Method of making silicon nitride base cutting tools -II
US4264550A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 20, 1979 |
| Grant date | Apr 28, 1981 |
| Priority date | — |
| Expiry date | Dec 20, 1999 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC04B35/593
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A method of making a unitary silicon nitride comprising object is disclosed. A uniform powder mixture is prepared of Si.sub.3 N.sub.4 containing SiO.sub.2 as an oxide surface coating, 4-12% by weight Y.sub.2 O.sub.3, and 0.50-2.5% Al.sub.2 O.sub.3. The mixture is heated to 1000.degree.-1400.degree. C. under a pressure of at least 2,000 psi for a time of at least one minute but sufficient to permit a nucleating reaction to take place in secondary phases. Heating is then increased to a temperature of 1680.degree.-1750.degree. C. under a pressure and for a period of time sufficient to produce 99.0% or more of full theoretical density in the pressed object.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.