A cubic boron nitride particle population having highly-etched surfaces and a high toughness index is produced by blending a reactive metal powder with a plurality of cubic boron nitride particles to form a blended mixture. The blended mixture is compressed to form a compressed mixture. The compressed mixture is subjected to a temperature and a pressure, where the temperature is controlled to cause etching of the plurality of cubic boron nitride particles by reaction of cubic boron nitride with the reactive metal powder, thereby forming a plurality of etched cubic boron nitride particles. Also, the temperature and pressure are controlled to cause boron nitride to remain in a cubic boron nitride phase. Afterwards, the plurality of etched cubic boron nitride particles is recovered from the compressed mixture to form the particle population. Preferably, the particle population contains no hexagonal boron nitride.

An oxidation protection system disposed on a substrate is provided, which may comprise a base layer comprising a first pre-slurry composition comprising a first phosphate glass composition, and/or a sealing layer comprising a second pre-slurry composition comprising a second phosphate glass composition and a strengthening compound comprising boron nitride, a metal oxide, and/or silicon carbide.

An oxidation protection system disposed on a substrate is provided, which may comprise a base layer comprising a first pre-slurry composition comprising a first phosphate glass composition, and/or a sealing layer comprising a second pre-slurry composition comprising a second phosphate glass composition and a strengthening compound comprising boron nitride, a metal oxide, and/or silicon carbide.

A glass furnace including an additive-containing product including an additive selected from: phosphorus compounds other than glasses and vitroceramics, tungsten compounds other than glasses and vitroceramics, molybdenum compounds other than glasses and vitroceramics, iron in the form of metal, aluminum in the form of metal, silicon in the form of metal, and their mixtures, silicon carbide, boron carbide, silicon nitride, boron nitride, glasses including elemental phosphorus and/or iron and/or tungsten and/or molybdenum, vitroceramics including elemental phosphorus and/or iron and/or tungsten and/or molybdenum, and their mixtures, and having the following chemical analysis, exclusively of the additive, as a percentage by weight on the basis of the oxides: Cr.sub.2O.sub.3?2%, and Cr.sub.2O.sub.3+Al.sub.2O.sub.3+CaO+ZrO.sub.2+MgO+Fe.sub.2O.sub.3+SiO.sub.2+TiO.sub.2?90%, and Cr.sub.2O.sub.3+Al.sub.2O.sub.3+MgO?60%, the content by weight of additive being in the range 0.01% to 6%.

A glass furnace including an additive-containing product including an additive selected from: phosphorus compounds other than glasses and vitroceramics, tungsten compounds other than glasses and vitroceramics, molybdenum compounds other than glasses and vitroceramics, iron in the form of metal, aluminum in the form of metal, silicon in the form of metal, and their mixtures, silicon carbide, boron carbide, silicon nitride, boron nitride, glasses including elemental phosphorus and/or iron and/or tungsten and/or molybdenum, vitroceramics including elemental phosphorus and/or iron and/or tungsten and/or molybdenum, and their mixtures, and having the following chemical analysis, exclusively of the additive, as a percentage by weight on the basis of the oxides: Cr.sub.2O.sub.3?2%, and Cr.sub.2O.sub.3+Al.sub.2O.sub.3+CaO+ZrO.sub.2+MgO+Fe.sub.2O.sub.3+SiO.sub.2+TiO.sub.2?90%, and Cr.sub.2O.sub.3+Al.sub.2O.sub.3+MgO?60%, the content by weight of additive being in the range 0.01% to 6%.

An agglomerate abrasive grain includes a mixture of individual abrasive grains and hollow bodies, wherein the abrasive grains and the hollow bodies are held together via a binding matrix of aluminosilicate and alkali silicate, and the agglomerate abrasive grain has an open porosity and a closed porosity in each case ranging from 5% by volume to 40% by volume, wherein the total porosity of the agglomerate abrasive grain is less than 50% by volume.

An agglomerate abrasive grain includes a mixture of individual abrasive grains and hollow bodies, wherein the abrasive grains and the hollow bodies are held together via a binding matrix of aluminosilicate and alkali silicate, and the agglomerate abrasive grain has an open porosity and a closed porosity in each case ranging from 5% by volume to 40% by volume, wherein the total porosity of the agglomerate abrasive grain is less than 50% by volume.

Hexagonal Boron Nitride (hBN) is a synthetic material that may be used in several applications due to its chemical inertness, thermal stability, and other beneficial properties. hBN composite materials and method for making such composites are described here. In particular composite materials including both functionalized hBN and cement or cementitious materials and methods for making the same are discussed. Such materials may be useful for construction, well cementing (both primary and remedial cementing), nuclear industry, 3D printing of advanced multifunctional composites, and refractory materials.

Hexagonal Boron Nitride (hBN) is a synthetic material that may be used in several applications due to its chemical inertness, thermal stability, and other beneficial properties. hBN composite materials and method for making such composites are described here. In particular composite materials including both functionalized hBN and cement or cementitious materials and methods for making the same are discussed. Such materials may be useful for construction, well cementing (both primary and remedial cementing), nuclear industry, 3D printing of advanced multifunctional composites, and refractory materials.

A powder essentially composed of aggregates based on boron nitride, the powder exhibiting an overall chemical composition, as percentages by weight, including between 40 and 45% of boron, between 53 and 57% of nitrogen, less than 400 ppm by weight of calcium, less than 5%, in total, of other elements and more than 90% of boron nitride, limit included, as percentage by weight and on the basis of the combined crystalline phases, a mean circularity of greater than or equal to 0.90, a median pore size of less than or equal to 1.5 m and an apparent porosity of less than or equal to 55%.