‘Fire-shielded’ nano knights: Carbon-clad nano-YSZ thermal barrier coating boosts heat insulation

To tackle the shortcomings of conventional nano-YSZ thermal-barrier coatings—infrared semitransparency, low nanoparticle retention, and the formation of partially melted agglomerates during plasma spraying—researchers have encased each YSZ nanoparticle in a sacrificial carbon shell that protects it from melting throughout the deposition process. Once burned off, the film leaves nano-pores that, together with the preserved nanoparticles, greatly boost infrared scattering and lower simulated metal temperatures by 111.2 K—offering a scalable route to thermal-barrier coatings with superior radiation blocking and long-term high-temperature stability.

Recently, Researchers at Northwestern Polytechnical University have unveiled a low-cost way to help gas-turbine engines run hotter and therefore more efficiently. By wrapping nano-sized yttria-stabilized zirconia (YSZ) particles in a thin carbon film before plasma spraying, the team created thermal-barrier coatings (TBCs) that scatter infrared radiation far better than today’s industry workhorse. The advance appears in Journal of Advanced Ceramics.

“Our carbon-film approach boosts nanoparticle retention and generates huge number of nano-pores in situ, giving the coating a mirror-like ability to reflect infrared thermal radiation while staying mechanically robust,” said first author Liu-Chao Zhang, a PhD candidate in materials science. “In modeling, that translated to a 111 K drop in the temperature of the underlying alloy when compared to conventional YSZ TBCs—enough to extend component life or permit higher working temperatures for greater fuel efficiency.”

The team published their work in Journal of Advanced Ceramics on June 10, 2025

Why it matters

Turbine blades already operate above the melting point of their nickel-based superalloys, relying on ceramic TBCs to keep metal temperatures in check. Because radiative heat flux through a semi-transparent coating rises roughly with the cube of absolute temperature (∝T³), its share of the total heat load climbs steeply as new engine designs push for higher efficiency and even hotter firing temperatures. Yet conventional 8YSZ is partially transparent to the 1–5 µm infrared radiation that dominates inside combustion chambers, so raising working temperatures—as the aviation and power industries plan—would drive still more radiative heat through today’s coatings.

How the new coating works

1. Carbon film protect the nano YSZ particles: During plasma spraying, nano-YSZ normally melts and merge into larger grains, erasing its optical advantage. Encasing each particle in a carbon shell prevents that, improving the retention rate of nano YSZ particles.
2. Nano-pores form on demand: A brief 800 °C air heat-treatment burns off the carbon, leaving nano pores that further mismatch the refractive index and turbo-charge scattering.
3. Durability proven: After 100 h at 1300 °C, the scattering coefficient in the critical 1–5 µm waveband stayed almost constant, because the coarsened nanoparticles (≈700 nm) happened to match the radiation wavelength.

Other contributors include Fa Luo, Yaru Cao, Junjie Yang, Yuchang Qing from the School of Materials Science and Engineering at Northwestern Polytechnical University, China; Yingying Zhou from School of Materials Engineering at Xi’an Aeronautical University, Yuqin Li from Air Force Engineering University, China.

This work was financially supported by the National Science and Technology Major Project (Grant No. J2019-VI-0015-0130), Shaanxi Provincial Innovative Talent Promotion Plan - Youth Science and Technology New Star Project (Talent) (No. 2023KJXX-075) and the Youth Innovation Team of Shaanxi Universities Project (No. 23JP072).

About Author

Liu-Chao Zhang is a doctoral researcher in materials science at Northwestern Polytechnical University, Xi’an, China. His work centers on designing high-temperature, wear-resistant thermal-barrier coatings that combine carbon-based pore formers with computational heat-transfer modeling. Before beginning his Ph.D., Zhang spent seven years at Samsung Electronics refining thin-film deposition processes, experience that now informs his pursuit of scalable coating technologies. He has published multiple first-author papers on infrared-scattering-enhanced YSZ coatings in the Journal of the European Ceramic Society and Journal of Advanced Ceramics. Zhang holds a master’s degree in materials science from the same university and is proficient in COMSOL Multiphysics and MATLAB. Contact: jackzhanggood@mail.nwpu.edu.cn.

About Journal of Advanced Ceramics

Journal of Advanced Ceramics (JAC) is an international academic journal that presents the state-of-the-art results of theoretical and experimental studies on the processing, structure, and properties of advanced ceramics and ceramic-based composites. JAC is Fully Open Access, monthly published by Tsinghua University Press, and exclusively available via SciOpen. JAC’s 2023 IF is 18.6, ranking in Top 1 (1/31, Q1) among all journals in “Materials Science, Ceramics” category, and its 2024 CiteScore is 25.9 (5/130) in Scopus database. ResearchGate homepage: https://www.researchgate.net/journal/Journal-of-Advanced-Ceramics-2227-8508