複合化中間層Fe-FeOを用いたFe/Al₂O₃接合体の強度特性

抄録

Solid state bonding of carbon steel (written as Fe hereafter) and Al₂O₃ using Fe-FeO composite interlayers (written as I hereafter), and fabrication of Fe-FeO composite materials were carried out by hot pressing at 1450 K for 36 ks in a vacuum of 10⁻³ Pa under pressure of 29.3 MPa. The interface chemistry and the bonding strength related to Fe/I/Al₂O₃ systems were investigated by means of EPMA and an Instron testing machine. A complex oxide which consisted of Fe, Al and O, was formed at the Al₂O₃/I boundary region. A new reaction layer about 6 μm in thickness was formed in the boundary region in a similar way to the case of the Al₂O₃/FeO bonding. In the Fe/I boundary region, the Fe in the bulk united with Fe in the interlayer to form strong bonding. The tensile strength of Fe/I/Fe and Al₂O₃/I/Al₂O₃ systems had the values of 145 MPa and 135 MPa, respectively, when an Fe-25 mol%FeO interlayer was applied. The composition dependence curve of tensile strength for the Fe-FeO composite materials showed similar behaviour to that for the Fe/I/Fe systems. The Al₂O₃/I/Al₂O₃ systems showed the maximum tensile strength at 25 mol%FeO, and it rapidly decreased when the concentration of FeO decreases below 25 mol%. The 25 mol%FeO for the composite interlayer, therefore, was the optimum for the Fe/I/Al₂O₃ bonding.