Kazuya Oguri

Misting-free diamond surface created by sheet electron beam irradiation

We developed a diamond surface that does not mist near the room temperature under a saturated humidity atmosphere, by sheet electron beam irradiation (SEBI) treatment. SEBI treatment decreased the time to clear vision of the diamond surface. Following SEBI treatment for 1.91 s (= 0.72 MGy) to a diamond surface, the time to clear vision was less than 2 s. The effective duration time was a few hours. Based on the results of the size distribution of the drops on the misting-free diamond surface following blowing for 3 s, we proposed an explanation for the short time to clear vision of the diamond surface treated by SEBI.

Effects of electron beam irradiation on time to clear vision of misted dental mirror glass

A misting free dental mirror is obtained near the human temperature under the saturated humidity atmosphere by use of the sheet electron beam irradiation treatment. It is shown that electron beam irradiation treatment decreases the time to clear vision in a misted mirror. This effect is due to an enhancement of the interfacial energy between the dental mirror glass and water.

High fracture resistance of carbon fiber treated by electron beam irradiation

A crack reduction by electron beam (EB) irradiation treatment for carbon fiber, used without the traditional method of accompanying heat, was developed to modify the mechanical properties at lower temperature. The EB treatment improved the resistance to fracture. Namely, the maximum ratio of fractured samples ( max R f ) and the minimum bending strain on fracture ( min e f ) were defined as simple indicators of fracture resistance and became smaller by the EB treatment. Furthermore, a critical density of dangling bonds for a fracture was suggested and determined for carbon fiber treated by EB irradiation. The EB irradiation to reduce cracking and the determination of the critical density of dangling bonds are new concepts that can be broadly applied in the fields of aerospace and rapid-transit production engineering.

Effects of EB irradiation on spring constant of C/C composite coil

In order to enhance a spring constant of C/C composite coil spring, the electron beam irradiation was homogeneously performed. The EB irradiation largely enhanced initial spring constants, which were higher than that before EB irradiation. The constant spring constant was also obtained by 150 Mrad-irradiation for the C/C composite coil spring.

Effects of sheet electron beam irradiation on aircraft design stress of carbon fiber

Using sheet electron beam (EB) irradiation, reinforcement for carbon fiber was achieved. In order to annihilate twisting strain in carbon fiber, the fracture stress was precisely obtained by means of a twisting free tensile test developed. The EB treatment enhanced the fracture stress at different integrated fracture rates (Rf) and increased Weibull modulus. It also enhanced design stress, when the integrated fracture probability (Pf) is 10−5 for aircraft materials. The aircraft design stress (5 GPa) was approximately 4 GPa larger than that (1 GPa) before EB treatment.

Effect of electron-beam irradiation on water wettability of hydroxy apatites for artificial bone

The influence of electron-beam irradiation on the wettability of hydroxy apatites (HAP) has been investigated. The wettability was evaluated from the interfacial energy between HAP and water. It was measured by the contact angle of distilled water on HAP. Electron-beam irradiation increases the wettability. Based on the rate process, the influence of electron-beam irradiation on wettability is discussed. Using electron-beam irradiation, we can precisely control the surface condition of HAP.

Abnormal Tc change of Bi1.6Pb0.4Sr2Ca2(Cu1−zTiz)3Ox (0.01<z<0.1)

Influence of Ti addition (substitution for Cu) on Tc is studied for high Tc Bi1.6Pb0.4Sr2Ca2(Cu1−zTiz)3Ox. An abnormal Tc change is found between z=0.01 and 0.1. Based on results of the electrical resistivity and x‐ray diffraction, the abnormal Tc change is discussed.

New method for the evaluation of brittleness in ceramics

Using Vickers indentation method, plastic deformation (Ef) is suggested to be a convenient measurement to determine the ductility (brittleness) of brittle new materials. It was found that Ef is related empirically to KIC and GIC through a logarithmic linear relationship.

pH Self-Controlling Induced by Tourmaline

The effect of tourmaline on pH controlling is investigated. The hydrogen ion concentration tremendously decreases for 1 h. The concentration approaches 10-7 mol/l at infinite time. On the other hand, the materials intelligence (Ih) has been suggested. If the fh value is 50, we can determine the Ih value [Ih (50)] for tourmaline. The Ih (50) and Pr values are 0.38 and 0.70 for tourmaline.

Endurance limit of reversible Tc increase with compressive stress of YBa2Cu3O7−y oxide

Effect of compressive stress on Tc is studied for YBa2Cu3O7−y oxide. Tc increases with compressive stress for small strain, reversibly. Excess strain decreases Tc, irreversibly. We obtain a compressive stress between reversible Tc increasing and irreversible Tc decreasing as endurance limit (16.5 N/mm2). The maximum Tcoff is about 94.4 K at 16.5 N/mm2. We suggest that the YBa2Cu3O7−y oxide sample should be formed below the endurance limit of the compressive stress on sample preparation.