Synthesis of Zr2Al3C4 coatings on zirconium-alloy substrates with Al-C/Si interlayers as diffusion barriers

• Zr2Al3C4 coatings are potential candidates to prevent claddings of traditional Zr-based alloys from severe oxidation in water steam at high temperature. However, the diffusion of aluminum between coating and substrates at high temperature results in a coating composition deviating from the compositional domain for formation of the Zr2Al3C4 phase. Thus, synthesis of Zr2Al3C4 coatings on zirconium-alloy substrates is challenging. Here, we report that the Zr2Al3C4 phase can be obtained on zirconium alloy (ZIRLO) substrates where an Al-C/Si interlayer deposited by magnetron sputtering is introduced. The Al-C/Si interlayer prevented elemental diffusion of aluminum between the Zr-Al-C coating and the substrates during a post-annealing process at 800 degrees C for 3 h. The Al/Zr ratio of the Zr-Al-C coating after annealing was 0.96 and 0.59 in the cases of with and without Al-C/Si interlayer, respectively. Hence, the Al-C/Si interlayer acts as diffusion barrier and greatly decreases the deviation from the standard stoichiometric ratio of the Zr2Al3C4 phase, which facilitates the formation of the Zr2Al3C4 phase in the final coating.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Kemiteknik -- Korrosionsteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Chemical Engineering -- Corrosion Engineering (hsv//eng)

Nyckelord

Zr2Al3C4; Coating; Interlayer; Diffusion

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