Influence of deposition parameters on microstructure and contamination of electrodeposited nickel coatings from additive-free sulphamate bath

The microstructural features at different scales and the chemical composition of nickel coatings were studied in link with deposition parameters in direct-current and pulsed modes. Complementary characterization tools were used, allowing a scale relationship to be established between the nodule sizes, the sizes of coherent scattering regions and the grain sizes. The influence of deposition conditions on crystallographic texture and nodule size was formalized by maps versus pulsed current density (jp) and duty cycle (γ). The analysis of these maps offers the opportunity to demonstrate that the decrease in grain size is dependent on texture formation in relation with nucleation and growth processes. The chemical contamination, especially by light elements, seems to be the main factor linking deposition parameters and microstructure (texture and grain size).

► In additive-free sulphamate bath, grain refinement is obtained by decreasing pulsed current density.
► Relations are found between sizes of grains, surface nodules and coherent scattering regions.
► Correlations between grain size, crystallographic texture and chemical contamination are discussed.