Nature of the growth of plasma electrolyte oxidation coating on Aluminum

Improved oxidation resistance of high emissivity coatings on fibrous ceramic for reusable space system

To develop high emissivity coatings on fibrous ceramic substrates with improved thermal resistance for reusable space systems, WSi2-MoSi2-Si-SiB6-borosilicate glass coatings were prepared on fibrous ZrO2 by slurry dipping and subsequent high temperature rapid sintering. A coating with 50 wt% WSi2 and 50 wt% MoSi2 presents optimal thermal stability with only 10.06 mg/cm2 mass loss and 4.0 % emissivity decrease in the wavelength regime of 1.27 to 1.73 microns after 50 h oxidation at 1773 K. The advantages of double phase metal silicide coatings combining WSi2 and MoSi2 include improved thermal c…

Coating of Aluminum Alloys by Micro Arc Oxidation in Nitrate Salt

Plasma electrolytic oxidation (PEO) is a process for obtaining oxide coatings on valve metals. Mostly PEO is done in an aqueous solution electrolyte which limits the size of treated parts due to the system heating up. In presented work an alternative method of PEO processing applied in aluminum 1050 alloy in nitrate molten salt was investigated. The morphology, phase and chemical compositions, micro-hardness, and corrosion resistance were examined using. The obtained results showed that formed coating contains from two sub-layers, outer soft layer with the thickness of 4 micrometer and inner, …

Zeolite-based photocatalysts immobilized on aluminum support by plasma electrolytic oxidation

The preparation and properties of zeolite-containing oxide coatings obtained by plasma electrolytic oxidation are investigated and discussed. Pure and Ce-exchanged natural (clinoptilolite) and synthetic (13X) zeolites are immobilized on aluminum support from silicate-based electrolyte. Obtained coatings are characterized with respect to their morphology, phase and chemical composition, photocatalytic activity and anti-corrosion properties. It is observed that all mentioned properties of obtained coatings are dependent on processing time and type of immobilized zeolite. Coatings with Ce-exchang…

Wear-resistant thin films of MRI-230D-Mg alloy using plasma-driven electrolytic oxidation

Wear resistant coatings were produced on a permanent mould cast MRI 230D Mg alloy by (a) PEO in silicate based electrolyte, (b) PEO in phosphate based electrolyte, (c) hybrid coatings of silicate PEO followed by laser surface alloying (LSA) with Al and Al2O3, and (d) hybrid coatings of phosphate PEO followed by LSA with Al and Al2O3. Microstructural characterization of the coatings was carried out by scanning electron microscopy (SEM) and X(ray diffraction. The tribological behavior of the coatings was investigated under dry sliding condition using linearly reciprocating ball-on-flat wear test…

Optimization of allotropic and hardness of aluminum oxide coating by PEO

One of the most important methods of producing materials and oxide coating is plasma electrolytic oxidation (PEO). Coatings made on aluminum in PEO method have two allotropes of $α$-Al$_2$O$_3$ and $γ$-Al$_2$O$_3$. Coatings containing $α$-Al$_2$O$_3$ have more hardness and wear resistance; therefore, the main goal of the present study is to optimize aluminum oxide allotrope for increasing the ratio of $α$-Al$_2$O$_3$ in coating made with PEO method. Results of the present study shows that the optimum electrolyte compound for making highest phase of $α$-Al$_2$O$_3$ has 2.9 g/lit of KOH, 1.15 g/…

Pt/Ru比例对NiCoCrAlYTa涂层改性层氧化机制的影响

Influence of Pt/Ru ratios on the oxidation mechanism of MCrAlYTa coatings modified with Pt-Ru overlays

研究探讨Pt/Ru比例对NiCoCrAlYTa涂层氧化机制的影响，发现Pt含量增加可增强氧化抵抗性，而Ru含量增加则导致氧化层缺陷，提示通过优化Pt/Ru比例可设计低成本高效系统。