Avaliação do comportamento termomecânico de uma matriz flexível de silicone contendo fitas de ligas com memória de forma NiTi embebidas.

Abstract

NiTi alloys belong to a class of metal alloys that Has emphasis in the technological and scientific field, the Leagues with Shape Memory Alloy (SMA), because they have unique functional characteristics of Effect Memory of Form (EMF) and superelasticity (SE), in addition to high mechanical resistance. These properties of EMF and SE have led to the development of active composites that can be used for shape and vibration control, as well as the controlled variation of damping and stiffness. One way to achieve this goal is by combining SMA properties with polymer properties. Given this, this work present a study of the thermomechanical behavior of an active composite obtained by the introduction of NiTi SMA ribbons into a flexible polymeric matrix (silicone). Accordingly, there were produced two active composite with difference in number of embedded ribbons NiTi (4 and 6 ribbons). Initially, the ribbons were obtained from cold rolling of NiTi superelastic wires, with subsequent heat treatment. The NiTi wires and ribbons, the silicone polymer matrix and the compounds systems formed were characterized by Dynamic Mechanical Analysis (DMA) and Differential Scanning Calorimetry (DSC), checking behavior of elastic modulus, damping factor and phase transformation temperatures. An analysis of the interface between the SMA NiTi/matrix was also carried out through pullout tests and Scanning Electron Microscopy (SEM). From the results, it was verified the activation capacity of the Silicone-NiTi active systems, which had positive change of elastic modulus and damping factor when heated above transformation temperatures of the NiTi ribbons. The composite systems containing higher volume fraction of NiTi SMA ribbons showed the best values of these properties. It was also verified that the NiTi ribbons generated a better interface between matrix and SMA in relation to the wires, opening up more possibilities of applications.