In spite of the fact that aluminium and its combinations are regularly used like lightweight materials in a great deal of enterprises, they experience the ill effects of low erosion resistance. Corrosion is a natural phenomena that leads to the deterioration of the metal properties through its electrochemical interaction with the corrosive environment. The costs related to corrosion can be either direct (due to the replacement and maintenance) or indirect. A few strategies and methods have been utilized to mitigate corrosion in aluminium and its compounds under various conditions. Concerns raised over climate and human wellbeing have constrained industries to search for a more appropriate option for the protection of aluminium and its alloys from corrosion. This review emphasizes on the plant extracts applied for aluminium combination consumption restraint in NaCl medium. It summarizes the different techniques used for extraction. Additionally, an understanding to the adsorption isotherms has been discussed in brief.

The present work emphasizes the corrosion mitigation behavior of Pterocarpus marsupium stem extract (PMSE) on mild steel (MS) in various concentrations of hydrochloric acid (HCl) solution using an electrochemical technique. The experiments were conducted in three different levels of acid concentrations (0.1, 0.25, and 0.5 M), three levels of inhibitor concentration (0.03, 0.12 and 0.24 g/L), and at three different temperatures (303 to 313 K) and optimized to get maximum inhibition efficiency. The inhibition efficiency increased with an increase in PMSE concentrations in all the acid concentrations and decreased with an increase in temperature. The Tafel polarization technique revealed mixed inhibition behaviour of PMSE with maximum inhibition efficiency (% IE) of 88.9 % at 303 K containing 0.24 g/L of PMSE in 0.1 M HCl solution. The adsorption mechanism of PMSE on the surface of MS is consistent with physisorption by obeying Freundlich’s adsorption isotherm. The corrosion inhibition of PMSE predominantly owing to protective film formation on the metal surface and is confirmed by surface morphological and FTIR spectral studies. RSM studies using the Taguchi method revealed the highest inhibition efficiency to be predicted at minimum temperature and acid concentration and at the maximum inhibitor concentration as obtained in the experiments.

The metals affect the growth of microorganisms and their activity. Microbes use different mechanisms to interact with metal and metalloids present in the environment. Few trace elements are required for their metabolism and absorb these metal ions present in natural and synthetic environment. Some of the metal play important role in physiological functions of organism but if it is in excess may cause toxic. But few metal doesn’t have any significant role in organism’s metabolism, but still microbes interact with them. Electrochemical and chemical interactions cause the gradual decaying of metals’ exteriors and interiors. Metal degrades with the action of microorganisms. Microbial corrosion is a special type of metal corrosion in which microbes act on such metals where it does not have any intrinsic function. In present article interaction of Aluminioum Alloy (AA) 6061 with Bacillus sp in 3.5% NaCl (W/V) solution has been reported. The interaction study was performed under static and dynamic conditions for 4 weeks and 2 weeks respectively. Weight loss of the metal coupons was performed regularly. Microbial load in both conditions were checked by doing viability cell count to ensure metal toxicity. Scanning Electron Microscope observation was done for biofilm formation on metal coupons.