Open AccessEffect of current density on physical and chemical properties of microarc oxidation coatings of aluminium alloy
Author(s) -
WU Han-hua,
Jianbo Wang,
Long Bei-yu,
Lyu Xian-Yi,
Long Bei-hong,
Zengsun Jin,
Bai Yi-Zhen,
BI Dong-mei
Publication year - 2005
Publication title -
wuli xuebao
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.199
H-Index - 47
ISSN - 1000-3290
DOI - 10.7498/aps.54.5743
Subject(s) - materials science , indentation hardness , microstructure , anode , corrosion , current density , scanning electron microscope , alloy , coating , aluminium , metallurgy , substrate (aquarium) , pitting corrosion , composite material , electrode , chemistry , oceanography , geology , physics , quantum mechanics
Ultra-hard ceramic coatings with microhardness of 42.14GPa have been synthesized on the Al alloy substrate by microarc oxidation (MAO) technique. The effects of anodic current density ja and the ratio of cathodic to anodic current density jc/ja on the mechanical property and phase composition of MAO coatings have been studied by microhardness test and x-ray diffraction, respectively. In addition, the microstructure and corrosion resistance of the coatings were analyzed by scanning electron microscopy and pitting corrosion test, respectively. The results show that the samples prepared at high anodic current density consist mainly of α-Al2O3, while the samples fabricated at low anodic current density are composed almost entirely of γ-Al2O3. Microhardness test shows that these kinds of samples have high hardness, and the microhardness of the coating prepared at ja=15A/dm2 and jc/ja=0.7 is t highest of all coatings prepared. Pitting corrosion test shows that the structure of coatings is strongly influenced by the variation in jc/ja.