A comparative study on the crystallization behavior of electroless NiP and NiCuP deposits
ABSTRACT The crystallization behavior of electroless NiP and NiCuP was studied comparatively by using differential scanning calorimetry and X-ray diffractometry. It is apparent that low-P NiP deposits transform to the stable phase Ni3P directly, but low-P (high-Cu) NiCuP deposits transform to the metastable phase Ni5P2 first, and then to the stable Ni3P. Both the hypereutectic amorphous NiP deposits and amorphous NiCuP deposits with high phosphorus content transform to the metastable phases Ni5P2 and Ni12P5 first, then to the stable phase Ni3P. For the amorphous NiP and NiCuP deposits with P content of approximately 10 wt.%, the crystallization temperature of the latter is markedly higher than that of the former. In addition, the crystallization temperature of the hypereutectic NiP deposit is nearly the same as that of the amorphous NiCuP deposit with a similar P content. For the crystalline NiP and NiCuP deposits with low P content, the temperature at which the stable Ni3P forms in the latter is obviously higher than that of the former.
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- "Krasteva et al. (1994) demonstrated that the introduction of copper into electroless deposited Ni-P alloys conferred higher thermal and nonmagnetic stability. Yu et al. (2001) compared the crystallization behavior of electroless Ni-P and Ni-Cu-P coatings using differential "
ABSTRACT: A simple electroless Ni-Cu-P plating process for preparing an EMI-shielding and corrosion-resistant wood-based composite has been developed. The effects of solution pH value on the metal deposition, surface resistivity, chemical composition, anti-corrosion properties, and crystal structure of the coatings were studied. The coatings were characterized using X-ray photoelectron spectroscopy, X-ray diffraction, and scanning electron microscopy. When the solution pH was increased from 8.5 to 10.0, the metal deposition increased and the surface resistivity decreased. Chemical composition indicated that the nickel deposition increased, whereas the opposite effect was obtained on copper and phosphorus elements with a pH increase from 9.0 to 10.0, and the crystal structure of the Ni-Cu-P coatings changed from an amorphous state to a microcrystalline one. Tafel curves of the Ni-Cu-P coatings prepared at pH 9.0 or 9.5 showed that they had excellent anti-corrosion properties in a 3.5 wt% NaCl solution. The morphology of the coating containing 69.86% Ni-7.65% Cu-22.49% P is superior to that with 75.99% Ni-6.60% Cu-17.41% P after corrosion tests. The plated birch veneers exhibited electromagnetic shielding effectiveness higher than 58 dB in frequencies ranging from 9 KHz to 1.5 GHz, and the coating firmly adhered to the wood surface.Bioresources 08/2013; 8(4). DOI:10.15376/biores.8.4.6097-6110 · 1.55 Impact Factor
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ABSTRACT: Conductive aramid fiber with nickel-copper composite coating is prepared by consecutive steps of metalation swelling, sensitization, activation, nickel electroless deposition, and copper electroless deposition, respectively. The metalation swelling of aramid fiber makes the follow-up sensitization and activation feasible. The as-prepared samples are characterized by SEM, TEM, XRD and XPS. After metalation swelling, the aramid fibers look like cotton fibers with numerous nano-scale pits of 50–300 nm in diameter. Pd metal as nuclei for Ni crystal growth with the size of 10±5 nm is originated from Pd2+, which can be reduced to Pd0 by Sn2+. The Ni-Cu composite coating of 1-µm thickness has polycrystalline structure. And the electrical resistance of conductive Ni-Cu aramid fiber is 0.035 Ω/cm. The synthesis mechanism of the conductive aramid fiber with Ni-Cu composite coating is given.Fibers and Polymers 03/2013; 14(3). DOI:10.1007/s12221-013-0453-4 · 1.11 Impact Factor