Characterization of Sputtered Micropatterned TiNi-based Thin Film Actuators

Thursday, May 21, 2015: 9:35 AM
Conference Theater (Crowne Plaza)
Dr. Christoph Bechtold , Acquandas GmbH, Kiel, Germany
Dr. Rodrigo Lima de Miranda , Christian-Albrechts-Universität zu Kiel, Kiel, Germany
Dr. Christiane Zamponi , Acquandas GmbH, Kiel, Germany
Mr. Christoph Chluba , Christian-Albrechts-Universität zu Kiel, Kiel, Germany
Prof. Eckhard Quandt , Christian-Albrechts-Universität zu Kiel, Kiel, Germany
Recently, NiTi alloys fabricated and structured by microsystem technology processes, i.e. magnetron sputtering, UV lithography and wet etching, have experienced increasing interest as shape memory components with excellent fatigue and corrosion properties due to their lack of oxide or carbide inclusions. In addition, the lateral design freedom of lithographic structuring allows for designing flat actuators with optimized force and stroke, making them also promising as high quality actuator materials.

In this study, the actuator behavior of sputtered micropatterned Ti-rich TiNi and TiNiCu thin films with thickness in the range of 20 – 30µm is characterized using a specifically designed thermo-mechanical testing setup. The temperature dependence of electrical resistivity and strain at various preloads is presented, revealing an intermediate R-phase transformation for binary NiTi at low loads. The cyclic degradation of actuator performance is investigated up to a test run out at 50K cycles at various preloads. TiNiCu films, showing also a high stability during superelastic cycling [1], reveal likewise a highly stable actuator performance. The effects of thermo-mechanical fatigue on the microstructure of NiTi and NiTiCu thin films are furthermore examined by microstructure analysis methods.

[1] Appl. Phys. Lett. 101, 091903 (2012)

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