The shape factors of twelve calcined cokes of 50 × 70 mesh particle size were measured. The shape factors of the nine delayed petroleum cokes were all higher than those for the fluid coke, coal-tar pitch coke, and gilsonite coke. Heating a delayed petroleum coke between 1000 and 2750°C prior to grinding had a minor effect on the shape factor of the 40 × 70 mesh material. The relative crystallite orientation in the calcined cokes (as measured by four different X-ray diffraction criteria) varied markedly. Heat treatment up to 2750°C of a delayed petroleum coke produced a substantial increase in relative crystallite orientation, but the orientation fell far short of that found in Ceylon natural graphite. The relative grindability of the calcined cokes varied markedly, with the cokes of best crystallite alignment generally being the easiest to grind. On the other hand, the ease of grindability decreased sharply following heat treatment of a delayed petroleum coke between 1000 and 2000°C; the grindability was essentially constant for higher heat treatment temperatures.

The effect of using anthracite as a substitute filler material for petroleum coke in the manufacture of baked and graphitized bodies was studied. Bodies were prepared from two anthracites and a fairly typical petroleum coke, each of which was mixed with an equal proportion of the same coal-tar-pitch binder and extruded in ½ in. diameter rods. All of these rods were baked to 900°C, and part of them were further graphitized in a helium atmosphere to 2400 and 2800°C. A number of physical and chemical properties of the rods were studied and compared. At both graphitization temperatures, the bodies fabricated from the anthracites had (1) electrical resistivities at least 70% greater than those of the bodies fabricated from the petroleum coke, (2) lower apparent densities, (3) higher specific surface areas, (4) higher ash contents, (5) higher transverse breaking strengths, (6) smaller crystallite sizes, (7) less crystallite alignment, (8) larger interlayer spacings, and (9) mixed reactivity results with CO2. For the baked bodies, differences in properties (1) and (6) were less marked and differences in properties (2), (3), (4), and (5) were more marked.

Investigations are being continued by infrared, ultraviolet-visible, magnetic resonance, and mass spectral studies of coal and derivatives of coal. Infrared spectral studies of chars have provided further information on the assignment of infrared bands to oxygenated structures. In infrared spectra of coal the intensities of the infrared CH stretching absorption bands are found to be unexpectedly low. The experimental difficulties encountered with halide pellets of coal are discussed. Proton nuclear magnetic resonance studies have been carried out on a variety of coal derivatives. Indirect determinations of aromaticity, ring size, and degree of substitution have been made. These quantities have also been determined from the nuclear resonance spectrum of the pyridine extract of coal using pyridine-d5 as the solvent. The carbon-13 nuclear magnetic resonance technique can be used to study directly the chemical nature of carbon atoms in molecules. The method is of the most potential value in the detection of carbon atoms that have no hydrogen atoms because of complete substitution, as in tertiary butyl compounds, or because of unsaturation, as in completely substituted olefins and carbonyl compounds. Coal derivatives and similar substances are being investigated by the C13 technique. The decreased free-radical concentrations in coal vitrains have been investigated by electron paramagnetic resonance after chemical reduction. Considerable decrease of the free-radical content is effected; the ultraviolet-visible spectra also indicate this decrease. Ultraviolet-visible absorption and reflectance spectra of polycrystalline graphite have been determined; an absorption maximum was found at 2750 Å for graphite.

Magnetic susceptibility, electron spin resonance and analytical data are presented for chars and carbons prepared at 300–3000°C from polyvinyl and polyvinylidene chloride, representative of graphitizing and “non-graphitizing” materials respectively. The diamagnetic susceptibilities of the carbons formed from the respective polymers apparently reflect the differences in crystallite growth and organization accompanying their treatment at high temperature; but the development of unpaired electron spins in the polyvinylidene chloride chars exhibited certain anomalies, characterized by two maximal values of the electron spin concentration in chars formed in the region of 450 and 950°C respectively. The presence of traces of nitrogen in certain high-temperature carbons prepared from polyacrylonitrile, has no distinctive effect on their magnetic properties. The magnetic behavior of the carbons formed above about 800°C, and exhibiting a transition from positive to negative temperature dependence of susceptibility when prepared in the region of 1500°C, can be explained, at least qualitatively, on the basis of the two-dimensional electron gas model of carbon.

Polymeric deposits showing an electron spin resonance absorption were made by passing an electrical discharge through vapors of relatively simple organic compounds. Very high spin concentrations (1020/g) were obtained in films formed using naphthalene (C10H8) and anthracene (C14H10) vapors. Paramagnetic spin centers were also found in films deposited from vapors of decalin (C10H18) and of secondary butyl alcohol (C4H10O) but with much lower concentration. The free radial structures are either formed in the discharge itself and then trapped in the deposit or created by bombardment of the film after deposition, and seem to be predominantly of an aromatic nature. By studying the heat treatment dependence of the spin resonance in the temperature range 0–1000°C it is shown that they are distinct from those formed when such films are charred at temperature above 400°C.

Cationic surface sites have been identified on both production and vacuum heat treated carbon blacks, after oxidation in the presence of acid. Reduction of the electron deficient (oxidized) carbon surface by hydride-transfer mechanisms is described. Acid chemisorption in an oxygen atmosphere has been quantitatively related to the reduction of oxidized surface sites by hydride ion donation in concentrated formic acid. The anion exchange properties of oxidized carbons are discussed in terms of displacement reactions in water and aqueous base. The apparent stability of charged surface structures is attributed to aromatic resonance in the graphitic layer planes of microcrystalline carbons.

Surfaces Sand sections through a Pyrographite plate (Raytheon) have been investigated microscopically. Pyrographite consists of conical fiber bundles. The size of bundles varies; they start either at the beginning of deposition or during the growth of the plate. The divergence of cone bundles diminishes during deposition. When stress is applied cracks appear in Pyrographite, first parallel to the basal planes and they go through cone boundaries. At higher stresses an additional system of crevices develop, roughly perpendicular or inclined to the first cracks. The structural details have been made visible by etching with CrO3.

An apparatus has been constructed for measuring the static Young's modulus of carbons in bending at high temperature. The specimen is heated in a graphite tube furnace and its deflection under load is determined by measuring the deflection at three points with Linear Variable Differential Transformers and appropriate electronic circuits. The force-deflection curves are recorded on an X–Y recorder. Four basic types of carbons were measured, namely, those prepared from (1) soft filler–soft binder, (2) soft filler–hard binder, (3) hard filler–soft binder, and (4) hard filler–hard binder. The usual maximum at about 1800°C was observed for graphitized soft filler bodies; bodies with hard filler showed only a continuous decrease in modulus with increase of temperature. A system of temperature curves was obtained for soft filler–soft binder and for hard filler–hard binder rods as they were heat treated to successively higher temperatures. All the Young's modulus curves show maxima shifting in position with heat treatment except for the graphitized hard filler material.

The paper describes various regimes of gas flow encountered during permeability studies carried out on many types of artificial graphite. The materials investigated ranged from British nuclear reactor grade graphites, with permeabilities of about 1 cm2/sec, to fine pored graphites, developed for nuclear and rocket applications, with permeabilities approaching 10−12 cm2/sec. The techniques of measurement used to cover this very wide range are described, the accent being on the determination on the viscous, Knudsen and inertial permeability constants, which are basic parameters substantially independent of the physical properties of the fluid and the temperature of measurement.

In this review, the subject of electron spin resonance (ESR) in carbonaceous materials is critically examined, with particular emphasis on the physics of the phenomena. The literature contains many misinterpreted ESR experiments resulting from the lack of attention given to both the basic ESR phenomena and the microwave techniques necessary for their meaningful observation. Although a large number of experiments have been reported for the low-temperature chars, coals, and similar carbonaceous substances, there is still no completely satisfactory explanation for the origin of the observed ESR. On the other hand, for high-temperature carbons and graphites, there now exists convincing evidence that the ESR is due to charge carriers.