Effects of pretreatment on the structure and properties of electroless nickel coatings
The pretreatment process can significantly affect the corrosion resistance of electroless nickel (EN) coatings. One of the most important reasons is that different pretreatment processes can give different surface morphologies of the substrate. The scanning electron microscope (SEM) and the scanning tunneling microscope (STM) have been used to investigate the structure and properties of EN coatings in the as-plated condition for various deposition times, in relation to different mechanical/chemical pretreatment processes. The morphology of the substrate surface is found to be a key factor in control of the porosity of EN coatings. It can significantly affect the formation of EN deposits, not only in the early stage but also in the morphology/ structure during the continued growth of the deposit
In Situ Scanning Tunneling Microscopy Observation of Electroless-Deposited NiP Film
Preliminary results of an in situ scanning tunneling microscopy (STM) observation of electroless-deposited NiP film as well as that of electrodeposited film were demonstrated. The electroless-deposited film is observed to develop rough features consisting of small grains, suggesting the successive nucleation of the grains and their three-dimensional growth. The electro-deposited film, in contrast, consists of larger grains with smooth features.
Analytical techniques in surface topography and their application to a running-in experiment
Abstract The importance of the application of surface topographic parameters is discussed and their relevance to production processes and tribology is examined. It is shown that of the surfaces which require specification more than 90% are subsequently used in tribological situations. Both amplitude distribution and spatial approaches to surface specification are described and their relative usefulness discussed. Relocation techniques are considered and a novel wear rig is described in which the associated problems are minimised. Experimental results are presented showing significant statistical parameters which highlight the topographical changes occurring during running-in.