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With the continuous development of the aerospace field, the service conditions of high temperature structural components such as metal and carbon materials are increasingly harsh. The service life of high temperature structural components can be effectively improved by preparing silicon-based ceramic coatings on the surface of high temperature structural components and giving them special properties through appropriate processes. In recent years, the polymer precursors conversion ceramic coating has gradually become a novel method for preparing inorganic coatings. The new approach has the advantage of excellent processability and functional scalability, which gets more and more attention from researchers. The research progress of high temperature resistant ceramic coatings based on silicon-containing polymeric precursors was reviewed in this paper. Firstly, the preparation of ceramic coatings from the polymers was introduced, including the influences of silicon-based polymer precursors, fillers, coating and pyrolysis process on the structure and properties of the obtained coatings. Then, the applications of polymer-derived ceramic coatings in high temperature protection fields, such as anti-oxidation, environmental barrier and thermal barrier coatings were discussed. Finally, The problems in improving coating performance and defect control of polymer ceramic coatings were pointed out, and the development direction of polymer ceramic coatings was prospected, for example, by introducing ultra-high temperature elements such as Hf, Zr, Ta into silicon-based precursors, improving the temperature resistance level of ceramic coatings, and developing new efficient ceramic technology to improve the existing efficiency and applicability.

Copyright of Journal of Materials Engineering / Cailiao Gongcheng is the property of Journal of Materials Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Broadband microwave absorption is essential on the realms of electromagnetic compatibility and protection in civil application scenarios. However, coordination of material and structure is difficult without proper iterative design between material and structure resulting in insurmountable drawbacks of traditional microwave absorption medium operating under high temperature erosion. Herein, SiC metastructure is manufactured in bulk by stereolithographic 3D printing. The dielectric loss tangent of SiC sintered body is over 0.5 and up to 1.5 at most showing good electromagnetic energy dissipation properties. The optimized SiC metastructure with complicated suspended features achieves −10 dB broadband microwave absorption from 6.96 to 40 GHz at room temperature (RT) across total frequency range of 33.04 GHz. The proposed SiC metastructure is able to endure in situ 1000 °C and ex situ 1600 °C erosion in air atmosphere maintaining −10 dB effective bandwidth in 4.54–40 and 10.89–39.67 GHz, respectively. Broadband microwave absorption under oblique incidence from 0° to 60° is also achieved in a wide temperature range from RT to 1600 °C. The densification of SiC results in a high mechanical strength of 217.36 MPa for structural load bearing applications. The intrinsic electromagnetic variation of SiC under different temperature is relaxed and adapted to the metastructure design. The functions of broadband microwave absorption and high temperature protection are integrated into one metastructure. [ABSTRACT FROM AUTHOR]

Copyright of Rolling Stock (1002-7602) is the property of Rolling Stock Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

T hermal barrier coatings(TBCs)technology is an effective means for gas turbines to reduce the surface temperature of hot-end components,resist the hot corrosion,and obtain the high thrust-weight ratio.If the coating fails,it will influence the safety of aero-engine usage.In this paper,the composition and structure of TBCs are firstly introduced.Secondly three common thermal barrier coatings failure modes including erosion and foreign object damage,sintering oxidation and corrosion are summarized.And then the repair and remanufacturing methods of damaged and failed coatings at home and abroad are elaborated.Finally the prospect of how to inhibit the crack formation and propagation and improve the reliability of TBCs is carried out.

In this paper, the compound active agent was used to modify the soil powder. The variation of the powder composition was analyzed by SEM and XRD, and the rheological properties and antioxidant properties of the metal surface composite coating suspension prepared by the modified soil were studied. The experimental results show that the suspension rate of the suspension agent reached 96 % after 72 h. Under the action of the shear rate, the suspension agent had a good shear viscosity and stress, and could form a net-like structure to ensure the stability of the suspension agent. After heat treatment at 1 000 °C for 2 h, the suspension could cover the surface of carbon steel with a composite coating. The carbon steel had a carbon layer depth of only 0.05 mm, which was better to inhibit the phenomenon of high temperature carbon oxidation of carbon steel. [ABSTRACT FROM AUTHOR]

Highlights • The effect of Ti on oxidation resistance and microstructural evolution of two composite coatings were studied. • Ti from substrate reacted with [N] ions in composite coatings and formed TiN in reaction zone. • The position of reaction zone was determined by the relative content of [N] ions and metallic Al in composite coatings. • The transportation of T i A l ∙ in alumina resulted in a higher oxidation rate of coating. Abstract Two composite coatings are manufactured by reactive magnetron sputtering on superalloys. The effect of titanium on oxidation resistance and microstructural change of composite coatings were studied. Titanium in superalloys reacted with [N] ions in composite coating due to interdiffusion. The position of reaction zone was determined by the relative content of [N] ions and metallic aluminum in coating. Doping of titanium in alumina lead to a decrease of charged oxygen vacancies but Ti• Al forms in this process. The transportation of Ti• Al in oxide scale resulted in the formation of TiO 2 and a higher oxidation rate of coating. [ABSTRACT FROM AUTHOR]

To address the poor high-temperature oxidation resistance of tungsten, a new high temperature protective gallium coating (O Ga) is designed in this paper. This O Ga material is modified with liquid metallic gallium by a mechanical stirring process, and a mixture of Ga x O y (Ga 2 O 3 and Ga 2 O) and Ga is obtained. Not only does it have good flexibility and adhesion, but it can also be easily printed to form a coating on tungsten surfaces. After isothermal oxidation at 800 °C for 24 h, the weight gain of the coating sample is 0.96 mg·cm−2, much lower than that of tungsten. This is attributed to the oxidation of the gallium coating on the tungsten surface to produce a βGa 2 O 3 layer, which prevents oxygen contact with the internal O Ga and W substrates. In addition, the inherent flexibility of the intermediate layer of O Ga prevents a mismatch in the coefficient of thermal expansion (CTE) between the βGa 2 O 3 layer and the W substrate, ensuring the integrity of the coating. Gallium coatings are expected to be an alternative to conventional protection systems. • The gallium is used as a coating to protect tungsten from oxidation in high temperature. • The oxidation weight gain of the coating was only 0.96 mg·cm−2 in air at 800 °C for 24 h. [ABSTRACT FROM AUTHOR]