We have prepared ceramic thin films on a glass substrate by a sol-gel method. Film thickness can be controlled by a set of operating conditions. Base sheet, however, is needed because those films are very thin. In this case internal stress certainly occurs in a thin film in every material. Internal stress is the cause of crack and exfoliation.
Stress in sol-gel coating films was mainly tensile. It decreased with an increase of film thickness. This trend was opposite to those observed in sputter and vacuum evaporation methods.
The occurrence cause of stress was that volume shrank with the decrease of pore at heat treatment. This was confirmed from the BET value at heat treatment temperature. Resistivity was not dependent on stress but on the occurrence cause of stress.

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The stirred mill is regarded as one of the most efficient devices for micronizing materials and has come to be actively used for preparation of fine particles. Recently, the demand for ultrafine particles was increased in many kinds of industries.
In this paper, an autogenous grinding to get submicron or micronized particles based on frictional action of feed material has been carried out using a stirred mill. The mill used was made of stainless steel and its volume was about 5.5 liters and has 12 impellers. Sample used was limestone. The feed mass was 6kg and the feed size was 13-20mm.In the present work, a operating parameter was stirring speed. The ground products were sieved in the size range from feed size to 325mesh (45μm), and from 45 to 0.17 μm, the size distributions were measured by a laser diffraction and scattering method. The progress of grinding was evaluated by the increasing rate of submicron or micronized particles in products.
As a result, the following experimental equation was obtained Q₁=9.1×10^-5 (nt) ^0.60, where Q₁ is the mass fraction of submicron particles, n, the rotational speed of impeller and t, grinding time.

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In recent years, the high-precision, high-speed control of the proportional control solenoid-valve in the hydraulic system has become an important subject of research. Under certain driving conditions, it has been improved in the fluid forces which occur within the spool and the solenoid force. This is very valuable to the advancement of design.
The aim of this study is to design and develop the high efficiency in the proportional control solenoid-valve used with respect to design parameters which are improved stability and speed of response. The present study deals with the estimation of the dynamic characteristics of the proportional control solenoidvalve used in variance analysis. From these results, one of the characteristics was selected as the most important design parameter which simulates the best dynamic characteristics of the proportional control solenoid-valve.

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Dense sintered composites of ZrO₂ (2mol% Y₂O₃) and WSi₂ have been fabricated by hot isostatic pressing for 2 h at 1500°C under 196 MPa. They contain a small amount of W₅Si₃; during sintering, WSi₂ decomposes into W₅Si₃ and amorphous Si. The ZrO₂ particles in the composites consist of only t-ZrO₂ Microstructures and mechanical properties are examined, in connection with increased Zr0₂ content. The fracture toughness and bending strength of the composite with 40 mol% ZrO₂ addition are 7.1 MPa·m^1/2 and 1010 MPa, respectively.

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Well-densified composites with the compositions of ZrO₂ (2Y) /WSi₂=60/40 and 80/20mol% have been fabricated by hot isostatic pressing for 2 h at 1500°C and 196 MPa.Electric resistivities (ρ) between both composites change drastically; the former and latter composites correspond to the metallic and insulating materials, respectively. They are strongly dependent on the textures. Laminated materials with the compositions of ZrO₂ (2Y) /WSi₂=(60/40)/(80/20)/(60/40)mol% have been able to be prepared by the same technique. Overall electric resistivities in the perpendicular and parallel directions for the interfaces are determined to be ρ⊥≈1×10¹¹ and ρ₁₁≈1×10^-4Ω·cm, respectively. The residual stress as much as≈200 MPa is induced in the interfaces.The fracture toughness (K_IC) is much affected by the residual stress.

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Recently we have proposed a new room temperature preparation method for the Co-Cr perpendicular magnetic recording medium with large perpendicular magnetic anisotropy and high coercivity. In this paper, the microstructure change of the films with increasing thickness was observed by a high resolution SEM and compared with their magnetic properties.It was found that the Co-Cr film shows a dense microstructure with faint grain boundaries at the initial growing stage, but channels develop with film growth. The film with a high coercivity has a fine grained structure with a grain size of about 20nm. No segregation in grains was observed unlike that of the conventionally sputter deposited Co-Cr films.It is concluded that the magnetic separation between grains due to the developed channels is responsible for the increase in coercivity.

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A software based random pulser operated on a personal computer is reported in this paper. A printer I/O port of the computer which removes completely a hardware burden is used as the outlet of the pulse train. The random pulser sends out pulses whose intervals obey an exponential distribution. Series of exponentially random numbers which govern the time intervals are provided by uniformly distributed pseudo random numbers generated by Turbo-C. The mean rate f₀ of a pulse train can be set at will. In addition, a time-dependent f₀ which follows a function f₀ (t) of t can also be furnished in the pulser. The maximum rate depends on the computer employed. With PC486HG (EPSON: i486DX2, 50MHz), a maximum rate 9.1×10⁴ cps was achieved.

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Deterioration of initial permeability (μ_i) with respect to frequency and ef ect of Fe²⁺ on low core loss has been investigated with reference to chemical composition, sintering condition and microstructure on the MnMgZn ferrites. Frequency deterioration of μ_i increased with MnO addition to the MgZn ferrite most likely. This seems due to a relaxation phenomenon. Relaxation time (τ) and activation energy (Q) were calculated by using the relationshipsωτ=1 and the Bolzmann factor. Activation energies for MgZn and MnMgZn ferrites were found to be 0.14eV and 0.36eV, respectively. Results suggest that the diffusion magnetic aftereffect of MgZn and MnMgZn ferrites is generated by electron and cation migrations, respectively.

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Based on the isotropic growth law, GSⁿ-GS₀ⁿ=Kt, the n-value of high purity Al₂O₃ was found to be n=2.4 during sintering, and to be n=3 at annealing stage after reaching the theoretical density. The grain growth rates, K-values, of pure Al₂O₃ and of Al₂O₃ doped with additives were evaluated; for example, K (Al₂O₃) =5.11×10^-22 (m³/s) at 1400°C. The influence of ten inorganic additives on the isotropic grain growth law, the pinning effect of the secondary phase on the grain boundaries, and pore elimination are also discussed.

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Methods of purifying sepiolite-paygorskite series were reviewed and discussed under the two purification categories: extraction of elements and elimination of minerals.
A number of previous works focused on the extraction of elements from sepiolite by acid treatment because knowledge gained from basic studies on dissolution kinetics, structural changeand surface properties, and/or application studies for fillers and catalysts can be applied to such treatments.
On the other handmethods for the elimination of impurity minerals have developed followiong more empirical approaches using elutiation and/or acid treatment.Recentlybasic works on selective dissolution of carbonate in sepiolite-ore has been developed. Importance of the pH control in accordance with a solubility diagram was emphasized.

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The palygorskite and sepiolite occur widely in marine and non-marine sediments and in the oceans. Geological situation of these minerals insedimentary basins are reviewed. They are considered to be generated in logoon, shallow lacustrine playa which are formed during the last part of drying process of Mgrich and pH lakes or seas. Hence, these minerals are believed to be good palaeoclimatic indicators.
Since it is currently believed that fibrous minerals are potentially active to induce mesothelioma, several clay minerals were tested for their cytotoxicity in vitro using an established cytotoxicity assay. However, it is difficult to evaluate the cytotoxicity and hemolytic action of clay minerals for a number of reasons, because of the presence of variable amounts of impurity in clays, e.g. quartz or cristobalite. The crytotoxicity of the clay minerals in vitro may not accurately reflect their pathogencity in vivo. Our studies of biological effects of pure palygorskite and sepiolite are reviewed to show severe of biological effects of pure palygorskite and sepiolite are reviewed to show severe biological effects of these minerals to rats. With increasing temperature, their toxicity and hemolytic action were reduced. This may be attributed either to structural changes or to the diminution of their surface area.

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