OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 24 No. 4 2022 a b Fig. 5. High-temperature oxidation resistance of samples at a temperature of 900 oC in air (a) and X-ray patterns of its surface after high-temperature oxidation resistance test (b) Figure 5, a shows the change in the mass of samples with Fe-Ti-Si coatings and AISI304 steel at a temperature of 900 °C. The weight gain of samples with coatings for 100 hours of testing ranged from 23.3 to 37.9 g/m2. The smallest weight gain was observed for the Si2.6 sample, which also showed the best corrosion resistance. Coated specimens were damaged by corrosion in 7–12 times less than AISI304 steel. The weight gain is due to the fixation of oxygen on the surface of the samples in the form of oxides of iron, titanium and chromium in the modifications of hematite, rutile and iron (II) chromite FeCr2O4 (Fig. 5, b). In contrast to AISI304 steel, on X-ray patterns of the coating’s surface, the reflections of ferrochrome, which is resistant to oxidation, are observed. The high oxidation resistance of coated samples is due to the limited contact of oxygen with the substrate, primarily due to the Ti5Si3 phase, which is resistant to oxidation at temperatures up to 1,000 °C. This is explained by the formation of a thin silicon dioxide barrier layer on the surface of Ti5Si3 particles [20]. Conclusions A technique is proposed for obtaining Fe-Ti-Si coatings by electrospark treatment of stainless steel AISI304 with an anode consisting of titanium granules and 2.6 – 6 vol.% of a mixture of titanium and crystalline silicon powders. It is shown that a stable positive weight gain of the cathode is observed when the fraction of silicon in the mixture of powders does not exceed 32%. The phase composition of the coatings included: a solid solution of chromium in iron, titanium silicide Ti5Si3, titanium, and silicon, which is confirmed by the energy dispersive analysis data. Titanium silicide Ti5Si3 is present in the coatings as separate inclusions. The thickness of the coatings ranged from 21.7 to 24.8 µm. The conducted studies have shown that Fe-Ti-Si coatings, prepared by a new method of electrospark deposition with a non-localized electrode with silicon and titanium powders, can increase corrosion resistance, oxidation resistance and hardness, as well as reduce the friction coefficient and wear of the AISI304 stainless steel surface. References 1. Rybalka K.V., Beketaeva L.A., Davydov A.D. Opredelenie skorosti korrozii stali AISI 304 v rastvorakh HCl metodom izmereniya omicheskogo soprotivleniya issleduemogo obraztsa [Determination of AISI 304 steel corrosion rate in the HCl solutions by the method of measuring specimen ohmic resistance]. Elektrokhimiya = Russian Journal of Electrochemistry, 2019, vol. 55, no. 9, pp. 1147–1152. DOI: 10.1134/S0424857019080139. (In Russian).
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