The generation and propagation of cracks are critical factors that affect the performance and life of large structures. Therefore, in order to minimize maintenance costs and ensure personal safety, it is necessary to monitor key structures. The sensor based on ultra-high frequency radio frequency identification (UHF RFID) antenna has the advantages of passive wireless, low cost, and great potential in the field of metallic structure health monitoring. In this paper, aimed at the key parts of a metallic structure, a dual-tag system is used for crack monitoring. In conjunction with mode analysis, the principles of the sensing tag and the coupling principles of the dual-tag are analyzed. Considering that the dual-tag is placed in different methods, the effect of mutual coupling on the sensing performance of the tag is studied. The results show that the frequency of the sensing tag can be tuned by adding the interference tag, and the dual-tag sensor system has reasonable sensitivity. The results also provide potential guidance for the optimal placement of multiple tags in the near-field region.

Thermal barrier coatings (TBCs) typically have low thermal conductivity and high resistance to oxidation at elevated temperatures. TBCs are used to protect the turbine blades of aircraft engines operating at high temperature. The commonly used YSZ (8 wt% Y₂O₃-stabilized ZrO₂) cannot function at temperatures higher than 1200°C for an extended period of time, which hinders the necessary improvement in the aircraft thrust-to-weight ratio. In this work, thermal barrier coatings consisting of a YSZ ceramic layer and of a lanthanum zirconate (LZ) + YSZ composite structure were prepared on a nickel-based high-temperature substrate using atmospheric plasma spraying. Thermal insulation properties and high temperature oxidation performance of TBCs with single layer structure and double layer structure were compared. The growth mechanism and influencing factors of high-temperature oxidation of thermally grown oxide (TGO) were discussed. The results showed that the LZ had good thermal insulation performance and oxygen isolation compared to the YSZ layer. This performance effectively reduces the growth of TGO in TBCs, thereby delaying the coating failure.

In order to improve the tribological properties of an engine piston ring and enhance its service life, magnetron sputtering technology and low temperature ion sulphurizing treatment technology were used to prepare CrMoN/MoS₂ solid lubricant coating on the surface of an engine piston ring. The morphologies and compositions of the surface and cross-section of the sulfuration layer were analyzed by field emission scanning electron microscopy (FESEM), and wear property under high load, high speed and high temperature conditions were tested by a SRV^®4 friction and wear testing machine. The results show that the CrMoN/MoS₂ composite coatings appear as a dense grain structure, and the coating is an ideal solid lubrication layer that possesses an excellent high temperature wear resistance, reducing the engine operating temperature abrasion effectively and prolonging the service life of the engine.