Fabrication of PdxNiyP100-x-y Metallic Glass Film by Electroless Alloy Plating and its Catalyst Activity
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Fabrication of PdxNiyP100-x-y Metallic Glass Film by Electroless Alloy Plating and its Catalyst Activity Yoshihide Imamura, Masato Sone, Akinobu Shibata, Chiemi Ishiyama, and Yakichi Higo Precision and Intelligence Laboratory, Tokyo Institute of Technology, Yokohama, 226-8503, Japan ABSTRACT Pd-Ni-P films were systematically plated using a mixture of Pd and Ni-P plating solutions. The films were plated by electroless alloy plating using three Pd/Ni-P mixture ratios (1/1, 3/1, and 1/3) at plating temperatures adjusted within a range from 303 to 333K. An increase in the Ni-P mixture ratio or in the plating temperature led to an increase in the Ni content of the plated film and a decrease in the Pd content. The P content of the plated film remained almost constant. These results indicate that the composition of the fabricated film can be effectively controlled by adjusting the plating temperature and mixture ratio. The plated film had a flat surface morphology without defects such as pinholes or nodules. TEM observation of the film revealed an amorphous structure. DSC analysis during heating revealed an endothermic peak and exothermic peak corresponding to the glass transition and crystallization, respectively. On the basis of these results, we concluded that the plated Pd-Ni-P film was metallic glass. The plated Pd-Ni-P film was also confirmed to have catalytic activity, as the Ni-P alloy was plated directly onto the film without catalyzation by electroless plating. The high flatness and uniformity of the surface of the Ni-P film plated onto the Pd-Ni-P film suggests that the Ni-P film grew via a onedimensional growth mechanism.
INTRODUCTION Unlike conventional amorphous alloys, bulk metallic glasses (BMGs) exhibit a clear glass transition during continuous heating and have large supercooled liquid regions. Many scientists have been intrigued by the unique mechanical, corrosion, and magnetic properties of metallic glasses, and there have been several studies fundamental to application research on these materials [1,2]. Because of its amorphous structure, BMG remains isotropic even when specimen sizes shrink to a micro or nano order. The supercooled liquid region also offers advantages, as it can be used to remove internal stress and to fabricate micro components. Metallic glasses are thus expected to be a very important for micro-sized materials [3-5]. Thin films of metallic glass can be fabricated by conventional processes such as sputtering [5,6]. The films fabricated by sputtering, however, are marred with abundant voids and defects, and the step coverage of sputtering is fairly poor. These defects significantly affect the mechanical properties of micro-sized materials, and might thus rule out sputtering as a practical strategy for fabricating metallic glass films. Perceiving the need for a new and better method, we turned our attention to electroless plating. Electroless plating fabricates uniform thin films with few voids and defects, works at a low process temperature, and can be used to plate film
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