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This study shows the effect of Yttrium addition (2-6 wt%) on the mechanical properties and the corrosion resistance of Mg-Y binary fabricated from sacrificial magnesium anode. The beneficial of Mg anode source was tremendous for magnesium alloy especially for corrosion resistance. Improvement of mechanical properties due to the addition of Yttrium was caused by grain refinement solid solution strengthening. Tensile strength increased with the addition of Yttrium. Mg-Y binary is immersed in the SBF solution to see the corrosion resistance. The hydrogen evolution was increased from 0,32 mL/cm2 day, 1 mL/cm2 day, and 34,42 mL/cm2 day for Mg-2%wt Y, Mg-4%wt Y, and Mg-6%wt Y respectively.

Lapisan epoksi sering digunakan untuk melindungi baja karbon dari korosi. Namun baja yang diberi lapisan epoksi dapat terserang korosi. Prosedur pelapisan yang kurang baik, preparasi permukaan, pemilihan komposisi lapisan dan kerusakan mekanis adalah beberapa faktor yang dapat menyebabkan rusaknya lapisan epoksi pada baja. Pada penelitian ini akan dipelajari pengaruh konsentrasi thinner terhadap ketahanan korosi lapisan epoksi. Lapisan epoksi dengan konsentrasi thinner yang bervariasi diaplikasikan pada substrat baja menggunakan metoda spray. Konsentrasi thinner yang divariasikan adalah 0, 15 dan 30 % volume. Pengukuran ketebalan, kekasaran, kekerasan dan permeabilitas pelapisan dilakukan sebagai data pendukung. Ketahanan korosi lapisan ini diuji pada lingkungan NaCl 5% dengan pengujian korosi siklus kabut garam. Hasil pengujian menunjukkan bahwa sampel dengan konsentrasi thinner 15% memiliki nilai daya lekat paling tinggi yaitu 1,875 MPa. Pengujian korosi siklus kabut garam menunjukkan bahwa lapisan epoksi dengan 15% thinner memiliki ketahanan korosi underfilm yang sangat baik, dengan Xmax 0,64 mm dan Ymax 0,69 mm. Seiring dengan peningkatan konsentrasi thinner, ketebalan dan kekasaran permukaan lapisan menurun. Hasil pengujian FTIR menunjukkan bahwa penambahan thinner tidak mempengaruhi struktur kimia dari lapisan epoksi yang terbentuk.Kata kunci: pelapisan, daya lekat, ketahanan korosi, thinner

In this work, the oxidation behavior of Fe-20wt.%Cr alloys with different titanium contents: 0, 0.5, and 1 wt.% are studied as a function of time in air atmosphere. The samples were isothermally oxidized at 700°C for 24, 48, and 96 h in a box furnace. The area specific resistance of oxides formed at the alloys surface during oxidation is measured by four-point probe methods at 700°C for 24 h. For Ti containing alloys, surface morphology observation by SEM shows that a few of TiO2 particles formed on the top of Cr2O3 scales. Continous TiO2 layer was not formed at the alloys surface after oxidation. XRD analysis on the oxide scales of Fe-20Cr-Ti alloys confirms that Cr2O3 and TiO2 oxide formed on the alloys. Ti addition into the alloys increases the oxidation rates of alloys at the initial stages. Oxidation behavior of Fe-20Cr-0.5Ti and Fe-20Cr-1Ti alloys showed two regimes. The parabolic rate constant, kp (in gr2/cm4s) were 1.57 x 10-13 and 3.08 x 10-13 respectively for initial stage of oxidation then changed to-9 x 10-15 and-3 x 10-14 respectively for the remainder of the test. ASR measurement shows that the presence of Ti in the alloys decreases the electrical resistance up to 60%. Ti addition into Fe-Cr alloys affect the oxide growth rate and increase the conductivity of Cr2O3 scales.

In the present work, Zn-ZrO2 nanocomposite coatings were deposited on the copper substrate through DC and pulse electrodeposition technique with low current density (10 mA/cm2). The effect addition of ZrO2 nanoparticles and pulse current were studied. The surface morphology, microhardness and erosion resistance of Zn-ZrO2 nanocomposite coating were evaluated. The result shows that, with the addition of ZrO2 particles, the surface morphology of Zn-ZrO2 nanocomposite coating was smoother. Phase identification by XRD confirm that Zn layer had been sucessfully deposited. The presence of ZrO2 nanoparticles was not detected. Compared to DC, pulsed current electrodeposition technique showed higher cathodic efficiency, better microhardness and good erosion resistance.

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In this work, Cr-ZrO2 composite coating were prepared by electrodeposition method on aluminium substrate from chromic acid based electrolytes containing gelatin. The effect of gelatin on the corrosion resistance of Cr-ZrO2 coatings were studied in 3 wt.% sodium chloride solutions. Potentiodynamic polarization studies were performed using a Versastat 3 (Princeton Applied Research) electrochemical system with a three-electrode cell. Results shows that the corrosion resistance of Cr-ZrO2 coating on Al substrate was improved by the addition of gelatin to the coating solution. The addition of gelatin shifted the potentiodynamic polarization curved in the noble direction. The corrosion potential changed positively from -778 mV to -259 mV. The corrosion rate of Cr-ZrO2 coating decreased from 4.44±0.93 mpy to 0.13±0.01 mpy with the addition of 3g/L gelatin.