1,720,987 research outputs found
Electrochemical and localized corrosion behaviour of stainless steel in chloride solution: a stochastic approach.
No full textInfluence of the particle size on the mechanical and electrochemical behaviour of micro- and nano-nickel matrix composite coatings
No full textThe aim of this work is the production and characterization of composite nickel matrix electrodeposits. Pure nickel and composite nickel matrix deposits containing either micro- or nano-particles of silicon carbide were prepared using a Watts type bath. The electrodeposition was carried out under both direct and pulse current conditions at different frequencies. With the same quantity of powder in the bath, the embedded micro-powder content is about 25-30%w while the nano-powder content is always less than 1%w. The mechanical properties of the nano-composites increases despite the low ceramic content. SEM micrographs of the microstructure and XRD-line profile analysis show that the presence of ceramic powder in both baths changes the crystallisation process leading to enhanced mechanical properties even at ceramic contents less than 1%, as in the nano-composite case. The presence of the ceramic phase and changes in the microstructure both decrease the mass loss during abrasion by up to 70% for micro-composites and 45% for nano-composites
Misura del potenziale critico di pitting in acciai inossidabili austenitici in ambienti clorurati
No full text
Effect of ultrasound vibration during electrodeposition of Ni-SiC nanocomposite coatings
No full textThe deposition of pure Ni and Ni/SiC nanocomposite coatings was carried out using an additive free Watts type bath. In order to avoid porosity and defects induced by the hydrogen evolution ultrasonic vibration was used during the electrodeposition. The effects of the ultrasound treatment on both pure Ni and Ni/SiC nanocomposite codeposition was investigated by means of coatings microstructure and surface morphology study and SiC content measurements. Moreover, it was demonstrated that the ultrasonic vibration reduced the layer porosity. The role of ultrasounds in reducing porosity was shown
Scaling-up of the electrodeposition process of nano-composite coating for corrosion and wear protection
No full textThe codeposition of hard nanoparticles into metal matrix electrodeposits usually leads to the increase of the coating hardness and abrasion resistance and causes a change to the microstructure of the deposits leading to more compact, nanostructured coatings with an increased corrosion resistance. Very often the laboratory scale results are not easily transferable to an industrial scale due to the introduction of new process variables such as the geometry and the dimensions of the component to coat. The aim of the present work was the study, in laboratory scale, of nano-composite nickel matrix coatings containing SiC nanoparticles and the transfer of this technology in industrial scale. The deposits have been produced using a Watts type bath containing 20 g/l of nanoparticles, under galvanostatic conditions using a current density of 2 A/dm2. The deposits have been studied regarding their microstructure, abrasion and corrosion resistance. Based on the satisfactory results of the laboratory tests, the second part of this work contains the scaling-up and the industrialization of the process and the electrodeposition of the composite coating on ship propeller models and profiles as well as on train axles. The prototype parts were tested under actual working conditions
- …
