بررسي ريز ساختار ، رفتار خوردگي و تريبو خوردگي پوشش كامپوزيتي الكترولس نيكل فسفر- زير كونيا بر روي فولاد ساده كربني

چكيده انگليسي :

80 Evaluation of microstructure corrosion and tribocorrosion behavior of NiP ZrO2 composite coatings Shirin Vardak s vardak@ma iut ac ir Date of Submission Jan 25 2014 Department of Materials Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiSupervisors K Raeissi Associate Professor k raeissi@cc iut ac irA Saatchi Emeritus Professor saatchi@cc iut ac irAbstractElectroless NiP coatings due to their high corrosion and wear resistance hardness desirable physicaland mechanical properties have introduced as hard coatings Also composite electroless coatings asnew generation of electroless coatings attracted the attention of researchers in the last few decades Corrosion and wear behavior of electroless composite have been widely studied over the past decades Essentially size type and distribution of co depoisited particles determine the corrosion and wearresistance of composite coatings But tribocorrosion of these coatings have not studied widely Aszirconia shows outstanding mechanical properties it was selected as second phase of NiP electrolesscomposite coatings in this study Therefore NiP NiP ZrO2 5 m size of ZrO2 particles and NiP ZrO2 submicron composite coatings were deposited from a commercial electroless bath with 40 mthickness Characterization of coatings was performed by X ray diffraction scanning electronmicroscope and energy dispersive spectroscopy Tribocorrosion experiments were conducted in3 5wt NaCl solution under 10 N normal load and 1800 sliding cycles at 0 5Hz against SiC counterball at room temperature Hardness evaluation of coationgs illustrates that hardness of NiP coatingincreased from 601 to 655 HV1 by co deposition of ZrO2 5 m particles and decreased to 588 HV1 by co deposition of submicron particles Cyclic polarization results shows that current density of NiPcoatings increased from 0 28 to 0 61 A cm2 by co deposition of ZrO2 particles and corrosionpotential decreasd from 300 to 348 mVAg AgCl Also as a result of ZrO2 particles co deposition pitting potential decreased and repassivation capacity of coatings increased Corrosion behavior of thecoatings was studied by cyclic potentiodynamic polarization and electrochemical impedancespectroscopy before and after tribocorrosion tests In tribocorrosion experiments the effect of ZrO2particles of the coating on open circuit potential anodic current friction coefficient and weight losswas evaluated The results obtained from OCP variation and EIS confirm that the repassivation rate ofcomposite coatings increases during tribocorrosion via separation of zirconia particles Evaluation ofthe synergistic effect between corrosion and wear shows that the corrosion resistance of NiP ZrO2 5 m during sliding is more than NiP coating but wear resistance of composite coatings is lower thanNiP coating Keywords Corrosion Tribocorrosion NiP ZrO2 Composite Coating

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بررسي ريز ساختار ، رفتار خوردگي و تريبو خوردگي پوشش كامپوزيتي الكترولس نيكل فسفر- زير كونيا بر روي فولاد ساده كربني

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