2016-Sustainable Industrial Processing Summit
SIPS 2016 Volume 11: Physics, Advanced/Multifunctional Materials, Composite, Quasi-crystals, Coating
| Editors: | Kongoli F, Marquis F, Lu L, Xia H, Masset P, Rokicki P |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2016 |
| Pages: | 180 pages |
| ISBN: | 978-1-987820-56-0 |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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Heat-resistant iron-chromium alloys for protective coatings of operating units of power plants
Aleksandre Kandelaki1; Omar Mikadze2; Vazha Garibashvili1; George Mikadze2; Zurab MirijanaShvili1;1FERDINAND TAVADZE INSTITUTE OF METALLURGY AND MATERIALS SCIENCE, Tbilisi, Georgia; 2GEORGIAN TECHNICAL UNIVERSITY, Tbilisi, Georgia;
Type of Paper: Regular
Id Paper: 77
Topic: 19
Abstract:
Intensive progress of the various modern technologies (aeronautics, space exploration, nuclear energy, etc.) causes the need for the new structural materials operating in extreme conditions (high temperatures, aggressive media, high mechanical loads, etc.). However, the practice shows that tailoring of materials with the combination of all required properties is a rather hard task. As a result, the technique of coating used to protect refractory matrix from corrosion- and wear resistance, radiation, etc. acquires special relevance.
As a material for protective coating of heat-resistant matrices there was selected a high-chromium alloy (Fe-45%Cr-4% Al) doped with the rare earth metals (0.25% La or Y) [Georgian Patent, P 3273, 24.06.2002, O.Mikadze, E.Kutelia et al.].
Reliable protection of matrix is provided by a formed Al2O3 layer at the interface of phases – the coating- matrix . It is important that this layer remained stable under harsh conditions of operating unit (high temperatures, cyclic loading, etc.): remains entirely solid and should not exfoliate upon cooling. These requirements are satisfied after doping of the coating material with rare earth metals.
In the present work, for similar purposes, the authors offer an iron-chromium alloy (up to 16% Cr) doped with Zr and Ce (Fe-16%Cr-5,0%Al-0,5%Zr -0,3%Ce). Adding of Ce changes the mechanism of formation of the protective oxide (Al2O3) layer at the coating – matrix interface, resulting in the improved properties (adhesion, abrasion resistance, strength characteristics, etc.).
Positive influence of Ce on the formation of a protective oxide (Al2O3) layer is enhanced by its co-doping with Zr. Here an economic aspect of the technology is important factor - it is significantly cheaper. The reduced chromium content (to 16%) makes it possible to provide air melting under flux and fabricate the product easy to forge, roll and process by cutting.
Keywords:
Alloys; Coatings; Corrosion; Heat; HighTemperature; Surface; Technology; Wear;References:
[1] O.I.Mikadze, E.R.Kutelia and et al. ”Special Heat Resistant and Corrosion Resistant Alloys” Georgian Patent P 3273 (2002.06.24)[2] Omar Mikadze and Aleksandre Kandelaki “Influence of Cerium Additives on High-Temperature Corrosion of Chromium” Bull. of the Georgian National Academy of Sciences, 4, №3 (2010), 66-69
[3] Yasutoshi Saito “Effects of Rare Earth Elements of the High Temperature Oxidation of Heat Resisting Alloys”. Amsterdam-Oxford-New York-Tokyo. 1989, 227-260.
[4] O.I.Mikadze, M.N.Okrosashvili and et al. “Design of New Compositions and Technological Procedures of High-Temperature Coating on Chromium Superalloys”. Metallofiz. i Noveishie Tekhnol., Kiev, 27 (2005), 1297-1305.