Improvement of Impact Strength for Transparent Inorganic Glass by Electron Beam Irradiation
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Improvement of Impact Strength for Transparent Inorganic Glass by Electron Beam Irradiation Keisuke Iwata1, Akira Tonegawa2, and Yoshitake Nishi3 1 Department of Science and Technology, Tokai University, 1117 Kitakaname, Hiratuka, Kangawa, Japan 2 Department of Science and Technology, Tokai University, Tokai university, 1117 Kitakaname, Hiratsuka city, Kanagawa, Japan 3 Department of Science and Technology, Tokai University, Tokai university, Tokai university, 1117 Kitakaname, Hiratsuka city, Kanagawa, Japan
ABSTRACT Low-energy electron beam (EB) irradiation, generally applied to enhance hardening and wear resistance of polymers, has been recognized as a successful surface treatment. The possible beneficial effects of low-energy electron beam (EB) irradiation on the impact value of transparent inorganic glass was investigated. Results showed the EB irradiation increased the impact value of transparent inorganic glasses. Based on ESR signals of the transparent glasses before and after EB irradiation, a high density of dangling bonds was confirmed. The EB irradiation homogeneously activated the surface atoms and broke the chemical bonds in the surface layer network structure. Partial relaxation occurred at points of residual strain in the network structure when EB irradiation generated the dangling bonds at the weaker-bonded metal-oxygen atomic pairs in the glass network structure. It was clear that the increased rigidity was mainly due to an increase in the bonding energy of the stronger-bonded metal-oxygen atomic pairs in the atomic network structure. INTRODUCTION Low-energy electron beam (EB) irradiation, generally applied to enhance hardening and wear resistance of polymers, has been recognized as a successful surface treatment. By enabling freedom from misting and easy sterilization, EB irradiation techniques are presently being developed to assist in the production of dentists’ mirrors, sapphire lenses for endoscopes, and diamond windows. EB-strengthening methods, caused by annihilation of dangling bonds, have been established for carbon fiber and carbon fiber reinforced polymers [1-7]. On the other hand, another effect of EB irradiation is the homogeneous activation of surface atoms and the breaking of chemical bonds in the surface layer network structure of inorganic glasses [8-9]. When EB irradiation generates dangling bonds at the weaker-bonded metal-oxygen atomic pairs in the glass network structure, partial relaxation occurs at points of residual strain in the network structure. It is clear that the increased rigidity is mainly due to an increase in the bonding energy of the stronger-bonded metal-oxygen atomic pairs in the atomic network structure.
We have undertaken the present study to investigate the possible beneficial effects of EB irradiation on the impact value of transparent inorganic glasses. To clarify the results, ESR observations were used to confirm the existence of dangling bonds. EXPERIMENTAL Transparent glass sheets were homogeneously irradiated using an electron-curtain pr
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