Kaoru Igarashi

Manufacture and mechanical properties of magnesium potassium titanate short fiber/glass composite

We generated a composite of short magnesium potassium titanate fibers (K2MgTi7O16) and glass by calcining hydrated potassium tetratitanate fibers/non-swelling synthetic fluorine mica with a mass ratio of 7 : 3 at calcination temperatures of 1000°C or higher for 1 h. The sintered density and bending strength of the K2MgTi7O16 obtained was 79% and 27 MPa, respectively, at a calcination temperature of 1100°C. We also isolated magnesium potassium titanate fibers approximately 3 μm in diameter by treatment with a 5% fluoric acid solution for 30 min.

Operation of rhodamine 6G dye laser in water solution

The ethanolic solution of Rhodamine 6G is used for dye lasers in the atomic vapor laser isotope separation (AVLIS) system. However, the water solution is preferable from the standpoint of easy treatment and safety. In this paper, we systematically investigated the laser efficiency of a Rhodamine 6G dye laser pumped by a frequency-doubled Nd:YAG laser, for various water-based solutions with surface-active agents and alcohols. By adding an appropriate amount of surface-active agent (Triton X or Emulgen) or alcohol (ethanol or propanol), we obtained almost the same level of laser efficiency as in the pure ethanolic solution. The improvement in the laser efficiency with these additives was attained by the deaggregation of nonradiative dimers. It was also confirmed that the water-based solution showed better performance against thermal distortion than the ethanolic solution, and was suitable for copper vapor laser (CVL) pumping.

Hydroxyapatite Coatings Deposited on Titanium Substrate by Pulsed Laser Deposition

Hydroxyapatite (HA) coatings were deposited on titanium substrate by means of pulsed laser deposition (PLD) with Nd:YAG laser. Deposition was carried out at 20 Pa of water vapor atmosphere and at room temperature. An Nd:YAG laser operating at a repetition rate of 10 HZ was used for deposition. In above deposition condition, the HA coatings deposited by PLD at room temperature are amorphous phase, and Ca/P ratio in HA coatings decreases with increasing water vapor pressure. The amorphous HA coatings were recrystallized after hydrothermal treatment at 190°C for 10 h. The bonding strength of the HA coating to the Ti substrate is up to 19.6 MPa. The structure and morphology of samples were characterized by X-ray diffraction, Fourier transform infrared reflection specterophotometry, scanning electron microcopy. The atomic ration of Ca and P was semiquantitatively determined by electron probe micro analyzer.

Precipitation of Hydroxyapatite on Oxide Film Containing Ca and P by Hydrothermal Treatment

An oxide film containing Ca and P was obtained in an electrolyte containing calcium glycerphosphate (Ca-GP) and calcium acetate (CA) by microarc oxidation. The surfaces of the oxide films were porous and rough, and the Ca/P ratio in the oxide film was 1.71 when the oxide film was formed in the electrolyte containing 0.06 M Ca-GP and 0.25 M CA at current density 50 A/m2 and final voltage 350 V. The oxide film with Ca/P ration 1.71 was treated hydrothermally at 190°C for 10 hours in an autoclave. It was found that hydroxyapatite crystals were precipitated on the oxide film after hydrothermal treatment. The oxide films were investigated by means of electron probe micro analyzer, X-ray diffraction, scanning electron microcopy before and after hydrothermal treatment.