Barrier Coatings for Refractory Metals and Superalloys

Sabol, SM ; Randall, BT ; Edington, JD ; Larkin, CJ ; Close, BJ

Bettis Atomic Power Laboratory

关键词: Building Materials;    Alloys;    Working Fluids Nrpct;    Decarburization;    Refractory Metals;   

DOI  :  10.2172/884669
RP-ID  :  B-MT-(SPME)-25
RP-ID  :  DE-AC12-00SN39357
RP-ID  :  884669

美国|英语

来源: UNT Digital Library

【 摘 要 】

In the closed working fluid loop of the proposed Prometheus space nuclear power plant (SNPP), there is the potential for reaction of core and plant structural materials with gas phase impurities and gas phase transport of interstitial elements between superalloy and refractory metal alloy components during service. Primary concerns are surface oxidation, interstitial embrittlement of refractory metals and decarburization of superalloys. In parallel with kinetic investigations, this letter evaluates the ability of potential coatings to prevent or impede communication between reactor and plant components. Key coating requirements are identified and current technology coating materials are reviewed relative to these requirements. Candidate coatings are identified for future evaluation based on current knowledge of design parameters and anticipated environment. Coatings were identified for superalloys and refractory metals to provide diffusion barriers to interstitial transport and act as reactive barriers to potential oxidation. Due to their high stability at low oxygen potential, alumina formers are most promising for oxidation protection given the anticipated coolant gas chemistry. A sublayer of iridium is recommended to provide inherent diffusion resistance to interstitials. Based on specific base metal selection, a thin film substrate--coating interdiffusion barrier layer may be necessary to meet mission life.