Consolidation and densification methods for fibrous monolith processing
View Patent ↗Methods for consolidation and densification of fibrous monolith composite structures are provided. Consolidation and densification of two- and three-dimensional fibrous monolith components having complex geometries can be achieved by pressureless sintering. The fibrous monolith composites are formed from filaments having at least a first material composition generally surrounded by a second material composition. The composites are sintered at a pressure of no more than about 30 psi to provide consolidated and densified fibrous monolith composites.
1. A process for consolidation and densification of multi-phase fibrous monolith composite materials comprising:
placing preformed fibrous monolith composite materials formed of one or more filaments each having a central portion of a first uniformly suspended mixture and an outer portion of a second uniformly suspended mixture essentially surrounding the central portion, wherein the second uniformly suspended mixture forms essentially a separate phase between the central portion of the one or more filaments in the composite materials, in a sintering furnace; and
heating the fibrous monolith composite materials at a pressure of between about 1 to about 30 psi at a temperature effective to achieve full density of the first and second uniformly suspended mixtures and provide sintered fibrous monolith composite materials.
2. The process of claim 1 wherein the fibrous monolith composite materials are sintered at a temperature below the lowest melting temperature of the first and second uniformly suspended mixtures.
3. The process of claim 1 wherein the fibrous monolith composite materials are sintered at a temperature below at least one of the melting temperatures of the first and second uniformly suspended mixtures.
4. The method of claim 1 wherein in the step of heating the fibrous monolith composite materials the fibrous monolith composite materials are initially heated to at least one interim temperature and held for a period of time before heating to the temperature effective for achieving full density.
5. A method for manufacture of an article comprised of multi-phase fibrous monolithic composite materials comprising the steps of:
a) forming fibrous monolithic composite materials in the form of a filament and including a first material composition generally surrounded by a second material composition;
b) compressing the fibrous monolithic composite materials filament to consolidate and densify the first and second material compositions;
c) forming the compressed fibrous monolithic composite materials filament into a preform of the fibrous monolithic composite materials article; and
d) sintering the preform at generally atmospheric pressure at a temperature effective for providing an essentially fully dense, sintered fibrous monolithic composite materials article.
6. The method of claim 5 wherein the preform is sintered at a temperature below a lowest melting temperatures of the first and second material compositions.
7. The method of claim 5 wherein the preform is sintered at a temperature lower than a melting temperature of at least one of the first and second material compositions.
8. The method of claim 5 wherein during sintering the pressure is between about 1 to about 30 psi.
9. The method of claim 5 wherein in the step of sintering the fibrous monolith composite materials the fibrous monolith composite materials are heated at a controlled rate to at least one interim temperature and held for a period of time.