Research progress of core-shell composite absorbing materials

With the rapid development of anti-stealth technology and the iterative renewal of firepower destruction weapons, the battlefield survivability of modern weapons and equipment has been severely tested. In the modern warfare of over-the-horizon, radar detection technology is currently the most widely used method; therefore, reducing the radar echo signal is the most important factor to improve the stealth ability of weapon equipment. Generally, stealth technology is divided into structural stealth and material stealth. Reasonable shape structure design can reduce the radar cross section (RCS) value of a weapon equipment. However, due to the high cost of shape structure and the easy reduction of the comprehensive performance of equipment, there are many limitations in application. Because the stealth technology of materials is relatively simple and the design difficulty is relatively low, the research and application of stealth materials are popular and have been well explored. Although the traditional absorbing materials have the advantages of low cost, good flexibility, and easy processing, they also have the defects of high density, narrow working frequency band, and limited strength. Core-shell microwave absorber is a composite multiphase structure with a spherical particle as the core and one or more layers of heterogeneous materials coated on the outer surface. Because of its unique structure and excellent performance, it is a promising material to solve the existing problems. On the basis of reviewing the working principle of microwave absorbing materials, the advantages of core-shell structure materials in the field of microwave absorbing were discussed. This paper mainly introduced the research progress of different types of core-shell structure microwave absorbing materials explored in recent years as well as summarized and commented on their preparation methods, structure, and microwave absorbing properties; these materials are mainly based on ferrite, magnetic metal powder and its oxide, ceramic, conductive polymer, and carbon series materials. Finally, the development trend of core-shell structure mircrowave absorbing materials was predicted, including multi-layer core-shell structure, yolk-shell stucture and special structure combined with other structures, whisch can provide reference for futher study of core-shell shtucture composite absorbing materials.