Composition, Structure, and Catalytic Activity of SiO2+TiO2/Ti and MnOx+SiO2+TiO2/Ti Composites Formed by Combination of the Methods of Plasma Electrolytic Oxidation, Impregnation and Annealing

2015 ◽  
Vol 245 ◽  
pp. 238-242 ◽  
Author(s):  
Marina S. Vasilyeva ◽  
V.S. Rudnev ◽  
Alexander Yu. Ustinov
Keyword(s):  
Catalytic Activity ◽  
Co Oxidation ◽  
Plasma Electrolytic Oxidation ◽  
Manganese Oxides ◽  
Outer Part ◽  
Oxide Layers ◽  
Co Conversion ◽  
Electrolytic Oxidation ◽  
Composition Structure ◽  
Plasma Electrolytic

New data on the structure of silicon-containing oxide layers SiO2+TiO2 on titanium formed by the method of plasma electrolytic oxidation (PEO) as well as on the structure and catalytic activity in CO oxidation of MnOx+SiO2+TiO2/Ti composites formed on their basis using impregnation and annealing methods have been obtained. It has been demonstrated that silicon and titanium are rather homogeneously distributed over the SiO2+TiO2 coating bulk. The coating outer part is silicon-enriched titanium-depleted. The MnOx+SiO2+TiO2/Ti composites catalyze the CO conversion at temperatures above 100°C. Nanowhiskers consisting predominantly of manganese oxides have been found on the surface of the MnOx+SiO2+TiO2/Ti composites.

Composition, Surface Structure and Catalytic Properties of Manganese- and Cobalt-Containing Oxide Layers on Titanium

2014 ◽  
Vol 875-877 ◽  
pp. 351-355 ◽  
Author(s):  
M.S. Vasilyeva ◽  
V.S. Rudnev
Keyword(s):  
Surface Structure ◽  
Plasma Electrolytic Oxidation ◽  
Catalytic Properties ◽  
Oxidation Of Co ◽  
Oxide Layers ◽  
X Ray ◽  
Electrolytic Oxidation ◽  
Catalytically Active ◽  
Plasma Electrolytic ◽  
Scanning Electron

Silicon-containing oxide layers deposited on titanium using the plasma electrolytic oxidation (PEO) method were modified with manganese and cobalt compound through impregnation followed by annealing. The obtained manganese composites are catalytically active in the process of oxidation of CO at 100 оС, while cobalt-containing structures demonstrate this type of activity at temperatures above 200оС. The composition and surface structure of the obtained systems were investigated by means of X-ray phase and energy dispersive analyses and by high resolution scanning electron microscopy (SEM). Granule-like particles with diameters of a few dozens of nanometers were observed on the surface of oxide-cobalt layers on titanium, whereas the surface of oxide-manganese layers was coated by nano-whiskers of diameters <50 nm and length <1 μm. The presence of manganese-containing nano-whiskers substantially increases the catalyst specific surface, thus facilitating the attainment of higher degree of transformation of initial gaseous substances.

scholarly journals CHARACTERISTICS OF PLASMA ELECTROLYTIC OXIDATION COATINGS ON 6061 AL ALLOY PREPARED AT DIFFERENT CURRENT DENSITIES

2020 ◽  
Vol 58 (6) ◽  
pp. 699
Author(s):  
Quang-Phu Tran ◽  
Van-Da Dao ◽  
Van-Hoi Pham
Keyword(s):  
Plasma Electrolytic Oxidation ◽  
Current Mode ◽  
Coated Sample ◽  
Al Alloy ◽  
Properties Of Coatings ◽  
Sem Images ◽  
Oxide Layers ◽  
Electrolytic Oxidation ◽  
Plasma Electrolytic ◽  
6061 Al Alloy

Plasma electrolytic oxidation (PEO) has earned much attention due to its powerful and easy formation of hard and corrosion-resistant oxide layers on valve metals, such as Al alloys. Here we report the effects of current density (CD) on microstructure and properties of coatings on 6061 Al alloy by PEO using direct current mode. The electrolyte contains the chemicals of Na2SiO3, Na2WO4´2H2O, and NaH2PO2´H2O. The CDs adopted 5.0, 7.5, 10.0, and 12.5 A/dm2, respectively, for a fixed PEO time of 30 min. The thickness, surface morphology, phase composition, hardness, and corrosion resistance of PEO coatings as the function of the applied CD have been studied and discussed. Studied results show the coating thickness is proportional to the applied CD. When the applied CD increases 2.5 times from 5.0 to 12.5 A/dm2, the growth rate of oxide layers increased by more than 3.5 times, from 0.423 to 1.493 μm/min, respectively. SEM images are characterized by a reduction in the ratio of agglomerate-bumps-region/flatten-region as applied CD increases. However, cracks and larger pores appear when the applied CD is higher than 10.0 A/dm2. X-ray diffraction pattern shows that the main phases of Al, g-Al2O3, α-Al2O3, and W are contained in all coatings. PEO coated sample has the highest hardness of 1290 HV and highest polarization resistance of 8.80 ´ 106 Wcm2 obtained at applied CD 10 A/dm2 which shows the best performance of the coating. The variation in coating performance is explained by microstructure details, specifically phases, compositions of oxide-layers, and micro-pores and cracks.

Study on coating growth characteristics during the electrolytic oxidation of a magnesium–lithium alloy by optical emission spectroscopy analysis

RSC Advances ◽  
2015 ◽  
Vol 5 (84) ◽  
pp. 68806-68814 ◽  
Author(s):  
Zhongping Yao ◽  
Qixing Xia ◽  
Han Wei ◽  
Dongqi Li ◽  
Qiu Sun ◽  
...  
Keyword(s):  
Emission Spectroscopy ◽  
Plasma Electrolytic Oxidation ◽  
Optical Emission Spectroscopy ◽  
Optical Emission ◽  
Growth Characteristics ◽  
Spectroscopy Analysis ◽  
Electrolytic Oxidation ◽  
Composition Structure ◽  
Plasma Electrolytic ◽  
Peo Coatings

The aim of this study is to analyze the composition, structure and growth characteristics of plasma electrolytic oxidation (PEO) coatings through optical emission spectroscopy (OES).

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