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The roof of an HCl fiber-reinforced plastic (FRP) chemical tank failed by accident after it had been operated for less than its expected lifetime. A possible cause is the change in day and night temperature, which lead to the cyclic change in the concentration of HCl vapor in contact with roof part. To investigate this possibility, a detailed analysis on the durability of the material exposed to cyclic solution concentration is required. In this research, vinyl ester-glass fiber composite specimens were exposed to 35 mass % and 0 mass% of HCl alternately at 40°C to replicate cyclic concentration exposure in both the vapor and liquid phases. The mass uptake and penetration depth of HCl as well as the strength loss of the material were investigated. Mass uptake and thickness change in vapor phase shows two times higher than liquid phase, at 3.5% and 6% respectively. This occurs due to differences in the concentration of solutions that diffuse to the specimen in the vapor phase and liquid phase. This phenomenon arises from variations in the concentration of solutions that diffuse to the specimen in both vapor and liquid phases. The diffusion process is facilitated by osmotic pressure, leading to material swelling and contributing to their degradation. The result of flexural strength measurement of specimens indicated a decreasing trend as exposure time increased. The flexural strength decreases by up to 36% due to plasticization. The Cl and water content profile in specimens that obtained from elemental mapping of cross-sections using Energy-Dispersive X-ray Spectroscopy (EDS) are enhancing the study on how materials degrade, which may be a reason for damage to FRP tank roofs.
Background of this paper investigates dogonyaro-leaf-extract as inhibitor for aluminum corrosion in 0.3-M hydrochloric acid, and its acceptability as original. In the methods, the extract was analyzed for phytochemicals and corrosion test performed on aluminum sheet before immersion in acid incorporated extract. Electrochemical Impedance Spectroscopy (EIS), tests were performed over frequency of 100 KHz–10 mHz and 10 mV peak to peak perturbation amplitude to obtain the corrosion potential. Tests were run at 30oC ± room temperature in aerated quiescent solutions. In weight loss method, coupons were suspended in aerated solutions before immersion in 20% mixture of sodium hydroxide and zinc dust to stop further corrosion. Morphology of the mirrorlike finished arid surface aluminum was measured with scanning electron microscope SEM. In the results, various phytochemicals were observed; significant effect of incorporating inhibitor on EIS data recorded and optimum extract efficiency was 99.46%, at 10 g/l, 60oC, within 6 hours. This result was validated and 99.3% efficiency obtained. Introduction of extract into acid corrodents caused increase of charge transfer resistance and reduced double layer capacitance. A warm arid clean coupon evolved after SEM test. In conclusion, there was increase in efficiency of inhibition as inhibitor concentration and temperature increased. Similarly, close responses towards the factors for Inhibition occur. Measured polarization showed that extract inhibited both cathodic and anodic reaction processes and thus, is classified as mixed type inhibitor. The investigations thus proved the extract as excellent corrosion inhibitor for aluminum in 0.3-M hydrochloric-acid.