Search

Marine propellers operate under severe service conditions and experience various corrosion forms. Electrochemical, mechanical, and biological corrosion are the three main common types of corrosion that occur on marine propellers. Electrolysis (electrolytic corrosion), being one of the electrochemical corrosion forms, has been extensively observed on marine propellers. It is the forced introduction of an external current in metals when submerged in seawater. However, it has rarely been studied for marine propellers, mostly on underground pipelines. This paper investigates the effect of electrolysis on a chromium-containing coating on copper substrate by studying the surface and cross-sectional microstructure of the substrate. It is likely that cathodic disbondment caused by high alkalinity and hydrogen evolution at the defect location were the primary reasons contributing to the failure of the coating, and the silver-colored layer deposition around the delaminated area is the corrosion product of copper–chromium oxide. The purpose of this study is to understand the electrolysis corrosion mechanism on Cu substrate and to develop a highly effective anticorrosion coating for marine propellers. [ABSTRACT FROM AUTHOR]

In this work silicon nitride (Si3N4) fibres, with diameters D50 = 300 nm, were successfully functionalised with a monolayer of γ-glycidoxypropyl trimethoxysilane (GPS) coupling agent. The surface modification was used as a method to enhance the dispersion and interfacial adhesion of the fibres in epoxy polymer composites. It is well known that strong interfacial adhesion between dispersed inorganic fibres and a polymer matrix improves the mechanical properties of the composite by providing an effective stress-transfer pathway between the matrix and the fibres. The functionalised Si3N4 fibres were dispersed into a commercial epoxy resin via tumble-mill mixing and ultra-sonication. Setting was initiated via addition of a poly-amine hardener and the composites were cured at room temperature for 24 hours. The fractured surfaces of the cured composite materials were analysed via SEM imaging and the mechanical properties of the composites were tested. The GPS-Si3N4 composites were shown to have improved bonding at the interface, which resulted in enhanced mechanical properties compared to the unfunctionalised Si3N4 composites, with improved tensile strengths and hardness values. This study shows the importance of achieving a strong interphase region between the surface of a fibre and the polymer matrix in fibre-reinforced polymer composites. [ABSTRACT FROM AUTHOR]

Fire performance of water-based plaster systems containing acrylic copolymer binder and non-flammable mineral and ceramic fillers intended for decorative coating application was determined by cone calorimetric method. The coatings were applied on common building substrate materials used in construction sector, namely, Medium Density Fibre (MDF) boards, Gypsum Boards (GIB) and Stainless Steel (SS), and the different plaster finishes attempted on these substrates were Tierrafino, Suave and Bone China respectively. Group numbers of the different test samples were also evaluated following the Kokkala method. Based on various measurements, especially heat release, smoke evolution, mass loss data and the Group number estimates, it is evident that these organic fire retardant free coatings can offer good fire safety if applied on appropriate substrates like GIB or SS. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]