Provided is a boron nitride sintered body including boron nitride particles and pores, the boron nitride sintered body having a sheet shape and a thickness of less than 2 mm. Provided is a method for manufacturing a boron nitride sintered body, the method including a sintering step of molding and heating a blend containing a boron carbonitride powder and a sintering aid to obtain a sheet-shaped boron nitride sintered body including boron nitride particles and pores, in which a thickness of the boron nitride sintered body obtained in the sintering step is less than 2 mm.

Provided is a boron nitride sintered body including boron nitride particles and pores, the boron nitride sintered body having a sheet shape and a thickness of less than 2 mm. Provided is a method for manufacturing a boron nitride sintered body, the method including a sintering step of molding and heating a blend containing a boron carbonitride powder and a sintering aid to obtain a sheet-shaped boron nitride sintered body including boron nitride particles and pores, in which a thickness of the boron nitride sintered body obtained in the sintering step is less than 2 mm.

An aspect of the present invention provides a semi-cured product composite containing: a porous body; and a semi-cured product of a thermally curable composition impregnated in the porous body, wherein the thermally curable composition contains an epoxy compound and a cyanate compound, and an equivalent ratio of an epoxy group of the epoxy compound to a cyanate group of the cyanate compound in the thermally curable composition is 1.0 or more.

An aspect of the present invention provides a semi-cured product composite containing: a porous body; and a semi-cured product of a thermally curable composition impregnated in the porous body, wherein the thermally curable composition contains an epoxy compound and a cyanate compound, and an equivalent ratio of an epoxy group of the epoxy compound to a cyanate group of the cyanate compound in the thermally curable composition is 1.0 or more.

A preform intended for the production of a dental prosthesis. The preform includes a group of agglomerated ceramic, glass-ceramic or glass particles, such that, as volume percents: more than 40% and less than 90% of the particles of said group have a size greater than 0.5 μm and less than 3.5 μm, said particles hereinafter being denoted “enamel particles”, and more than 10% and less than 60% of the particles of said group have a size greater than 3.5 μm and less than 5.5 μm, said particles hereinafter being denoted “dentine particles.” The microstructure of the preform is such that there is an axis X, termed “axis of variation”, along which the Ve/(Ve+Vd) ratio changes continuously, Ve and Vd denoting the volume percents of enamel particles and of dentine particles, respectively. The enamel and dentine particles representing, together, more than 90% of the volume of the agglomerated particles.

A preform intended for the production of a dental prosthesis. The preform includes a group of agglomerated ceramic, glass-ceramic or glass particles, such that, as volume percents: more than 40% and less than 90% of the particles of said group have a size greater than 0.5 μm and less than 3.5 μm, said particles hereinafter being denoted “enamel particles”, and more than 10% and less than 60% of the particles of said group have a size greater than 3.5 μm and less than 5.5 μm, said particles hereinafter being denoted “dentine particles.” The microstructure of the preform is such that there is an axis X, termed “axis of variation”, along which the Ve/(Ve+Vd) ratio changes continuously, Ve and Vd denoting the volume percents of enamel particles and of dentine particles, respectively. The enamel and dentine particles representing, together, more than 90% of the volume of the agglomerated particles.

Provided is a boron nitride sintered body including boron nitride particles and pores, in which an average pore diameter of the pores is less than 2 μm. Provided is a method for manufacturing a boron nitride sintered body, the method including: a nitriding step of firing a boron carbide powder in a nitrogen pressurized atmosphere to obtain a fired product containing boron carbonitride; and a sintering step of molding and heating a blend containing the fired product and a sintering aid to obtain the boron nitride sintered body including boron nitride particles and pores, in which the sintering aid contains boron oxide and calcium carbonate, and the blend contains 1 to 20 parts by mass of a boron compound and a calcium compound in total with respect to 100 parts by mass of the fired product.

Provided is a boron nitride sintered body including boron nitride particles and pores, in which an average pore diameter of the pores is less than 2 μm. Provided is a method for manufacturing a boron nitride sintered body, the method including: a nitriding step of firing a boron carbide powder in a nitrogen pressurized atmosphere to obtain a fired product containing boron carbonitride; and a sintering step of molding and heating a blend containing the fired product and a sintering aid to obtain the boron nitride sintered body including boron nitride particles and pores, in which the sintering aid contains boron oxide and calcium carbonate, and the blend contains 1 to 20 parts by mass of a boron compound and a calcium compound in total with respect to 100 parts by mass of the fired product.

Provided is a boron nitride sintered body including boron nitride particles and pores, in which a compressive elastic modulus is 1 GPa or more. Provided is a method for manufacturing a boron nitride sintered 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; and a sintering step of molding and heating a blend containing the fired product and a sintering aid to obtain the boron nitride sintered body including boron nitride particles and pores, in which the sintering aid contains a boron compound and a calcium compound, and the blend contains 1 to 20 parts by mass of the boron compound and the calcium compound in total with respect to 100 parts by mass of the fired product.

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.