Adhesion of electrolessly deposited Ni(P) layers on alumina ceramic. II. Interface characterization

Abstract

The interface microstructure and interface chemistry of electrolessly deposited Ni(P) on alumina ceramics is studied in order to obtain insight into the influence of molecular interactions upon the adhesion. Detailed static secondary-ion-mass spectrometry, x-ray photoelectron spectroscopy, Auger electron spectroscopy, and transmission electron microscopy (TEM) analyses have been carried out with samples with various roughnesses, of which the mechanical analyses are described in the companion article. TEM cross-section micrographs showed a close contact between the two phases on a nanometer scale for all sample types. In addition, a 1–2-nm-thick interfacial layer was observed. This layer consists of nucleation material and compounds from the metallization solution. Fracture surface analyses showed that fracture takes place through this layer, which is therefore considered to be the weak boundary layer in this system. The presence of this weak boundary layer explains the importance of substrate surface roughness and mechanical interlocking for the fracture energy.