Method of improving quality of hot pressed Si.sub.3 N.sub.4 bodies
US4623498A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 12, 1984 |
| Grant date | Nov 18, 1986 |
| Priority date | — |
| Expiry date | Jul 12, 2004 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC04B35/584
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A method of improving the quality of hot pressed Si.sub.3 N.sub.4 bodies is disclosed. Unpurified silicon powder and admixed oxygen carrying agents are compacted to form a preform. The preform is nitrided, facilitated by the presence of certain impurities, to agglomerate the mixture to an increased density no greater than 2.7 gm/cm.sup.3. The nitrided preform is immersed in one or more stages in one or more leaching solutions of effective concentration to remove the selected impurities. The treated preform is then hot pressed to full density accompanied by a substantial reduction or absence of undesirable impurities such as iron silicide, which can conventionally form during hot pressing.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.