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Pulse Electrodeposition of Ni-ZrO2-MoS2 Composite Coatings and Its Tribological Properties

Rajabi Khosh Andam, Mohsen | 2010

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 41322 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Ghorbani, Mohammad
  7. Abstract:
  8. In this study solid lubricants MoS2 nanoparticles with average size 50 nm and hard ZrO2 nanoparticles with average size 51 nm were used in watts bath and Ni/ZrO2-MoS2 composite coatings were prepared by pulse plating technique. Effect of current density, frequency, duty cycle, surfactant type and concentration of particles in the electrolyte on the amount of particles in the coatings were investigated and optimum conditions were determined to create composite coatings. Scanning Electron Microscopy (SEM) and x-ray diffraction (XRD) analysis were performed to study the morphology, structure, chemical composition of coatings. Corrosion testing of coatings by potentiodynamic polarization in solution 0.5 M Na2SO4 was investigated. To study the mechanical properties of the coating hardness and wear resistance tests were performed.By reducing the amount of peak current density from 9 A/dm2 to 3 A/dm2, the frequency to 10 Hz and the duty cycle to 30 percent in the presence of CTAB surfactant, the total volume percent of nanoparticles in the coating reached to 10.83 which 6.51 and 4.32 are related to the ZrO2 and the MoS2 particles, respectively. While the corrosion resistance of composite coatings compared to pure nickel coating was not changed significantly, coating microhardness changed from 413 Vickers for Nickel coating from Watts bath containing 1 g/L saccharin to 1076 Vickers for composite coatings with 6.51 and 4.51 volume percents of ZrO2 and MoS2 nanoparticles respectively. Moreover, the coefficient of friction value reached from 0.6 for Nickel coating from Watts bath from containing 1 g/L saccharin to 0.11 for coatings of contains 6.73 and 3.04 volume percents from ZrO2 and MoS2 nanoparticles. XRD test also showed that the addition of ZrO2 and MoS2 nanoparticles in nickel coating change the prefered crystal orientation of nickel from pages (200) to pages (111)
  9. Keywords:
  10. Pulse Plating ; Nickel Coating ; Zirconia ; Molybdenum Sulfur ; Tribology

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