Toru Nonami

National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki, Japan

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Publications (22)17.63 Total impact

  • Key Engineering Materials 01/2005;
  • Key Engineering Materials 01/2003; 240-242:931-934.
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    ABSTRACT: For uniformly implanting hydroxyapatite (HA) granules into curved surfaces of titanium alloy implants such as dental roots, a new superplastic forming system was developed. By fixing PVA films with HA granules on a die's curved inner surface, HA granules are uniformly scattered and hold on the surface. The pressing system has a couple of wedges that enable press load to act on the both sides of a cylindrical titanium alloy sample arranged with its long axis perpendicular to the direction of the load in the die, and thereby the sample to expand in its radius direction. This technique could uniformly press HA granules into all the curved surface of titanium alloy. As a result, HA-granule-implanted titanium alloy composites with a cylindrical shape were formed under the conditions of 1023 K, 1 h, 1960 N in vacuo.
    Journal of Materials Science Materials in Medicine 03/2002; 13(2):233-6. · 2.38 Impact Factor
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    ABSTRACT: In order to improve the biocompatibility of superplastic Ti-alloys such as Ti–6Al–4V or Ti–4.5Al–3V–2Fe–2Mo, coating of the alloy with pure titanium and TiO films by magnetron DC sputtering was examined. The sputter-deposition of the pure titanium film and the TiO films were carried out in Ar gas and in ArO2 gas mixtures, respectively. Both the pure titanium film deposited in Ar and the TiO films deposited in ArO2 appeared to be uniform and adhesive. Under AES, the Ti/O ratio in depth direction was nearly constant in each of the films and oxygen concentration increased with increasing oxygen content of the sputter gas. Based on XRD, it was concluded that oxygen atoms dissolved into α-titanium crystals at lower oxygen contents, while suboxides such as Ti4O7 and Ti6O11 and oxides such as TiO2(anatase) were formed at higher oxygen contents. It was found that the orientation of the α-titanium phase formed in the TiO films changed from (002) dominant to (011) dominant with increasing oxygen content. The Vickers hardness of the films increased linearly with increasing oxygen content, and the maximum hardness reached over Hv=1600. Furthermore, it was found that the ductility of the deposited pure titanium film was improved under such high temperatures as 800°C and that its elongation reached over 160%, while the TiO films were still brittle under such a high temperature.
    Thin Solid Films 05/2001; 386(2):227–232. · 1.87 Impact Factor
  • Key Engineering Materials 01/2001;
  • Key Engineering Materials 01/2001; 192-195:437-440.
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    ABSTRACT: Titanium and some of its alloys are commonly accepted materials for orthopedic implants such as artificial tooth roots mainly due to their superior durability. Enhancement of bone formation around the implants can make a considerable contribution to long-term stable fixation of the implants. However, the surface of titanium is less osteoconductive than bioactive ceramics such as hydroxyapatite (HAP). In this study, spherical HAP ceramics were implanted on the surface of pure titanium by a loading rate of 0.1 kN/min up to 1 kN at 1123 K to provide the surface of pure titanium with osteoconductive spots. By this method, the spherical HAP ceramics were mechanically held by deformed pure titanium.
    Materials Science and Engineering C 09/2000; 13:105-107. · 2.74 Impact Factor
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    ABSTRACT: TiO2-coated hydroxyapatite single crystals were prepared by hydrolysis of Ti-bearing dicalcium phosphate powder. On the surface of the TiO2-coated hydroxyapatite single crystals, TiO2 regions and hydroxyapatite regions can function as photocatalysts and adsorbents for organic contaminants, respectively, allowing simultaneous decomposition of organic contaminants by the photocatalysis of TiO2 under irradiation. Therefore, the TiO2-coated hydroxyapatite single crystals can favorably be applied for antibacterial applications and environmental purification.
    Journal of Materials Research. 05/2000; 15(06):1243 - 1244.
  • T Nonami, S Tsutsumi
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    ABSTRACT: Glass-ceramics were investigated to obtain a glass with a composition of CaO. MgO. 2SiO(2). 0.375TiO(2). 0.007Ag(2)O. The glass melted at 1500 degrees C and could be cast. Crystallization of diopside of this glass is controlled by volume nucleation and growth processes. In a crystallization treatment at 850 degrees -870 degrees C, this glass presented a milky white, semitransparent color. The crystals formed were diopside, their crystal grain diameter was 1-2 micrometer, and crystallization was 15-25%. The bending strength of the glass produced by a crystallization treatment of 25 min at 850 degrees C was 400 MPa, which is suitable for artificial bones. This crystallized glass also was extremely stable, with no weight loss after stability testing in artificial saliva. The softening point, as determined from the viscosity curve, was 830 degrees C, and the crystallization temperature was 895 degrees C. Thus this glass can be press-formed at a temperature of 830 degrees -880 degrees C. Actual press-forming at a pressure of 0.64 MPa was carried out for 40 min at 850 degrees C and resulted in the formation of desired shapes. Given its ready formation into desired shapes and its great strength after crystallization, such glass is applicable for use as artificial bones and as dental roots and crowns.
    Journal of Biomedical Materials Research 05/2000; 50(1):8-15.
  • Toru Nonami, Sadami Tsutsumi
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    ABSTRACT: Glass–ceramics were investigated to obtain a glass with a composition of CaO · MgO · 2SiO2 · 0.375TiO2 · 0.007Ag2O. The glass melted at 1500°C and could be cast. Crystallization of diopside of this glass is controlled by volume nucleation and growth processes. In a crystallization treatment at 850°–870°C, this glass presented a milky white, semitransparent color. The crystals formed were diopside, their crystal grain diameter was 1–2 μm, and crystallization was 15–25%. The bending strength of the glass produced by a crystallization treatment of 25 min at 850°C was 400 MPa, which is suitable for artificial bones. This crystallized glass also was extremely stable, with no weight loss after stability testing in artificial saliva. The softening point, as determined from the viscosity curve, was 830°C, and the crystallization temperature was 895°C. Thus this glass can be press-formed at a temperature of 830°–880°C. Actual press-forming at a pressure of 0.64 MPa was carried out for 40 min at 850°C and resulted in the formation of desired shapes. Given its ready formation into desired shapes and its great strength after crystallization, such glass is applicable for use as artificial bones and as dental roots and crowns. © 2000 John Wiley & Sons, Inc. J Biomed Mater Res, 50, 8–15, 2000.
    Journal of Biomedical Materials Research 01/2000; 50(1):8 - 15.
  • Toru Nonami, Sadami Tsutsumi
    [Show abstract] [Hide abstract]
    ABSTRACT: Glass–ceramics were investigated to obtain a glass with a composition of CaO · MgO · 2SiO2 · 0.375TiO2 · 0.007Ag2O. The glass melted at 1500°C and could be cast. Crystallization of diopside of this glass is controlled by volume nucleation and growth processes. In a crystallization treatment at 850°–870°C, this glass presented a milky white, semitransparent color. The crystals formed were diopside, their crystal grain diameter was 1–2 μm, and crystallization was 15–25%. The bending strength of the glass produced by a crystallization treatment of 25 min at 850°C was 400 MPa, which is suitable for artificial bones. This crystallized glass also was extremely stable, with no weight loss after stability testing in artificial saliva. The softening point, as determined from the viscosity curve, was 830°C, and the crystallization temperature was 895°C. Thus this glass can be press-formed at a temperature of 830°–880°C. Actual press-forming at a pressure of 0.64 MPa was carried out for 40 min at 850°C and resulted in the formation of desired shapes. Given its ready formation into desired shapes and its great strength after crystallization, such glass is applicable for use as artificial bones and as dental roots and crowns. © 2000 John Wiley & Sons, Inc. J Biomed Mater Res, 50, 8–15, 2000.
    Journal of Biomedical Materials Research 01/2000; 50(1):8-15.
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    ABSTRACT: Titanium and some of its alloys are commonly accepted as materials for orthopedic implants such as artificial tooth roots mainly due to its superior mechanical strength. Bone formation around titanium implants can make a contribution to long-term stable fixation of the implants. Therefore, enhancement of osteoconductivity of the surface of the implants has been a key to improve the implant. We are attempting to improve the fixation of the titanium implants to bone by implanting hydroxyapatite (HAP) spots on the implant’s surface. The spherical HAP ceramics were pressed against the surface of pure titanium substrate by a loading rate of 0.1 kN/min up to 1 kN at 850°C. By this method, most part, except near surface, of the spherical HAP ceramics was surrounded by deformed titanium, resulting in mechanical holding of the spherical HAP ceramics. The HAP spots on the titanium surface are expected to bond to bone much faster than titanium. Furthermore, cavities made by the implantation have sufficient volume to induce bone ingrowth that contributes long-time stability of the implants by microanchoring.
    Proceedings of the 12th International Symposium on Ceramics in Medicine; 10/1999
  • Toru Nonami, Sadami Tsutsumi
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    ABSTRACT: Diopside was prepared by sintering a powder compact of composition CaO-MgO-2SiO2 at 1300 C for 2 h. The bending strength of diopside was 300 MPa and the fracture toughness was 3.5 MPa m1/2. It was proved that diopside has no general toxicity in cell culture. Diopside implanted in rabbits came in close contact with the newly grown bone. X-ray microanalysis spectral diagrams show a change of composition across the junction from the diopside to the newly grown bone. High-resolution transmission electron microscopy revealed crystal growth at the interface between diopside and the newly grown bone, and continuity between diopside lattices and those of the new crystals.
    Journal of Materials Science Materials in Medicine 01/1999; 10(8):475-479. · 2.38 Impact Factor
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    ABSTRACT: To obtain a biomaterial that has both biological affinity and high mechanical strength, hydroxyapatite granules were implanted into the surface of pure titanium film coated titanium alloy. The film was coated by reactive DC sputtering method on the alloy substrate. Hydroxyapatite granules (32- in diameter)were spread over titanium alloy substrate and pressed to implant the granules in the substrate. They can be implanted into substrate under 17MPa at for 10minutes. The only tops of the granules were exposed and they were firmly stuck in substrate. The hydroxyapatite implanted titanium alloy composites were expected to be useful for biomaterials as artificial bones and dental roots.
    Journal of the Korean institute of surface engineering. 01/1999; 32(3).
  • Materials Science Forum 01/1999;
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    ABSTRACT: Hydroxyapatite granules (32–50 μm in diameter) were spread over a superplastic titanium alloy substrate and pressed to implant the granules in the substrate. The more the stress increases, the deeper the granules were buried. Under 17 MPa for 10 min at 750°C, the only tops of the granules, which were surrounded by the alloy, were exposed and they were firmly stuck in the substrate. The granules and the titanium alloy were closed, and a reactive layer was formed at the interface between both of them. The implantation process of granules is divided in the following two steps. (1) First, the granules are implanted in the depth which is corresponding to the diameter with small stress. (2) Second, the whole of specimen is composed, and titanium alloy moves to the upper parts of the granules. Therefore, this composite is expected to be applied to artificial bones, like artificial hip joints and dental roots, as new biomaterials.
    Materials Science and Engineering C 12/1998; 6(4):281-284. · 2.74 Impact Factor
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    ABSTRACT: In order to obtain a biomaterial that has both biological affinity and high mechanical strength, hydroxyapatite (HAp) granules were implanted into the surface of superplastic titanium-alloy. HAp granules (32-38 microm diameter) were spread over a superplastic titanium-alloy substrate and pressed to implant the granules into the substrate. This was achieved at 17 MPa, 750 degrees C for 10 min. Only the tops of the granules, which were surrounded by the alloy, remained exposed and they were firmly stuck in the substrate. The granules were enclosed in titanium-alloy and a reaction layer was formed at their interface. The HAp-implanted titanium-alloy composites are expected to be useful as biomaterials, such as artificial bones and dental roots.
    Journal of Materials Science Materials in Medicine 05/1998; 9(4):203-6. · 2.38 Impact Factor
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    ABSTRACT: In order to find the optimum conditions to obtain films with high photocatalytic property by sol-gel method, depth profiling of oxygen in TiOx film deposited on SiO2 was carried out using resonant backscattering of 3.045 MeV He ions by the nuclear reaction of 16O(α, α)16O. Depth profiling of hydrogen in the TiOx film was also conducted using elastic recoil detection analysis (ERDA). For the depth profiling by the resonant backscattering analysis, it is necessary to change the incident energy of He ions from about 3.03 to 3.1 MeV in steps of less than 10 keV. In our analyzing system, the ion beam energy of He++ was scanned by changing a bias voltage supplied to the target holder up to +30 kV without changing the accelerator terminal voltage. The effect of the bias voltage supplied on the sample holder on the energy and the yield of the oxygen peak relative to the titanium and the silicon signal were investigated. The automatic analysis system and the analyzed results are presented.
    Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms 03/1998; 136-138:557-562. · 1.19 Impact Factor
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    ABSTRACT: TiO2 photocatalysts film supported on glass plate was soaked in a pseudo body solution (PBS) containing excess phosphate ions. The surfaces were characterized by scanning electron microscopy, energy-dispersive spectroscopy, thin-film X-ray diffraction, and Fourier-transformed infrared methods. After soaking in the pseudo body solution for 1 day, a bone-like apatite layer was formed on the surface of the TiO2. The apatite layer was approximately 0.7 mm thick and made up of thin plate-like crystals. The haze values of dry and wet specimens were 28.47 and 9.51%, respectively. The apatite-coated TiO2 thin film could be used for antibacterial and environmental purification purposes.
    Materials Research Bulletin 01/1998; 33(1-33):125-131. · 1.97 Impact Factor
  • Journal of the Ceramic Society of Japan. 01/1997; 105(1224):710-712.