L-Dopa as Corrosion Inhibitor for Mild Steel in Mineral Acid Medium
Corrosion inhibition of mild steel was studied using L-Dopa in aqueous hydrochloric acid and sulphuric acid so- lutions. The corrosion behaviours of the steel specimen in the presence of inhibitor weret studied by galvanostatic polari- zation and weight loss techniques. The measured electrochemical data indicated good inhibition of corrosion in both the corrosive medium in presence of L-DOPA. The corrosion inhibition may be explained on the basis of adsorption and for- mation of surface film of L-DOPA on the metal surface. The surface of the steel specimen subjected to electrochemical corrosion in the presence and absence of the inhibitor was studied using scanning electron microscopic images. In the present investigation, L-DOPA is used as corrosion inhibitor for mild steel in aqueous hydrochloric acid and sulphuric acid solutions. The corrosion inhibition efficiency of the compound is studied by potentiodynamic polarization and weight loss studies. The surface morphology of the metal surface before and after corrosion is studied by SEM images. 2. EXPERIMENTAL Analytical Reagent (AR) grade chemicals (sd. fine chemicals, Mumbai) were used for the study. The aqueous solution of sulphuric acid and hydrochloric acid was used as the corrosive media. L-dopa was used as received and the structure of the L-dopa was used as corrosion inhibitor is as shown in Fig. (1).
Protection of mild steel against corrosion by polynitroaniline films
Abstract Electrochemical polymerization of o-nitroaniline was carried out using graphite electrode in hydrochloric acid medium. The electrochemically synthesized polynitroaniline (PNA) was used to modify the surface of mild steel against corrosion by chemical method. The corrosion behavior of the modified steel surface was tested by weight-loss, potentiodynamic polarization and electrochemical impedance spectroscopic technique in 1N solutions of H2SO4, HCl and NaCl at 303 K. The results indicated that the surface modification of steel specimens enhanced the resistance to corrosion in the above corrosive media. The corrosion protection offered by PNA was due to the formation of its stable layer on the surface of steel. Ecorr of the modified steel specimen was in the passive region and thus inhibits the corrosion process. The surface of the steel specimen before and after treatment with PNA was studied by SEM images. The FTIR spectra of the polymer and the compound collected from the modified samples after polarization were recorded. The process of corrosion inhibition and protection of PNA film on steel was established.
Failure analysis for poor solderability of Au surface of PCB
Nonwetting is one of the common problems and is always rejected in electronic assemblies. ENIG pads of a PCBA exhibited nonwetting after lead-free reflow soldering. With the aid of stereomicroscope, SEM&EDS and XRF, a series of analysis was performed. And after visual inspection, surface and cross section analysis, thickness measurement and solderability test, it can be inferred that oxidation of plating surface was the main reason for nonwetting, and corrosion in Ni plating caused an adverse impact on solderalibity.