2015-Sustainable Industrial Processing Summit
SIPS 2015 Volume 6: Coatings, Cement, Rare Earth & Ferro-alloys
| Editors: | Kongoli F, Yildirim H, Hainer S, Hofmann K, Proske T, Graubner C.A., Albert B |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2015 |
| Pages: | 200 pages |
| ISBN: | 978-1-987820-29-4 |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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Resisting Corrosion at High Temperatures by Adds Nb to Fe-Al Intermetallic Coating
ZeLei Zhang1;1NANJING UNIVERSITY OF AERONAUTICS AND ASTRONAUTICS, Nanjing, China;
Type of Paper: Regular
Id Paper: 177
Topic: 19
Abstract:
Using surface coverage technology of hot-dip aluminized prepared Fe-Al alloy coating on the surface of 45 steel substrates and then double glow plasma surface modification technology with alloying Nb was employed to prepare the Fe-Al-Nb alloy coating on the surface of Fe-Al alloy coatings. Firstly the microstructure's composition distribution and organization structure of the Fe-Al-Nb alloy coating were characterized by scanning electron microscope (SEM)energy dispersive spectrometer (EDS) and X-ray diffraction (XRD), and then the high-temperature oxidation resistance properties of the alloy coating prepared under optimal conditions deeply through the experiments of isothermal oxidation were researched and analyzed.
The results showed that the optimal process parameters were as follows: source electrode voltage 800V~900V, substrate electrode voltage 350V~450V, operating atmospheric pressure 35Pa~45Pa, inter-electrode distance 20mm, testing temperature 900a„ƒ~1000a„ƒ and soaking time 3h Fe-Al-Nb alloy coating surface was flat and compact, which was mainly composed of simple substance Nb, the other hard phase AlNb2-Fe7Nb6-Fe2Al5 and Fe3Al etc. dispersed in the surface layer which increased the surface hardness significantly. The thickness of coating was about 150µm in the diffusion layer, Al concentration exhibited gradient distribution, decreased gradually away from surface, Fe concentration was about 45wt%, both of them formed the ductile Fe3Al and FeAl phases which contained 1.5wt%~2wt% Nb in the form of dispersed second-phases. During the 100-hour isothermal oxidation experiments at the temperature of 600a„ƒ and 700a„ƒ, Fe-Al-Nb alloy coating surface formed a compact oxidation film, its high-temperature oxidation resistance increased dramatically as compared to the Fe-Al alloy coating and substrates.