Process for encapsulating a shaped body for hot isostatic pressing by sol-gel method
AssigneeThe United States of America as represented by the Secretary of the Army
InventorKerry Richards
Life of this patent
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Abstract
There is disclosed a process for encapsulating a preform of arbitrary size and shape for the purpose of manufacturing a body by means of hot isostatic pressing. The preform is encapsulated with glass using a sol gel technique. The glass initially forms a hard, porous layer. Heating the glass in the hot isostatic press results in the formation of a gas-impermeable capsule around the preform.
Claims14
A process for encapsulating a preform, prepared from a powder, with glass for the purpose of preparing a shaped body by hot isostatic pressing comprising the steps of:
- preparing a mixture comprising a sol and a filler glass having an identical composition as the sol, which gels upon application to a preform,
- the glass fillers selected from the group consisting of a high-temperature filler and a low-temperature filler:
- coating an outer surface of the preform with at least one layer of the sol mixture;
- after the mixture has gelled, drying the sol gel coating;
- baking out the coated preform;
- heating the coated preform under vacuum and at temperature sufficient to cause the sol gel coating to seal the outer surface of the preform;
- and
- subjecting the sealed preform to hot isotstatic pressing at high temperatures and pressures in an inert atmosphere.
process for encapsulating a preform with glass for the purpose of preparing a shaped body by hot isostatic pressing, comprising the steps of:
- preparing a first sol which gels on application to a preform comprising a mixture of a high-temperature sol and a high-temperature glass filler:
- preparing a second sol which gels on application to a preform comprising a mixture of a high-temperature sol and a low-temperature glass filler;
- forming an inner layer by coating the preform with at least one layer of the first sol, and after the first layer has gelled, drying the first gel coating;
- forming an outer layer by coating the preform with at least one layer of the second sol, and after the second sol layer has gelled, drying the second gel coating;
- baking out the preform;
- heating the coated preform under vacuum and at a temperature sufficient to cause the second sol gel coating to seal the outer surface of the preform;
- subjecting the sealed preforms to hot isostatic pressing at high temperatures and pressures in an inert atmosphere;
- and
- recovering the preforms.
A method for encapsulating a preform prepared from a powder with glass for the purpose of preparing a shaped body by hot isostatic pressing comprising the steps of:
- preparing a mixture comprising a sol and a filler glass having an identical composition as the sol which gels on application to a preform
- coating the outer surface of the preform with a barrier layer;
- coating the preform with at least one layer of the sol mixture;
- coating the preform with at least one layer of the sol mixture;
- after the sol had gelled, drying the sol gel coating;
- baking out the coated preform;
- heating the coated preform under vacuum and at a temperature sufficient to cause the sol gel coating to seal the outer surface of the preform;
- and
- subjecting the preform to hot isostatic pressing at elevated temperatures and pressures in an inert atmosphere and:
- recovering the product.
Dependencies are inferred from the claim text.