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 environmental barrier coating, comprising an environmental barrier coating applied to a substrate containing silicon; the environmental barrier coating comprising an oxide matrix surrounding a fiber-reinforcement structure and a self-healing phase interspersed throughout the oxide matrix.

An environmental barrier coating, comprising an environmental barrier coating applied to a substrate containing silicon; the environmental barrier coating comprising an oxide matrix surrounding a fiber-reinforcement structure and a self-healing phase interspersed throughout the oxide matrix.

Loose particulate materials can be problematic in various aspects. For example, loose particulate materials may generate dust or be difficult to consolidate together. Fines in loose particulate materials may also be an issue. Coated particulates may alleviate some of the foregoing issues. Suitable coated particulates may comprise a particulate material comprising sand or a ceramic, and a polysaccharide composition coated upon the particulate material, the polysaccharide composition comprising a functionalized polysaccharide. Other particulate materials such as wood chips and animal litter particulates may be coated with functionalized polysaccharides to achieve similar advantages.

Loose particulate materials can be problematic in various aspects. For example, loose particulate materials may generate dust or be difficult to consolidate together. Fines in loose particulate materials may also be an issue. Coated particulates may alleviate some of the foregoing issues. Suitable coated particulates may comprise a particulate material comprising sand or a ceramic, and a polysaccharide composition coated upon the particulate material, the polysaccharide composition comprising a functionalized polysaccharide. Other particulate materials such as wood chips and animal litter particulates may be coated with functionalized polysaccharides to achieve similar advantages.

The disclosure describes techniques for forming a surface layer of an article including a CMC using a cast. In some examples, the surface layer includes three-dimensional surface features, which may increase adhesion between the CMC and a coating on the CMC. In some examples, the surface layer may include excess material, with or without three-dimensional surface features, which is on the CMC. The excess material may be machined to remove some of the excess material and facilitate conforming the article to dimensional tolerances, e.g., for fitting the article to another component. The excess material may reduce a likelihood that the CMC (e.g., reinforcement material in the CMC) is damaged by the machining.

An apparatus and method is described to coat small and large quantities of solid particles using atomic layer deposition, with increased material utilization and decreased cycle times. The resulting higher coating efficiency ALD process is achieved by a controlled pressure differential acting across a rotating porous vessel that contains a plurality of solid particles. The apparatus is comprised of two coaxial cylindrical porous vessels with a means for one to rotate, and a two stage rotary feedthrough with a specialized hollowed out shaft, which enables both rotation of the vessel and reactant, purge, and product gas transport across a particle bed that undergoes mixing.

An apparatus and method is described to coat small and large quantities of solid particles using atomic layer deposition, with increased material utilization and decreased cycle times. The resulting higher coating efficiency ALD process is achieved by a controlled pressure differential acting across a rotating porous vessel that contains a plurality of solid particles. The apparatus is comprised of two coaxial cylindrical porous vessels with a means for one to rotate, and a two stage rotary feedthrough with a specialized hollowed out shaft, which enables both rotation of the vessel and reactant, purge, and product gas transport across a particle bed that undergoes mixing.

The localized formation of graphene and diamond like structures on the surface of boron carbide is obtained due to exposure to high intensity laser illumination. The graphitization involves water vapor interacting with the laser illuminated surface of boron carbide and leaving behind excess carbon. The process can be done on the micrometer scale, allowing for a wide range of electronic applications. Raman is a powerful and convenient technique to routinely characterize and distinguish the composition of Boron Carbide (B.sub.4C), particularly since a wide variation in C content is possible in B.sub.4C. Graphitization of 1-3 m icosahedral B.sub.4C powder is observed at ambient conditions under illumination by a 473 nm (2.62 eV) laser during micro-Raman measurements. The graphitization, with 12 nm grain size, is dependent on the illumination intensity. The process is attributed to the oxidation of B.sub.4C to B.sub.2O.sub.3 by water vapor in air, and subsequent evaporation, leaving behind excess carbon. The effectiveness of this process sheds light on amorphization pathways of B.sub.4C, a critical component of resilient mechanical composites, and also enables a means to thermally produce graphitic contacts on single crystal B.sub.4C for nanoelectronics.

The localized formation of graphene and diamond like structures on the surface of boron carbide is obtained due to exposure to high intensity laser illumination. The graphitization involves water vapor interacting with the laser illuminated surface of boron carbide and leaving behind excess carbon. The process can be done on the micrometer scale, allowing for a wide range of electronic applications. Raman is a powerful and convenient technique to routinely characterize and distinguish the composition of Boron Carbide (B.sub.4C), particularly since a wide variation in C content is possible in B.sub.4C. Graphitization of 1-3 m icosahedral B.sub.4C powder is observed at ambient conditions under illumination by a 473 nm (2.62 eV) laser during micro-Raman measurements. The graphitization, with 12 nm grain size, is dependent on the illumination intensity. The process is attributed to the oxidation of B.sub.4C to B.sub.2O.sub.3 by water vapor in air, and subsequent evaporation, leaving behind excess carbon. The effectiveness of this process sheds light on amorphization pathways of B.sub.4C, a critical component of resilient mechanical composites, and also enables a means to thermally produce graphitic contacts on single crystal B.sub.4C for nanoelectronics.