Oxygen Sensors Based on Titanium Oxide Layers Produced By Plasma Electrolytic Oxidation

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.

Download Full-text

Characteristics of Oxide Layers Formed on Al2021 Alloys by Plasma Electrolytic Oxidation in Aluminate Fluorosilicate Electrolyte

Journal of the Korean institute of surface engineering ◽

10.5695/jkise.2008.41.6.308 ◽

2008 ◽

Vol 41 (6) ◽

pp. 308-311 ◽

Cited By ~ 1

Author(s):

Kai Wang ◽

Bon-Heun Koo ◽

Chan-Gyu Lee ◽

Young-Joo Kim ◽

Sung-Hun Lee ◽

...

Keyword(s):

Plasma Electrolytic Oxidation ◽

Oxide Layers ◽

Electrolytic Oxidation ◽

Plasma Electrolytic

Download Full-text

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

Vietnam Journal of Science and Technology ◽

10.15625/2525-2518/58/6/15053 ◽

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.

Download Full-text