Study of the evaluations of the severe corrosivity of body and oral cavity environments and environmental degradation and dissolution of adequately high corrosion resistant alloys
Grant-in-Aid for Scientific Research (C)
|Allocation Type||Single-year Grants|
|Research Institution||Waseda University|
SAKAI Jun'ichi Waseda University, Faculty of Science and Engineering, Professor, 理工学術院, 教授 (90329095)
NAKAE Hideo Waseda University, Faculty of Science and Engineering, Professor, 理工学術院, 教授 (40164123)
ISHIKAWA Yuichi Yokohama National University, School of Foreign Students Center, Professor, 留学生センター, 教授 (40334627)
YOKOYAMA Ken'ichi Tokushima University, School of Dentistry, Assistant Professor, 歯学部, 助手 (80308262)
SAITO Yoshiyuki Waseda University, Faculty of Science and Engineering, Professor (60277829)
|Project Period (FY)
2003 – 2005
Completed(Fiscal Year 2005)
|Budget Amount *help
¥3,700,000 (Direct Cost : ¥3,700,000)
Fiscal Year 2005 : ¥1,000,000 (Direct Cost : ¥1,000,000)
Fiscal Year 2004 : ¥800,000 (Direct Cost : ¥800,000)
Fiscal Year 2003 : ¥1,900,000 (Direct Cost : ¥1,900,000)
|Keywords||Ti alloys / Hydrogen embrittlement / oral cavity environment / Shape memory alloy / Superelastic alloy / Hydrogen absorption / Corrosion / Fretting corrosion fatigue / 腐食・防食 / 表面・界面制御 / 生体・福祉材料 / 疲労 / 歯科理工学|
Corrosion behavior, surface film analysis, hydrogen absorption behavior, estimation of the state of absorbed hydrogen, change of the mechanical properties, and co-reaction of these phenomena which were the results of the reaction with the alloys like alfa, alfa+beta, beta, Ni-Ti alloys and simulated oral cavity environment were investigated..
1) Mechano-chemical reactions : Mechano-chemical reactions in the oral cavity was investigated by means of fretting corrosion fatigue tests. Corrosion environments were controlled by applied potential. At anodic potential region where passive film forms easily, the fatigue life tends to shortened. This is considered as the result of the acceleration of the dissolution of the alloy by the film brake down.
2) Analysis of the environmental effects : Fluorides which were often used in the oral cavity acted as the corrosion accelerating agent. Corrosion behavior, hydrogen absorption behavior under the various concentration of NaF and APF solutions were s
tudied. Applying less noble potential in NaF solution to alfa Ti resulted in increment of the absorbed hydrogen, while this phenomenon was not observed to 6-4-Ti alloy. In acidic APF solution, this alloy absorbed plenty of hydrogen under the less noble potential region. Hydrogen peroxide develops localized corrosion of Ti alloys because of its strong oxidizing capability. This event was noticeable in Ni-Ti alloy. Preferential dissolution of Ni may lead to localized corrosion.
3) Polarization behavior : Corrosion resistance of the alloys in 0.2〜2% APF solution depends on the concentration of the solution, and higher the concentration higher the corrosiveness. Both anodic and cathodic reactions were enhanced with the concentration. Surface film properties were also depended on the concentration.
Furthermore, most absorbed hydrogen locates in the vicinity of the surface. They are relocate as the time passage and the mechanical properties also changed with the time. Hydrogen embrittlement behavior of Ti alloys was also unveiling. Less
Research Products (39results)