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 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 C/C composite having a long life in an environment including a heating process and a cooling process and having less adverse effects on surrounding facilities and the quality of treatment objects. A C/C composite in which, in measurement for open pores by mercury porosimetry, an open porosity for open pores with a radius of not less than 0.4 μm and less than 10 μm in the C/C composite is 2.0% or less.

Provided is a C/C composite having a long life in an environment including a heating process and a cooling process and having less adverse effects on surrounding facilities and the quality of treatment objects. A C/C composite in which, in measurement for open pores by mercury porosimetry, an open porosity for open pores with a radius of not less than 0.4 μm and less than 10 μm in the C/C composite is 2.0% or less.

A method for making a low cost, lightweight carbon aggregate from coal at, above, or below atmospheric pressure, and a lightweight concrete composition utilizing the lightweight carbon aggregate is described.

A method for making a low cost, lightweight carbon aggregate from coal at, above, or below atmospheric pressure, and a lightweight concrete composition utilizing the lightweight carbon aggregate is described.

Disclosed is a gypsum board comprising a set gypsum core disposed between two cover sheets. The set gypsum core is formed from a slurry comprising stucco, water, and at least one pregelatinized starch having a viscosity of from about 20 cP to about 300 cP as measured according to the VMA method described herein. The starch is present in an amount of greater than 10% by weight of the stucco. In preferred embodiments, the board has good strength properties even at lower densities, such as about 31 pcf or less. Also disclosed are a related method of making a gypsum wallboard and a slurry.

Disclosed is a gypsum board comprising a set gypsum core disposed between two cover sheets. The set gypsum core is formed from a slurry comprising stucco, water, and at least one pregelatinized starch having a viscosity of from about 20 cP to about 300 cP as measured according to the VMA method described herein. The starch is present in an amount of greater than 10% by weight of the stucco. In preferred embodiments, the board has good strength properties even at lower densities, such as about 31 pcf or less. Also disclosed are a related method of making a gypsum wallboard and a slurry.

A method for making a low cost, lightweight carbon aggregate from coal at, above, or below atmospheric pressure, and a lightweight concrete composition utilizing the lightweight carbon aggregate is described.