Abstract. The investigation of coating incorporated with various percentages of henna has been conducted by means of weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy method. Mild steel has been studied at ambient temperature and 50°C in order to examine the effect of temperature. The potentiodynamic polarization measurements indicate that henna extract acts as a mixed inhibitor while the corrosion rate (CR) value decreases as the current density (I corr ) decreases in the presence of 10% henna extract for both temperatures. Surface and protective film analysis have been carried out using Fourier transform infrared (FTIR) and scanning electron microscopy (SEM).The inhibition activity is mainly correlated with the major active functional groups of lawsone. The main components can be found in lawsone structures are phenols O-H, carboxylic acid C=O and alkenes C=C. The morphology of the uninhibited sample showsa rough surface of mild steel as a result of corrosion process and severe damage can be seen. In the presence of henna, a smooth surface of mild steel anda uniform deposition of henna were observed.

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Metallic materials are the most applicable materials in various industries. They are useful due to their excellent mechanical properties. However, they are exposed to corrosion because the environment contains oxygen, humidity and some other factors. This paper describes about a paint incorporated with organic inhibitor, i.e., henna extract. This paint was produced to enhance its anticorrosive property. Henna extract was chosen as the corrosion inhibitor as it is organic, environmentally acceptable, readily available and a renewable source of material for a wide range of corrosion problems. The extractions were characterised by using Fourier Transform Infrared. Meanwhile, the inhibitive action of henna extract was investigated through an electrochemical technique. The inhibitive effects of henna extract were investigated with percentages of 0%, 4%, 8% and 10% incorporated into a rosin (epoxy)-based matrix. The specimens were characterised by electrochemical impedance spectroscopy measurement. The morphology study was investigated through surface analysis by using scanning electron microscopy. The inhibition efficiency increased as the concentration of henna extract was increased. The results showed that Paint 3 has the lowest corrosion rate of 0.001767 mm/yr as compared to Paint 1 with 0.005148 mm/yr. The inhibitive action of the henna extract is discussed. Paint 3 was proposed as the most effective paint that contains a natural inhibitor for aluminium alloy.

The corrosion performance of aluminum alloy 5083 (AA5083) was investigated in the splash zone area simulated in salt spray cabinet at ambient temperature. Three paint formulations were prepared in accordance with different percentages of henna extract. FTIR method was used to determine the constituent of henna while weight loss and electrochemical method were applied to investigate the inhibition behaviour. The findings show that corrosion rate of aluminum alloy decreased with the increases of henna extract in the coating formulation. The rise of charge transfer resistance (Rct) value has contributed to the greater protection of the coated aluminum. The decrease in double layer capacitance value (Cdl) is another indicator that a better protective barrier has been formed in the presence of henna in the coating matrix.

Problem statement: The stresses to humidity, DC and AC bias, multiple impulse voltages and high temperatures are known to affect the varistor performance and it is also interesting to know the effect of both DC bias and temperature stresses at the same time. Approach: Here, the simultaneous DC and temperature stresses degradation was investigated to see the changes of nonlinear coefficient (α) in Zn-Bi-Ti oxide low-voltage varistor ceramics sintered at various sintering temperatures (1140-1260°C) and two sintering duration times of 45 and 90 min. The current-voltage characteristics of the varistor ceramics were evaluated. Results: The α of ceramic was observed to be decreased with increasing sintering temperature. After loaded with DC and temperature stresses of 0.75V_1mA/80°C/12 h, the α of ceramics for 90 min sintering time decreases with sintering temperature, however that sintered for 45 min sintering time increase with sintering time. Conclusion: The application of DC and temperature stresses in Zn-Bi-Ti oxide ceramics sintered at very long time cause the α to decrease as evidence from higher leakage current