Niichi Hayashi

A new method of analysing electro-osmosis using FET models

Abstract To reduce volumes of liquid or slurry waste, it may be necessary to extract water, and the best way to achieve this in practice is often by flow current adjustments. Current has been observed to reach a maximum at some point after the application of a voltage, and to decrease thereafter. The cause for this seems to lie in the movement of impurity particles, so-called electrophoresis. By controlling this movement, it is possible to increase flow rates. Analyses of the problem in the past have included studies into transfer characteristics, mutual conductance and amplification. In contrast to this earlier work, the authors have experimented with placing a gate electrode between the upper and lower electrodes in order to approach the whole reaction in the manner of a field effect transistor (FET) problem. It is well known that varying the gate voltage in a FET leads to a corresponding change in the drain current. If the displaced particles are regarded in a similar way to electrons, the same method of analysis can be used in the case of electro-osmosis. In the experiment reported, this method was used to investigate associated transfer characteristics. It was found that the insertion of the gate allowed a greater liquid flow rate to be obtained than would be possible with more traditional methods.

Precision position control systems using moire signals

A positioning accuracy of a nanometer has been obtained by a precise positioning system using moire technique. Two precise position control techniques using moire signals have been investigated. One is a differential moire technique using two grating pairs in which the control signal is the differential signal between two moire signals. The other is a technique using one grating pair. The system using the latter technique is simpler in construction. However, in the former technique, since in-phase noises in the moire signals are cancelled and the effect of the drift of the laser intensity on the positioning accuracy is small, higher positioning accuracy is obtained than in the latter technique. The positioning accuracy of /spl plusmn/4 nm was obtained by optimization of the system.

Manufacture of insulating agents for electric field relaxation using functionally graded materials, with electric field calculations

The authors of this paper have previously developed a successive layer accretion method based on vacuum filtration, for the manufacture of functionally graded materials (FGMs) by a progressive lamination procedure. For this, they have been granted a U.S. Patent. Using this method, it is possible to manufacture FGMs with thicknesses ranging from several millimetres to several centimetres. The authors have previously manufactured functionally graded materials consisting of iron (III) oxide-kaolin, copper oxide-kaolin and titanium oxide-kaolin, using the said successive layer accretion method. The manufactured FGMs were examined using an SEM to investigate their grading characteristics. Electrical properties such as resistivity, permittivity and permeability were also measured. In the present paper, they report results of permittivity and resistivity measurements conducted on an FGM consisting of titanium oxide and kaolin.

An experiment to purify diesel exhaust gas using an electric trap and three types of catalysers

Abstract Diesel engine exhaust gas is known to be one cause of photochemical smog, which is so damaging to city environments. However, because of its high thermal efficiency and economic advantages, the diesel engine is not easily dispensable. The authors have previously conducted a series of experiments to assess the purifying effects of a diesel gas purification device employing an electric trap. It has been confirmed that an extraction rate of 60 ∼ 75 % for black smoke can be achieved using this apparatus, but the extraction effect for nitrogen oxides (NOx) is insufficient if the electro-trap device is used on its own. To improve its performance, experiments have now been undertaken using the same device in combination with various types of attached catalysers to oxidise and remove the nitrogen in the exhaust gas. Utilising a commercial 3-way catalyser, it proved difficult to maintain the gas at a suitable temperature, so that no outstanding result could be obtained. Nor was any significant result observed from the use of an ozoniser. However, with a zeolyte catalyser, it was possible to achieve a NOx reduction of 20 ∼ 30 %. This latter experiment is reported in the present paper.

Automatic angular alignment in mask aligner using computer controlled moire technique

A novel method for the automatic alignment of masks with respect to a wafer in a mask-aligner is developed and reported. Alignment marks are used in the form of gratings of 25 /spl mu/m pitch. The effect of various parameters on moire fringes is studied theoretically and experimentally, and the results are found to be in good agreement. A computer controlled moire sensor is employed to obtain the angular alignment accuracy of the order of /spl plusmn/130 nanoradians. This high accuracy is maintained for more than 5 minutes. Feasibility experiments are performed for wafers of various sizes and very high accuracy is obtained in each case.

Mechanical Properties of TiO2-Kaolin FGM Produced by Progressive Lamination Method for NOx Reduction

Mechanical properties of TiO2-Kaolin Functionally Graded Materials (FGMs) that combined TiO2 and Korean kaolin (Al2Si2O5(OH)4) in a graded distribution were experimentally investigated. TiO2 is an excellent photocatalysis material, however, it does not have the mechanical strength sufficiently. Therefore, FGMs were used as the photocatalysis materials with mechanical strength. To improve the mechanical properties, Korean kaolin was selected as a binder. Bulk FGMs were produced by vacuum filtration and compression involving wet filtration, mechanical compression and sintering. By this process, it is easy to control the thickness of FGMs. The porosity in FGM depends on the content of TiO2. The porosity in FGM decreases with increasing pressure of the compressor. The shrinkage decreases with increasing compression pressure at all ratios of TiO2 and kaolin. The materials have almost no shrinkage at 10 MPa. The bending strength and the Young’ modulus depends on content of TiO2. The bending strength of material was found to be approximately 2.5 MPa for 10 MPa compression pressure at TiO2 side. The bending strength and the Young’ modulus increases with increasing compression pressure. These results indicate that kaolin particles are useful to improve the strength of FGM. These properties of FGM, such as porosity, shrinkage, mechanical strength, etc., can be controlled by content of TiO2 and compression pressure. Based on an optimal design of production conditions, FGMs were developed for the nitrogen oxides (NOx) removal. The NOx reduction increases with increasing compression pressure. NO of 11.7 mg/m2h was removed under present conditions. The sintering temperature ensured the optimal removal of NOx was 800 oC. After NOx removal test, the FGMs were found to be free from erosion due to photocatalysis. And kaolin particles do not interfere in photocatalysis effect of TiO2. It can be concluded that TiO2-Kaolin FGM have a possibility for application to the air purification.

The Crystalline Structure and Photocatalysis of TiO2-based Functionally Graded Materials

《まえが き》 大気汚染を浄化す る一方法 として光触媒 の利用が知 られ てい る。大阪府や千葉県では 二酸化チ タンを利用 した基礎実験が開始 された。実験ではチ タン表面に吸着 されたNOxやSOxが 紫 外線によって酸化 されイオン とな り、 さらに水分 により硝酸や硫酸に変化 した後、雨水 とともに除去 され ることも知 られてい る。光触媒は特別 なエネル ギーを必要 としないので排気 ガスの浄化 には最適 な方法 と考 え られてい る。 しか し除去効果 を高めるにはチ タンの面積 を増大す ることも必要で、種々 の研究が行 われている。筆者 らは表面積 を増加 させ る方法 として濾過技術 を用い、傾斜機能材料 を作 製する とともに窒素酸化物除去実験を行 ったので報告す る。写真1に 大阪府の実験を示す。 《二酸化チ タ ンの構造》 二酸化チタンには正方晶系のルチル型、アナ ターゼ型お よび斜方晶系のブ ル ッカイ ト型 の3種 類が存在 している。 二酸化チタンの多 くは正方晶系で、ルチル型は塗料な どに使 われてい る。 また熱的 にはルチル型がよ り安定で、アナターゼ型は900°C 以上になるとルチル型 に変 化する ともいわれてい る。表1に ルチル型 とアナ ターゼ型 の違いを示す ゚ 《二酸化チタ ン傾斜機能材料》 粒径のそろった朝鮮 カオ リンと二酸化チタンをそれぞれ15種 類の 異 なる重量比 で混合す ると共 に、純水を加 え撹はん した。 この試料 を順次 シ リンダーに入れ真空濾過 を行 った。 この作製方法は段階添加法 と呼 ばれている。最後の濾過ケー クが形成 され た後に圧密機 を 用い24時 間圧密操作 と自然 乾燥 を行い電 気炉で焼成 した。 《光触媒の測定》 光触媒 特性 の測 定に は400、600、800、1000お よび1100°C で焼結 した傾斜機能 材料を用いた。それぞれの温度で作製 され た傾斜機能材料 を標 準ガス(NO10.1ppm)で 満た したパイ レックス容器 に入れ、波長254~356nmの ランプ(10W)で2時 間照射 した。その後、傾斜機能材 料 を蒸留水500mlに1時 間浸 して硝酸イ オンを溶解 させ た ゚蒸留水中の亜硝酸イオ ンの検出にはフ ローイ ンジェ クシ ョン分析法(Flow Injection Analysis)を 用い、波長 可変 可視分光検出器で測定 した。 得 られた結果 を図1に 示す。今回用いた傾斜機能材料の面積は28cm2、 光源 と試料の距離は26cmで あった。 《ま とめ》 実験結果か らルチル型はアナ ターゼ型二酸化チ タン傾斜機能材料 に比べ光触媒機能の高 い ことも確認 された。 またルチル型、アナ ターゼ型傾斜機能材 料 とも窒素酸化物の吸 着は800°C が最 も良い。 これ は気孔率の測定か ら眺めても同 じ傾向 を示 してい る。今後は さらに除去の効率化 につい て実験 を進 める計画で ある。

The Electrical and Photocatalysing Properties of a Functionally Graded Material Based on Titanium Oxide

The authors have developed titanium oxide-based functionally graded materials (FGMs) offering special properties of high relative permittivity and photocatalysing capability. In the experiment reported, four such FGMs, sintered at furnace temperatures of 673, 873, 1073 and 1273 °K, were examined for their electrical behaviour, particularly relative permittivity and dielectric loss tangent. The measurement frequencies used were 0.25 ∼ 50 MHz. The paper concludes with a discussion of whether these materials can be used as photocatalyses for the sake of improving the environment. This would open up new applications for FGMs in the area of field relaxation and photocatalysis.

Field relaxing materials: production temperature and relaxation effectiveness

To prevent breakdown in the insulation of electric equipment requires the development of new materials and the control of electric fields. The authors have previously been engaged in the manufacture of functionally graded materials (FGMs) based on titanium oxide and barium titanate. These FGMs possess structured properties that cause a graded change in relative permittivity. It has been found that a change in the manufacturing temperature causes the relative permittivity to vary. The present paper describes an attempt to discover optimal conditions for field control by manufacturing FGMs at a range of temperatures from 673 K to 1273 K and investigating the properties of the resulting materials. The FGM studied was composed of barium titanate and kaolin. The highest values for relative permittivity were obtained at 1273 K. Investigations with a scanning electron microscope (SEM) showed that in comparison with the materials produced at lower temperatures, the pores between the grains were smaller. Similarly, the porosity and water absorption properties showed minimal values for material manufactured at 1273 K. It was concluded that this was because this material contained less air. The smaller the porosity, the larger the value for relative permittivity.

Precise micromaterial processing by excimer laser ablation

An ablation wave from materials based on laser supported detonation and laser supported combustion has been created by exposing them with laser. The purpose of this study is to analyse the mechanism of the ablation wave using a high speed streaked camera and to realize more precise microprocessing by controlling the wave. The laser used in this experiment was an ultraviolet XeCl excimer laser of high photon energy with a wavelength of 308nm, a maximum pulse energy of 500mJ, a pulse width of 30ns and a maximum frequency of 50Hz. The high speed streaked camera had a resolving power of 100ps. Metal-ceramics functionally graded materials (FGMs) were selected as sample materials. An experimental system of laser microprocessing was constructed and the behavior of the ablation wave from FGMs were observed. The experimental results showed that the mechanism of the ablation wave from FGMs was a photochemical reaction with thermal interaction.