Packing experiment by press moulding with various pressures on high purity sea-water magnesia grain mixes corresponding to the Andreasen continuous-grading below 4mm showed that the q of mix for the closest packing (q_ρm) shifted from 0.3 to 0.4 as pressure got higher, because a body with a higher q would have a higher degree of crushing of grain, and degree of crushing was less than roseki and silicon carbide grain.
Batch compression equations the Kawakita equation in particular were examined with using the packed density by packing method with stick penetration for the initial density, and it was found that the coefficient could be expressed as a function of q.
When the moulded mixes were fired at SK 18# and SK 34#, the q_ρm shifted from 0.4 to 0.2 as firing temperature got higher, because a body with a lower q have a higher firing shrinkage as firing temperature got higher. And it was proved that the firing shrinkage of a body could be expressed as a function of q. On the other hand, a closed pore was increased as firing temperature and q got higher respectively.
Thus from the relation above, it was proved that the packing density of fired body could be expressed as a function of q and applied pressure with the packed density by stick penetration, in its turn, with that of calculation by previous report.
Attempts at a grading has removal tendency of intermediate component from continuous-grading showed to be ineffective for obtaining a closer packing, lower permeability and higher hot-strength.
On the other hand, a spring back phenomenon was noticed in press moulding, but that of continuous-grading was smaller than that of a grading has removal tendency of intermediate component. It was predicted from the results that the continuous-grading would be more adequate for achieving the closer packing with more high pressure.
From the results, for achieving the closer packing, the lower closed porosity, the lower permeability and the higher hot-strength, the grading should be continuous-grading and the q of mix should be 0.2-0.3.

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Studies have been made on the heat of wetting (ΔH_i) at 25°C in water for various BeO powders which were prepared at various temperatures from 200° to 1000°C and the shrinkage of compacts under heating rate of 10°C/min.
1) The values of ΔH_i increase from about 400 to 1500 erg/cm² with outgassing temperature from 200° to 800°C.
2) ΔH_i reaches maximum at about 800°C for those except CF-BeO (NGK Insulators, Ltd.), ΔH_i of which increases monotonously to 1000°C.
3) Although ΔH_i of BeO powders obtained from hydroxide show the highest values and ΔH_i from sulfate are higher than CF-BeO between 200° and 1000°C, sinterability increases with decreasing ΔH_i.
4) The amounts of gas desorbed from the BeO powders are decreased with increasing the outgassing temperature except CF-BeO, those of which are less between 600° and 800°C than between 800° and 1000°C.

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A metastable crystal was found to precipitate in K₂O-Ta₂O₅-Nb₂O₅ glasses with addition of small amounts of Al₂O₃ and SiO₂ on heating prior to precipitation of a perovskite-type K(Ta, Nb)O₃ crystal.
X-ray fluorescence analyses showed that the major components of the metastable crystal are K₂O, Ta₂O₅ and Nb₂O₅ and the ratio of KO_0.5 to the sum of TaO_2.5 and NbO_2.5 is from 0.60 to 0.80. Powder X-ray diffraction analyses revealed that this metastable crystal is a pyrochlore-type and its cell dimention is 10.62Å. From the relative intensities of X-ray diffraction lines, the composition of the crystal was calculated to be K_1.5(Ta_0.65, Nb_0.35)₂O_5.75.
Both the X-ray diffraction pattern and infra-red spectrum of the mother glasses were much more alike to those of the pyrochlore-type crystal than the perovskite-type K(Ta, Nb)O₃ crystal which formed in the glasses after the precipitation of the pyrochlore-type crystal.
The pyrochlore-type crystal could be produced only by crystallization of its mother glasses or the melts, but not by ordinary solid state reaction of its raw materials.
On the basis of the above results, the precipitation of the metastable pyrochlore-type crystal prior to the formation of the stable perovskite-type K(Ta, Nb)O₃ crystal was ascribed to the similarity in structure between the pyrochloremtype crystal and the mother glasses. Furthermore, in view of the finding that the metastable pyrochlore-type crystal precipitated has a structure with deficiencies of K⁺ and O^2- ions in lattice sites, the structure of the mother glasses is considered to be essentially composed of a random network of TaO₆ and NbO₆ octahedra and K⁺ ions being situated in some holes of the network.

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La-doped BaTiO₃-Bi₂O₃ composite ceramics prepared by a soaking method (sintered bodies of La-doped BaTiO₃ being dipped into an alcoholic solution of BiCl₃ for several days, then fired to give rise to Bi₂O₃ matrix along the grain boundaries) exhibit a two-step anomalous increase of resistivity around room temperature and above the Curie point, when non-ohmic contact electrodes such as Ag are applied. A surface barrier-layer built in the interface between the non-ohmic electrode and the sintered body with a modified texture gives rise to an anomaly not only in the resistivity-temperature characteristic but also in the capacitance (C)-voltage (V) characteristic.
The plots of 1/C² vs. V deduced from the C-V characteristics under reverse bias to the surface barrier suggest a constant value of ca. 1.3V for the built-in voltage in the temperature range between room temperature and 58°C (at 1kHz) and in the frequency range between 0.5 and 30kHz (at 1°C). Each straight line in the 1/C² vs. V plot reaches the maximum at the critical reverse bias, which shifts to higher voltages with temperature and frequency. It is demonstrated that the type of the surface barrier-layer is the one of modified MOS type.

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The properties of the porous materials, such as permeability, moisture adsorption, water absorption and durability for slag-action, are affected by the pore structure. In this study, the pore size distribution of the accessible pore of the sintered MgO was measured with the mercury pressure porosimeter and the through pore was measured with the back diffusion method. The validity of these methods of pore size distribution measurement especially for the back diffusion method was discussed. The slip flow component (K₀) of the permeability coefficient calculated from the pore size distribution of the back diffusion method agreed well with that obtained by permeability measurement. It was found that the back diffusion method is very available for the through pore size distribution measurement.
The shrinkage and the change in the pore size distribution by sintering were measured. The pore structure is changed by sintering not only in porosity but also remarkably in tortuosity. The tortuosity plays very important roles in permeability and slag-action of refractory as well as the pore size distribution.

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The waste mud eliminated from aggregate plants dotting in Rokko district, Hyogo Prefecture, was studied on its utilization for a raw material of artificial light weight aggregate.
The mud was subjected to chemical and mineral analyses and also to measurements of the softening and the bloating temperatures. On the basis of these data, heating tests were made by using both a laboratory furnace and a test rotary kiln, and the following process was proposed.
1st stage: Mixing of the mud with 1.0-1.5% coke and 2-4% iron oxide (Fe₂O₃).
2nd stage: Pelletizing of the mixture to a suitable size for light weight aggregate.
3rd stage: Heating of the pellet at a temperature range between 1200°C and 1220°C for 30-35 minutes.
The light weight aggregate produced by this process has a density of 1.25 at dry pellet, a water absorption ratio of 7.8% and compression strength of 434 kg/cm² at the standard concrete test. These qualities are sufficiently compatible with conventional articles of light weight aggregate. The proposed process is practicable for the utilization of various kinds of waste mud.

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