Research of Coatings Obtained in the Activated Thermo-Chemical Condensate Deposition Method, Al-O System

Abstract

Nanocrystalline γ-Al2O3 type coatings of 20 μm thickness were obtained in the activated thermo-chemical condensate deposition method, without special preparation of the surface being coated, without formation of an underlayer and without extra thermal processing, on the steel X15Ю5 (Russian standard) plates of 40 μm thickness, which temperature did not exceed 250 °C during coating formation. The article presents investigations of the system: coating-substrate, thermally processed at different temperatures (discrete range of temperatures 100, 300, 500, 700, 900 and 1100 °C), adhesion, phase composition, size of crystallites, microstrain, cross-section, topography. The tests are given for 50-cycle resistance of coated test pieces to thermal shock: heating up to 1000 °C – sudden cooling in water. Preliminary, comparative resistance of the system “coating – substrate” is shown for long-term chemical effect in solutions of alkali NaOH and acids H2SO4, H3PO4, HNO3, HCl, HCl-HNO3, during the tests of 300 hours.