Crack propagation behavior of a chemical vapor deposited (CVD) Si₃N₄–TiN composite was investigated by micro-indentation fracture (MIF) and high-resolution electron microscopy (HREM) techniques. TiN fibers are homogeneously dispersed in large Si₃N₄ grains (about 8 μm in diameter), leading to an intragranular nano-composite structure, and their interfaces were directly bonded without any other phases. The main fracture mode is a mixed type of intergranular and transgranular fracture. Nanometer-sized TiN dispersed in the matrix grains interacts with cracks, generating crack bridging and microcracking which toughens the composite.

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Morphology of platelet-type hematite particles (α-Fe₂O₃) produced by the gel-sol method was investigated by both scanning electron microscopy and transmission electron microscopy. In order to determine the orientation of crystal surfaces and make clear structural defects inside the particles, thin samples for transmission electron microscopy were prepared by using an ultra-microtome. The platelet-type particles were found to be single crystals with thickness about 0.2 μm, and most of the particles were bound by {0001} basal planes and {01\bar12} side planes. These results were obtained from the experimental condition of the incident electron beam being parallel to both basal planes and side planes of the sliced samples, which was confirmed by sharpness of the contrast of crystal edges at low magnification and also the homogeneous contrast of lattice images near the crystal edges at high magnification. Furthermore, it was disclosed that some of the particles contained stacking faults on {0001} planes and/or twins.

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In the roasting process of chromite, the problems such as aggregation of pellets or sticking to the wall cause the irregular operation of the rotary kiln. In order to solve these problems, the duplex-pellet method was proposed for roasting of chromite ore. This pellet consists of core and shell. The shell is intended to play a role to prevent aggregation or sticking by the addition of much residue of roast. The residue which is produced in leaching of the roast of chromite ore has a higher melting point than the conventional roast charge.
In the present study, to research the basic problem of the duplex pellet technology, the conversion ratio of core and shell having various contents of residue was measured and identification of roast by X-ray analysis was also conducted. From these results, the appropriate compositions of core and shell were determined.

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A study has been made to investigate the effects of methanol and ethanol additions in dilute hydrochloric acid leaching of polymetallic sea nodules. In the absence of additives, the hydrochloric acid solution in an aqueous medium (2.75 kmol/m³) leaches out only copper and iron in considerable amounts and more than 90% recovery of all the metals are achieved only when a very strong concentration of acid (11 kmol/m³) is used. It has been found that metal recoveries can be considerably improved even in 2.75 kmol/m³ hydrochloric acid solution if an appropriate amount of methanol or ethanol is incorporated with it. The addition of 75 vol% of methanol in the 2.75 kmol/m³ hydrochloric acid system has been found to recover more than 90% of each metal. The requirement of ethanol has been found to be 18.5 vol% to achieve the same degree of recovery of metals in dilute hydrochloric acid solution. The effects of other parameters such as period of leaching and acid concentration on the recovery of metals in the alcoholic hydrochloric acid leaching system have also been studied.

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The aluminothermic reduction of titanium oxide was studied at 1973 K in an atmosphere of argon and alumina crucible. The overall reaction, TiO₂+4/3Al=Ti+2/3Al₂O₃, was finished within about 10 min.
When the molar ratio of aluminum to titanium oxide (X_Al⁄X_TiO2) was 4/3 (which corresponds to the stoichiometric ratio), an alloy containing 5 mass% oxygen and 15 mass% aluminum was obtained. If the ratio was increased, aluminum content increased and oxygen decreased. For an intermetallic composition where 36 mass% of aluminum is necessary, oxygen content was 1.5 mass%. The possibility of reducing oxygen content was demonstrated by decreasing the activity of alumina in the slag.

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The relationship between erase-write characteristics or write/erase repetition characteristics and the layer structure of magneto-optical disks, was studied both experimentarily and by computer simulation. For tri-layer structure disks such as Sub./SiN_x/TbFeCo/SiN_x, an erase power of 11.5 mW is needed to erase a recorded domain, perfectly. The carrier level of tri-layered disks decreases with increasing write/erase repetition cycle. This is due to structure relaxation in the recording film which is caused by heating above a maximum temperature of 350°C.
A quadri-layer structure is studied which has a thinner recording layer and a metal layer, whose thermal conductivity is low. With this structure, the carrier level decreases after repeated write/erase processes. As the maximum temperature on the recording film is higher than 370°C, there is also structure relaxation in the recording film. When Al, whose conductivity is large, was used as the metal layer, the number of the write/erase repetition cycles was increased and there was no structure relaxation when the maximum temperature was lower than 300°C. The disk incorporating this structure has a large carrier to noise ratio. Using these results, the disk structure was optimized. After repetition of erase and write, C/N did not change. This disk has high reliability against thermal resistance.

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An attempt to apply CVD Al₂O₃ coating as an intermediate layer to ZrO₂-8 mass% Y₂O₃/Ni–22Cr–10Al–1Y thermal barrier coatings (TBCs) for protecting the Ni–22Cr–10Al–1Y bond coat from oxidation during cyclic operations was evaluated in this study. Results of this study showed that the intermediate CVD Al₂O₃ layer between the zirconia top coat and the Ni–22Cr–10Al–1Y bond coat can effectively reduce the oxidation rate of the bond coat and hence remarkably improve the performance of TBCs under thermal cycling tests at 1273 K. However, optimization of the CVD process parameters is needed to exclude the adverse effects induced by the application of CVD Al₂O₃ in the TBC systems; i.e., an increase in operationally induced stresses and premature failures resulting from undesirable Al₂O₃ morphologies. It was concluded that the thickness and microstructure of CVD Al₂O₃, which are affected by the processing parameters, are the main factors influencing the cyclic life of triplex ZrO₂-8 mass% Y₂O₃/CVD Al₂O₃/Ni–22Cr–10Al–1Y thermal barrier coatings.

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As a means for improving the iron loss in grain oriented silicon steel sheet, a TiN ceramic film was formed by CVD method on polished silicon steel sheet. The following results were obtained.
(1) The TiN ceramic film moderately increased the magnetic flux density B₈ (T) of the silicon steel sheet by 0.009–0.012 T, while the iron loss W_17⁄50 (W/kg) was dramatically improved by 0.11–0.23 W/kg. This improvement in iron loss is more marked in silicon steel sheet with a higher magnetic flux density. For example, in the silicon steel sheet products with B₈=1.93 T, W_17⁄50=0.89 W/kg, the final magnetic properties after magnetic domain refinement manifested an ultra-low iron loss of 0.57 W/kg, which corresponds to an improvement in iron loss of 36%.
(2) The improvement in iron loss when the TiN film was formed on a polished silicon steel sheet by the thermal CVD method was superior by 0.01–0.03 W/kg than that by plasma CVD.
(3) In a comparison between the results by the CVD and PVD methods, a similar degree improvement in iron loss by the PVD method (HCD) of 0.01–0.05 W/kg resulted than that by CVD.

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Solute contents of cellular structure formed in a rapidly quenched Al-8 mass% Fe alloy at different growth rates calculated with the LKT theory are examined. The rate of increase of the average cell composition with growth velocity is compared with that predicted by the Ivantsov model.

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Two long relaxation times, τ₁ and τ₂, and large static dielectric constants are obtained from the dielectric dispersion curves of slightly reduced rutile in the temperature range from 100 to 300 K by a time-domain spectroscopy. Temperature dependence of dc resistivities estimated with these values after Spenke is in good agreement with the previous data obtained by a four probe method. The deep donor level and the effective mass of the donor in rutile crystals are nearly equal to those of SnO₂ crystals. It is found that the quite small mobility of rutiles is not due to large effective mass, but due to large static dielectric constant but much larger relaxation time.

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