Microstructural Development and Surface Characterization of Electrodeposited Nickel/Yttria Composite Coatings

Abstract

The addition of yttria particles to a Watts nickel plating bath is shown to significantly change the surface morphology and preferred crystallographic orientation of the composite coatings deposited on Inconel 625 substrates. The typical morphology for nickel deposits from an additive-free Watts bath is pyramidal, however the addition of yttria particles in concentrations Ͼ2 g dm Ϫ3 changes this morphology to hemispherical. The preferred growth direction was also influenced by yttria with a change from a ͗100͘ to a ͗111͘ preferred growth direction occurring when the particle loading exceeded 2 g dm Ϫ3 . The results here show that both the nucleation and growth process of the nickel matrix was greatly influenced by the yttria additions. When yttria was absent from the electroplating bath the growth took place preferentially on ͑200͒ orientated planes. However, yttria acts to inhibit growth on grains of this orientation, leading to a requirement for additional nucleation, which takes place preferentially on ͑111͒ planes. This constant inhibition of growth and renucleation causes the changes to a hemispherical morphology observed.

Analysis of thermionic emission from electrodeposited Ni–Si Schottky barriers

“…A typical J -V characteristic of evaporated Ni-Si, SBs, with Si resistivity of [10][11][12][13][14][15][16][17][18][19][20] cm is also shown in Fig. 1 for comparison.…”

“…In order to investigate the physical origin of inhomogeneity at the electrodeposited SBs, X-ray diffraction measurements were performed, and are presented in [14] and the references therein).…”

Oxidation at 900 °C of the Chromized Coatings on A3 Carbon Steel with the Electrodeposition Pretreatment of Ni or Ni-CeO2 Film

“…Similar pyramid-like Ni electrodeposits [20,21] were formed, due to a typical Ni growth texture. The XRD characterization indicates that the Ni film was deposited along the most favored 200 h i direction and the second 111 h i direction (it is assumed that the pyramid is composed of a basal {100} plane and four wallside {111} planes), and that the CeO 2 codeposition caused the growth of the Ni deposits along a more random orientation, along 200 h i, 100 h i, and 111 h i.…”

Electrodeposition of Metal Matrix Nanocomposites: Improvement of the Chemical Characterization Techniques

“…The particles distribution gradient in the metallic deposit can be intentionally achieved in a single electrolyte bath by the simple alteration of the applied current density or potential and/or by modulation of the particles hydrodynamics and concentration in the solution (Low et al, 2006). AFM analysis provides available surface morphology characterization at the nanometric scale and due to high resolution imaging, surface roughness values can be estimated (Gomes et al, 2005;McCormack et al, 2003). Tu et al have investigated by XPS the interaction between Al 2 O 3 or SiO 2 nanoparticles and a nickel metal matrix.…”