The purpose of the present PhD research project was to evaluate the feasibility of the electrodeposition of novel thin Ni composite coatings with lubricant particles from an additive-free Watts bath and their application as diffusion barrier layers in journal bearings for medium-speed diesel engines. Overall, the main objective was to develop thin Ni composite coatings with the following characteristics: • Improved tribological performance. • Good adhesion properties. • Good ‘anti-diffusion’ performance. Ultrasound was used in the preparation of pure Ni coatings and Ni composite coatings with lubricant particles under different conditions in order to understand how ultrasonic cavitation influences electrodeposition and characteristics of said Ni-based coatings. Two main studies were conducted related to this: 1. Study of the effect of ultrasonic power on the electrodeposition of pure Ni coatings to understand the influence of cavitation phenomena near the surface of the cathode on the properties of Ni deposits 2. Study of the effect of ultrasound on the production of Ni composite coatings to understand the influence of ultrasound in the dispersion of particles, the electrodeposition of Ni composite coatings and the properties of said Ni composite coatings. The influence of ultrasound on the dispersion of particles in the Watts bath was evaluated by observing the visual appearance of the resulting dispersions and analysing the particle size distribution of diluted solutions by laser diffraction-based particle sizing methods. The effect of ultrasound on the characteristics of Ni deposits and Ni composite coatings electrodeposited from the additive-free Watts bath was evaluated by different material characterization techniques: Abstract • X-Ray Diffraction (XRD) analysis was employed to observe the orientation of the Ni crystals that formed the coatings. • Field Ion Beam – Scanning Electron Microscopy (FIB-SEM) was employed to analyse the surface morphology and microstructure of the coatings. • Microhardness tests were performed to observe how the modification of the grain structure and the presence of particles may affect the hardness of the coatings. • Glow Discharge – Optical Emission Spectroscopy (GD-OES) was also employed to estimate the particle content in the Ni composite coatings.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:650118 |
| Date | January 2015 |
| Creators | Tudela Montes, I. |
| Publisher | Coventry University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://curve.coventry.ac.uk/open/items/d5937c67-9161-4709-8852-fa73c566aa26/1 |
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