Efficient multiscale strategy for toughening HfB₂ ceramics: A heterogeneous ceramic–metal layered architecture

Abstract

HfB 2-based ceramics, with their high melting points exceeding 2700°C, excellent strength, high thermal conductivity, and low thermal expansion coefficient, have been regarded as promising ultra-high temperature ceramics (UHTCs) for hypersonic cruise aircraft, thermal heat protection, or reentry vehicles. 1-5 Nevertheless, covalent bonding within the ceramics hinders the generation of plastic mechanisms and ductile behavior seen in metals. The resulting brittleness, which leads to catastrophic failure, 6 limits the application range of these materials. Therefore, the development of ceramics with high damage tolerance is urgently required. SiC whiskers (SiC w) or SiC fibers (SiC f) are commonly used additives for UHTCs due to their large aspect ratios and their ability in antioxidative ablation performance, grain growth restrictions, and sinterability improvement in UHTCs. 7 In addition, the toughness of monolithic UHTCs

Oxidation inhibition behaviors of HfB2‐MoSi2‐SiC oxygen blocking coating prepared by spark plasma sintering

“…To investigate the effect of pre‐oxidation treatment on the oxygen blocking ability of the coating, another group of the samples was pre‐treated in air at 1773 K for 2 h/4 h/6 h/8 h, and then oxidized at 1973 K in air. The weight gain, weight change rate, oxidation protection efficiency, and oxygen permeability were calculated based on the change in mass of the samples 36,37 …”

“…The weight gain, weight change rate, oxidation protection efficiency, and oxygen permeability were calculated based on the change in mass of the samples. 36,37…”

10 years of research on toughness enhancement of structural ceramics by graphene

“…Filled and empty symbols correspond to rGO and GNP platelets. Other structures developed in recent years ( f ) laminated composites [ 29 , 45 , 51 , 72 , 73 ] and ( g ) bioinspired composites [ 37 , 45 , 54 , 74 ]. Dashed lines mark the average K IC obtained for each type of structure.…”

The diffuse interface phase‐field model for in situ interlayer phase formations in low‐temperature reaction bonding of alumina laminates—A theoretical and experimental comparison

“…As the bonding process is thermodynamic dependent rather than kinetic, the homogeneity of the interlayer is directly related to the geometrical (like size and thickness) and reactivity conditions 8 , which is indicated by the interfacial energy 9 . These chemical reactions led to partial dissociation of ceramic layers in laminates 10 and solution during heating and super saturation—precipitation during cooling processes 11 . High temperature–pressure bonding ensures completion of reaction at interface but causes destructive occurrence of diffuse out of elements, 12 isolated voids, 6 interface movement, 13 kirkendall porosities, 14 deleterious reaction products, and severe volume change during reaction and local stressfiges 15 .…”

“…9 These chemical reactions led to partial dissociation of ceramic layers in laminates 10 and solution during heating and super saturation-precipitation during cooling processes. 11 High temperature-pressure bonding ensures completion of reaction at interface but causes destructive occurrence of diffuse out of elements, 12 isolated voids, 6 interface movement, 13 kirkendall porosities, 14 deleterious reaction products, and severe volume change during reaction and local stressfiges. 15 A new approach of improving bond quality 16 and even decreasing bonding pressure and temperature 17 can be based on simultaneous reduction of interlayer materials/adjacent ceramic interface 18 and formation of homogeneous bonding products 19 with minimum mismatch with ceramic laminates.…”