Structure and properties of composite layers on the basis of the amorphous nickel modified of tungsten and nickel oxide
* Magdalena Popczyk, * Antoni Budnik, ** Jerzy Cybo, ** Grzegorz Służałek * Uniwersytet Śląski, Instytut Fizyki i Chemii Metali, ul. Bankowa 12, 40-007 Katowice ** Uniwersytet Śląski, Katedra Materiałoznawstwa, ul. Śnieżna 2, 41-200 Sosnowiec
Annals 2 No. 3, 2002 pages 68-72
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abstract Electrodeposited Ni-P+W and Ni-P+NiO+W composite layers were obtained in the galvanostatic conditions at the current density jdep = 0.200 A/cm2 with the following electrolyte (g/dm3): 28 NiSO4 • 7H2O, 32 NaH2PO2 • H2O, 5 NH4Cl, 9 H3BO3, 8 CH3COONa, 29 C6H5O7Na3 • 2H2O, 40 W in the one case (Ni-P+W) and 100 NiO and 40 W in the other (Ni-P+NiO+W). Twice distilled water and „analytical grade” reagents were used for preparation of electrolytes. For comparision the Ni-P layer was also obtained and investigated in the same manner. The phase composition of the layers was performed by the X-ray diffraction (XRD) method using a Philips diffractometer and the CuKα radiation. The chemical composition of the layers was determined by the atomic absorption method using a Perkin-Elmer spectrometer. Metallographic microscope, stereoscopic microscope, Form Talysurf - type profilograph and X-ray microanalyser were used for cross-section and surface characterisation of the composite layers. All Ni-P, Ni-P+W and Ni-P+NiO+W layers electrolytically deposited, show good adhesion to the copper substrate. In contradistinction from smooth Ni-P layers, obtained Ni-P+W and Ni-P+NiO+W composite layers to characterize of a mat and rough surface, with visible grains of embedded powder. The surfaces of Ni-P+W and Ni-P+NiO+W composite layers are more developed in comparision to Ni-P layer, with proportionate of distribution grains of nickel oxide and tungsten (Fig. 1 and Fig. 2). Linear analysis of distribution of nickel and tungsten in the Ni-P+W and Ni-P+NiO+W composite layers, show o local differentiation of chemical composition of the elements. In the places, where to observe a minimum of capacity of nickel, to observe maximum of capacity of tungsten and inversely (Fig. 3a and 3b). The Ni-P+W layer contains about 71% of nickel, about 14% of phosphorus and about 15% of tungsten. The Ni-P+NiO+W layer contains about 74% of nickel, about 13% of phosphorus, about 5% of nickel oxide and about 8% of tungsten. Electrolytic composite Ni-P+W is formed of amorphous matrix and the crystalline tungsten embedded in it, however electrolytic composite Ni-P+NiO+W is formed of amorphous matrix and the crystalline tungsten and nickel oxide embedded in it. Introduction of tungsten powder in the one case, and nickel oxide and tungsten powder in the other to electrolytic Ni-P matrix is a causing of obtaining layers about very rough surface. Thus obtained layers, to characterize a local differentiation of chemical composition of the elements, what maybe useful in application of this layers as electrode materials in electrochemistry.