TiNi Substrate Research Articles

Surface characterization and immersion tests of TiNi alloy coated with Ta

The surface chemical composition and chemical state of Ti–50.6 at.% Ni alloy samples coated with tantalum by an arc ion plating method were investigated by X-ray photoelectron spectroscopy (XPS). The results of XPS survey and high resolution spectra show that a thin oxide film with Ta 2O 5 in the outmost layer and tantalum suboxides in the inner layer are formed on the tantalum coating as a result of natural passivation of Ta in the atmosphere. The Ni ion release with time from uncoated and coated samples immersed in 0.9%NaCl solution was also investigated by atomic absorption spectrometry (AAS). Compared to the coated samples, the uncoated samples show a higher release rate that decreases slightly with time. The degree of dissolution for the coated sample is reduced from 0.28 to 0.74 μg/cm 2 after 49 days, implying the coating has a beneficial effect on the inhabitation of Ni ion release from the TiNi substrate. The atomic force microscope (AFM) images and section analysis show that the root mean square (RMS) roughness increases from 10.349 to 65.587 nm, and the maximum roughness ( R max) increases from 36.027 to 278.22 nm, confirming that immersion in the NaCl solution results in roughening of the coating surface.

Electronic structure of low-index surfaces in austenitic and martensitic phases of TiNi and TiPd alloys

The electronic structure of some low-index surfaces for austenitic and martensitic phases of TiNi and TiPd were investigated using the full-potential linearized augmented plane-wave method. The changes in the surface densities of states (DOS) for B19′-TiNi and B19-TiPd in comparison with those for B2-phase are analyzed. According to our calculations, only insignificant changes in the electronic structure near the Fermi level were found as for bulk ground state. The formation of titanium oxide layers on TiNi substrate is discussed.

Smart thin film TiNi/piezoelectric heterostructures

Thin film layers of shape memory alloys and ferroelectric ceramics can produce a family of ‘‘smart’’ heterostructures capable of performing both sensing and actuating functions. Important issues in the synthesis of these active structures are the ability to generate the appropriate crystalline phases of each material while producing defect-free homogeneous high quality films. The compatibility of sol–gel processed Pb(Zr,Ti)O3 (PZT) thin films with thin film shape memory effect TiNi substrates were investigated. Thin film TiNi was deposited on quartz substrates by physical sputter deposition utilizing a TiNi target in a ultrahigh vacuum chamber, which was followed by in situ vacuum annealing. The ferroelectric tetragonal phase of PZT was deposited on TiNi by sol–gel and spin coating processes followed a by 600 °C anneal for 5 min in air. The heterostructures obtained were nominally defect-free, unlike those obtained through deposition onto bulk TiNi substrates.

Thin Film Multilayers of Ferroelastic TiNi-Ferroelectric PZT: Fabrication and Characterization

Heterostructure multilayers of ferroelastic TiNi coupled to thin film TiO2 and ferroelectric lead zirconate titanate (PZT) produce a smart material capable of performing both sensing and actuating functions. An important issue is the ability to generate the appropriate crystalline phases of each of the materials and to minimize the chemical interactions from the surrounding material. TiO2 and PZT thin films were deposited onto commercially available TiNi substrates by the sol-gel process. Minimum crystallization temperatures for the TiO2 phases and PZT perovskite phases were determined and characterized by X-ray diffraction (XRD). For testing of the properties of these meso-scale structures to occur, the mechanical and electrical properties of the individual components need to be characterized. The mechanical properties of the PZT thin film were characterized by Scanning Electron Microscopy and optical microscopy. Cracking and defects in the PZT were observed for thick films; however thin PZT films of 1 micron or less showed better mechanical integrity. The ferroelectric properties of the PZT thin films were smaller than for bulk PZT; this was likely associated with leakage currents caused by the mechanical imperfections of the films.

Synthesis of thin-film ferroelectrics on Si and shape memory effect TiNi substrates

Synthesis and characterization of ferroelectric multilayers are described. These multilayers possess both active and adaptive properties and so represent an initial attempt to manufacture multilayers that are considered to be smart. In this investigation, deposition and processing of thin-film effect TiNi and thin-film ferroelectric BaTiO3 SrTiO3 and Pb(Zr,Ti)O3 are discussed. Growth conditions as well as the thermodynamic conditions for successful synthesis using sol-gel techniques are described. It was found that amorphous thin films of TiNi and BaTiO3 can be crystallized simultaneously by air annealing at 600 degrees C. Pb(Zr,Ti)O3 was synthesized successfully onto bulk TiNi samples with good mechanical bonding.

Compatibility of BaTiO3 and SrTiO3 with Shape Memory Alloy TiNi

AbstractThin film layers of shape memory alloys and ferroelectric ceramics can produce a family of ‘smart’ heterostructures capable of performing both sensing and actuating functions. The compatibility of sol-gel processed BaTiO3 (BTO) and SrTiO3 (STO) thin films with shape memory effect TiNi substrates were investigated. Important issues in the synthesis of these active structures are the ability to generate the appropriate crystalline phases of each material while producing defect-free homogeneous high quality films.

Smart Thin Film TiNi/Pzt Heterostructures

AbstractThin film layers of shape memory alloys and ferroelectric ceramics can produce a family of ‘smart’ heterostructures capable of performing both sensing and actuating functions. Important issues in the synthesis of these active structures are the ability to generate the appropriate crystalline phases of each material, while producing defect-free homogeneous high quality films. The compatibility of sol-gel processed Pb(Zr,Ti)O3 (PZT) thin films with thin film shape memory effect TiNi substrates were investigated. Thin film TiNi was deposited on quartz substrates by physical sputter deposition utilizing a TiNi target in a ultra-high vacuum chamber, and followed by in-situ vacuum annealing. PZT was deposited on TiNi by sol-gel and spin coating processes. The ferroelectric tetragonal phase of PZT was obtained by a 600 °C anneal for 5m in air. The heterostructures were nominally defect-free, unlike those obtained through deposition onto bulk TiNi substrates.x