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Wear-Resistant Nickel-Titanium Nitride Composite Coating by Electrochemical Method

Parhizkar, Nafise | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 43659 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Dolati, Abolghasem
  7. Abstract:
  8. Metal matrix nanocomposites contains ceramic ultrafine particles in a metal matrix, are used to improve the mechanical properties such as hardness and wear of coatings. For developing metal matrix nanocomposites, there are many methods. Electrochemical deposition process is one of these methods that have some advantages like uniform depositions on substrates with complex shapes, low cost, good repeatability and reducing waste. In this project, for increasing the hardness and wear resistance of nickel, composite coatings of nickel - titanium nitride was created by using electrochemical deposition of Watts bath contained titanium nitride particles. In order to increase the amount of incorporated particles in the coating process, the effect of deposition current density, electrolyte agitation speed and the number of particles in the solution were investigated. The optimum deposition current density and agitation speed were determined 4 A/dm2 and 450rpm respectively. The incorporation of the particles was determined by using EDS analysis of the coating and the coating morphology by scanning electron microscopy (SEM). Corrosion samples were also investigated by using linear polarization in solution of 3.5 wt% NaCl. It was observed that the increase of incorporated particles in composite coatings, due to the fine grains and increase of boundaries, increases the corrosion current density slightly. The effect of incorporation of anionic and cationic surfactants SDS and CTAB respectively were investigated for increase the amount of particles in the coatings . It was Observed that the maximum amount of incorporated particles (with a value of 7.5% by volume) is created in the current density of 4A/dm2, agitation speed of 450rpm, the particles of 30g/lit and in the presence of 0.6g/lit of SDS anionic surfactant. The hardness of pure nickel coating and optimal composite coating also was measured by AFM and the results showed that the hardness of the coating increases from 1.86Gpa to 3.23Gpa, in the presence of particles.

  9. Keywords:
  10. Electrochemical Deposition ; Nanocomposite ; Titanium Nitride Nanoparticles

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