The advancement of absorption materials and coating preparation technology is crucial to address the challenges posed by electromagnetic interference and pollution in high-temperature extreme environments. Here, by using a granulation and plasma spraying strategy, we successfully fabricated a series of La 0.8 Sr 0.2 MnO 3 /Al 2 O 3 –13%TiO 2 (LSMO/AT13) high-temperature microwave absorption coatings that have excellent dielectric properties and extremely thermal stability. The results showed that the LSMO/AT13 coatings exhibited remarkable oxidation resistance , withstanding high-temperature aerobic environments of up to 1000 °C. Based on the temperature-dependent permittivity of the coatings, the establishment process of polarization and the transformation of loss mechanism were observed and explained. With the increase of temperature, the main dielectric loss mechanism of the coatings transitions from polarization loss to conductive loss. Thanks to the coordinated effects of impedance and loss, the coatings are capable of effectively absorbing microwave over a wide temperature range. When the LSMO content was 30 wt% and the thickness was 1.9 mm, the effective bandwidth ranged from 1.7 GHz to 2.4 GHz at temperatures below 773 K. This study demonstrates the promising application of LSMO/AT13 microwave absorption coatings for ultra-high temperature environment, and provides a reference for the design and optimization of high-temperature microwave absorption coatings.
Ti 3 SiC 2 exhibits considerable potential for high-temperature microwave absorption due to its relatively high melting point and conductivity. In this study, we successfully prepared Ti 3 SiC 2 /Al 2 O 3 -13%TiO 2 heterogeneous coatings through granulation and plasma spraying techniques. This investigation covered composition, microstructure, oxidation resistance, and a focused analysis of the temperature-dependent permittivity of the coatings. The augmentation in Ti 3 SiC 2 content leads to an escalation in the polarized component, consequently elevating susceptibility to dielectric dispersion. With rising temperature, polarization within the coatings gradually establishes, prompting a transition from polarization relaxation loss to conduction loss as the dominant dielectric loss mechanism. At 5 wt% Ti 3 SiC 2 content, the coating achieves an effective bandwidth of 2.2 GHz at 873 K, with a mere 1.4 mm thickness. Moreover, the coating maintains exceptional oxidation resistance below 700 °C. Ti 3 SiC 2 /Al 2 O 3 -13%TiO 2 coatings manifest as strong contenders for high-temperature microwave absorption applications, and plasma spraying emerges as a promising technique for fabricating high-performance microwave absorption coatings.
Superhydrophobic coatings simultaneously exhibiting high substrate binding, mechanical durability and self-healing properties are of great significance for anti/de-icing applications. In this study, we fabricated a high substrate binding and mechanical durability anti/de-icing superhydrophobic coatings (SL-AP/SPS-SiO 2 ) with self-healing performance by spray-coating a photothermal self-healing organic layers (AP/SPS-SiO 2 ) plasma-sprayed porous Al 2 O 3 –13%TiO 2 underlayer (SL), the resulting soft-hard interlocking structure significantly increased the adhesion strength of the coating to 16.7 ± 0.36 MPa while reducing the ice adhesion strength to 46.5 ± 3.0 kPa. In the as-obtained organic layers, self-stratifying acrylic resin (AR)/20%polymethylsiloxane (PDMS) (AP), not only enhanced the bonding strength with the underlayer but also imparted photothermal self-healing capability to the coating through the action of the photothermal agent (SPS-SiO 2 ). And sodium alginate (SA) guided the self-oxidative polymerization of dopamine (DA) and its deposition on hydrophilic SiO 2 to form a π-π stacked fiber structure photothermal agent (SPS), after hydrophobic SiO 2 modification increased the coating's roughness and photothermal performance. Remarkably, the coating achieved a contact angle of up to 158.4 ± 0.89° and a rolling angle of 3.5 ± 0.89°, maintaining its superhydrophobic properties even after exposure to acid-base immersion and mechanical abrasion. Furthermore, the coating exhibited self-healing capabilities in superhydrophobicity against O 2 plasma etching, with a contact angle recovery rate of up to 98.9% after undergoing 10 cycles of O 2 plasma etching and light exposure. Enhancing mechanical and chemical stability with self-healing capabilities is beneficial for extending the lifespan of superhydrophobic coatings used in anti-/de-icing applications.
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