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Electrochemical Deposition of Composite Coatings of Nickel - Silicon Carbide Under Pulsed Current Using a Rotating Disk Electrode

Zarghami, Vahid | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 43591 (07)
  4. University: Sharif University Of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Ghorbani, Mohammad
  7. Abstract:
  8. Ni-SiC composite coatings are widely used in industry (equipment high wear resistance coatings, corrosion resistant coatings, ship and boiler coatings, . . . ). Its unique properties in high wear resistance, corrosion resistance and tribological properties, researchers tend to investigate this coating. This study covers Ni-SiC composite coating under pulsed current using a rotating disk electrode to achieve optimal conditions in synthsis process, increaseing hardness and resistance to corrosion in coatings.waats' bath established for electrodeposition in this research. Bath parameters, current parameters and hydrodynamic of solution is examined. Changing of current type from direct current to pulse current increased of SiC content in coating. Optimum condition obtained in D.C=80% and f=10 Hz. Under these conditions, Ni-SiC composite coating was obtained with 16.2 volume percent SiC in matrix. The size of SiC powders is 50 nm in this investigation. Rotating of electrode optimized in 600 rpm. In this condition, amount of nano SiC particles inside the deposit was calculated at 8.8% as volume percent. The size of SiC powders is 100 nm in this state. Optimum current density is obtained in 5 A/cm2. Under this condition, Ni-SiC composite coating was obtained with 7.9% as volume percent of SiC in matrix. The size of SiC powders is 100 nm in this study. Increasing the current density, electrode rotation speed and reducing the particle size decrease the surface roughness. In nano composite coating with particles sizes of 10, 50 and 100 nm with increasing of particle volume percent in coat the EIS resistant and corrosion resistance is increased. The minimum corrosion current density and maximum EIS resistant revealed in Ni-SiC coating with 7.8% as volume percent of SiC inside the coating. In this coating, partial size of SiC is 50 nm. Optimum amounts for corrosion current density and EIS resistant is 0.0153 µA/cm2 and 7232 ohm respectively. Hardness and friction coefficient optimized in 4.10 GPa and 0.32 respectively. In this investigation the coating include 11.5% as volume percent of SiC with 10 nm as partial size. SEM figures of morphology changes with changing of pulse parameters. By increasing the duty cycle, the combination of flower and pyramidal morphology were obtained.
  9. Keywords:
  10. Rotating Disk Electrode ; Pulse Current ; Nickel-Silicon Carbide Coating

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