电介质复合材料用Al粉的控制钝化及其表征
Controlled passivation and characterization of Al flakes for dielectric composites

作为嵌入式电容器用电介质之一, 低成本、易加工、高介电常数的Al粉/高分子复合材料有潜在的应用前景。为了降低这种材料的介电损耗, 分别以空气和微量水为氧化剂, 对Al粉进行二次钝化, 并表征了钝化膜的结构和化学组成, 测量了这种钝化Al粉及其聚四氟乙烯(PTFE)复合材料的介电性能。结果表明:生成的数纳米厚的二次钝化膜覆盖在Al粉自钝化膜上面, 空气钝化膜以Al2O3为主, 水钝化膜以Al(OH)3为主;空气钝化缓慢, 二次钝化膜薄, 表面光滑, 而水钝化较快, 二次钝化膜厚, 但结构疏松。与空气钝化相比, 水钝化能够更好地设计钝化膜厚度, 从而调控Al粉/PTFE复合材料的介电性能。 As one of dielectric materials for embedded capacitors, Al powder/polymer composites have good application potentials due to low cost, easy processability and high dielectric constant. To lower the dielectric loss of these materials, the secondary passivation processes of Al flakes using air and tiny water respectively as the oxidants were studied. The structure and chemical composition of passivation films were characterized, and dielectric properties were evaluated for the passivated Al flakes and their polytetrafluoroethylene (PTFE) composites. The results show that several-nanometer thick secondary passivated film forms outside the self-passivated film of Al flakes, mainly consisting of Al2O3 and Al(OH)3. The former contains main Al2O3, and the latter contains main Al(OH)3. Air passivation occurs very slowly, the resulting secondary passivated films are thin but smooth, in contrast, tiny-water passivation proceeds quickly; the resulting ones are thick but loose. Tiny-water passivation exhibits better applicability in tailoring the thickness of passivated films than air passivation, so as to adjust the dielectric properties of Al flakes/PTFE composites. 国家自然科学基金(51164026);内蒙古自治区自然科学基金(2015BS0512);内蒙古科技大学创新基金(2014QDL016);内蒙古科技大学材料与冶金学院青年人才孵化器平台资助项目(2014CY012)