Superplastic forging nitride ceramics
Patent
·
OSTI ID:7072573
A process is disclosed for preparing silicon nitride ceramic parts which are relatively flaw free and which need little or no machining, said process comprising the steps of: (a) preparing a starting powder by wet or dry mixing ingredients comprising by weight from about 70% to about 99% silicon nitride, from about 1% to about 30% of liquid phase forming additive and from 1% to about 7% free silicon; (b) cold pressing to obtain a preform of green density ranging from about 30% to about 75% of theoretical density; (c) sintering at atmospheric pressure in a nitrogen atmosphere at a temperature ranging from about 1,400 C to about 2,200 C to obtain a density which ranges from about 50% to about 100% of theoretical density and which is higher than said preform green density, and (d) press forging workpiece resulting from step (c) by isothermally uniaxially pressing said workpiece in an open die without initial contact between said workpiece and die wall perpendicular to the direction of pressing and so that pressed workpiece does not contact die wall perpendicular to the direction of pressing, to substantially final shape in a nitrogen atmosphere utilizing a temperature within the range of from about 1,400 C to essentially 1,750 C and strain rate within the range of about 10[sup [minus]7] to about 10[sup [minus]1] seconds[sup [minus]1], the temperature and strain rate being such that surface cracks do not occur, said pressing being carried out to obtain a shear deformation greater than 30% whereby superplastic forging is effected.
- Research Organization:
- Jupiter Technologies
- DOE Contract Number:
- AC01-84ER80167
- Assignee:
- Jupiter Technologies, Inc., Ithaca, NY (United States)
- Patent Number(s):
- A; US 4732719
- Application Number:
- CNN: SB1R 1985-10; PPN: US 6-816040
- OSTI ID:
- 7072573
- Country of Publication:
- United States
- Language:
- English
Similar Records
Composites comprising silicon carbide fibers dispersed in magnesia-aluminate matrix and fabrication thereof and of other composites by sinter forging
Investigation of separation-lubrication substances for use in isothermal forging. Final report, 16 December 1974--1 July 1976. [Ti--6Al--4V, 1300F to 1800F]
Gelcasting of sintered reaction-bonded silicon nitride for improved mechanical properties
Patent
·
Tue Oct 03 00:00:00 EDT 1989
·
OSTI ID:867123
Investigation of separation-lubrication substances for use in isothermal forging. Final report, 16 December 1974--1 July 1976. [Ti--6Al--4V, 1300F to 1800F]
Technical Report
·
Thu Mar 31 23:00:00 EST 1977
·
OSTI ID:6807922
Gelcasting of sintered reaction-bonded silicon nitride for improved mechanical properties
Conference
·
Fri Mar 31 23:00:00 EST 1995
·
OSTI ID:48249
Related Subjects
36 MATERIALS SCIENCE
360201* -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
ATMOSPHERES
COLD WORKING
CONTROLLED ATMOSPHERES
FABRICATION
FORGING
MATERIALS WORKING
MECHANICAL PROPERTIES
NITRIDES
NITROGEN COMPOUNDS
PLASTICITY
PNICTIDES
SILICON COMPOUNDS
SILICON NITRIDES
SINTERING
TEMPERATURE DEPENDENCE
360201* -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
ATMOSPHERES
COLD WORKING
CONTROLLED ATMOSPHERES
FABRICATION
FORGING
MATERIALS WORKING
MECHANICAL PROPERTIES
NITRIDES
NITROGEN COMPOUNDS
PLASTICITY
PNICTIDES
SILICON COMPOUNDS
SILICON NITRIDES
SINTERING
TEMPERATURE DEPENDENCE