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Featured researches published by Kazuyuki Hosoi.


Key Engineering Materials | 2003

Joining Hydroxyapatite Ceramics and Titanium Alloys by Hydrothermal Method

Takamasa Onoki; Kazuyuki Hosoi; Toshiyuki Hashida

Solidificatioin of hydroxyapatite (HA) and its bonding with titanium (Ti) alloys was achieved simultaneously by using a hydrothermal hot-pressing (HH P) method. The reaction temperature used for the HHP treatment was as low as 150 ̊C. Tw o types of Ti alloys; Ti-15Mo-5Zr-3Al and Ti-6Al-2Nb-1Ta were tested to examine the eff ct of NaOH hydrothermal treatment. The NaOH treatment was shown to be useful to enhance the interfac e fracture property in the bonded HA/Ti body for both Ti alloys. The use of Ti-15Mo-5Zr-3Al was more effective in the NaOH treatment and the bonded HA/Ti body provided approximately three im s higher interface toughness compared with that for the non-treated Ti alloy. Introduction Titanium (Ti) and its alloys are widely used as orthopedic and dental implant mater ials b cause of their high mechanical strength, low modulus and good corrosion re sistance [1]. However, when embedded in the body, a fibrous tissue encapsulates the implant, isolat ing it from the surrounding bone. Some bioactive ceramics such as hydroxyapatite (Ca 10(PO4)6(OH)2) (HA), bioglass and glass ceramics can directly bond to living bones when used as a bone replac ement materials [2]. The mechanical properties of HA only allow its applications in the sma ll non-loaded structures. The possibility of HA deposited into the films and its bioactive properti es exploited in the structural prostheses, for instance teeth root, hip, knee and shoulder joint replacement . Therefore, the HA is used as coating materials of those prostheses surface in order to pr pare the bioactive layers on the Ti alloys. The HA surface improves the fixation of the implants due to the penetrative growth of the bone into the coating, forming a mechanical interlock. Plasma spraying techniques traditionally have been used in process f hydroxyapatite coating [3]. However, this high temperature method results in a number of sig ni icant problems, including phase and chemical decomposition of the HA, absence of a chemical int erface/bond between the HA coating and substrate. We have recently reported a new method for bonding HA ceramics and pur e Ti disk by using a hydrothermal hot-pressing (HHP) [4]. The hydrothermal reaction of calcium hydrogen phosphate dihydrate (CaHPO4.2H2O; DCPD) and calcium hydroxide (Ca(OH) 2) occurs in a liquid phase as follows: 6CaHPO4.2H2O + 4Ca(OH) 2 Ca10(PO4)6(OH)2 + 18H2O . (1) The water of crystallization in DCPD is slowly lost below 100 °C is well known phenome a [5]. If the released water can be utilized as a reaction solvent duri ng the HHP treatment, then the synthesis and solidification of HA and joining the HA to metal can be achieved simultaneously under the hydrothermal condition. Recently, it has been reported that if the Ti and its alloys surface is treated with natrium hydroxide (NaOH) solution it obtains the ability of joining HA directly by a bi omimetic method [6]. This paper describes a new bonding technique of HA ceramics and Ti alloys and discusses the effects of the NaOH solution treatment on the interface property of bonded HA/Ti alloy bodies in HHP method. Experimental Sample preparation. Firstly DCPD powder is used as a starting material was prepared by mixing 1.0M calcium nitrate solution (Ca(NO)3.4H2O ; Kanto Chemical Co., Inc., 99.0%, Japan) and 1.0M diammonium hydrogen phosphate solution ((NH 4)2 PO4 ; Kanto Chemical Co., Inc., Key Engineering Materials Online: 2003-05-15 ISSN: 1662-9795, Vols. 240-242, pp 571-574 doi:10.4028/www.scientific.net/KEM.240-242.571


Key Engineering Materials | 2006

Syntheses of Bulky Y-Zeolite by Hydrothermal Hot-Pressing (HHP) Technique

Shinichi Takezoe; Kazuyuki Hosoi; Masahiko Tajika; Yuki Yamasaki; Atsushi Nakahira

Synthesis of bulky Y-zeolite was attempted by a hydrothermal hot-pressing (HHP) method. These bulky products synthesized under hydrothermal conditions were identified as Y-zeolite single phase. Especially, bulky Y-zeolite having translucency, high density and large surface area was obtained by HHP treatment at 423K for 2h with 17wt% of 5M-NaOH solution. This solidified zeolite like single-crystal was considered to be made by dissolution and precipitation mechanism. High-density bulky zeolites can be expected as novel molecular sieves and catalysts with high activity.


WATER DYANMICS: 3rd International Workshop on Water Dynamics | 2006

Effects of Water Location in Starting Materials on Bonding Behavior of Hydroxyapatite and Titanium via Hydrothermal Hot-pressing

Takamasa Onoki; Kazuyuki Hosoi; Toshiyuki Hashida

Solidification of hydroxyapatite (HA:Ca10(PO4)6(OH)2) and its bonding with titanium (Ti) was achieved simultaneously by using the hydrothermal hot‐pressing method at temperatures as low as 150° C with no special surface treatment of Ti. A mixture of calcium hydrogen phosphate dihydrate and calcium hydroxide was used as the starting powder material for solidifying HA. Three point bending tests were conducted to obtain an estimate of the fracture toughness for the HA/Ti interface as well as for the HA ceramics only. The fracture toughness tests showed that the induced crack from the pre‐crack tip deviated from the HA/Ti interface and propagated into the HA. It is cleared that water in starting materials must be crystallized in starting materials in order to achieve the bonding HA ceramics and Ti by the HHP method. The fracture toughness determined on the bonded HA/Ti specimen was close to that of the HA ceramics only (approximate 0.3 Mpam1/2).


WATER DYANMICS: 3rd International Workshop on Water Dynamics | 2006

Effects of Pressure and Reaction Time on Bonding of Hydroxyapatite Ceramics and Titanium by Hydrothermal Hot‐pressing

Masa‐aki Tanaka; Takamasa Onoki; Kazuyuki Hosoi; Toshiyuki Hashida

Solidification of hydroxyapatite (HA) and its bonding with titanium (Ti) was achieved simultaneously by using a hydrothermal hot‐pressing (HHP) method at the low temperature as low as 150 °C. A mixture of calcium hydrogen phosphate dihydrate(DCPD) and calcium hydroxide was used as a starting powder material for solidifying HA. 3‐point bending tests were conducted to obtain an estimate of the fracture toughness for the HA/Ti interface. Application of pressures greater than 20MPa was necessary for bonding, and the interface strength increased with the increasing applied pressure. However, the degree of HA formation was lower when the pressure was increased. Excessively long term HHP treatment was shown to be ineffective for the bonding and there was an optimal treatment time. The optimal pressure and treatment time for bonding were estimated to be 40MPa and 12hrs, respectively.


Journal of the American Ceramic Society | 2005

New Processing Technique for Hydroxyapatite Ceramics by the Hydrothermal Hot‐Pressing Method

Kazuyuki Hosoi; Toshiyuki Hashida; Hideaki Takahashi; Nakamichi Yamasaki; Takashi Korenaga


Archive | 2001

Surface-coated calcium carbonate particles, method for manufacturing same, and adhesive

Go Nakai; Takao Fukuda; Kazuyuki Hosoi


Scripta Materialia | 2005

New technique for bonding hydroxyapatite ceramics and titanium by the hydrothermal hot-pressing method

Takamasa Onoki; Kazuyuki Hosoi; Toshiyuki Hashida


Journal of the American Ceramic Society | 2005

Fabrication of Porous Hydroxyapatite Using Hydrothermal Hot Pressing and Post-Sintering

Atsushi Nakahira; T. Murakami; Takamasa Onoki; Toshiyuki Hashida; Kazuyuki Hosoi


Archive | 2002

Material for imparting thixotropy and pasty resin composition

Yoshisada Kayano; Isao Morioka; Kazuyuki Hosoi


Materials Science and Engineering: C | 2008

Effects of titanium surface modifications on bonding behavior of hydroxyapatite ceramics and titanium by hydrothermal hot-pressing

Takamasa Onoki; Kazuyuki Hosoi; Toshiyuki Hashida; Yasuhiro Tanabe; Tomoaki Watanabe; Eiichi Yasuda; Masahiro Yoshimura

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Takamasa Onoki

Osaka Prefecture University

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Atsushi Nakahira

Osaka Prefecture University

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Eiichi Yasuda

Tokyo Institute of Technology

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Masahiro Yoshimura

Tokyo Institute of Technology

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Shinichi Takezoe

Kyoto Institute of Technology

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T. Murakami

Kyoto Institute of Technology

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