Corrosion inhibition of carbon steel by eucalyptus leaves in acidic media: An overview

This paper concerns the overview of previous studies on the corrosion and inhibition of carbon steel that is allowed to degrade in a corrosive medium by the extract of the eucalyptus plant, with an emphasis on the extract's adsorption behaviour. Many researchers have largely employed eucalyptus plant bark, oil, and leaf extracts to prevent the corrosion of mild steel in acidic environments under various temperature settings. According to the results, when the bark extract of the eucalyptus plant was added to HCl (5%) at a concentration of 900 ppm, the inhibitor's maximum efficiency was 98.2 %. The leaf extract, on the other hand, had the maximum inhibitory efficacy of 93.09 % at 600 mg/L extract concentration in the H2SO4 (0.5 M) medium. The extracts' potency was shown to diminish with increasing temperature. The mechanism for eucalyptus extract's protection of carbon steel from corrosion in diverse corrosive situations was largely associated with the adsorption of the extract's inhibitive components on the steel's surface to reduce the interaction between the metal and the corrosive surroundings. The majority of the reported inhibitive behaviour of the eucalyptus extract was consistent with the Langmuir adsorption isotherm model

Overview of corrosion behaviour of ceramic materials in molten salt environments

This study reviewed previous studies between the years 2015 and 2021 on how ceramic materials degraded in the presence of molten salt environments. The processes of corrosion resistance of various ceramic compositions subjected to various molten salt compositions and temperatures were also scrutinized. The results offer important new insights into the variables affecting ceramics' corrosion behaviour and the production of corrosion products.  The reported result reveals that the ceramic material with the composition (Sm0.5Sc0.5)2Zr2O7 performed better than that of Sm2Zr2O7 in terms of hot corrosion resistance in molten salt (V2O5 + Na2SO4). It has also been reported that corrosion behaviour is influenced by particle size. Notably, zirconia (n-YSZ) with nanoscale grain sizes was more susceptible to hot corrosion, which was explained by increased specific surface areas. On the other hand, sintering and additives have been found to enhance corrosion resistance. The Y-Y2Si2O7 ceramic's resistance to corrosion in (V2O5 + Na2SO4) molten salt was enhanced by the addition of alumina. The results of these investigations help us understand how corrosion works and what influences ceramic materials' susceptibility to deterioration in molten salt media. This information can direct the creation of more corrosive-resistant ceramic materials for use in high-temperature environments or molten salt-based energy systems, among other corrosive uses

Recent findings on corrosion of ferritic stainless steel weldments: A review

This study covers the review of the degradation of ferritic stainless-steel weldments between 2015 and 2022. The industrial and automotive sectors make extensive use of ferritic stainless steel (FSS) due to its superior oxidation and corrosion resistance, low price, high thermal conductivity, and low thermal expansion. However, it has been reported that ferritic stainless steel is harder to weld than austenitic stainless steel and that doing so would probably result in a weaker welded joint owing to the coarsening of grains high welding temperatures. According to past research, the amount of heat applied during the welding procedure affected how soon the FSS (409 M) weldment degraded after being exposed to NaCl (3.5%) medium. The coarsening of the grains was considered to be the cause of this. When the shielding gas' CO2 content increased, the intergranular corrosion of the FSS weld metal was found to increase. Welds made with the ER430LNb filler metal had significantly lower intergranular corrosion of FSS (AISI 441) than those made with the ER430Ti filler metal. It was discovered that boiling Cu-CuSO4 - 50% H2SO4 solution increased the corrosion rate for the FSS (AISI 430) weldment more than boiling 40% HNO3 Solution. Weldments made of FSS (AISI 430) were found to be negatively affected by the CuCuSO4 - 50% H2SO4 environment in terms of intergranular corrosion attack

Predictive model for the corrosion inhibition of mild steel in 1.5 M HCl by the leaf-juice of Carica papaya

This current study employed the predictive models driven by the artificial neural network (ANN) and multiple regression (MR) to forecast the corrosion inhibition of mild steel in 1.5 M HCl by the leaves of the Carica papaya plant. Corrosion studies were carried out using the weight loss method at room temperature. The corrosion rate of the mild steel coupon, obtained from the study environment was predicted taking into cognizance the influence of the independent variables viz: the time of exposure, the concentration of HCl (1.5 M), and the concentration of the papaya leaf juice. The fresh papaya leaves were obtained within the surrounding of the Federal University of Technology, Owerri, Imo State, Nigeria. A grinding machine powered by an internal combustion engine was used for grinding the fresh leaves, and a white cloth was utilized to squeeze out the juice. Filtration of the produced juice was done twice with a clean white cloth. Different bowls containing mild steel coupons (5.0 x 5.0 x 0.1 cm) and HCl (1.5 M) solutions were treated with Carica papaya leaf extracts at concentrations of 5 ml, 10 ml, 15 ml, and 20 ml. Results indicated that the highest inhibition efficiency of 95.91% was observed after 120 hours when 20 ml of papaya leaf extract was added. Conversely, the highest corrosion rate of 114.19 mpy was recorded after 24 hours of exposure to HCl (1.5 M) with 5 ml of papaya leaf extract. Generally, the addition of papaya leaf extract in different concentrations added to 1.5 M HCl resulted in a decrease in the rate of mild steel corrosion over time. It was noted that the prediction of the experimental corrosion rate by the artificial neural network offered a lesser error in comparison with that obtained by multiple regression according to the error margin obtained after the prediction of the experimental corrosion rate