The Influence of Thermal Treatments on the Adhesion of Electrolessly Deposited Ni (  P  )  Layers on Alumina Ceramic

Abstract

The adhesion of electrolessly deposited Ni(P) on 96 and 99.5% pure alumina was studied as a function of annealing temperature, up to 580~ The adhesion was measured with the direct pull-off test and the peel test. The interface structure was analyzed with cross-section transmission electron micrographs. Fracture surfaces were analyzed with scanning electron microscopy/energy dispersive x-ray analysis, static-secondary ion mass spectroscopy, and x-ray photoelectron spectroscopy. The optimum annealing temperature was found to be 400~ at which an increase in peel energy and adhesion strength by a factor of two to three was measured, with respect to the as-deposited value. The weak boundary layer, which was previously reported to be present in this system, is still present after annealing and the fracture path remains through this interracial layer of a few nanometers in thickness. Therefore, the adhesion improvement is ascribed to stronger cohesion of the material in the weak boundary layer.

The influence of substrate chemistry on the adhesion of electrolessly deposited Ni(P) on metal oxide coated ceramics

“…The oxidized Ni and P species, the nucleation material and the sulphur compounds, detected with the aid of XPS on fracture surfaces of all of the sample types, indicate the presence of similar compounds as found in the previous studies [4,5]. On the other hand, the TEM cross-section micrograph of the sample with the ZrO2 substrate coating does not show a discrete interfacial layer.…”

“…From these studies evidence has been obtained that, in contrast to what is commonly believed [2], the adhesion is influenced not only by mechanical interactions but also by interface chemical interactions [4,5]. Osaka et al [6] reported similar evidence.…”

“…If these gaps or pores are wider than a few nanometres, Ni(P) is likely to penetrate and form microscopic anchoring sites. The Ni(P) films generally follow the surface topography of the substrate on this scale [1,4,5]. This type of roughness was termed microroughness by Venables [17], who observed an improvement of adhesion of polymer layers to phosphoric acid anodized aluminium due to roughness structures of 5-10 nm.…”

“…A much higher peel energy of 44 J m-2 was measured for the rough-type substrates, which is largely explained by mechanical interactions. After annealing of these samples at temperatures above 250 °C, a two-to threefold higher peel energy was measured [5]. Since the fracture path remained through the interfacial layer, the improved adhesion was as-cribed to stronger cohesion within the layer after annealing.…”

“…Up to now, we have investigated the adhesion of electrolessly deposited Ni(P) on polycrystalline alumina substrates [1][2][3][4][5]. From these studies evidence has been obtained that, in contrast to what is commonly believed [2], the adhesion is influenced not only by mechanical interactions but also by interface chemical interactions [4,5].…”