The Influence of Processing Time on Morphology, Structure and Functional Properties of PEO Coatings on AZ63 Magnesium Alloy

The plasma electrolytic oxidation (PEO) surface modification technique was employed for improving the mechanical and anti-corrosion properties of the AZ63 magnesium alloy. Different PEO processing times (5, 10 and 20 min) in a 10 g/L NaAlO2 electrolyte, with no other additives, led to the formation of ceramic coatings with mean thicknesses between 15 and 37 microns. Scanning electron microscopy (SEM) showed that the porosity of the coatings decreased with processing time, but an increase in roughness was observed. X-Ray diffraction phase analysis indicated a coating structure composed of majority magnesium aluminate spinel. The corrosion rate of the coated samples decreased with an order of magnitude compared with the bare alloy. The average micro-hardness values of the PEO-coated samples was up to five times higher than those of the AZ63 alloy

The Influence of Processing Time on Morphology, Structure and Functional Properties of PEO Coatings on AZ63 Magnesium Alloy

The plasma electrolytic oxidation (PEO) surface modification technique was employed for improving the mechanical and anti-corrosion properties of the AZ63 magnesium alloy. Different PEO processing times (5, 10 and 20 min) in a 10 g/L NaAlO2 electrolyte, with no other additives, led to the formation of ceramic coatings with mean thicknesses between 15 and 37 microns. Scanning electron microscopy (SEM) showed that the porosity of the coatings decreased with processing time, but an increase in roughness was observed. X-Ray diffraction phase analysis indicated a coating structure composed of majority magnesium aluminate spinel. The corrosion rate of the coated samples decreased with an order of magnitude compared with the bare alloy. The average micro-hardness values of the PEO-coated samples was up to five times higher than those of the AZ63 alloy

Photocatalytic activity of pulsed laser deposited TiO2 thin films in N-2, O-2 and CH4

We report on pulsed laser deposition of TiO2 films on glass substrates in oxygen, methane, nitrogen and mixture of oxygen and nitrogen atmosphere. The nitrogen incorporation into TiO2 lattice was successfully achieved, as demonstrated by optical absorption and XPS measurements. The absorption edge of the N-doped TiO2 films was red-shifted up to similar to 480 nm from 360 nm in case of undoped ones. The photocatalytic activity of TiO2 films was investigated during toxic Cr(VI) ions photoreduction to Cr(III) state in aqueous media under irradiation with visible and UV light. Under visible light irradiation, TiO2 films deposited in nitrogen atmosphere showed the highest photocatalytic activity, whereas by UV light exposure the best results were obtained for the TiO2 structures deposited in pure methane and oxygen atmosphere

Aluminum Oxide Ceramic Coatings on 316l Austenitic Steel Obtained by Plasma Electrolysis Oxidation Using a Pulsed Unipolar Power Supply

AISI 316 steel has good corrosion behavior and high-temperature stability, but often prolonged exposure to temperatures close to 700 °C in aggressive environments (e.g., in boilers and furnaces, in nuclear installations) can cause problems that lead to accelerated corrosion degradation of steel components. A known solution is to prepare alumina ceramic coatings on the surface of stainless steel. The aim of this study is to obtain aluminum oxide ceramic coatings on 316L austenitic steel, by Plasma Electrolysis Oxidation (PEO), using a pulsed unipolar power supply. The structures obtained by PEO under various experimental conditions were characterized by XPS, SEM, XRD, and EDS analyses. The feasibility was proved of employing PEO in NaAlO2 aqueous solution using a pulsed unipolar power supply for ceramic–like aluminum oxide films preparation, with thicknesses in the range of 20–50 μm, and a high content of Al2O3 on the surface of austenitic stainless steels

TiO 2 /ZrO 2 THIN FILMS SYNTHESIZED BY PLD IN LOW PRESSURE N-, C-AND/OR O-CONTAINING GASES: STRUCTURAL, OPTICAL AND PHOTOCATALYTIC PROPERTIES

Doped TiO 2 /ZrO 2 films were obtained by Pulsed Laser Deposition method under different synthesis conditions. The onset of absorption spectra was red shifted for the films obtained in N 2 containing gas mixtures, while a broad absorption in visible was observed in the case of films deposited in CH 4 atmosphere. The presence of O-Ti-N bonds revealed by XPS corresponded to the highest photocatalytic performance. XPS spectra of the samples obtained in N 2 /CH 4 gas mixtures evidenced a more effective incorporation of nitrogen in the structure due to oxygen deficiency. Nevertheless, no atomic carbon presence in the TiO 2 /ZrO 2 structures has been detected

Tio2/zro2 thin films synthesized by pld in low pressure n-, c- and/or o-containing gases: structural, optical and photocatalytic properties

Doped TiO2/ZrO2 films were obtained by Pulsed Laser Deposition method under different synthesis conditions. The onset of absorption spectra was red shifted for the films obtained in N-2 containing gas mixtures, while a broad absorption in visible was observed in the case of films deposited in CH4 atmosphere. The presence of O-Ti-N bonds revealed by XPS corresponded to the highest photocatalytic performance. XPS spectra of the samples obtained in N-2/CH4 gas mixtures evidenced a more effective incorporation of nitrogen in the structure due to oxygen deficiency. Nevertheless, no atomic carbon presence in the TiO2/ZrO2 structures has been detected