Preparation of silicon nitride powder by partially nitriding in a fluidized bed and then completing nitridation in a moving bed
US5232677A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 29, 1991 |
| Grant date | Aug 3, 1993 |
| Priority date | — |
| Expiry date | Jan 29, 2011 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01B21/0682
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Silicon nitride powder is produced in two steps, by supplying metallic silicon powder to a fluidized bed composed of silicon nitride and nitrogen or ammonia gas where primary nitriding reaction is effected until the silicon powder is nitrided to an amount of at least 50% and transferring the nitrided product from the fluidized bed into a moving bed where secondary nitriding reaction is effected for nitriding the unreacted silicon with nitrogen or ammonia gas. This method is adapted for manufacture on a commercial scale because the silicon nitride powder thus obtained is consistent and has a very high degree of nitriding and a minimal variation in quality.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.