连续纤维3D打印陶瓷基复合材料的界面结构与性能规律

Ceramic matrix composites are extremely important strategic thermal structural materials, but their wide applications are limited because of many challenges, such as poor toughness, difficult machining, complexity and inefficiency of molding. Traditional 3D printing ceramics with powders or precursors as raw materials have shown the advantages of rapid replication and smart molding, but it is difficult to solve the problem of ceramics brittleness fundamentally for high adhesive residual porosities and low reinforcement contents. In this project, a new method of introducing continuous fibers into 3D printing ceramics is proposed. The method subverts the traditional additive manufacturing modes of the ceramic materials, and it is expected not only to thoroughly improve the toughness of ceramics for load bearing of high strength and toughness fibers, but also to print ceramic matrix composites with controllable interface and designable enhanced direction with simultaneous fibers weaving and ceramics molding. Structures and ratio of the thermosetting and thermoplastic ceramic precursors will be studied to obtain the thermal behavior of the ceramic precursors, which can melt for 3D printing at low temperature and dissociate into ceramics at high temperature. The relationship between printed geometrical structures, weaving and twining structures, mesh structures, and bearing stress will be studied to obtain the printing-weaving molding methods and strengthening direction designable rules. Studying the interfacial mechanical behaviors of fibers at different scales reinforced ceramics to obtain the multi-scale performance composite laws from short fibers to continuous fibers. The advantages of high strength and toughness of light continuous fibers will be taken with combining the features of 3D printing rapid prototyping without mold, and it will enrich the preparation methods and strengthening and toughening theories of ceramic matrix composites.

陶瓷基复合材料是极为重要的战略性热结构材料，但陶瓷韧性差、加工难、效率低、成型复杂限制了其应用发展。以粉末或前驱体为原料的传统3D打印陶瓷已经显示出快速复制智能成型优势，然而粘结剂残留孔隙高增强体含量低很难从根本上解决陶瓷的脆性。本项目提出将连续纤维引入陶瓷3D打印新方法颠覆了传统陶瓷增材制造模式，高强韧纤维承载不仅有望彻底改善打印陶瓷的脆性，还可实现缠绕编织与陶瓷成型一步完成高效打印界面可控、增强方向可设计的纤维陶瓷复合材料。研究热固性与热塑性陶瓷前驱体结构配比获得低温可熔化3D打印高温可裂解为陶瓷的热行为规律。研究打印的几何结构、缠绕编织、网孔结构与承载应力的关系获得打印编织成型方法及增强方向设计规律。研究不同尺度纤维打印陶瓷界面力学行为获得短纤维向连续纤维跨尺度性能复合规律。既发挥连续纤维高强韧轻量化优势又具有3D打印无需模具快速成型特点，可丰富陶瓷基复合材料的制备方法和强韧化理论。

陶瓷基复合材料（CMCs）是极为重要的战略性热结构材料，但陶瓷韧性差、加工难、成型复杂限制了其应用发展。目前陶瓷3D打印技术已经显示出快速复制智能成型优势，但残留孔隙高、增强体含量低，导致强韧性能难以满足应用需求。本项目向打印陶瓷中引入纳米线、晶须、短纤维和连续纤维等增强体，制备了不同尺度纤维增强CMCs，研究其强韧化机理。①研究了烧结温度、镂空结构、叠层角度和配位数对打印陶瓷力学性能的影响，揭示结构设计对力学性能的影响规律。②通过浆料掺配、浸渍裂解和原位生长等工艺，实现了微纳米纤维增强打印陶瓷的制备，研究了微纳米纤维种类对打印陶瓷力学性能的影响，优化了晶须的掺配比例，分析了短纤维长度和含量与打印陶瓷力学性能之间的关系，揭示了微纳米纤维小尺度、大面积、强界面结合特性与CMCs力学性能的关系，及增强体尺度变化的性能复合规律。③在此基础上，通过连续纤维3D打印工艺成功制备了连续纤维增强CMCs，实现了增强体尺度和含量的跨越，研究了陶瓷前驱体的热行为规律，分析了热解温度和前驱体产物之间的关系；对复合材料的界面进行调控，揭示了界面对复合材料力学性能的至关重要作用，获得了界面控制方法；表征了复合材料的物相组成与微结构，结合力学性能测试与断口形貌分析，研究了基体致密度、纤维体积分数、纤维排布方式对力学性能的影响规律，揭示连续纤维的强韧化机理；同时研究了连续纤维3D打印CMCs的电磁屏蔽效能。④实现了多种不同结构单元的陶瓷基轻量化波纹桁架的快速制备，结构设计使得连续纤维更好地发挥了增强作用，研究了结构单元对波纹桁架承载性能的影响，通过数字图像相关法分析了桁架的微变形特征和失效机理；同时研究了桁架的力学-电阻响应特性，分析了桁架的自感知响应机理，有望应用于结构原位健康监测。本项目获得了3D打印纳米线、晶须、短纤维向连续纤维增强CMCs的跨尺度界面优化与性能规律，对丰富连续纤维3D打印CMCs的制备方法和强韧化理论具有重要的科学意义。