Spherical boron nitride particles and method for preparing them
US6652822B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 17, 2001 |
| Grant date | Nov 25, 2003 |
| Priority date | — |
| Expiry date | Nov 5, 2021 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01P2004/61
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Spherical and polyhedral particles of boron nitride and method of preparing them. Spherical and polyhedral particles of boron nitride are produced from precursor particles of hexagonal phase boron nitride suspended in an aerosol gas. The aerosol is directed to a microwave plasma torch. The torch generates plasma at atmospheric pressure that includes nitrogen atoms. The presence of nitrogen atoms is critical in allowing boron nitride to melt at atmospheric pressure while avoiding or at least minimizing decomposition. The plasma includes a plasma hot zone, which is a portion of the plasma that has a temperature sufficiently high to melt hexagonal phase boron nitride. In the hot zone, the precursor particles melt to form molten particles that acquire spherical and polyhedral shapes. These molten particles exit the hot zone, cool, and solidify to form solid particles of boron nitride with spherical and polyhedral shapes. The molten particles can also collide and join to form larger molten particles that lead to larger spherical and polyhedral particles.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.