- Email: [email protected]
Irradiation of graphite impregnated with furfuryl alcohol
543
CARBON Carbon 1966.Vol. 3. Printed in Great Britain.
Irradiationof Graphite Impregnated with Furfiuyl Alcohol* (Received 14 December 1964; in revised form24 November 1965) DIMENSIONAL changes induced by fast neutrons in graphite impregnated with furfuryl alcohol are reported in this note. The impregnation treatment is a process used to reduce the gas permeability of commercial graphite.(*) The process is based on introducing a thermosettingmonomer into the pores of the graphite, solidifying it by heating, and finally decomposing it to a carbon residue by further heating. This series is termed an “impregnation cycle” and is repeated a number of times until the desired permeability is obtained. A final heat treatment at greater than 2650°C is usually made. The monomer used in the work reported here was a mixture of ten moles of furfuryl alcohol to one mole of maleic anhydride. Theresiduewascarbonixed and heat-treated independent of the base stock and was shown, by conventional X-ray methods, to be a nongraphitixing carbon.
‘This work was supported by the U.S. Atomic Energy Commission under Contract AT(O4-3)-167, Project Agreement No. 12.
Figure 1 shows the effects of a series of impregnations on the pore structure of a commercial graphite. The den&y of the graphite ranged from 1.75 to 1.85 g/cm*, and the impregnation process raised this value by 4-7 %, depending on the carbon pickup. The irradiation experiments were carried out in a series of capsules in the core of the General Electric Test Reactor (GETR). The average irradiation temperatures were estimated by comparing the dimensional contractions of several samples of a reference needle coke graphite (NPR) with the contractions of a set of samples from the same material that were irradiated in an instrumented capsule.(*) Fast neutron exposures were calculated from fast flux data supplied by the Physics Group at the GETR. The irradiation data are shown in Tables 1 and 2. The HLM-85 base stock and impregnated material both appear to be more isotropic than the needle coke graphite on the basis of the contraction data from Capsule Experiments 311-9, 10 and 11. The dimensional stability was affected only slightly, if at all, by the 4-7 % increase in density in the impregnated carbon. After a short irradiation at 450” or 75O”C, little difference in dimensional stability was observed among the two corn-, mercially impregnated graphites (UC and HLM-85) and a conventional needle coke graphite (NPR). Thermal. expansion changes were noted in the samples which were cut perpendicular to extrusion but not in the samples cut parallel to extrusion.
-BASE STOCK 0 ONE IMPREGNATION TO 4 X 10-2CM2/SEC
0
. 0 0 l
THREE IMPREGNATIONS TO 2X 10-3CM2/SEC GRAPHlTlZATlON OFABOVE TO 4 X 10-3CM2/SEC FOURTH IMPREGNATION TO 4X IO-*CM2/SEC FIFTH IMPREGNATION TO 7XIO-5 CM2/SEC GRAPHITIZATION OF ABOVE TO IX IO-* CM2/SEC
0
-J 0.01
I .o
0.1 PORE
FIG. 1. Effect of five impregnation
DIAMETER
10.0
100
(+I
cycles on pore structure stock.
of commercial
graphite base
LETTERS
544
TO
THE
EDITOR
TABJX 1. DIMENBIONAL CHANGBS Irradiation Sample and treatment Temp.
(‘C)
conditions
Dimensional change,
Exposure, nvt X 10-‘I, E~0.18 MeV
M/L Parallel to extrusion
( %) Perpendicular to extrusion
HLM-85,
base stock
625-775
0.7
+0.12
+0.06
HLM-8.5,
impregnated
3 times
62.5-775
0.7
-0.10*0.02
-0.05
HLM-85,
impregnated
4 times
-0.10
+0.13
625-775
0.7
NPR, needle coke
62.5-775
0.7
HLM-85.
base stock
450-800
4
HLM-85,
impregnated
3 times
450-800
HLM-85,
impregnated
4 times
450-800
NPR, needle coke HLM-85,
base stock
HLM-85,
impregnated
HLM-85,
impregnated
HLM-85,
impregnated
311-9 *to.05
311-9 311-9
-0.04
311-9
-0.96
-0.36
311-10
4
-0.98
&O.OOS -0.25
4
-1.22
-0.54
311-10
450-800
4
-1.59
-0.49
31110
575-700
4
-0.91
-0.64
311-11
3 times
575-700
4
-0.92
-0.64*o.a2
31111
4 times
575-700
4
-0.90
-0.67
311-11
575-700
4
-1.04
-0.65
425-475
1
-0.22jro.02
-0.22
NPR, needle coke 5 times
0.00
Capsule experiment number
&to.07
f0.005
311-10
311-11 fO.02
311-7
UC, impregnated
425-475
1
-0.34*0.00
-0.28*0.06
311-7
NPR, needle coke
425-475
1
-0.22*0.05
-0.191to.01
311-7
675-800
1
-0.12*0.01
-0.08~0.02
311-8
UC, impregnated
675-800
1
-0.09~0.01
+0.01
311-8
NPR, needle coke
675-800
1
-0.03
+0.07*0.19
HLM-IS,
impregnated
5 times
f0.02
f0.08
311-8
TABLE 2. THQWAL EXPANSION Irradiation
Thermal expansion coefficient “C x lo@, RT” to lOOO=C
conditions
Sample and treatment Temp.
CC)
HLM-85,
impregnated
-
HLM-85,
impregnated
425-475
HLM-85,
impregnated
HLM-85,
base stock
4.50-800 -
HLM-85,
base stock
450-800
HLM-85,
base stock
450-800
Exposure,
E>O.l8
nvt X 10-*I, MeV
Parallel to extrusion
1 1
Perpendicular to extrusion
-
3.47
-
4.25
-
4.00
2.87
4.04
1
2.80
4.21
1
2.91
4.41
-
lRT = room temperature. REFERENCES TULLY G. R., JR.,and DIBSBLHOR~TB. F., A Process for making graphite less permeable to gases at high Report GA-2318. temperatures, p. 91, USAEC General Atomic Division, General Dynamics Corporation (February 1963). HXLM J. W., The H-4, H-5, and H-6 irradiation graphiteexperiments : irradiation of N-reactor Interim report No. 1, p. 99, USAEC Report HW81250A, Hanford Atomic Products Operation (October 1964).
General AtwmksDivision General Qvnamics Corporation John JAY H@ki~~~~toty for
Purr
&Jn D@J,
and
Applied Science
Cariforn~
G. B. ENGL~ B. F. DI~BBLHOXJJT G. R. TJJLLY Jr. w. P. WALLACE
CARBON Carbon 1966.Vol. 3. Printed in Great Britain.
Irradiationof Graphite Impregnated with Furfiuyl Alcohol* (Received 14 December 1964; in revised form24 November 1965) DIMENSIONAL changes induced by fast neutrons in graphite impregnated with furfuryl alcohol are reported in this note. The impregnation treatment is a process used to reduce the gas permeability of commercial graphite.(*) The process is based on introducing a thermosettingmonomer into the pores of the graphite, solidifying it by heating, and finally decomposing it to a carbon residue by further heating. This series is termed an “impregnation cycle” and is repeated a number of times until the desired permeability is obtained. A final heat treatment at greater than 2650°C is usually made. The monomer used in the work reported here was a mixture of ten moles of furfuryl alcohol to one mole of maleic anhydride. Theresiduewascarbonixed and heat-treated independent of the base stock and was shown, by conventional X-ray methods, to be a nongraphitixing carbon.
‘This work was supported by the U.S. Atomic Energy Commission under Contract AT(O4-3)-167, Project Agreement No. 12.
Figure 1 shows the effects of a series of impregnations on the pore structure of a commercial graphite. The den&y of the graphite ranged from 1.75 to 1.85 g/cm*, and the impregnation process raised this value by 4-7 %, depending on the carbon pickup. The irradiation experiments were carried out in a series of capsules in the core of the General Electric Test Reactor (GETR). The average irradiation temperatures were estimated by comparing the dimensional contractions of several samples of a reference needle coke graphite (NPR) with the contractions of a set of samples from the same material that were irradiated in an instrumented capsule.(*) Fast neutron exposures were calculated from fast flux data supplied by the Physics Group at the GETR. The irradiation data are shown in Tables 1 and 2. The HLM-85 base stock and impregnated material both appear to be more isotropic than the needle coke graphite on the basis of the contraction data from Capsule Experiments 311-9, 10 and 11. The dimensional stability was affected only slightly, if at all, by the 4-7 % increase in density in the impregnated carbon. After a short irradiation at 450” or 75O”C, little difference in dimensional stability was observed among the two corn-, mercially impregnated graphites (UC and HLM-85) and a conventional needle coke graphite (NPR). Thermal. expansion changes were noted in the samples which were cut perpendicular to extrusion but not in the samples cut parallel to extrusion.
-BASE STOCK 0 ONE IMPREGNATION TO 4 X 10-2CM2/SEC
0
. 0 0 l
THREE IMPREGNATIONS TO 2X 10-3CM2/SEC GRAPHlTlZATlON OFABOVE TO 4 X 10-3CM2/SEC FOURTH IMPREGNATION TO 4X IO-*CM2/SEC FIFTH IMPREGNATION TO 7XIO-5 CM2/SEC GRAPHITIZATION OF ABOVE TO IX IO-* CM2/SEC
0
-J 0.01
I .o
0.1 PORE
FIG. 1. Effect of five impregnation
DIAMETER
10.0
100
(+I
cycles on pore structure stock.
of commercial
graphite base
LETTERS
544
TO
THE
EDITOR
TABJX 1. DIMENBIONAL CHANGBS Irradiation Sample and treatment Temp.
(‘C)
conditions
Dimensional change,
Exposure, nvt X 10-‘I, E~0.18 MeV
M/L Parallel to extrusion
( %) Perpendicular to extrusion
HLM-85,
base stock
625-775
0.7
+0.12
+0.06
HLM-8.5,
impregnated
3 times
62.5-775
0.7
-0.10*0.02
-0.05
HLM-85,
impregnated
4 times
-0.10
+0.13
625-775
0.7
NPR, needle coke
62.5-775
0.7
HLM-85.
base stock
450-800
4
HLM-85,
impregnated
3 times
450-800
HLM-85,
impregnated
4 times
450-800
NPR, needle coke HLM-85,
base stock
HLM-85,
impregnated
HLM-85,
impregnated
HLM-85,
impregnated
311-9 *to.05
311-9 311-9
-0.04
311-9
-0.96
-0.36
311-10
4
-0.98
&O.OOS -0.25
4
-1.22
-0.54
311-10
450-800
4
-1.59
-0.49
31110
575-700
4
-0.91
-0.64
311-11
3 times
575-700
4
-0.92
-0.64*o.a2
31111
4 times
575-700
4
-0.90
-0.67
311-11
575-700
4
-1.04
-0.65
425-475
1
-0.22jro.02
-0.22
NPR, needle coke 5 times
0.00
Capsule experiment number
&to.07
f0.005
311-10
311-11 fO.02
311-7
UC, impregnated
425-475
1
-0.34*0.00
-0.28*0.06
311-7
NPR, needle coke
425-475
1
-0.22*0.05
-0.191to.01
311-7
675-800
1
-0.12*0.01
-0.08~0.02
311-8
UC, impregnated
675-800
1
-0.09~0.01
+0.01
311-8
NPR, needle coke
675-800
1
-0.03
+0.07*0.19
HLM-IS,
impregnated
5 times
f0.02
f0.08
311-8
TABLE 2. THQWAL EXPANSION Irradiation
Thermal expansion coefficient “C x lo@, RT” to lOOO=C
conditions
Sample and treatment Temp.
CC)
HLM-85,
impregnated
-
HLM-85,
impregnated
425-475
HLM-85,
impregnated
HLM-85,
base stock
4.50-800 -
HLM-85,
base stock
450-800
HLM-85,
base stock
450-800
Exposure,
E>O.l8
nvt X 10-*I, MeV
Parallel to extrusion
1 1
Perpendicular to extrusion
-
3.47
-
4.25
-
4.00
2.87
4.04
1
2.80
4.21
1
2.91
4.41
-
lRT = room temperature. REFERENCES TULLY G. R., JR.,and DIBSBLHOR~TB. F., A Process for making graphite less permeable to gases at high Report GA-2318. temperatures, p. 91, USAEC General Atomic Division, General Dynamics Corporation (February 1963). HXLM J. W., The H-4, H-5, and H-6 irradiation graphiteexperiments : irradiation of N-reactor Interim report No. 1, p. 99, USAEC Report HW81250A, Hanford Atomic Products Operation (October 1964).
General AtwmksDivision General Qvnamics Corporation John JAY H@ki~~~~toty for
Purr
&Jn D@J,
and
Applied Science
Cariforn~
G. B. ENGL~ B. F. DI~BBLHOXJJT G. R. TJJLLY Jr. w. P. WALLACE