The structures of tungsten and tungsten carbide scaffolds play a key role in determining the properties of their infiltrated composites for multifunctional applications.However,it is challenging to construct and contr...The structures of tungsten and tungsten carbide scaffolds play a key role in determining the properties of their infiltrated composites for multifunctional applications.However,it is challenging to construct and control the architectures by means of self-assembly in W/WC systems because of their large densities.Here we present the development of unidirectionally porous architectures,with high porosities exceeding 65 vol.%,for W and WC scaffolds which in many respects reproduce the design motif of natural wood using a direct ice-templating technique.This was achieved by adjusting the viscosities of suspensions to retard sedimentation during freezing.The processing,structural characteristics and mechanical properties of the resulting scaffolds were investigated with the correlations between them explored.Quantitative relationships were established to describe their strengths based on the mechanics of cellular solids by taking into account both inter-and intra-lamellar pores.The fracture mechanisms were also identified,especially in light of the porosity.This study extends the effectiveness of the ice-templating technique for systems with large densities or particle sizes.It further provides preforms for developing new natureinspired multifunctional materials,as represented by W/WC-Cu composites.展开更多
基金the National Natural Science Foundation of China(Grant Nos.51871216 and 51501190)the Opening Project of Jiangsu Province Key Laboratory of High-end Structural Materials(Grant No.hsm1801)provided by the U.S.Air Force Office of Scientific Research,under MURI grant AFSOR-FA9550-15-1-0009 to the University of California Riverside through a subcontract to the University of California Berkeley。
文摘The structures of tungsten and tungsten carbide scaffolds play a key role in determining the properties of their infiltrated composites for multifunctional applications.However,it is challenging to construct and control the architectures by means of self-assembly in W/WC systems because of their large densities.Here we present the development of unidirectionally porous architectures,with high porosities exceeding 65 vol.%,for W and WC scaffolds which in many respects reproduce the design motif of natural wood using a direct ice-templating technique.This was achieved by adjusting the viscosities of suspensions to retard sedimentation during freezing.The processing,structural characteristics and mechanical properties of the resulting scaffolds were investigated with the correlations between them explored.Quantitative relationships were established to describe their strengths based on the mechanics of cellular solids by taking into account both inter-and intra-lamellar pores.The fracture mechanisms were also identified,especially in light of the porosity.This study extends the effectiveness of the ice-templating technique for systems with large densities or particle sizes.It further provides preforms for developing new natureinspired multifunctional materials,as represented by W/WC-Cu composites.
