Abstract: A hexagonal boron nitride (h-BN) powder is disclosed in which primary particles of the powder exhibit a ratio (D/d) of long diameter (D) to thickness (d) in a range of 5 to 10. Agglomerated particle bodies made of the primary particles have an average particle diameter (D50) in a range of 2 ?m to 200 ?m, inclusive, and the powder has a bulk density in a range of 0.5 g/cm3 to 1.0 g/cm3. In an exemplary method for producing the h-BN, boron carbide is nitridizated in a nitrogen partial pressure of at least 5 kPa at 1800° C. to 2200° C., inclusive. B2O3 (or precursor thereof) is added to the nitridization product to produce a mixture. The mixture is decarbonized in a non-oxidizing atmosphere at a 1500° C. to 2200° C., inclusive. The decarbonization product is pulverized and subject to particle-size classification, yielding H-BN powder. The method includes a depressurizing step, performed at 100 kPa or less either during nitridization or after decarbonization.

Abstract: A hexagonal boron nitride (h-BN) powder is disclosed in which primary particles of the powder exhibit a ratio (D/d) of long diameter (D) to thickness (d) in a range of 5 to 10. Agglomerated particle bodies made of the primary particles have an average particle diameter (D50) in a range of 2 ?m to 200 ?m, inclusive, and the powder has a bulk density in a range of 0.5 g/cm3 to 1.0 g/cm3. In an exemplary method for producing the h-BN, boron carbide is nitridizated in a nitrogen partial pressure of at least 5 kPa at 1800° C. to 2200° C., inclusive. B2O3 (or precursor thereof) is added to the nitridization product to produce a mixture. The mixture is decarbonized in a non-oxidizing atmosphere at a 1500° C. to 2200° C., inclusive. The decarbonization product is pulverized and subject to particle-size classification, yielding H-BN powder. The method includes a depressurizing step, performed at 100 kPa or less either during nitridization or after decarbonization.