[in Japanese]

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Effects of various heat treatments on the peak shift and the change of contour of infra-red spectra of frits in PbO-B₂O₃-SiO₂ system were investigated. The infra-red reflection peak due to Si-O-Si streching vibration in the range of 900-1300cm^-1 shifted to higher wave number and the width of it decreased rapidly in the transformation range.
When the temperature was elevated to the deformation range the contour of the band became broad again. The peak shift to higher wave number was attributed to the increase of Si-O-Si bond strength in the silica rich phase after phase separation. It was considered that the decrease of peak width in the transformation range was due to the temporary good arrangement of Si-O-Si bond during phase separation. The increase of peak width in the deformation range was dependent on the development of the shoulder at 1050cm^-1 and 1150cm^-1 of the main reflection peak.

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Cubic polycrystalline Ni-Zn ferrite was hot-worked at 1300° to 1470°C and at stresses of 160 to 480kg/cm² using a press forging technique. The ferrite deformed easily at higher temperatures than 1400°C. However, as expected, grain elongation and orientation of cubic polycrystalline ferrite during hot forging were much harder than hexagonal polycrystalline ferrite. On the other hand, nonuniform microstructures in a forged sample were usually obtained, because of a severe shear strain gradient during deformation. The microscopic observation of outer surface of the forged sample showed that dislocation movement within the grains had much contribution to plastic deformation of the cubic polycrystalline ferrite. And this provided a possibility for controlling the microstructure of cubic polycrystalline ferrite by hot forging.

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Homogeneous and fairly largesized manganese-zinc ferrite single crystals, which are applicable to ferrite head in VTR, has been grown by the flame fusion method. The operation conditions of the flame fusion apparatus and the preparation of suitable powder by calcination of the manganese-zinc-iron oxalate are described. The flame fusion technique is feasible for the single crystal growth of ferrite by the use of particular raw powder, when the conditions for the growth are controlled properly.
X-ray microanalyser revealed that the distributions of manganese and zinc were homogeneous in the single crystal boule except the surface layer with the thickness of 0.5mm.
The dislocation density was determined by an etch-pit technique. The pit-density of annealed sample was about 4.5×10⁴ per cm and about one-tenth times smaller than that of the as-grown sample. The magnetic and the electric properties of the single crystals are also described.
The output and the mechanical wear resistances of the ferrite head manufactured from the single crystal under investigation are dependent on the orientation of crystal axes in head construction.

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A reliability and an applicability of the dispersion method for determining the thermal conductivity of granular solid materials proposed in previous report were discussed using the granular refractory materials (such as graphite-clay composite, SiC-clay composite material, steatite, forsterite, granite, marble, fused silica and electrocast alumina) and the following results were obtained.
When the thermal conductivity of granule was low, the values thermal conductivity of granule calculated using the modified Maxwell-Eucken's equations were not affected very much by the error in measurement for the two-phase mixture composed of granule and silicon rubber (about 15%). However, the range of scattering of the values of measurement was approximately 50% for the granular solid materials having a high value (about 15×10^-3cal/cm⋅sec⋅°C).
The thermal conductivity of granules having a middle value (8×10^-3cal/cm⋅sec⋅°C) was measured within an error of 7%.
The applicability of the dispersion method was given, based on the modified Maxwell-Eucken's equation, and was illustrated by a diagram (Fig. 3). When silicon rubber was used as a medium, maximum value of thermal conductivity of granules determined by the dispersion method was about 2×10^-2cal/cm⋅sec⋅°C.
When the open pores included in the granular solid materials were filled with silicon rubber during the preparation of two-phase mixture, the dispersion method could not be applied to determination of the thermal conductivity of porous solid materials.

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[in Japanese]

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The defective spinel in the system RO⋅Al₂O₃-Al₂O₃ at the lower temperature below about 1100°C, was synthesized, and it was named as γ-spinel and its meta-stable region was explanatorily draw by G. Yamaguchi in 1953.
In the present investigation, this phase boundary has been revealed experimentally by the X-ray diffraction procedures and the differential thermal analysis, and this defective spinel has been termed η-spinel according to the common nomenclature of the γ alumina group in which an alumina phase with the spinel symmetry is called as η alumina.
These η-spinel solid solution were synthesized from mixtures of the gibbsite Al(OH)₃ and the magnesium nitrate Mg(NO₃)₂⋅6H₂O aqueous solution.
The lattice parameters of all specimens quenched from 1150°C continuously varied from the stoichiometric composition of 50MgO:50Al₂O₃ to δ, γ orη alumina, while the specimens of 10MgO:90Al₂O₃ and 30MgO:70Al₂O₃ quenched from 1200°C and 1280°C, respectively, deviated from this continuous change. Simultaneously, in these specimens the α alumina phase exsoluted from these meta-stable solid solutions was observed (Fig. 1 & Fig. 2).
The starting point of the exsolution was decided on the intersection of the base line and the tangential line of the inflection point of the exothermic peak in the differential thermal analysis (Fig. 3 & Table 1).
The results of the X-ray diffraction fairly coincided with those of the differential thermal analysis. Consequently, the upper limit phase boundary of the meta-stable region for the η-spinel solid solution was decided on the system MgO⋅Al₂O₃-Al₂O₃ (denoted as the broken line in Fig. 4).

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The system BeO-ThO₂ was studied for the purpose of realizing the secondary fixed point for temperatures over 2000°C in the perfect binary system and of taking some informations on both nuclear materials and their ceramic coatings in a nuclear reactor.
Two sorts of DTA apparatus were used. One of them was to obtain the transition temperature of BeO and the eutectic temperature and also to measure peak areas attending with eutectoid. The other one was to determine the liquidus temperature of this system.
Both oxides were mixed with acetone in an agate mortar, pressed under the pressure of 3t⋅cm^-2 into discs and calcined for 25hrs at 1350°C in dry air. Measurements were made in a tungsten furnace filled with He gas of 1 atm.
The phase diagram of the system BeO-ThO₂ was obtained as a perfect binary system. It was found that both of the end members of this system showed no solid solubility, that the system had only one eutectic point and that the liquidus curve of this system was concave upwards near the eutectic composition which suggested that a deviation from an ideal solution would be large near that composition.
As the results, following data were obtained. Both α-BeO and ThO₂ coexisted below 2107±15°C at which temperatures α→β transition of BeO occurred all over the compositions. Both β-BeO and ThO₂ coexisted between 2107±15 and 2175±8°C. Eutectic temperature was 2175±8°C and its composition was at 21±1 mol%ThO₂. The heats of fusion of pure BeO and ThO₂ which were very difficult to obtain were estimated from the liquidus lines, assuming the ideal solution law near the both end members, obtained as 7.6±2.1 and 14.7±2.2kcal⋅mol^-1, respectively.
The transition temperatures of BeO in the system BeO-ThO₂ were constant all over the compositions, though its reproducibility was slightly decreased by the addition of ThO₂ component. The eutectic temperature was obtained with a very stable and reliable precision, so it would be possible to use as a secondary fixed point of temperature near 2200°C, like the transition temperature of pure BeO might be used near 2100°C.

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