Green Corrosion Inhibition on Carbon-Fibre-Reinforced Aluminium Laminate in NaCl Using Aerva Lanata Flower Extract

Cold-Sprayed Composite Metal-Fluoropolymer Coatings for Alloy Protection against Corrosion and Wear

Results of studying the properties of composite fluoropolymer-containing coatings formed by the cold spray (CS) method on the surface of constructional steel are presented. Different ways of protective coating formation are proposed. The composition of coatings was studied using SEM/EDX analysis. The incorporation of super-dispersed polytetrafluoroethylene (SPTFE) into the coating increases the corrosion resistance of the copper-zinc-based cold-sprayed coating. Analysis of the electrochemical properties obtained using EIS (electrochemical impedance spectroscopy) and PDP (potentiodynamic polarization) indicates that samples treated with SPTFE on a base copper-zinc coating showed lower corrosion current density and higher impedance modulus (j_c = 8.5 × 10^-7 A cm^-2, |Z|_{f=0.1 Hz} = 5.3 × 10⁴ Ω∙cm²) than the specimen with cold-sprayed SPTFE (j_c = 6.1 × 10^-6 A cm^-2, |Z|_{f=0.1 Hz} = 8.1 × 10³ Ω∙cm²). The best anticorrosion properties were revealed for the sample with a cold-sprayed base Cu-Zn layer annealed at 500 °C for 1 h, followed by SPTFE friction treatment and re-annealed at 350 °C for 1 h. The corrosion current density j_c of such a coating is 25 times lower than that for the base Cu-Zn coating. The antifriction properties and hydrophobicity of the formed layers are described. Obtained results indicate that cold-sprayed polymer-containing coatings effectively improve the corrosion and wear resistivity of the treated material.

Study on the Impact and Water Absorption Performance of Prosopis juliflora & Glass Fibre Reinforced Epoxy Composite Laminates

Current global trends demand the replacement of synthetic fibres with natural fibres in polymeric composites. The present work makes use of Prosopis juliflora, a plant that is a threat to the environment as a partial replacement in a hybrid composite. Individual Prosopis juliflora fibres are added to matrices at ratios of 12, 6, 9 and 8 wt % and glass fibres are added discretely at ratios of 28, 24, 21 and 32 wt % into matrices as well. The composites are prepared with four different combinations and tested in terms of the mechanical benefits and water absorption performance. This work exploits the mechanical advantage of impact energy in addition to producing Prosopis juliflora particles, fibre glass mats, and resin appropriate for structural uses. Water absorption tests are conducted for four different compositions. Among the four samples, sample 3 (9 wt % Prosopis juliflora fibres and 21 wt % glass fibres) has a higher rate of water absorption than the others, although sample 2 (6 wt % Prosopis juliflora fibres and 24 wt % glass fibres) has a lower rate. The difference in the quantity of water absorption between the hybrid composites can be attributed to the weight percentage of fibres. On the other hand, sample 1 (12 wt % Prosopis juliflora fibres and 28 wt % glass fibres) is reported to have absorbed 2.6 J of energy in the impact strength test. The increase in impact strength is attributed to the increase in the weight percentage of glass fibres. A scanning electron microscope is employed to study the fractured surfaces of the composites. This study shows that the developed hybrid composite could be employed in structural and automotive applications because of its improved impact strength and water resistance.