Surface modification of high-temperature alloys: A protective and adhesive scale-forming process
- Argonne National Lab., IL (United States)
- Utah Univ., Salt Lake City, UT (United States). Dept. of Metallurgical Engineering
To develop a high-quality protective/adhesive scale-forming surface modification technique, several stepwise experiments were performed on the alloys of Fe-25Cr, Fe-25Cr-(0.3-1)Y, and Fe-25Cr-(O.3-1)Ce: alloy grain-growth behavior, surface coatings by ion-beam-assisted deposition (IBAD) and high-temperature chemical vapor deposition (CVD), and oxidation/sulfidation tests. Silicon-based oxide, nitride, and oxinitride coatings were prepared by IBAD. During annealing, the silicon diffuses into and reacts with the substrate to form a metal-silicide. To verify the scale-forming mechanism, oxidation tests (at temperatures of 700--1000{degrees}C and oxygen partial pressure of 10{sup {minus}4} atm) were performed on substrates with and without the coating layer. The results showed that Cr{sub 2}O{sub 3} was formed as the outer scale and that a thin SiO{sub 2} layer was observed at the alloy/scale interface. Based on these results, an alternative surface-modification approach was tried. A durable protective coating for high-temperature alloys was achieved by CVD followed by chemical reaction in a controlled environment. By thermogravimetric analysis with a microbalance, several oxidation/sulfidation tests (at 700 and 1000C) were performed with and without the coating on Fe-25Cr-1Ce and Fe-25Cr-1Y. After each run, samples were examined by scanning electron microscopy, energy-dispersive X-ray analysis, and Auger and X-ray photoelectron spectroscopy. The results elucidated the nature of the protective coating that provides high-temperature corrosion protection.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 198689
- Report Number(s):
- ANL/ET/CP-87474; CONF-9510232-4; ON: DE96005112
- Resource Relation:
- Conference: International conference on beam processing of advanced materials, Cleveland, OH (United States), 30 Oct - 2 Nov 1995; Other Information: PBD: [1995]
- Country of Publication:
- United States
- Language:
- English
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