Protective Si–Al–O–Y glass coatings on stainless steel in situ prepared by combustion flame spraying

Abstract

Surface treatments are a common solution for reducing wear and friction, as well as for increasing oxidation and corrosion resistances. Two refractory glass compositions in the SiO 2–Al 2O 3–Y 2O 3 system have been in situ deposited on AISI 304 stainless steel substrates by combustion flame spraying, with an oxyacetylene torch. Both compositions, 66SiO 2–22Al 2O 3–12Y 2O 3 mol.% ( G) and 50SiO 2–30Al 2O 3–20Y 2O 3 mol.% ( D), were formulated in the glass forming area; however, G is situated in the pure glass zone and D in a zone of glass formation where partial crystallizations occur. As-sprayed coatings had a thickness of 150–240 μm and were of glassy nature, although in D composition formation of Y 3Al 5O 12 and Y 2Si 2O 7 phases was observed. The influence of the Si/Al/Y ratios on the microstructure and properties of the coatings has been studied by scanning electron microscopy/energy-dispersive spectrometry (SEM-EDS), X-ray diffraction (XRD) and microhardness indentation tests. Properties of these coatings were compared to the bulk properties of the same composition glasses finding direct relationships between them.