Papers by Author: Mitsuhiko Ohta

Abstract: In this study, porous hydroxyapatite (HAp) bodies were prepared by the simple process. We fabricated porous fibers consisting of polyacrylonitrile (PAN) and HAp by an extrusion method of the mixture of PAN and HAp in dimethylformamide (DMF) solution. Fibers obtained by this extrusion method were chopped and molded. Subsequently, these compactions from chopped fibers consisting of HAp and PAN were sintered at various temperatures in air atmosphere. The sintered HAp bodies had high porosity and a number of pores with diameter some hundreds μm. These porous HAp bodies can be used as a scaffold in the body.

Abstract: 12 mol%CeO2 based composites were fabricated by a pressureless sintering technique and post-HIP treatments. The mixture of 12CeO2-ZrO2/3Y2O3-ZrO2 (= 80 wt%/20 wt%) powders from various methods were prepared by a ball milling technique and consequently sintered at 1400
in air atmosphere and post-HIP treatment at 1350
. The 12Ce-ZrO2/Y-ZrO2 composites sintered from mixture of 12CeO2-ZrO2 powder and 3Y2O3-ZrO2 powders possessed the high strength over 1300 MPa and also high fracture toughness over 11 MPam1/2. Furthermore, the significant inhibition of the ZrO2 phase transformation of tetragonal to monoclinic phase under an aqueous hydrothermal condition at 150
was obtained for these 12Ce-ZrO2/Y-ZrO2 composites prepared from this method. Microstructural observation was in detail performed by TEM and EDS.

Abstract: Amorphous calcium phosphate (ACP) was prepared by a sol-gel method from Ca alkoxide synthesized with Ca metal and ethanol in N2 atmosphere. As-prepared products by sol-gel method were spherical ACP particles of approximately 3 to 10 nm in diameter before heat-treatments. The results from Ca-K edge of as-synthesized ACP showed only one peak around 0.2 nm, suggesting the presence of the first neighbor of Ca in Ca-PO4 cluster.