An infiltrated carbon foam composite and method for making the composite is described. The infiltrated carbon foam composite may include a carbonized carbon aerogel in cells of a carbon foam body and a resin is infiltrated into the carbon foam body filling the cells of the carbon foam body and spaces around the carbonized carbon aerogel. The infiltrated carbon foam composites may be useful for mid-density ablative thermal protection systems

Blacker, Jesse M.

Danford, Harry E.

Lucas, Rick D.

Merriman, Douglas J.

Plucinski, Janusz W.

NASA Technical Reports Server

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(12) United States Patent
Lucas et al.
(54) INFILTRATED CARBON FOAM
COMPOSITES
(75) Inventors: Rick D. Lucas, St. Clairsville, OH (US);
Harry E. Danford, Bethesda, OH (US);
Janusz W. Plucinski, Glen Dale, WV
(US); Douglas J. Merriman, Wheeling,
WV (US); Jesse M. Blacker, Bridgeport,
OH (US)
(73) Assignee: Touchstone Research Laboratory,
Ltd., Triadelphia, WV (US)
(*) Notice: Subject to any disclaimer, the term of this
patent is extended or adjusted under 35
U.S.C. 154(b) by 369 days.
(21) Appl. No.: 12/506,976
(22) Filed:	 Jul. 21, 2009
Related U.S. Application Data
(60) Provisional application No. 61/082,360, filed on Jul.
21, 2008.
(51) Int. Cl.
C01B 31100	 (2006.01)
C08J7/00	 (2006.01)
(52) U.S. Cl. .......... 264/29.5; 264/43; 264/44; 264/45.1;
423/445 R; 423/460; 428/306.6; 428/304.4;
428/305.5; 428/307.3; 428/307.7; 428/408
(lo) Patent No.:	 US 8,105,512 B1
(45) Date of Patent:	 Jan. 31, 2012
(58) Field of Classification Search ................. 264/29.5,
264/43, 44, 45.1; 423/445 R, 460; 428/304.4,
428/305.5, 306.6, 307.3, 307.7, 408; 521/62,
521/63, 180,181
See application file for complete search history.
(56) References Cited
U.S. PATENT DOCUMENTS
3,632,385 A * 1/1972 Schmitt et al ................. 427/228
5,770,127 A * 6/1998 Abrams et al ................ 264/29.1
6,245,313 B1 * 6/2001 Suzuki et al . 	 ............. 423/445 R
7,892,636 B2 * 2/2011 Miller et al .	 ............... 428/306.6
20 09/009 83 83 Al* 4/2009 Brown et al . 	 ................. 428/408
2011/0180032 Al* 7/2011 Mungas et al .	 ............ 123/193.5
* cited by examiner
Primary Examiner Irina S Zemel
(74) Attorney, Agent, or Firm Philip D. Lane
(57) ABSTRACT
An infiltrated carbon foam composite and method for making
the composite is described. The infiltrated carbon foam com-
posite may include a carbonized carbon aerogel in cells of a
carbon foam body and a resin is infiltrated into the carbon
foam body filling the cells of the carbon foam body and
spaces around the carbonized carbon aerogel. The infiltrated
carbon foam composites may be useful for mid-density abla-
tive thermal protection systems.
11 Claims, No Drawings
https://ntrs.nasa.gov/search.jsp?R=20120001629 2019-08-30T18:56:26+00:00Z
US 8,105,512 B1
1
INFILTRATED CARBON FOAM
COMPOSITES
CROSS-REFERENCE TO RELATED
APPLICATIONS
	
5
This application claims priority to U.S. Provisional Patent
Application No. 61/082,360, filed Jul. 21, 2008, herein spe-
cifically incorporated by reference in its entirety.
10
STATEMENT REGARDING FEDERALLY
SPONSORED RESEARCH OR DEVELOPMENT
This invention was made with Government support under
contract number NNX08CB08P awarded by NASA Ames 15
Research Center. The Government has certain rights in the
invention.
FIELD OF THE INVENTION
20
The present invention relates to infiltrated carbon foam
composites and methods for making the same. The carbon
foam composites may have utility in medium density ablative
thermal protection systems.
25
SUMMARY OF THE INVENTION
An embodiment of the invention may include an infiltrated
carbon foam composite comprising a carbon foam body hav-
ing a plurality of open cells distributed throughout the carbon 
30foam body, carbonized carbon aerogel located within at least
a portion of the cells of the carbon foam body, and a resin
filling at least a portion of the carbon foam cells containing
carbonized carbon aerogel.
The invention may also include a method for making an
infiltrated carbon foam composite comprising the steps of 35
forming a carbon aerogel in the cells of a carbon foam body,
carbonizing the carbon aerogel within the cells of the carbon
foam body, and infiltrating the carbon foam body having
carbonized carbon aerogel within cell of the carbon foam
body with a resin.	 40
DETAILED DESCRIPTION OF EMBODIMENTS
OF THE INVENTION
composite materials. Some embodiments are directed to infil-
The present invention is directed to infiltrated carbon foam 
45
trated carbon foam composites in which carbonized carbon
aerogel is located within cells of a carbon foam body and a
polymer matrix is infiltrated into the cells of the carbon foam
body thus infiltrating the carbon foam body and carbonized
50carbon aerogel that is positioned in the cells of the carbon
foam body.
In some embodiments, the infiltrated carbon foam compos-
ite may comprise a carbon foam body having a plurality of
open cells distributed throughout the carbon foam body. As
used herein "carbon foam" is a porous carbon product con-  55
taining regularly shaped, predominately concave, homoge-
neously dispersed, cells which interact to form a three-dimen-
sional array throughout a continuum of material of carbon,
predominately in the non-graphitic state. Embodiments of the
invention utilize and open celled carbon foam. An open celled 
60
carbon foam is one in which the cells are open to neighboring
cells in the carbon foam. While the size of the cells throughout
the carbon foam will vary, the distribution of the cell sizes
throughout the carbon foam is relatively uniform. In some
embodiments, the carbon foam may exhibit a bimodal distri-
bution of cell sizes. 	 65
In some embodiments, the carbon foam may exhibit a
density ranging from about 0.05 g/cm 3 to about 0.1 g/cm3 , in
2
some embodiments from about 0.2 g/cm 3 to about 0.8 g/cm3,
and in further embodiments from about 0.2 to about 0.5
g/cm3 . In additional embodiments, the carbon foam may
exhibit a B.E.T. surface area less than about 5 M2 /g and
typically in the range of about 1 m2/g to about 2 m2/g.
The carbon foam may be semi-crystalline or turbostrati-
cally-ordered and largely isotropic i.e., demonstrating physi-
cal properties that are approximately equal in all directions.
The carbon foam may exhibit pore sizes on the order of less
than 300µ although pore sizes of up to 500µ are possible. In
some embodiments, the thermal conductivities of carbon
foam may be less than about 1.0 W/m/° K. The compressive
strength of the carbon foam may generally range from about
300 p.s.i. to about 10,000 p.s.i., or more. In further embodi-
ments, the carbon foam may demonstrate compressive
strengths on the order of from about 2000 p.s.i. to about 6000
p.s.i. at densities of from about 0.4 g/cm 3 to about 0.5 g/cm3.
Additionally, the may exhibit relatively low overall B.E.T.
surface areas. Such surface areas are typically less than about
5 m2/g and are commonly in the range of about 1 m2/g to
about 2 m2/g.
As referenced above, a carbon foam body is used in form-
ing the infiltrated carbon foam composite. Carbon foam is
generally available in sheets or blocks and is readily machin-
able. The thickness of the carbon foam body for the infiltrated
carbon foam composite is not particularly limited. In some
embodiments, the thickness of the carbon foam body may
range from about 0.25 inches to about 4 inches or greater. In
some embodiments the thickness of the carbon foam body
may range from about 0.75 inches to about 1.5 inches, and in
further embodiments may be about 1 inch.
Carbon foams may be produced using a variety of feed-
stocks known to those skilled in the art. Carbon foam may be
any produced, for example, from pitches, mesophase carbon,
mesophase pitches, coal, coal extracts, coal derivatives. Fur-
ther, carbon foam may also be produced by carbonizing poly-
meric foams. Such polymeric foams may include, but are not
limited to, phenolic foams and resorcinol foams. Other types
of polymeric foams may include, but are not limited to, those
polymeric foams made from vinylidene chloride, furfuryl
alcohol, furan resins, polyacrylonitrile, polyurethane, combi-
nations thereof, or other carbonizable polymers. One suitable
carbon foam is a coal-based carbon foam commercially avail-
able in varying densities as CFOAM815, CFOAM® 20, and
CFOAM® 25 (Touchstone Research Laboratory, Ltd., Tria-
delphia, W.V.).
The infiltrated carbon foam composite further comprises
carbonized carbon aerogel located within cells of the carbon
foam body. The carbonized carbon aerogel is a carbon aerogel
that has been located in the cells of the carbon foam body and
subsequently carbonized at relative high temperatures to car-
bonize the carbon aerogel. The carbonized carbon aerogel
preferably is located in a majority of the cells of the carbon
foam. In some embodiments the carbonized carbon aerogel is
located in at least about half of the carbon foam cells, for
additional embodiments in greater than about 75% of the
carbon foam cells, and for still further embodiments in greater
than about 90% of the carbon foam cells. In other embodi-
ments, the carbonized carbon aerogel is contained in pre-
dominately all of the cells of the carbon foam body.
In the infiltrated carbon foam composite, a resin is located
in and fills the cells of the carbon foam body and around the
carbonized carbon aerogel. The resin substantially fills the
void space in the cells of the carbon foam body and the void
space of the carbonized carbon aerogel. As used herein
"resin" includes polymer or resin-based materials. In some
embodiments the resin is a thermoset resin. In certain
embodiments, the resin is a phenolic resin, such as Cellobond
J2027L or SC1008.
To form the infiltrated carbon foam composite a carbon
foam body is selected. The carbon foam for the carbon foam
body should be an open celled carbon foam. In order to
US 8,105,512 BI
3
infiltrate the carbon foam body with the carbon aerogel solu-
tion and a resin, the carbon foam should be open celled to
provide pathways for infiltration of the carbon aerogel solu-
tion and resin. The physical properties of the carbon foam can
vary widely and can depend upon the particular application
for the carbon foam composite.
The carbon foam body is infiltrated with a carbon aerogel.
The open cells of the carbon foam body are infiltrated with a
carbon aerogel solution used for forming the carbon aerogel.
The solvent of the carbon aerogel solution is then removed
leaving the carbon aerogel within the cells of the carbon foam
body. Techniques for forming a carbon aerogel are known to
those skilled in the art and may be generally used to form the
aerogel in the cells of the carbon foam body.
Next, the carbon aerogel is carbonized. To accomplish the
carbonization of the carbon aerogel, the carbon foam body
with the carbon aerogel in the cells of the carbon foam body
is placed in a furnace. The temperature is slowly increased
from ambient conditions up to about 900° C. The upper
temperature is not critical except that the upper temperature
should be high enough to carbonize the carbon aerogel con-
tained in the cells of the carbon foam body. One example of a
heating profile for carbonization is heating at 0.2° C./min
from ambient temperature up to 900° C. with isothermal
holds at about 150° C., 450° C., and 900° C., which results in
the carbonization of the carbon aerogel, thus forming a car-
bonized carbon aerogel. Other heating rates and temperature
profiles may be used as well.
Once the carbon aerogel has been carbonized, the carbon
foam body with the carbonized carbon aerogel is infiltrated
with a resin. Vacuum assisted resin transfer molding tech-
niques may be used for impregnating the carbon foam body
with the carbonized carbon aerogel with resin. The resin is
infiltrated into the carbon foam body and cured according to
the resin system being used. In certain embodiments, the resin
system may include, but is not limited to, a phenolic resin
system. Upon curing of the resin, the infiltrated carbon foam
composite has been formed.
The following examples will serve to illustrate the produc-
tion of the carbon foams of the present invention.
EXAMPLE
Infiltrated carbon foam composites were prepared and
tested as a thermal protection system. Half inch and one inch
thick carbon foam bodies were prepared from CFOAM® 15
(about 0.22 g/cc to about 0.28 g/cc), CFOAM® 20 (about
0.31 g/cc to about 0.33 g/cc), and CFOAM® 25 (about 0.46
g/cc to about 0.47 g/cc). The carbon foam bodies were infil-
trated with carbon aerogel. The carbon foam body/carbon
aerogel was subjected to carbonization by heating the sample
at 0.2° C./min from ambient temperature up to 900° C. with
isothermal holds at about 150° C., 450° C., and 900° C., to
produce carbonized carbon aerogel within the cells of the
carbon foam body. The carbon foam body/carbonized carbon
aerogel sample was infiltrated with phenolic resin using stan-
dard VARTM techniques.
Each of the infiltrated carbon foam composites was tested
as a thermal protection system. Samples were ex^osed to a
COz laserheat source at 150 W/cm2 and350 W/cm . Nitrogen
was flowed across the heated surfaces of the samples at Mach
0.4 flow conditions. The backside temperature (cold surface)
and mass loss of the samples were measured.
All samples tested saw less that 100° F. backside tempera-
ture rise during extreme heating. In general, the thick samples
performed better than thin ones. Comparison between carbon
foam densities showed that the higher density carbon foam
composites (CFOAM® 25) had better thermal characteristics
4
than the lower density carbon foam composites (CFOAM®
20) although in expense of much larger mass loss (25% vs.
5%). The composite prepared from one inch thick CFOAM®
20 with carbonized aerogel and J2027L phenolic resin illus-
5 trated unexpectedly good thermal and mechanical responses
at 350 W/cm2 . The temperature increase was less than 15° F.,
and the mass loss was around 14%.
All of the one inch thick samples tested at the 150 W/cm2
heat flux were consistent with the results from the 350 W/cm2
heat flux with the one inch thick CFOAM® 20/carbonized
10 aerogel/72027L phenolic resin composite performing the
best. Plain carbon foams, CFOAM® 20 and CFOAM® 25
and also aerogel infiltrated CFOAM® 25 were practically
unaffected mechanically at this thermal load due to their mass
loss values being less than 5%.
15 As the invention has been described, it will be apparent to
those skilled in the art that the same may be varied in many
ways without departing from the spirit and scope of the inven-
tion. Any and all such modifications are intended to be
included within the scope of the appended claims.
20	 What is claimed is:
1. An infiltrated carbon foam composite comprising:
a carbon foam body having a plurality of open cells dis-
tributed throughout the carbon foam body;
carbonized carbon aerogel located within at least a portion
of the cells of the carbon foam body; and
25	 a resin filling at least a portion of the carbon foam cells
containing carbonized carbon aerogel.
2. The infiltrated carbon foam composite of claim 1
wherein the carbon foam body has a density ranging from
about 0.05 g/cm3 to about 0.8 g/cm3.
30 3. The infiltrated carbon foam composite of claim 1
wherein the carbon foam body has a density ranging from
about 0.2 to about 0.6 g/cm3.
4. The infiltrated carbon foam composite of claim 1
wherein the resin is phenolic resin.
5. The carbon foam of claim 1 wherein the carbon foam
35 body has a density ranging from about 0.2 to about 0.6 g/cm3,
and wherein the resin is phenolic resin.
6. A method for making an infiltrated carbon foam com-
posite comprising the steps of:
forming a carbon aerogel in the cells of a carbon foam
40	 body;
carbonizing the carbon aerogel within the cells of the car-
bon foam body; and
infiltrating the carbon foam body having carbonized car-
bon aerogel within cell of the carbon foam body with a
45	 resin.
7. The method of claim 6 wherein the carbon foam body
has a density ranging from about 0.05 g/cm3 to about 0.8
g/cm3.
8. The method of claim 6 wherein the carbon foam body
has a density ranging from about 0.2 to about 0.6 g/cm 3 , and
50 wherein the resin is phenolic resin.
9. The method of claim 6 wherein the step of forming a
carbon aerogel in the cells of a carbon foam body forms a
carbon aerogel in at least half of the cells of the carbon foam
body.
55 10. The method of claim 6 wherein the step of forming a
carbon aerogel in the cells of a carbon foam body forms a
carbon aerogel in at least 75% of the cells of the carbon foam
body.
11. The method of claim 6 wherein the step of forming a
60 carbon aerogel in the cells of a carbon foam body forms a
carbon aerogel in predominately all of the cells of the carbon
foam body.


Infiltrated carbon foam composites

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