高速湿法球磨对羰基铁粉微结构及吸波性能的影响

Effect of High Speed Wet Ball Milling on Microstructure and Microwave Absorbing Properties of Carbonyl Iron Powder

采用高速球磨法快速制备片状羰基铁粉。通过扫描电子显微镜(SEM)、X射线衍射(XRD)、矢量网络分析仪(VNA)对材料的微观形貌、物相、吸波性能进行了表征与分析。结果表明:球磨0~60 min时,羰基铁粉的厚度随球磨时间延长逐渐减小,形成片状结构,直径厚度比最大可达80∶1;球磨90 min时,羰基铁粉由大片状破碎成小片状,部分片状羰基铁粉经球磨珠撞击后重叠堆积,材料的厚度逐渐增加,比表面积下降;球磨120~180 min时,多数羰基铁粉的片状结构被粉碎破坏,形状回归为类球形,少数羰基铁粉进一步堆叠成块状。球磨前后羰基铁粉的晶体结构未发生实质性改变,羰基铁粉的综合吸波性能随着球磨时间的延长呈现先上升后下降趋势,并在球磨90 min时达到最优的吸波效果:反射损耗最小值为-54.94 dB(12.64 GHz),匹配厚度为2.17 mm,有效吸波带宽达到了8.48 GHz。

Flake carbonyl iron powder was prepared by high speed ball milling.Scanning electron microscopy,X-ray diffraction and vector network analyzer were used to characterize and analyze the microstructure,phases and wave absorption properties of the materials.During ball milling for 0-60 min,the thickness of carbonyl iron powder gradually decreases with the extension of ball milling time,forming a flake structure,and the maximum diameter thickness ratio can reach 80∶1.During ball milling for 90 min,carbonyl iron powder is broken into small flakes from large flakes,and some flake carbonyl iron powder is piled up after being impacted by ball milling beads.The thickness of the material gradually increases and the specific surface area decreases.When ball milling for 120-180 min,the flake structure of most carbonyl iron powder is crushed and destroyed,reforming to spherical structure,and a small part of carbonyl iron powder is further stacked into blocks.The comprehensive absorbing performance of carbonyl iron powder increased firstly and then decreased with the extension of ball milling time,and reached the best absorbing effect when the ball milling time was 90 min.The minimum reflection loss was-54.94 dB,the matching thickness was 2.17 mm,and the effective absorption bandwidth reaches 8.48 GHz.