Hydrogen embrittlement of Ni-Ti superelastic alloy in fluoride solution.
Hydrogen embrittlement of Ni-Ti superelastic alloy in a fluoride solution (0.2% APF) has been investigated by means of a tensile test (after immersion) and hydrogen thermal desorption analysis. Upon immersion, the tensile strength of the alloy decreased to the critical stress level of martensite transformation. Hydrogen desorption of the immersed specimens appeared with a peak at around 500 degrees C. The amount of absorbed hydrogen in the alloy ranged from 100 to 1000 mass ppm when immersed in the fluoride solution for 2 to 24 h. The immersion in the fluoride solution led to the degradation of mechanical properties due to hydrogen embrittlement. The results of the present study imply that one reason that Ti and its alloys fracture in the oral cavity is the fact that hydrogen is absorbed in a fluoride solution, such as prophylactic agents.
Department of Dental Engineering, School of Dentistry, The University of Tokushima, 3-18-15 Kuramoto-cho, Tokushima 770-8504, Japan. yokken@dent.tokushima-u.ac.jp
Ken'ichi
K
Yokoyama
Kazuyuki
K
Kaneko
Keiji
K
Moriyama
Kenzo
K
Asaoka
Jun'ichi
J
Sakai
Michihiko
M
Nagumo
D003722:Dental Alloys / Q000737:chemistry*; D004548:Elasticity; D005459:Fluorides; D006859:Hydrogen; D008855:Microscopy, Electron, Scanning; D009532:Nickel / Q000737:chemistry*; D012996:Solutions; D013314:Stress, Mechanical; D013718:Tensile Strength; D013816:Thermodynamics; D014025:Titanium / Q000737:chemistry*
D003722:Dental Alloys; D012996:Solutions; C040654:titanium nickelide; D009532:Nickel; D006859:Hydrogen; D014025:Titanium; D005459:Fluorides