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Electrodeposition of the Ni-P by Pulse Plating

Kazerooni, Amir | 2011

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  1. Type of Document: M.Sc. Thesis
  2. Language: English
  3. Document No: 41973 (57)
  4. University: Sharif University of Technology, International Campus, Kish Island
  5. Department: Science and Engineering
  6. Advisor(s): Dolati, Abolghasem
  7. Abstract:
  8. Ni-P alloy coatings were electrodeposited using pulse current in a watt type bath in various conditions. The influences of different parameters were investigated and optimized for the highest amount of coating hardness using the Design Of Experiment (DOE) method. The optimized deposition parameters were current density 23.7 A/dm2, duty cycle 75%, frequency equal to 188 Hz, temperature equal to 70ºC and 17.5 gr/l of H3PO3. The DOE prediction of hardness for the optimized coatings was between 700 and 750 the achieved micro-hardness was about 725.8 HV. It was obtained that an increase of the current density will improve micro-hardness, decreases P content and increase deposition rate. Also, the increase in duty cycle improves micro-hardness, decreases P content and increases deposition rate. Moreover, an increase in frequency decreases the value of micro-hardness, increases P content and increases the deposition rate. Three type coatings were electrodeposited (pulse electrodeposited Ni-P(A), Dc electrodeposited Ni-P(B) and pulse electrodeposited Ni(C) ) with the optimized conditions for a comparison of their hardness, grain size, roughness and corrosion resistance. Using pulse current, the value of hardness increase about 30% in comparison to dc electrodeposition. The minimum roughness was found in pulse electrodeposited Ni-P about 1.375 nm. Electrodeposited Ni-P had the roughness of 3.816 nm and for pulse electrodeposited Ni was equal to 11.487nm. The comparison of corrosion rate between coatings Aand B (5.32, 6.01 μm/year, respectively) indicates that their corrosion resistance is in this trend; pulsed electrodeposited Ni-P > electrodeposited Ni-P. XRD analysis was employed on the coatings. FWHM of diffraction peaks, showed that both pulse electrodeposites of Ni-P and Ni are become nanosized by the values of 4nm and 143 nm, respectively
  9. Keywords:
  10. Pulse Current ; Experimental Design ; Electrodeposition

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