Correlation between structure and corrosion behaviour of nickel dispersion coatings containing ceramic particles of different sizes

The complex demands of construction units require an adjusted coating concept, in order to avoid unintentional changes of characteristics up to eventual failure. The paper makes a contribution to the clarification of the connections between the deposition parameters, the structure and the characteristics of nickel dispersion layers with incorporated micron and nano-particles. The material characterisation by different testing methods supplies abstractive results. Starting from the layer structure (incorporation rate, particle distribution, agglomeration, type of crystallisation of the matrix), correlations between textures, internal tensions and hardness are described. It is shown that the nature of the particles (material structure, hardness, conductivity, shape and size) influences the incorporation behaviour as well as the layer characteristics. The desired fine dispersion of the small particles in the Ni-layers is considerably improved by the use of ultrasound. As a promising result, the corrosion behaviour can be improved using particles the size of 200 nm up to particles the size of microns. The corrosion tests were carried out by means of potentiometric measurements. Applying a strip projection measuring instrument, the volumetric corrosion erosion was quantified. (c) 2006 Elsevier B.V. All rights reserved.