Provided is a method for manufacturing a composite body, the method including: a nitriding step of firing a boron carbide powder in a nitrogen atmosphere to obtain a fired product containing boron carbonitride; a sintering step of molding and heating a blend containing the fired product and a sintering aid to obtain a boron nitride sintered body including boron nitride particles and pores; and an impregnating step of impregnating the boron nitride sintered body with a resin composition, the composite body having the boron nitride sintered body and a resin filled in at least some of the pores of the boron nitride sintered body.

Provided is a boron nitride sintered body including: a plurality of coarse particles each having a length of 20 μm or more; and fine particles smaller than the plurality of coarse particles, in which, when viewed in a cross-section, the plurality of coarse particles intersect with each other. Provided is a method for manufacturing a boron nitride sintered body, the method including: a raw material preparation step of firing a mixture containing boron carbonitride and a boron compound in a nitrogen atmosphere to obtain lump boron nitride having an average particle diameter of 10 to 200 μm; and a sintering step of molding and heating a blend containing the lump boron nitride and a sintering aid to obtain a boron nitride sintered body including coarse particles each having a length of 20 μm or more in a cross-section and fine particles smaller than the coarse particles.

Provided is a boron nitride sintered body including: a plurality of coarse particles each having a length of 20 μm or more; and fine particles smaller than the plurality of coarse particles, in which, when viewed in a cross-section, the plurality of coarse particles intersect with each other. Provided is a method for manufacturing a boron nitride sintered body, the method including: a raw material preparation step of firing a mixture containing boron carbonitride and a boron compound in a nitrogen atmosphere to obtain lump boron nitride having an average particle diameter of 10 to 200 μm; and a sintering step of molding and heating a blend containing the lump boron nitride and a sintering aid to obtain a boron nitride sintered body including coarse particles each having a length of 20 μm or more in a cross-section and fine particles smaller than the coarse particles.

Provided is a boron nitride sintered body having a porous structure, the boron nitride sintered body including a lump particle formed by aggregation of primary particles of boron nitride and having a particle diameter of 15 μm or more. Provided is a method for manufacturing a boron nitride sintered body, the method including: a nitriding step of firing a raw material powder containing boron carbide in an atmosphere containing nitrogen to obtain a fired product including lump particles each having a core part with primary particles of boron carbonitride aggregated and a shell part surrounding the core part; and a firing step of molding and heating a blend containing the fired product including lump particles and a sintering aid to obtain the boron nitride sintered body having a porous structure and including lump particles of boron nitride.

Provided is a boron nitride sintered body having a porous structure, the boron nitride sintered body including a lump particle formed by aggregation of primary particles of boron nitride and having a particle diameter of 15 μm or more. Provided is a method for manufacturing a boron nitride sintered body, the method including: a nitriding step of firing a raw material powder containing boron carbide in an atmosphere containing nitrogen to obtain a fired product including lump particles each having a core part with primary particles of boron carbonitride aggregated and a shell part surrounding the core part; and a firing step of molding and heating a blend containing the fired product including lump particles and a sintering aid to obtain the boron nitride sintered body having a porous structure and including lump particles of boron nitride.

Composite materials that include a structural support are described, wherein the structural support defines a plurality of cavities at least partially filled with a polymeric foam. The polymeric foam may have a density less than 5 pcf and/or the composite material may have a compressive strength of at least 60 psi.

Composite materials that include a structural support are described, wherein the structural support defines a plurality of cavities at least partially filled with a polymeric foam. The polymeric foam may have a density less than 5 pcf and/or the composite material may have a compressive strength of at least 60 psi.

Disclosed are a ten-membered fergusonite structure high-entropy oxide ceramic and a preparation method thereof, where the high-entropy oxide ceramic has a monoclinic structure, with a chemical formula of RENbO.sub.4, and the RE is any ten rare-earth cations selected from a group consisting of La.sup.3+, Ce.sup.3+, Pr.sup.3+, Nd.sup.3+, Sm.sup.3+, Eu.sup.3+, Gd.sup.3+, Dy.sup.3+, Ho.sup.3+, Er.sup.3+, Tm.sup.3+, Yb.sup.3+, Lu.sup.3+ and Y.sup.3+. The ten rare-earth cations have a molar ratio of 1:1:1:1:1:1:1:1:1:1 and equal share of RE position. According to the application, by adopting solid state reaction, the fergusonite structure high-entropy oxide ceramic with single-phase structure, uniform element distribution and stable phase is obtained. The high-entropy oxide ceramic prepared by the application is simple in process, uniform in chemical composition and microstructure, and convenient to realize on-demand regulation on properties through a combination of different elements.

Disclosed are a ten-membered fergusonite structure high-entropy oxide ceramic and a preparation method thereof, where the high-entropy oxide ceramic has a monoclinic structure, with a chemical formula of RENbO.sub.4, and the RE is any ten rare-earth cations selected from a group consisting of La.sup.3+, Ce.sup.3+, Pr.sup.3+, Nd.sup.3+, Sm.sup.3+, Eu.sup.3+, Gd.sup.3+, Dy.sup.3+, Ho.sup.3+, Er.sup.3+, Tm.sup.3+, Yb.sup.3+, Lu.sup.3+ and Y.sup.3+. The ten rare-earth cations have a molar ratio of 1:1:1:1:1:1:1:1:1:1 and equal share of RE position. According to the application, by adopting solid state reaction, the fergusonite structure high-entropy oxide ceramic with single-phase structure, uniform element distribution and stable phase is obtained. The high-entropy oxide ceramic prepared by the application is simple in process, uniform in chemical composition and microstructure, and convenient to realize on-demand regulation on properties through a combination of different elements.

Inventive manufacture of CrB.sub.2—Al.sub.2O.sub.3 composites is based on pressureless sintering. According to typical inventive practice, CrB.sub.2 powder and Al.sub.2O.sub.3 powder are mixed together in selected volumetric proportions so that the volume of the CrB.sub.2 does not exceed 50% of the overall volume of the CrB.sub.2—Al.sub.2O.sub.3 mixture. The CrB.sub.2—Al.sub.2O.sub.3 mixture is shaped into a green body. The green body is pressureless sintered in a non-oxidizing atmosphere at a firing temperature in the approximate range between 1600° C. and 2050° C. The present invention succeeds in preparing, via pressureless sintering, a proportionality-associated range of compositions in the CrB.sub.2—Al.sub.2O.sub.3 system, which is a potentially “advanced” ceramic system. A typical inventively fabricated CrB.sub.2—Al.sub.2O.sub.3 composite is inventively configured in a complex shape, and has “advanced” material (e.g., mechanical) properties that are favorable for a contemplated application. Inventive manufacture of ceramic-ceramic composites is thus dually attributed, and uncommonly so, with complex shape-ability and advanced capability.