Microwave-absorbing functionalization of thermal barrier coatings

What is it about?

The new generation of hypersonic vehicles has put forward the requirement of electromagnetic (EM) absorption performance for thermal barrier coatings (TBC). The composite design of thermal barrier ceramics and EM wave absorbers is an effective way to realize the EM absorption of TBCs, which mainly lies in to choose the EM wave absorbers, and how to realize the EM matching and EM loss between the absorbers and thermal barrier ceramics? The basic requirements of TBC materials are low thermal conductivity, high temperature resistance, and good plasma spraying stability. Therefore, the selection of absorbers must have relatively low thermal conductivity and high-temperature stability. In this paper, FeSiAl (FSA) alloy powder with moderate thermal conductivity is determined as the absorber, and LaMAl11O19 (LMA) thermal barrier ceramic is selected for composite regulation of its electromagnetic parameters, resulting in good EM matching. The LMA–FSA composite agglomerated powders were prepared by spray granulation technology and then used to prepare the coatings by atmospheric plasma spraying. The microstructure, electromagnetic, EM reflection rate, EM attenuation loss, high-temperature stability, and thermal mechanical properties of the LMA–FSA powders and coatings were studied. LMA composite TBCs with moderate thermal conductivity and good EM wave absorption performance were successfully prepared, and the EM wave absorption performance remained good after heat treatment at 600–1000℃ for 3–50 h.

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Photo by Simon Fitall on Unsplash

Photo by Simon Fitall on Unsplash

Why is it important?

Electromagnetic matching absorber FSA for LMA thermal barrier ceramics was designed. The APS spraying of LMA–FSA composite powders successfully realized the microwave absorption functionalization of TBCs. It was found that the TBC coating had better microwave absorption performance than the sprayed powders.

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