رسوب دهي، بررسي و مقايسه خواص مكانيكي پوشش هاي الكترولس نيكل - فسفر نانوساختار - آمورف هيبريدي ( شيب عملكردي FGC و چند لايه )و تك لايه.

چكيده انگليسي :

Deposition Investigation and Comparison of Mechanical Properties of Nanostructured Amorphous Ni P Electroless Hybrid Functionally Graded and Multilayer and Monolayer Coatings Sayede Razieh Anvari sr anvari@ma iut ac ir Date of submission February 22 2016 Department of Materials Engineering Isfahan University of Technology Isfahan 8415683111 Iran1st Supervisor Dr Sayed Mahmoud Monirvaghefi1 vagh mah@cc iut ac ir2nd Supervisor Prof Mohammad Hossein Enayati ena78@cc iut ac irDepartment Graduate Program Coordinator Dr Keyvan RaeissiAbstractIn this research novel multilayer and functionally graded Ni P coatings were deposited withelectroless process The content of phosphorus was controlled to change stepwise and gradualthrough the thickness of the coatings Each of the hybrid coatings were deposited by using only asingle electroless bath During the plating bath temperature and pH were changed at specifiedintervals to obtain hybrid structure To compare the properties of hybrid coatings with Ni Pmonolayer coatings three types of coatings with different phosphorus contents were also deposited Annealing of coatings were performed at 400 C for 1 h Microstructure and phase composition ofcoatings were studied by scanning electron microscopy SEM transmission electron microscopy TEM and X ray diffractometry XRD The mechanical properties and tribological behavior ofcoatings were also investigated Low phosphorus and medium phosphorus monolayer coatings hadfully crystalline and amorphous crystalline structures respectively While high phosphorus coatingappeared to have a fully amorphous structure which crystallized upon annealing Annealing led toformation of a nano crystalline structure containing particles of different nickel phosphides As aresult hardness and wear resistance of coatings increased The results showed that the highphosphorus coatings had the minimum crack resistance due to their amorphous structure Mediumphosphorus coatings had maximum crack resistance due to their amorphous crystalline structure Hybrid coatings had more crack resistance than monolayer coatings For hybrid coatings top layerhad a significant effect on crack propagation Functionally graded coatings had the most crackresistance among hybrid coatings According to the wear test data medium phosphorus coating hadminimum wear resistance Hybrid coatings had better wear resistance than monolayer coatings Forhybrid coatings cracks were effectively prevented due to the gradual changes in composition andstructure through the thickness of coatings Relatively fine cracks were propagated on the wear trackof the graded coating inhibiting catastrophic failure under heavy load Annealing increased the wearresistance of coatings High temperature wear 300 C tests were done for annealed coatings Theresults showed that low phosphorus coating had the maximum wear volume so that this coating hadthe minimum hot wear resistance Functionally graded coating had the maximum hot wear resistance These results were similar to wear resistance of annealed coatings at ambient temperature Keywords Electroless Nickel phosphorus Hybrid coating Nano indentation Fracture toughness Wear resistance Hot wear 1 Associate Professor Department of Materials Engineering Isfahan University of Technology Isfahan Iran 1 Professor Department of Materials Engineering Isfahan University of Technology Isfahan Iran

انوري، راضيه

رسوب دهي، بررسي و مقايسه خواص مكانيكي پوشش هاي الكترولس نيكل - فسفر نانوساختار - آمورف هيبريدي ( شيب عملكردي FGC و چند لايه )و تك لايه.

نانوفرورونده , تافنس شكست , مقاومت به سايش , سايش دماي بالا , عمليات حرارتي