PENGARUH ENERGI AKTIVASI LOGAM PELAPIS TERHADAP KETEBALAN DAN LAJU KOROSI PLATING

This study aims to study the effect of the activation energy gradient (∆G) of metals on the thickness and corrosion rate of Ni layers; Cr, and Ni-Cr. The layer is obtained through the Ni electroplating process; Cr, and Ni-Cr in carbon steel specimens using a variation of current strength of 1.25; 1.5 and 1.75 Ampere at constant stress and coating time (15 minutes). Nickel plating is obtained in the electric layer process using a watt's bath electrolyte solution in a mixture of 150 g / l NiSO4, 30 g / l NH4Cl, 30 g / l H3BO3 with a temperature of 25-35 oC, pH around 4-6, air agitation, Chromium plating using anode in the form of an alloy of Pb (lead) and Sn (antimony) rods, a solution in the form of an electrolyte mixture of 300 g / l CrO3, 3 g / l H2SO4 in working temperature of 40–55 oC, pH around 0.4 - 0.5 and air agitation. Corrosion thickness was observed using an optical microscope at 200 X magnification while the corrosion rate of observation was carried out based on the method of resistance polarization in the medium of 0.9% Sodium Chlorid Solution. The results showed that, in the same treatment, the thickness of the layer increased in increasing current strength, slower chromium than nickel layer and Nickel-Chromium layer. Sequential thickness of layers is obtained for Ni: 51, Cr: 39 layers, while corrosion rates occur at 1.75 A current in nickel layer 0.0017 mm / year; Chromium layer, 0.0077 mm /year and Nickel-Chromium layer 0.0231 mm / year

Dynamic Light Scattering and Zeta Potential Studies of Ceria Nanoparticles

A Cerium (IV) oxide nanoparticle (nanoceria) is widely used in different applications such as biomedicine and catalysis due to its unique structural, morphological and catalytic properties. In this report, the dispersion of nanoceria in both aqueous and non-aqueous (methanol and ethanol) media were studied. Adsorption-desorption processes were observed upon addition of different classes of surfactants such as citric acid (CA), cetrimonium bromide (CTAB) and diethanolamine (DEA). Stable dispersions were obtained in both aqueous, non-aqueous and electrolyte assisted media with the overall mechanism being hydrolysis, dissolution and adsorption. XRD, FE-SEM, FTIR and DLS have been used in the present study to characterize the nanoceria and to quantitatively analyze their average particle size distributions in a unique electrolyte mixture of (0.1 M NaOH/ 65% HNO3:H2O, 1:1 v/v) which has not been reported previously. The surface charge study was carried out across a wide pH range between 1.4 – 9.6 and the isoelectric points (IEP) with respect to 15 ml H2O and 50 ml H2O dispersed phases occurred at a pH of about 6.5 and 6.7 respectively. The present study could be useful in a wide range of applications including nanoparticle synthesis, stabilization, and adsorption of toxic materials, biomedical and pharmaceutical.