Model of Alumina Coating Microstructure Developed on the Base of Electrical Insulation Properties

Abstract:

On the CCDS2000 installation, detonation spraying of coatings from M28 and METCO 6103 aluminum oxide powders on steel substrates was carried out, and the dependence of the electrical resistivity of coatings on the atmosphere humidity was studied. It is shown that when the relative humidity changes from 14 to 80%, the specific electrical resistance of the coating decreases by 2-3 orders of magnitude from ρ ˃10¹³ Ω·cm to ρ ≈ 10¹¹ Ω·cm. On the base of obtained data, the model of coating microstructure is proposed, according to which alumina layer contained through defects in a form of nanochannels with diameter in the range 1-10 nanometers. In a coating cross section, the area of nanochannels sums up to 1%. In presence of high atmospheric humidity, these nanochannels can be filled with absorbed water, increasing drasticcaly the coating electrical conductivity.

• Periodical: Key Engineering Materials (Volume 813)
• Pages: 13-18
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.813.13
• Online since: July 2019
• Authors: Vladimir Yu. Ulianitsky, Alexandr Shtertser*, Igor Batraev
• Keywords: Aluminum Oxide, Detonation Spraying, Electrical Resistance, Humidity, Insulation Coating, Microstructure

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