Preparation And Microwave Absorption Performance Of β-SiC@C/Ba Fe₁₂O₁₉ Nanocomposites

Absorbing material can be used as stealth technology of weaponry and military facilities,and it also can be used in radiation protection of daily life and production. It is a very important method to enhancing the absorbing properties via combining different nanomaterial. Si C has tremendous potential as absorbing materials for its excellent dielectric loss properity. There are many studies about using Si C composite material as absorbing material in previous report, while one of the most important issues is how to improve its absorbing properties.This study selects β-Si C nanowire as absorbing material system, through surface coating by a layer of amorphous carbon to form β-Si C@C core-shell nanowires in order to improve its absorbing properties. High temperature solid-phase method was used to prepared β-Si C nanowires with diameter equal to about 40 nm at 1500℃, and then the absorbing propertiesof β-Si C nanowires was tested. The tested results show that β-Si C nanowires reached minimum reflection loss about-18 d B in 4.1 mm thickness, which frequency band ranged from 5.1 to 6.2GHz and 16.9 to 18 GHz that the reflection loss below-10 d B. The preparation of β-Si C@C core-shell nanowires was discussed, including hydrothermal and Sol-gel method. Characterization method such as TEM, XRD, FT-IR and Raman were taken to confirm the surface of Si C nanowires formed smooth and homogeneous carbon coating. And the technology process was learned to determine the preparation technology parameters. The results show that β-Si C@C performed good absorbing property by using hydrothermal method when the sucrose concentration is 0.73mol/L.Then the β-Si C@C/Ba Fe12O19 nanocomposites absorbing property using β-Si C@C shell structure with M type barium ferrite and the prosess of preparation by hydrothermal and mechanical grinding was studied. It can be found that using hydrothermal method will be introduced Ba CO3 and Fe2O3 impurities, while this phenomenon has not appeared in mechanical grinding method. The absorbing property of β-Si C@C/ Ba Fe12O19 nanocomposites which prepared by mechanical grinding method has been tested. The results showed that the reflection loss of β-Si C@C/ Ba Fe12O19 can reach to-50 d B when the nanocomposite thickness of 1.5mm. β-Si C@C/ Ba Fe12O19 nanocomposite not only collected the absorbing property of each component but also formed synergy function.It has significantly improved the absorbing performance compared to β-Si C and β-Si C@C. In the meanwhile it has reduced the matching thickness of the Si C greatly, but the effective absorption frequencies(reflection loss less than-10 d B, the electromagnetic wave absorption > 90%) ranged from 16.3 to 18 GHz. It showed that β-Si C@C/ Ba Fe12O19 nanocomposite has little function to enhancing absorbing bands.