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150. Development of a technique to thermally shock graphites
732
CARBON
Zishment,Netherlund). The lattice thermal expansion perpendicular and parallel to the basal planes of different pyrocarbon structures formed in a ff uidized bed has been measured by X-ray diffraction over the temperature range ZOO-1200°C. The results are correlated to the structuraf parameters characterizing the deposits. 148. Specific heat of soft carbons at low temperatures (0.5*-4~2°K) Part I P. Delhaes* and Y. Hishiyamat (Carbon Research Laboratory, State University of New York at Buffalo, Bu$alo, New York). The specific heat of a soft carbon heat treated in the range 1600”-3100°C was measured using an apparatus built into an He, cryostat. It is found that both the part Iinear with temperature as well as the square and cubic parts increase about in the same proportion with increasing disorder of the lattice. Exact extrapolation to T 9 0 is made difficult by presence of a strong peak at 0.6”K of unknown origin. *State of New York Postdoctoral Fellow. Now back at University of Bordeaux. tCabot Postdoctoral Fellow. 149. Specific heat of soft carbons at low temperatures (O*S0-4+SoK) Part II Y. Hishiyama*, E. Klutht and A. S. Vagh (Carbon Research Laboratory, State University ofNew York at Bu$alo, Buffalo, New York). Studies of specific heat were extended to soft carbons heattreated in the range of 700”-16OO”C, by using raw coke carbon rods and He,-cryostat. It has been found that the specific heat is much higher for the low heattreated material, being at 4*2”K, 9.3 times as great than for poiycrystalline graphite HTT 3100°C and showing a large linear component (32 times greater than for pife graphite). Again extrapolation to T -+ 0 is difficult due to the peak at 0.6°K. *Cabot Postdoctoral Fellow. TSpeer Carbon Postdoctoral Fellow. 150. Development of a technique to thermally shock graphites C. R. King (Los Alamos Scientjfic Laboratory, Los Alamos, New Mexico). A method will be described for ranking graphites on the basis of their resistance to thermal shock. The thermal gradient for this test is created by inductively heating the periphery of thin disks using an RF power supply. All test apparatus has intentionally been kept very simple. The data are obtained quickly; and all data have proven to be very reproducible. Experimental data will be presented ranking several common graphites that have been investigated to date. in these tests SX5 was the poorest performer and ATJS was the best performer on the basis of their resistance to thermal shock. 151. Thermal shock testing using focused electron beam heating R. D. Reiswig, P. E. Armstrong and L. S. Levinson (Los Alumos Scientific Laboratory, University of California, Los Alamos, New Mexico). An apparatus was assembled for testing small graphite samples 0*078 in. thick and about 4 in. in diameter for thermal shock resistance. Energy was deposited in an area roughly 3 in. in diameter on one face of the specimens by means of a focused electron beam, with specimens in uucuo. Visual observations during the rapid heating and cooling cycle detected failures by cracking or rupture, and subsequent microscopic observations on the tested samples detected damage in the microstructure. These results produced a ranking of various graphites in order of their thermal shock resistance. 152. Effects of fabrication on thermal shock resistance of graphites* G. T. Yahr and R. S. Valachovic (Oak Ridge National Laboratory, Oak Ridge, Tennessee). Observations of apparent effects of fabrication variables on the measured thermal shock resistance and associated thermal and mechanical properties of a number of graphites are reported. Both commercial graphites and experimental graphites were examined. *Research sponsored by U.S. Atomic Energy Commission under contract with the Union Carbide Corporation.
153. X-ray measurements of thermal motion in highly oriented pyrolytic graphite J. C. Sparks, Jr. and J. E. Epperson (Metak; and Ceramics Division, ORNL, Oak Ridge, Tennessee). X-ray
CARBON
Zishment,Netherlund). The lattice thermal expansion perpendicular and parallel to the basal planes of different pyrocarbon structures formed in a ff uidized bed has been measured by X-ray diffraction over the temperature range ZOO-1200°C. The results are correlated to the structuraf parameters characterizing the deposits. 148. Specific heat of soft carbons at low temperatures (0.5*-4~2°K) Part I P. Delhaes* and Y. Hishiyamat (Carbon Research Laboratory, State University of New York at Buffalo, Bu$alo, New York). The specific heat of a soft carbon heat treated in the range 1600”-3100°C was measured using an apparatus built into an He, cryostat. It is found that both the part Iinear with temperature as well as the square and cubic parts increase about in the same proportion with increasing disorder of the lattice. Exact extrapolation to T 9 0 is made difficult by presence of a strong peak at 0.6”K of unknown origin. *State of New York Postdoctoral Fellow. Now back at University of Bordeaux. tCabot Postdoctoral Fellow. 149. Specific heat of soft carbons at low temperatures (O*S0-4+SoK) Part II Y. Hishiyama*, E. Klutht and A. S. Vagh (Carbon Research Laboratory, State University ofNew York at Bu$alo, Buffalo, New York). Studies of specific heat were extended to soft carbons heattreated in the range of 700”-16OO”C, by using raw coke carbon rods and He,-cryostat. It has been found that the specific heat is much higher for the low heattreated material, being at 4*2”K, 9.3 times as great than for poiycrystalline graphite HTT 3100°C and showing a large linear component (32 times greater than for pife graphite). Again extrapolation to T -+ 0 is difficult due to the peak at 0.6°K. *Cabot Postdoctoral Fellow. TSpeer Carbon Postdoctoral Fellow. 150. Development of a technique to thermally shock graphites C. R. King (Los Alamos Scientjfic Laboratory, Los Alamos, New Mexico). A method will be described for ranking graphites on the basis of their resistance to thermal shock. The thermal gradient for this test is created by inductively heating the periphery of thin disks using an RF power supply. All test apparatus has intentionally been kept very simple. The data are obtained quickly; and all data have proven to be very reproducible. Experimental data will be presented ranking several common graphites that have been investigated to date. in these tests SX5 was the poorest performer and ATJS was the best performer on the basis of their resistance to thermal shock. 151. Thermal shock testing using focused electron beam heating R. D. Reiswig, P. E. Armstrong and L. S. Levinson (Los Alumos Scientific Laboratory, University of California, Los Alamos, New Mexico). An apparatus was assembled for testing small graphite samples 0*078 in. thick and about 4 in. in diameter for thermal shock resistance. Energy was deposited in an area roughly 3 in. in diameter on one face of the specimens by means of a focused electron beam, with specimens in uucuo. Visual observations during the rapid heating and cooling cycle detected failures by cracking or rupture, and subsequent microscopic observations on the tested samples detected damage in the microstructure. These results produced a ranking of various graphites in order of their thermal shock resistance. 152. Effects of fabrication on thermal shock resistance of graphites* G. T. Yahr and R. S. Valachovic (Oak Ridge National Laboratory, Oak Ridge, Tennessee). Observations of apparent effects of fabrication variables on the measured thermal shock resistance and associated thermal and mechanical properties of a number of graphites are reported. Both commercial graphites and experimental graphites were examined. *Research sponsored by U.S. Atomic Energy Commission under contract with the Union Carbide Corporation.
153. X-ray measurements of thermal motion in highly oriented pyrolytic graphite J. C. Sparks, Jr. and J. E. Epperson (Metak; and Ceramics Division, ORNL, Oak Ridge, Tennessee). X-ray