Study of the structure and interface of NiTi SMA/FC composite films prepared by the sol–gel method

Ferroelectric ceramic (FC) films were prepared on a NiTi shape memory alloy (NiTi SMA) substrate by the sol–gel method. The effect of the heat treatment temperature on the crystallization of both the NiTi SMA and ferroelectric ceramic is discussed. The heterostructure of the interface was characterized by scanning electron microscopy and X-ray diffraction. The results indicate that aging reactions in the NiTi SMA substrate were restricted by the presence of the ceramic film. Also, the transitional TiO2 layer produced in-situ by the oxidation of the surface of the NiTi SMA substrate improves the adhesion between the ceramic film and NiTi SMA.