仿生层状骨架结构的可控构筑及其显微结构表征

Preparation and microstructural characterization of bioinspired ceramic matrix composites

发展兼具轻质、高强、高韧的高性能新材料始终是工程材料领域长期追求的目标之一。然而,高强和高韧、高强和轻质之间通常是相悖的。自然界中很多天然材料巧妙地解决了这一问题,受此启发,采用冰模板法实现了一系列仿生层状骨架结构的可控制备,并利用扫描电子显微镜对其显微结构进行了系统的结构表征,这些骨架结构有望成为新的结构增强基元,实现复合材料力学性能的提升。实验结果表明:与单向冰模板法相比,双向冰模板法制备的层状结构具有更高的有序度;通过精准调控浆料中氧化铝的含量,实现了层间次级结构从凸起、半连接到完全桥连的可控制备;同时,氧化铝层厚度可实现由8μm~20μm,层间距由65μm~50μm的连续可控调节;值得注意的是,双向冰模板法制备层状骨架的实验方法具有普适性,成功实现了多种层状陶瓷基、金属基骨架结构的可控制备。

High⁃performance materials with lightweight,high strength and high toughness are one kind of the targets in engineering materials.Strength and toughness are usually at odds with each other.Biomaterials with micro⁃nano structures can naturally balance the two sides.Inspired by this,the controlled preparation of an alumina laminar skeleton was achieved by freeze⁃casting method and its microstructure was characterized by scanning electron microscopy.These skeletal structures are expected to serve as new structurally reinforcing matrix elements to achieve improved mechanical properties.Experimental result show that the lamellar structure prepared by bi⁃directional freeze⁃casting is more ordered than that of unidirectional freeze⁃casting.As the alumina particle content in the paste increases,the viscosity of the paste increases and the alumina content gradually increases from 18 wt.%to 36 wt.%.The thickness of the ceramic layer increases from 8μm to 20μm and the interlayer distance decreases from 65μm to 50μm.It is noteworthy that the experimental method for the preparation of laminated skeletons by bidirectional freeze⁃casting method is universal.It has successfully achieved the controlled preparation of a wide range of laminated ceramic⁃based and metal⁃based skeletal structures.