5 years ago

Particle Size Influences on the Coating Microstructure through Green Chromia Inclusion in Plasma Electrolytic Oxidation

Particle Size Influences on the Coating Microstructure through Green Chromia Inclusion in Plasma Electrolytic Oxidation
Chen-Chia Chou, Chen-Yu Liu, Jian-Mao Wang, Dah-Shyang Tsai, James T. J. Tsai
In an effort to color the aluminum alloy surface green via plasma electrolytic oxidation (PEO), two alkaline solutions have been employed with particulate inclusions and sodium aluminate. Electrolyte I comprises a self-made chromia pigment with a mean particle size 69 nm, whereas electrolyte II contains a commercially available pigment, GN-M, with a larger particle size 351 nm. Both pigments are oxygen deficient Cr2O3-δ of corundum-type structure before coating, the oxidative environment of PEO converts them into stoichiometric Cr2O3. In electrolyte I and II, the oxides of chromium and aluminum deposit simultaneously under analogous PEO conditions, yet resulting in very different microstructures. The GN-M inclusion of large size amasses on top of the coating, while the self-made inclusion goes deep, and closely associates with alumina and pores. The oxide coating, grown in electrolyte II, consists of a top Cr2O3-rich layer and a dense alumina layer underneath, delineated by the boundary marked with microdischarge burns. On the other hand, the self-made particulate inclusion appears to bring the electric microdischarges inside the coating and create inner pores and damages. The structure difference, caused by the difference in microdischarge locations, is attributed to shifting of the Cr2O3–Al2O3 interface where p-type and n-type semiconductors meet.

Publisher URL: http://dx.doi.org/10.1021/acsami.7b03113

DOI: 10.1021/acsami.7b03113

You might also like
Discover & Discuss Important Research

Keeping up-to-date with research can feel impossible, with papers being published faster than you'll ever be able to read them. That's where Researcher comes in: we're simplifying discovery and making important discussions happen. With over 19,000 sources, including peer-reviewed journals, preprints, blogs, universities, podcasts and Live events across 10 research areas, you'll never miss what's important to you. It's like social media, but better. Oh, and we should mention - it's free.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.