In-situ high temperature X-ray diffraction study of Ni/Al₂O₃ interface reactions

In-situ experiments on the Ni/Al₂O₃ interface reaction were carried out with a high temperature X-ray diffractometer capable of measuring the X-ray diffraction pattern in 1-2 s using an imaging plate. The kinetic formation processes of the interface reaction layer were measured by short-period exposure experiments with a high temperature X-ray diffractometer. Ni/Al₂O₄ was formed at the Ni/Al₂O₃ interface from 1468 K to 1673 K in air. The formation of NiAl₂O₄ obeyed the parabolic rate law. The value of the activation energy suggests that the diffusion of Al through NiAl₂O₄ controls the rate of formation. The results of thermal expansion coefficient measurements suggest that when a sample is cooled to room temperature, the magnitude of the stress on the Al₂O₃ owing to NiAl₂O₄ is smaller than that caused by NiO.