A novel approach for developing boron carbide (B₄C)/cyanate ester (CE) co-continuous Functionally Graded Materials (FGMs) with eliminated abrupt interfaces

Although traditional functionally graded materials (FGMs) have weakened a certain extent abrupt changes along interfaces between layers, eliminating residual abrupt interfaces which results in great inter laminar stresses remains a major challenge. Herein, ceramic scaffolds with novel continuously graded channels have been firstly prepared through combining layer-by-layer casting with gelation-freeze-dry. Followed by infiltrating soft phase, the co-continuous FGMs without delamination and abrupt changes between layers can be successfully fabricated. The wet layering of suspensions and continuous ice crystals across the interface are the main reasons for the eliminated interfaces. More importantly, the performance of FGMs can be optimized to meet the practical requirement attributed to the varied porosity and pore size distribution of freeze-cast ceramic scaffolds. The novel process for co-continuous ceramics/ FGMs without abrupt interfaces can be extended to other polymers or even metals.