AbstractComposite coatings are of great academic and industrial importance to the UK and the wider world. They can offer many improvements over single-phase materials in microhardness, wear resistance, thermal resistance, hydrophobic behaviour and corrosion resistance, however, electrodeposited composite coatings are not without their drawbacks. Composites are difficult to recycle, and the particles used in them can be expensive and require energy intensive production methods to produce them, which can make them unsustainable in the long term. The Aim of this research was to produce copper and nickel composite coatings from a more sustainable source of filler particles (turmeric), and then characterise their properties. The coatings were deposited from various electrolytes including acid copper, Watts nickel and a low nickel ion concentration electrolyte (LICE).
The hardness, hydrophobic behaviour, surface roughness, and corrosion rate of the coatings were then characterised. To understand these properties the surface texture, grain structure, and composition of the coatings was analysed. The results showed the incorporation of turmeric into the copper coating reduced the grain size of the deposit and increased the microhardness, water contact angle and electrochemical corrosion resistance of the coating, however, there was a reduction in corrosion resistance when the coatings were tested using the salt spray standard method ASTM B 117 –03. An additional unexpected finding was that the size of turmeric particles in the electrolyte had a greater influence on the coating’s properties than the concentration of turmeric in the electrolyte, and that there was anoptimal size of turmeric particles (of circa 250 nm) for reducing the grain size of the copper deposit. This result correlates with the findings obtained from copper nano-diamond deposits in this research, which also showed an optimal particle size of 250nm for reducing the grain size of the deposit. The incorporation of turmeric into the nickel deposit also reduced the grain size and increased the microhardness corrosion resistance and the water contact angle of the coating. At 5.0 g/l of turmeric in the nickel electrolyte both the resistance to electrochemical and salt spray corrosion was also increased. This research demonstrates that turmeric particles could be used as a sustainable filler particle for nickel and copper composite coatings.
|Date of Award||Aug 2019|
|Supervisor||Andrew Cobley (Supervisor), John Graves (Supervisor) & Jamie Beddow (Supervisor)|