High temperature oxidation of PCD coated Zr alloy
- Department of Power Engineering, Czech Technical University in Prague (Czech Republic)
- Institute of Physics, Czech Academy of Science (Czech Republic)
Polycrystalline diamond (PCD) coating is a promising possibility for prevention, or reduction of high temperature oxidation of zirconium alloys and decrease corrosion rate of zirconium alloy during standard operation. Zirconium alloys are widely used as cladding and construction material in almost all types of nuclear reactors, where usually creates a barrier between nuclear fuel and cooling water in the primary circuit. Hydrogen and considerable amount of heat is released during steam oxidation that may occur in an eventual accident. In this paper zirconium alloy was covered by polycrystalline diamond layer using Plasma Enhanced Linear Antennas Microwave Chemical Vapor Deposition system reactor. X-Ray Diffraction and Raman spectroscopy measurements confirmed coverage of the surface area with crystalline and amorphous carbon layer. Characterizations (Raman spectroscopy) were done for zirconium alloy covered with polycrystalline diamond layer before and after high temperature steam exposure. Weight increase and hydrogen release were measured during steam exposure. The results show that the oxidation kinetics of PCD coated samples is similar to kinetics of uncoated samples at almost all temperatures, but with lower hydrogen production and lower weight gains. Most important difference is in later beginning of breakaway oxidation at 1000 Celsius degrees, when breakaway oxidation starts on PCD coated sample 15 minutes later. Raman spectroscopy revealed graphitization of the PCD layer and the diamond sp{sup 3} bounds are lost and the Raman signal consists only from the two graphite-related D bounds. It implies conversion of PCD layer to the homogeneous non-crystalline carbon layer with a large content of graphitic phase. Overall hydrogen production and weight gain values are generally lower then for uncoated samples.
- Research Organization:
- American Nuclear Society - ANS, 555 North Kensington Avenue, La Grange Park, IL 60526 (United States)
- OSTI ID:
- 22765203
- Resource Relation:
- Conference: TOP FUEL 2016: LWR fuels fuels with enhanced safety and performance, Boise, ID (United States), 11-15 Sep 2016; Other Information: Country of input: France; 5 refs.; Related Information: In: TOP FUEL 2016 Proceedings| 1670 p.
- Country of Publication:
- United States
- Language:
- English
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