7073

6615

كارشناسي ارشد

شناسايي و انتخاب و روش ساخت مواد

اصفهان: دانشگاه صنعتي اصفهان، دانشكده مهندسي مواد

1390

يازده، 80ص.: مصور، جدول، نمودار

ص.ع. به فارسي و انگليسي

مرتضي شمعانيان، مهدي صالحي

24/7/91

بهروز موحدي، مسعود عطاپور

1396/09/19

كتابنامه

مواد

مهندسي مواد

ID6615

به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي

81 Evaluation of Microstructure and Wear Resistance of Nanostructure Powder Mo Si C Cladding by Gas Tungsten Arc Welding Ahmad Shams A shams@ma iut ac ir March 12 2012 Department of Materials Engineering Isfahan University of Technology Isfahan 8415683111 Iran Degree M Sc Language FarsiSupervisor Morteza Shamanian mshamanian@cc iut ac ir Mahdi Salehi surfacesalehi@hotmail comAbstractThis research has been studied the microstructure and oxidation and wear behavior of nanostructuredMo Si C powder coated in situ on the nickel surface Before applying cladding process used ball millingprocesses for activating mixture powder and also the evulation formation silicate compounds such as MoSi2and SiC and more with product the used electrodes of powder mixtures by doing welding processes wascreated coating with a thickness of 1mm The microstructures of these coating were studied by opticalmicroscopy scanning electron microscopy SEM and X Ray Diffraction XRD The specimens werecharacterized by energy dispersion spectroscopy EDS and micro hardness test Wear tests were carried outusing reciprocating method The worn surfaces were examined by scanning electron microscopy Workingmill operation results show that Mo Si C powder mixed with the grinding time of 5 and 10 hours does notconstitute a new phase But we can say that reducing the grain size to the amount of Mo and Si is 15 nm Ball milling at 20 and 30 hours of work due to the phenomena of mechanical alloying to increase averagegrain size in the mixed compounds MoSi2 and SiC powder will happen Metallographic examination ofsamples shows that the ball milling operation for 20 hours the uniform distribution and dendritic morphologyis appropriate Phase detecting sample indicate that the addition of 1 5wt graphite powder to the mixtureformed Mo2Ni3Si NiSi and small amount of MoSi2 and SiC reinforcement Also view pictures related to thesample microstructure indicated low porosity and impurities in cladding layer and the coating adhesion tothe substrate Binary combinations Silicate such as MoSi2 and Mo5Si3 that one of its elements molybdenum the phases of fragility are a combination Silicate Mo2Ni3Si due to the presence of nickel in its structuretoughness higher breakdown in the sample of MoSi2 and composite MoSi2 SiC has created Reciprocatingwear test results showed that the presence of 1 5wt mixture of graphite powder and the reinforcing phaseSiC there is a good abrasion resistance By presence of SiC in coating the wearing samples decreases to90 The hardness test showed that the cladding process causes increasing hardness to 850 HV0 2 Coatedwith the powder mixture and formation phases of fusion work silicate Mo2Ni3Si and NiSi increasingdifficulty to 850 HV0 2 cladding layer will occur and in areas close to the interface of the mixing of the nickelsubstrate is increased reducing the hardness is observed Nickel surface layer increased dilution anddecreases hardness in the coating Also oxidation behavior by 900 C showed that the formation of acontinuous layer of SiO2 protective coating occurs desirable KeywordsNanostructure powder Mo Si C Weld cladding by GTAW Microstructure Wearbehavior Hardness Oxidation

مرتضي شمعانيان، مهدي صالحي

بهروز موحدي، مسعود عطاپور