Synthesis and Characterization of Ni P Ag Al2O3 Hybrid Nanocomposite Coating Shahram Alirezaei s alirezaei@ma iut ac ir November Department of Materials Engineering Isfahan University of Technology Isfahan 8415683111 Iran Seyed Mahmoud Monirvaghefi Supervisor st Advisor Ahmad Saatchi nd Adisor Mustafa rgen Keyvan Raeissi Department Graduate Coordinator Abstract In this research the formation of a novel coating as Ni P Ag Al O hybrid nanocomposite coating as well as the mechanical and tribological behavior of this type of coating Also the effect of parameters such as the concentrations of silver and alumina particles and heat treatment process on microstructural changes mechanical properties tribological behavior and wear mechanisms are investigated For this purpose zeta potential of wetted particles with CTAB cationic surfactant was measured After the surface preparation of steel samples the substrates were entered into the composite plating bath and then Ni P Ni P Ag Ni P Al O and Ni P Ag Al O coatings were deposited by electroless process Isothermal heat treatment was done at C and mechanical properties of the coatings were eva‎luated by microhardness and microindentation The tribological tests were implemented in ambient and high temperatures C by pin on disc method The eva‎luation of microstructure was done by XRD analysis and surface morphology cross sections of the coatings wear surfaces and debris were studied by field emission scanning electron microscope and transmission electron microscope D optical profilometry was used to determine the roughness topography and wear quantities of the coatings The results showed that the codeposition of alumina and silver particles in composite and hybrid coatings are strongly influenced by zeta potential and the concentration of the particles Also heat treatment leads to phase transformation just in the matrix of the coatings within the formation of Ni P secondary phases and then hardness and wear resistance were increased Comparison between hybrid and composite coatings demonstrated that the tribological properties of Ni P Ag Al O hybrid nanocomposite coating consist of wear resistance of Ni P Al O composite coating and lubrication property of Ni P Ag coating The formation of silver rich mixed layer on wear scars was detected as an important factor for self lubrication in the coatings including silver lubricant particles at low and high temperatures wear The mean values of friction coefficient were achieved about and for heat treated Ni P Ag coatings and and for heat treated Ni P Ag Al O at ambient and high temperatures respectively In addition the high temperature wear results showed that the diffusion of silver from inside of the coating to the surface of hybrid and composite coatings containing silver particles leads to the nucleation and formation of additional silver rich layers These tribofilms produce the self lubrication property at high temperature Keywords Electroless Alumina Silver Hybrid Nanocomposite Tribology Tribofilm Self lubrication Associate Professor Department of Materials Engineering Isfahan University of Technology Isfahan Iran Professor Department of Materials Engineering Isfahan University of Technology Isfahan Iran Professor Department of Metallurgical and Materials Engineering Istanbul Technical University Istanbul Turkey Associate Professor Department of Materials Engineering Isfahan University of Technology Isfahan Iran PDF created with pdfFactory trial version www pdffactory com

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