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115. The briquetting of graphite
387
ABSTRACTS resistivity, examined.
flexural
strength,
coefficient
of thermal
expansion
and X-ray
parameters
“Speer work partially supported under contract with General Electric-Hanford Atomic HLO work performed for the Atomic Energy Commission under Contract AT(45-l)-1250.
has also been
Products
Operation.
113. The effect of size reduction equipment on graphite properties Frank Rusinko, Jr. and W. E. Parker (Speer Carbon Company Research Laboratory, Niagara Falls, New York). Petroleum coke has been reduced in size in various types of size reduction equipment. Test samples were fabricated from the ground coke by molding and extrusion and, subsequently, graphitized. Properties of the final graphite were determined and did not show any marked effect from the type of side reduction equipment employed to grind the petroleum coke. 114. Effect of formulation on graphite strength R. B. Trask (Speer Carbon Company Research Laboratoryj Niagara Falls, New York). An analysis was made of the contributions of particle size distribution and pitch level to graphite flexural strength. Forty-two formulations, with a coarse filler fraction varied in six increments from 0 to 40 %, fine fractions varied from 60 to loo’/& and three pitch binder concentrations, were extruded into rods of 5 in. dia. These rods were baked to 75O”C, graphitized at constant rate to 2750°C sampled, and tested for flexural strength. Rods representing each formulation also were pitch impregnated after baking, were rebaked and graphitized along with the unimpregnated bars. An accurate prediction of strength along with the unimpregnated bars. An accurate prediction of strength based on particle size distribution alone was not possible because of pitch concentration effects. Graphite strength was correlated statistically with the amount of residual carbonized pitch per unit of baked rod volume and with the per cent of volume change during baking. 115. The briquetting of graphite R. H. de Vere, V. Fidleris, G. M. Jenkins and J. W. Phillips (General Electric Company Ltd., Wembley, Middlesex, England). The National Coal Board has developed techniques for briquetting coal without a binder by multiple compaction, or by introducing shear under load. In the present investigation these techniques have been applied to natural and artificial graphite in an attempt to produce strong dense materials suitable for use in atomic reactors. The densities of the compacts obtained were 2.18 g/ml in natural graphite and 2.06 g/ml in artificial graphite; the strengths were -2000 lb/in.’ in each case. It was found that, whereas these techniques improved the quality of materials normally briquettable by simple compaction, non-briquettable materials (e.g. + 350 B.S. mesh artificial graphite) could not be compacted satisfactorily by any means. The quality of the compacts was found to be very sensitive to particle size and size distribution in the subsieve range. On the whole, compact density decreased with decreasing particle size, whereas the strength increased. An empirical relationship S= KA’/’ between the strength (S) and the specific surface area (A) of the powder was obtained for electrographite powder compacted at 10 ton/in2. Annealing the compacts at 800°C reduced their densities by l-2 o/obut increased their strengths by -30%. The compacts were found to be extremely anisotropic, and experiments attempting to reduce this anisotropy are described. 116. The hot-working
of graphite bodies containing carbide particles*
J. L. White (General Dynamics, General Atomic, San Diego, California). In order to evaluate the feasibility of applying the concept of hot-working to fabricate graphite-matrix fuel compacts, an investigation has been made of the hot-working characteristics of a typical matrix graphite and of a matrix graphite containing carbide particles. The specimens for hot-working were prepared by hot-pressing a mixture of 90 o/ographite powder and 10 o/opitch. The carbide bearing specimens contained a dispersion of zirconium carbide particles approximately 100 microns in size. Deformations of the order of 40%
ABSTRACTS resistivity, examined.
flexural
strength,
coefficient
of thermal
expansion
and X-ray
parameters
“Speer work partially supported under contract with General Electric-Hanford Atomic HLO work performed for the Atomic Energy Commission under Contract AT(45-l)-1250.
has also been
Products
Operation.
113. The effect of size reduction equipment on graphite properties Frank Rusinko, Jr. and W. E. Parker (Speer Carbon Company Research Laboratory, Niagara Falls, New York). Petroleum coke has been reduced in size in various types of size reduction equipment. Test samples were fabricated from the ground coke by molding and extrusion and, subsequently, graphitized. Properties of the final graphite were determined and did not show any marked effect from the type of side reduction equipment employed to grind the petroleum coke. 114. Effect of formulation on graphite strength R. B. Trask (Speer Carbon Company Research Laboratoryj Niagara Falls, New York). An analysis was made of the contributions of particle size distribution and pitch level to graphite flexural strength. Forty-two formulations, with a coarse filler fraction varied in six increments from 0 to 40 %, fine fractions varied from 60 to loo’/& and three pitch binder concentrations, were extruded into rods of 5 in. dia. These rods were baked to 75O”C, graphitized at constant rate to 2750°C sampled, and tested for flexural strength. Rods representing each formulation also were pitch impregnated after baking, were rebaked and graphitized along with the unimpregnated bars. An accurate prediction of strength along with the unimpregnated bars. An accurate prediction of strength based on particle size distribution alone was not possible because of pitch concentration effects. Graphite strength was correlated statistically with the amount of residual carbonized pitch per unit of baked rod volume and with the per cent of volume change during baking. 115. The briquetting of graphite R. H. de Vere, V. Fidleris, G. M. Jenkins and J. W. Phillips (General Electric Company Ltd., Wembley, Middlesex, England). The National Coal Board has developed techniques for briquetting coal without a binder by multiple compaction, or by introducing shear under load. In the present investigation these techniques have been applied to natural and artificial graphite in an attempt to produce strong dense materials suitable for use in atomic reactors. The densities of the compacts obtained were 2.18 g/ml in natural graphite and 2.06 g/ml in artificial graphite; the strengths were -2000 lb/in.’ in each case. It was found that, whereas these techniques improved the quality of materials normally briquettable by simple compaction, non-briquettable materials (e.g. + 350 B.S. mesh artificial graphite) could not be compacted satisfactorily by any means. The quality of the compacts was found to be very sensitive to particle size and size distribution in the subsieve range. On the whole, compact density decreased with decreasing particle size, whereas the strength increased. An empirical relationship S= KA’/’ between the strength (S) and the specific surface area (A) of the powder was obtained for electrographite powder compacted at 10 ton/in2. Annealing the compacts at 800°C reduced their densities by l-2 o/obut increased their strengths by -30%. The compacts were found to be extremely anisotropic, and experiments attempting to reduce this anisotropy are described. 116. The hot-working
of graphite bodies containing carbide particles*
J. L. White (General Dynamics, General Atomic, San Diego, California). In order to evaluate the feasibility of applying the concept of hot-working to fabricate graphite-matrix fuel compacts, an investigation has been made of the hot-working characteristics of a typical matrix graphite and of a matrix graphite containing carbide particles. The specimens for hot-working were prepared by hot-pressing a mixture of 90 o/ographite powder and 10 o/opitch. The carbide bearing specimens contained a dispersion of zirconium carbide particles approximately 100 microns in size. Deformations of the order of 40%