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Title of article :
Surface characterization and immersion tests of TiNi alloy coated with Ta
Author/Authors :
Cheng، نويسنده , , Y. and Cai، نويسنده , , W. and Zheng، نويسنده , , Y.F. and Li، نويسنده , , H.T and Zhao، نويسنده , , L.C.، نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2005
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Abstract :
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 Ta2O5 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/cm2 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 (Rmax) increases from 36.027 to 278.22 nm, confirming that immersion in the NaCl solution results in roughening of the coating surface.
Keywords :
TiNi alloy , Ion plating , tantalum , Coating
Journal title :
Surface and Coatings Technology
Journal title :
Surface and Coatings Technology
Serial Year :
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