High strength monolithic carbon foam

Abstract

A carbon foam article useful for, inter alia, composite tooling or other high temperature applications, which includes a carbon foam having a ratio of compressive strength to density of at least about 7000 psi / g / cc.

Description

BACKGROUND OF THE INVENTION [0001] 1. Technical Field [0002] The present invention relates to high strength monolithic carbon foams useful for applications including as composite material tooling. More particularly, the present invention relates to carbon foams exhibiting improved strength, weight and density characteristics. The invention also includes methods for the production of such foams. [0003] 2. Background Art [0004] Carbon foams have attracted considerable recent activity because of their properties of low density, coupled with either very high or low thermal conductivity. Conventionally, Carbon foams are prepared by two general routes. Highly graphitizable foams have been produced by thermal treatment of mesophase pitches under high pressure. These foams tend to have high thermal and electrical conductivities. For example, in Klett, U.S. Pat. No. 6,033,506, mesophase pitch is heated while subjected to a pressure of 1000 psi to produce an open-cell foam containing intercon...

AI Technical Summary

Benefits of technology

"The present invention provides a carbon foam with unique characteristics that make it ideal for use in high-temperature applications such as composite tooling. The foam has a combination of strength and light weight, with a density of 0.05 to 0.4 grams per cubic centimeter and a compressive strength of at least 2000 psi. The foam has a bimodal cell structure with a relatively large amount of larger pores and a smaller amount of smaller pores, resulting in a high ratio of strength to density. The foam also has a relatively uniform distribution of pores, with most pores falling within a range of about 0.8 to 3.5 microns in diameter. The carbon foam has a unique combination of properties, including a density of 0.05 to 0.4 grams per cubic centimeter, a compressive strength of at least 2000 psi, and a porosity of between 65% and 95%. The carbon foam can be produced by carbonizing a polymer foam block, such as a phenolic foam, in an inert or air-excluded atmosphere at temperatures ranging from about 500°C to 3200°C. The carbon foam has a unique combination of characteristics that make it ideal for use in high-temperature applications."

Problems solved by technology

These foams tend to have high thermal and electrical conductivities.

Unfortunately, carbon foams produced by the prior art processes are not effective for many high temperature applications such as composite tooling.

The foams generally available are not monolithic and do not have the strength and strength to density requirements for such application.

In addition, open-celled foams with highly interconnected pores have porosities making them ill-placed for such applications.