【作者】 刘坤；

【导师】 邵刚；

【作者基本信息】 郑州大学 ， 材料与化工（专业学位）， 2025， 硕士

【摘要】 陶瓷基吸波材料在航空航天高温极端环境领域具有极大应用潜力,具备强吸收、吸收频带宽、可设计性强等特点的结构型吸波陶瓷材料日益成为主要研究方向之一。传统结构型吸波材料主要包括层板夹层结构、多孔结构以及蜂窝结构等,新型超材料结构的出现开启了通过人工电磁结构调控吸波性能的新思路,其具有吸波频段可设计性、结构与功能兼容性好以及电磁谐振等特性,尤其全介质三维超材料不仅能够利用介质材料的损耗特性,而且能够通过三维结构设计实现阻抗匹配特性。聚合物转化SiCN陶瓷（Polymer-derived SiCN ceramics,PDC-SiCN）具有优异的高温稳定性、抗氧化/腐蚀性等性能,可通过改变聚合物的分子结构以及热处理条件调控陶瓷材料的合成,在制备极端环境下吸波材料方面具有广泛的应用前景。结合三维（3D）打印技术结构可设计性强,一体化精确成型等优势,可实现陶瓷超结构因材料体系、结构以及外形的多样性和复杂性导致精确制造成型困难的问题。基于这个思路,本文设计了参数化陶瓷超材料模型,并对结构参数进行优化,在先驱体转化SiCN吸波陶瓷基体中引入由Ti₃C₂T_x MXene衍生的具有结构缺陷的二维层状高温吸波剂TiC,通过构筑纳米异质界面和TiC缺陷建立多重电磁波损耗机制,结合3D打印宏观吸波超结构协同优化设计,实现TiC/SiCN陶瓷宽频吸波特性。为发展新一代吸波、承载等结构功能一体化陶瓷材料提供理论支持和可行的技术途径。本文的主要研究内容如下:（1）以Ti₃AlC₂为原料通过HF刻蚀成功制备了分层均匀、层间距较大、片层较薄的多层Ti₃C₂T_x MXene,随后系统研究了不同Ti₃C₂T_x MXene添加量的光敏浆料在DLP 3D打印中的表现。结果表明,Ti₃C₂T_x MXene的添加首先会改变光敏浆料的颜色,增强其对紫外光的吸收能力,显著改善光敏浆料在DLP 3D打印过程中的打印精度;其次,Ti₃C₂T_x MXene的添加会影响光敏浆料的粘度,尤其在高添加量（>3 wt.%）下,会导致浆料流动性显著下降,保质期大大缩短。红外图谱分析结果显示,光敏浆料在DLP 3D打印过程中丙烯酸酯基团在与PSN中的乙烯基发生加成反应的同时,自身还发生了自光聚合反应。（2）通过TG-DSC研究了3D打印坯体在热解过程中的质量损失,主要分为三个阶段,且在800℃左右样品已经基本完成了从有机高分子状态到无机陶瓷的转变,并依据TG-DSC结果设定了热解制度。通过XRD、SEM和XPS等表征手段,详细探讨了不同Ti₃C₂T_x MXene添加量对光敏浆料制备的TiC/SiCN陶瓷微观形貌、相结构和元素组成的影响。研究发现,随着Ti₃C₂T_x MXene添加量的增加,陶瓷材料中TiC晶体的结晶峰强度增加,结合SEM结果证明TiC与SiCN陶瓷成功复合。材料中含有Si、C、N、Ti、F和O元素,O元素的存在与DLP 3D打印过程中空气环境的影响有关。Ti₃C₂T_x MXene的添加改善了TiC/SiCN陶瓷的电导率,增强了界面极化效应,从而提升了整体介电常数。实验结果显示,随着Ti₃C₂T_x MXene的添加,样品的吸波性能呈现先提升后下降的趋势。（3）基于ST-1样品的电磁特性,设计了一种梯形角锥超材料,并通过仿真优化了单元结构的尺寸参数（H₁=2.0 mm,H₂=0.8 mm,W₁=1.0 mm,W₂=1.0 mm,L=2.0 mm,T=2.0 mm）,显著提高了TiC/SiCN陶瓷的吸波性能。模拟结果显示,在10.17 GHz处,最小RL值为-21.06 d B,有效吸收带宽达到3.30 GHz,占X波段的79%。通过DLP 3D打印制备了仿真优化后的梯形角锥超材料,经1100℃热解后,测得其最小反射损耗为-26.49 d B,有效吸收带宽接近3.80 GHz,由于制造误差及测试环境干扰,实验结果的吸收峰在8.52 GHz-10.09 GHz频段向低频偏移,但总体来看,仿真结果与实测数据吻合较好,甚至部分频段的吸波效果优于仿真结果。基于等效电磁参数反演与角度特性分析发现,TiC/SiCN超材料不仅展现出了优异的宽频吸波能力,而且在入射角小于60°时,所设计的梯形角锥吸波超材料在TE极化和TM极化下均能达到90%以上的吸收效果。另外,添加Ti₃C₂T_x MXene的块体和超材料的压缩强度都有所提升,其中ST-1压缩强度为216.67±16.01 MPa,Meta ST-1压缩强度为46.45±11.99 MPa,Meta ST-1压缩强度低于ST-1的原因是梯形角锥超材料的应力分布主要在结构的棱边和连接节点处,导致局部应力集中,压缩强度下降。更多还原

【Abstract】 Ceramic-based absorbing materials exhibit significant potential for applications in high-temperature extreme environments within the aerospace industry.Structural absorbing ceramics,characterized by their robust absorption capabilities,broad bandwidth,and strong designability,are progressively emerging as a primary research focus.Traditional structural absorbing materials encompass laminate sandwich structures,porous configurations,and honeycomb architectures.The advent of metamaterials has introduced innovative approaches to enhancing absorbing performance via artificial electromagnetic structures.These materials feature tunable absorption frequency bands,excellent structural-function compatibility,and electromagnetic resonance properties.Notably,all-dielectric three-dimensional metamaterials can leverage both the loss characteristics of dielectric materials and achieve impedance matching through advanced three-dimensional design.Polymer-derived SiCN ceramics（PDC-SiCN）exhibit exceptional high-temperature stability and resistance to oxidation and corrosion.These properties can be tailored by modifying the molecular structure of the precursor polymer and adjusting the heat treatment conditions.PDC-SiCN ceramics hold significant promise for applications in extreme environments,particularly in the development of absorptive materials.Leveraging the advantages of three-dimensional（3D）printing technology,such as advanced structural design capabilities and integrated precision molding,this approach addresses the challenges associated with the precise manufacturing and complex shaping of ceramic superstructures,which are often complicated by the diversity and intricacy of material systems,structures,and shapes.Based on this concept,this paper presents a parametric ceramic metamaterial model and optimizes its structural parameters.A two-dimensional layered high-temperature absorber TiC,derived from Ti₃C₂T_x MXene with structural defects,was incorporated into the precursor-converted SiCN absorbing ceramic matrix.By constructing nano-heterogeneous interfaces and introducing TiC defects,multiple electromagnetic wave loss mechanisms were established.In conjunction with the coordinated optimization design of 3D-printed macroscopic absorbing superstructures,the high-temperature broadband absorbing characteristics of TiC/SiCN ceramics were achieved.This study provides theoretical support and practical technical approaches for the development of new-generation high-temperature absorbing,load-bearing,and multifunctional integrated ceramic materials.The primary research contents are as follows:（1）Multilayer Ti₃C₂T_x MXene with uniform stratification,large interlayer spacing,and thin layers was successfully synthesized via HF etching using Ti₃AlC₂ as the raw material.Subsequently,the performance of photosensitive slurries containing varying amounts of Ti₃C₂T_x MXene in DLP 3D printing was systematically investigated.The findings indicate that the addition of Ti₃C₂T_x MXene alters the color of the photosensitive slurry,enhances its ultraviolet light absorption capacity,and significantly improves printing accuracy during DLP 3D printing.Additionally,the addition of Ti₃C₂T_x MXene affects the viscosity of the photosensitive slurry,particularly at high concentrations（>3 wt.%）,leading to a significant decrease in fluidity and a shortened shelf life.Infrared spectrum analysis reveals that during the DLP 3D printing process,the acrylate group of the photosensitive slurry undergoes an addition reaction with the vinyl group in PSN and also undergoes self-photopolymerization.（2）The mass loss of the 3D-printed green body during the pyrolysis process was investigated using thermogravimetric analysis coupled with differential scanning calorimetry（TG-DSC）,which can be primarily categorized into three distinct stages.Around 800°C,the sample had nearly completed its transformation from an organic polymer state to an inorganic ceramic state.Based on the TG-DSC results,the pyrolysis parameters were established.The effects of varying Ti₃C₂T_x MXene addition amounts on the microstructure,phase composition,and elemental makeup of TiC/SiCN ceramics derived from photosensitive slurries were thoroughly examined using characterization techniques such as X-ray diffraction（XRD）,scanning electron microscopy（SEM）,and X-ray photoelectron spectroscopy（XPS）.It was observed that increasing Ti₃C₂T_x MXene content led to enhanced crystallization peak intensity of TiC within the ceramic matrix.SEM analysis confirmed the successful composite formation of TiC and SiCN ceramics.The material comprises Si,C,N,Ti,F,and O elements.The presence of the O element is attributed to the influence of the ambient air during the DLP 3D printing process.Incorporating Ti₃C₂T_x MXene boosts the electrical conductivity of TiC/SiCN ceramics and enhances interface polarization,thereby elevating the overall dielectric constant.Experimental findings indicate that wave absorption performance initially increases with Ti₃C₂T_x MXene addition before exhibiting a decline.（3）Leveraging the electromagnetic properties of the ST-1 sample,a trapezoidal pyramid metamaterial was designed.Through simulation optimization,the unit cell dimensions（H₁=2.0 mm,H₂=0.8 mm,W₁=1.0 mm,W₂=1.0 mm,L=2.0 mm,T=2.0mm）were refined,significantly enhancing wave absorption performance.Simulation results revealed a minimum reflection loss（RL）value of-21.06 d B at 10.17 GHz,with an effective absorption bandwidth of 3.30 GHz,covering 79%of the X-band.The optimized trapezoidal pyramid metamaterial was fabricated via DLP 3D printing.Post-pyrolysis at 1100℃,measurements indicated a minimum reflection loss of-26.49 d B and an effective absorption bandwidth approaching 3.80 GHz.Owing to manufacturing inaccuracies and interference from the test environment,the absorption peak of the experimental results shifted towards lower frequencies within the 8.52 GHz to 10.09GHz frequency band.However,the overall simulation results exhibit a high degree of consistency with the measured data,and in certain frequency bands,the absorption performance surpasses the simulation predictions.Through the inversion analysis of equivalent electromagnetic parameters and angular characteristics,it is evident that the TiC/SiCN metamaterial not only demonstrates superior broadband absorption capability but also achieves an absorption rate exceeding 90%for incident angles less than 60°under both TE and TM polarizations.Furthermore,the addition of Ti₃C₂T_xMXene enhances the compressive strength of the bulk material and the metamaterial.Specifically,the compressive strength of ST-1 is 216.67±16.01 MPa,while that of Meta ST-1 is 46.45±11.99 MPa.The lower compressive strength of Meta ST-1 compared to ST-1 can be attributed to the stress concentration at the edges and connection nodes of the trapezoidal pyramid structure,leading to localized stress concentration and reduced compressive strength.更多还原