
Wide Potential

Surfaces functionalized with metal nanoparticles (NPs) are of great interest due to their wide potential applications in sensing, biomedicine, nanophotonics, etc. However, the precisely controllable decoration with plasmonic nanoparticles requires sophisticated techniques that are often multistep and complex. Here, we present a laser-induced deposition (LID) approach allowing for single-step surface decoration with NPs of controllable composition, morphology, and spatial distribution. The formation of Ag, Pt, and mixed Ag-Pt nanoparticles on a substrate surface was successfully demonstrated as a result of the LID process from commercially available precursors. The deposited nanoparticles were characterized with SEM, TEM, EDX, X-ray diffraction, and UV-VIS absorption spectroscopy, which confirmed the formation of crystalline nanoparticles of Pt (3–5 nm) and Ag (ca. 100 nm) with plasmonic properties. The advantageous features of the LID process allow us to demonstrate the spatially selective deposition of plasmonic NPs in a laser interference pattern, and thereby, the formation of periodic arrays of Ag NPs forming diffraction grating

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