In this study, fracture characteristics of epoxy adhesively bonded butt-joint of dissimilar metals,namely SUS 304 stainless steel and YH75 aluminium alloy were examined on various adhesive bondthicknesses in associations with artificial interface crack subjected to pure mode I loading.Finite element analysis was also executed to investigate the stresses distribution in adhesive layer and also evaluating fracture toughness of adhesive joints by ANSYS 11 code.The results show that the strength of adhesive joints without crack decreased with increasing bond thickness.The interface corner toughnessHc can be applied for predicting the strength of joints provided that any non-linear or fractureprocess zone is fully embedded within the region of singular elastic H-field.Interfacial crack in adhesive joints propagates in two directions, that is, along the interface (i.e. interface failure) or deviatedin to adhesive layer (i.e. cohesive failure).Next, the evaluated fracture toughness Jc of adhesive joints with interfacial crack was independent of bond thickness when failure was associated with crack deviated into adhesivelayer.Nevertheless, Jc for adhesive joints with interfacial crack was dependent on bond thickness when the failure was apparently interfacial.However, if the interfacial crack is analogous to the center crack in adhesive layer constrained between two rigid substrates, Kc parameter can be used to asses the fracture toughness of adhesive joints with interfacial failure.

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This paper is concerned with high refractive index and tintable hard coating materials which consistof epoxysilane hydrolysate, aromatic epoxy resin and antimony pentoxide (Sb205) nanoparticles.These materials have the following characteristics corresponding to the compositions, (1) the epoxysilane hydrolysate is effective for improving scratch resistance, (2) the aromatic epoxy resin is effective for improving tintability and increasing refractive index, (3) the Sb205 is effective for increasingrefractive index and improving scratch resistance. The size of Sb205 nano particles is 5～50nm, which is shorter than visible ray wavelength and has excellent dispersing stability to epoxy compounds, and the resulting film is transparent.In the case of coating this material on high refractive index polymer substrate, the interference fringes are not observed, because of this coated film has same refractive index as the substrate.Further more, the film has improved the durability of adhesion by the effective ultraviolet rays absorption of the Sb205.

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