Biomimetik.dk

Based on the analysis on structure of natural biomaterials, two kinds of ceramic composites with high toughness have been designed and prepared: one is fibrous monolithic Si N rBN composite imitating bamboos or trees in structure, the other is laminated Si N rBN 3 4 3 4 composite imitating nacre in structure. Plastic forming methods, including extrusion and roll compaction, respectively, followed by hot-pressed sintering are used to prepare these two materials with particular structures. Both of the two composites have high values of fracture toughness and work of fracture: fracture toughness are 24 MPa m1r2 and 28 MPa m1r2, respectively, for fibrous monolithic and laminated Si N rBN composites, and works of fracture are both more than 4000 Jrm2. The load-displacement curves reveal that these 3 4 two materials with biomimetic structure exhibit non-brittle feature when applied load to fracture. Through analysis on fractographs of the materials, it is revealed that high toughness comes from the synergistic toughening among multi-level toughening mechanisms in different scales: weak interfaces, whiskers and elongated grains toughening in ceramic matrix cells.