【作者】 田焜；

【导师】 胡曙光； 丁庆军；

【作者基本信息】 武汉理工大学 ， 建筑材料与工程， 2010， 博士

【摘要】 水泥基电磁防护吸波复合材料(CEMC)是将电磁波转化成其它形式的能量而使电磁波耗散掉的一种建筑功能材料,它对建筑物的防护、电磁污染的净化、电磁信息的保密和地面军事建筑的隐身具有重要民用与军事意义。已有CEMC存在诸多问题,既包括组合结构、耐久性、功能性设计方面的问题,又包括频带窄、吸收效能低、稳定性差、环境适应差和质量重、成本高等材料自身的问题。严重制约了其在所须的建筑工程,尤其是在复杂地理与气候环境作用下建筑结构中的应用。论文针对这些问题,提出了新的设计理念,通过对CEMC的组成、结构与性能进行系统的研究,研究开发了基于球型谐振腔理论具有对电磁波吸收、散射与谐振损耗功能的CEMC吸波体设计方法；研究并掌握了其组成、结构与性能的相关规律和集吸波、抗裂、保温、耐久和环保于一体的高性能水泥基复合材料设计与制备关键技术,为该类材料的设计、制备及应用提供了重要的依据和理论指导。本文进行的主要工作和取得的重要成果有：运用球型谐振腔与球型颗粒瑞利散射原理,设计制备出具有吸收、散射和谐振损耗功能的结构单元：壳—核结构球型吸波谐振器。在此基础上,提出CEMC的理想结构模型。大量既充当透波骨料又充当球型谐振腔的吸波谐振器均匀分散于经辅助胶凝材料、聚合物与纤维改性后的水泥基体中,改善了电磁波在材料中的传输通道,降低表面反射,增加电磁波在球型腔体内的谐振损耗,显著提高了CEMC的吸波性能,改善了CEMC的物理力学性能、韧性和耐久性能,为制备CEMC提供了理论指导。确定了吸波谐振器的组成材料,它是以超轻多孔结构透波骨料为核,以电阻型吸波组分为壳,通过特殊的工艺制备得到。根据电磁学理论,建立了粒径为d的吸波谐振器散射的空间几何模型,并以此为研究对象,推导出吸波谐振器的散射、吸收与谐振损耗数学表达式,准确描述了电磁波入射到吸波谐振器表面时的散射、吸收与谐振损耗机理,对实现CEMC电磁波的高效吸收与频带的拓宽提供了理论依据。在此基础上,通过对吸波谐振器组成材料的结构与性能研究,确定了其配料与制备工艺关键参数,制备出粒径为0.6～4.75mm,堆积密度为490 kg·m-3,筒压强度为2.2 MPa,30 min吸水率为12.3%的壳—核结构吸波谐振器。掌握了壳—核结构吸波谐振器的制备工艺,通过数学分析与演算,建立了吸波谐振器壳层厚度控制数学关系式,实现了吸波谐振器结构、性能与吸波功能的可设计与可控制性,为CEMC的吸波体设计提供了关键功能骨料。系统研究了CEMC基体材料的性能以及吸波谐振器对其性能的影响规律。结果表明：辅助胶凝材料、聚合物和纤维对基体材料的协同改性作用,可显著提高基体的物理力学性能与韧性；随电磁波频率的变化,基体的厚度、水胶比、水化龄期、吸波剂与吸波谐振器的颗粒特征参数对CEMC基体材料的吸波性能影响差异较大；通过控制材料的厚度、水胶比、吸波谐振器参数并结合复掺辅助胶凝材料、纤维与聚合物技术,可制备出高吸收损耗,物理力学性能优良的CEMC;确定了配制CEMC的主要技术参数,提出其配合比设计方法。探明了CEMC的密度与强度特性,分别建立了改性基体与吸波谐振器两介质体的密度与强度数学模型,该模型反映了CEMC的密度与强度形成机理。并结合耐久性与功能性试验,揭示了聚合物改性与纤维乱向分布形成三维网络互穿结构以及吸波谐振器的内养护作用,使材料结构密实是提高CEMC耐久性与抗裂性的本质原因。吸波谐振器的高闭孔率保证了CEMC的低吸水率和高气孔率,减弱空气的对流是提高CEMC的保温性能主要原因。以上共同匹配作用,实现了CEMC的高性能化与功能的多样化。更多还原

【Abstract】 Cement-based composites with electromagnetic protection and microwave absorbing (CEMC) are buiding functional materials which can consume electromagnetic wave as energy of other form.lt plays important roles in civilian and military use which are protection of buildings, secrecy maintaining of electromagnetic information and stealth of surface structures. Pre-existing CEMC have many designing problems such as structure, durability and function. They include narrow frequency range, low absorbing efficiency, poor stability, poor suitability to invironment, heavy weight and high cost which seriously limited its application especially for complex geography and climatope conditions.In connection with those problems,new designing concepts have been raised.Through systemic investigation on composition, structure and performances of CEMC and based on spheroidal resonant cavity theory, methods of designing wave absorbing materials hve been studied and explored whose functions are electromagnetic wave absorption, scatterance and spheroidal energy reduction. Relative disciplines of composition, structure and performances were mastered, high-performance cement-based materials were designed and produced that were wave absorption, splitting resistance, heat preservation, durability and environmental protection. Significant basement and theoretical guidance were provided for designing, production and application of the materials.In this article, the main tasks and achievements are as below:Using spheroidal resonant cavity and spheroidal powder ray leigh scattering theory, structural unites with the functions of absorbing, scattering and wearing have been designed and produced which were core-stone and wave-absorbing spheroidal resonant equipments. Furthermore, the ideal structural model CEMC of was proposed. Lots of wave-absorbing spheroidal resonant equipments that functioned as wave-permeating aggregates were evenly distributed in cement-based materials whose performances were improved by assistant cementitious materials, polymer and fiber. Then, the transporting tunnels for wave in materials have been improved, surface reflectance was reduced, resonance loss of wave in materials was increased, wave-absorbing performances of CEMC were greatly enhanced, physical performances of strength, toughness and durability were improved. So, theoretical guidance was offered to production of CEMC.The constitution of microwave absorbing resonator has been fixed. The core of it is ultralight multiaperture wave-permeating aggregate. Through special technique, microwave absorbing resonator can be obtained. According to electromagnetics theories, special model that is microwave absorbing resonator scattering with radius of d has been established. Meanwhile, mathematical formula of microwave absorbing resonator’scattering, absorption and resonant loss has been exactly deduced which offered theoretical guidance to realization efficient absorption and bands’broadening of CEMC electromagnetic wave.Furthermore, through investigation on microwave absorbing resonator materials’structure and performance, the main paramaters of its charge mixture and producing technique have been fixed.Its grain size was 0.6-4.75mm, stacking density was 490 kg·m-3, crushing strength is 2.2 MPa and water absorption during the first 30 minutes was 12.3%. The preparation technology of microwave absorbing resonator with core-stone structure has been mastered. Through mathematical calculations, formula concerning its controlling of thickness was established. The possibilities of designing and controlling were realized to supply designing of CEMC with important functional aggregate.Performances of high-performance CEMC Materials and influence of microwave absorbing resonator on its characters have been systematically studied.Results showed that the cooperated roles of assitant cementitious materials, polymer and fibre on base materials can greatly improve its physical strength and toughness; accompanied with changes of electromagnetic waves of frequency, the influence of base thickness, water to cement ratio, hydration time, absorber and characteristic parameters of particles on wave-absorbing performance of CEMC-based materials changed a lot; through controlling materials’thickness, water to cement ratio and microwave absorbing resonator parameters and connecting technique of adding assitant cementitious materials, polymer and fiber, high-performance and high loss-absorbing CEMC with good physical and mechanical properties have been produced; the main technique parameters of composition of CEMC have been fixed and methods of mix design has been raised.Density and strength were made clear, density and strength formation models of two medium that are high-performance modified base and microwave absorbing resonator have been estabished which showed mechanism of CEMC density and strength formation. Furthermore, connecting durability and function experiments, three-dimensional crossing structure formed by modified polymer and fiber and inner maintenance of microwave absorbing resonator were the essential causes for improvement of durability and anti-crack performance; high rate of blind hole of CEMC ensured low water-absorbing rate and high air-hole rate. It is the main cause for increasing heat preservation performance; what are above functioned together to realize the high performance and multi-fuction.更多还原