Shuntaro Higa

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.

Three-dimensional shape measurement system using optical spatial modulator and zoom camera

An automatic measurement system of three-dimensional shapes by a projection method with striped patterns from an optical spatial modulator has been developed. Patterns on the surface of the object were taken into a computer by a CCD camera, and the 3D cocordinate of the surface of the object was calculated according to a principle of a trigonometry measurement. This system has the following advantages. (1) It is possible to capture the surface topography without any contact. (2) The time required for the measurements is shorter than the light-section method. (3) The optical spatial modulator using a liquid crystal projector is possible to control the striped patterns accurately by the computer. (4) It is possible to measure precisely and to expand the measurement area using a zoom camera. In this study, we developed the method with using zooming of a CCD camera image. By using zooming of a CCD camera image, the measurement accuracy improved and the measurement range was expandable.

High-density sampling technique using special projections of light variation patterns in three-dimensional shape identification

We have continued research on the three-dimensional shape measurement system, using spatial projections. This method is non-contact, non-invasive, and completes measurement in a short time. However, light diffusion influence on the measurable accuracy. In addition, if marking on the surface of target object, it will become difficult to perform exact measurement. And the sampling density is not fully high. We proposed methods using differentiation and light variation patterns to enhance accuracy of measurement, to eliminate the influence of marking on the surface of target object, and to increase the sampling density. Since our methods involve computational manipulation of the data obtained by the original system, it requires no additional equipment. It is a very practical and effective method.

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。

Acquiring even-striped pattern intensity in three-dimensional shape measurement system using an optical modulator

We have continued research on our 3D shape measurement system, using spatial projections of light variation patterns. This method is non-contact, non-invasive, and completes measurement in a short time. However, light diffusion influence on the measurable accuracy. We proposed a method using differentiation to enhance accuracy of measurement, and were successful in achieving this goal. Moreover, the measurable area was expanded. Since our method involves computational manipulation of the data obtained by the original system, it requires no additional equipment. It is a very practical and effective method.

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.

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.