6919

6461

كارشناسي ارشد

شناسايي و انتخاب مواد

اصفهان: دانشگاه صنعتي اصفهان، دانشكده مهندسي مواد

1390

چهارده، 90ص.: مصور، جدول، نمودار

ص.ع. به فارسي و انگليسي

علي سعيدي، محمد حسين فتحي

مريم كرباسي

14/5/91

احمد منشي، مرتضي شمعانيان

1396/09/18

كتابنامه

مواد

مهندسي مواد

ID6461

به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي

91 Production and characterization of nano structured WC Fe Co using activated powders Minoo Karbasi m karbasi@ma iut ac ir Date of Submission 2012 03 05 Department of Materials Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisor Ali Saidi a saidi@cc iut ac ir Mohammad Hossein Fathi Fathi@cc iut ac ir AbstractCemented carbides belong to a group of refractory hard material with high wear resistance in which hardparticles of carbide are adjoined each other by one metallic binder Cemented carbides are normally producedby powder metallurgy Usually tungsten carbide and cobalt are used as hard phase and binder phase respectively Cemented carbides are broadly used in various applications such as metal cutting miningpunching and cutting rocks Although WC Co are the most popular type of cemented carbide they havelimitations which have been the subject of many research works Most researches are directed into ways ofreplacing cobalt totally or partially with other binder and replacing WC with harder phase of TiC and othercarbides In this research in order to produce nanocomposite of WC 20wt Fe Co mechanical alloyingand liquid phase sintering were used The effect of variation of mechanical alloying time iron to cobalt ratio sintering temperature on the product properties was investigated X ray diffraction scanning electronmicroscopy analysis hardness test and transverse rupture strength and fracture toughness were employed tocharacterize the samples When powder mixtures with 80wt WC and different Fe Co ratios were milled for25hs even distribution of WC within binder phase was obtained in which WC grain size and particle sizewere less than 30 and 300nm respectively By increasing the milling time in each compound relative densityafter sintering increased and tungsten carbide particles had constant distribution and also in sample withequal ratio of iron to cobalt after 25hr of milling and sintering at 1350 C for 1 hour relative density reachedto 98 2 Composite powder produced by milling were compacted and sintered at 1350 C for 1h The resultsindicated that WC grain size were less than 65nm By increasing the milling time the hardness of samplesafter sintering increased and in sample with equal ratio of iron to cobalt hardness reached to 1241 Vickers Transverse rupture strength and fracture toughness of samples decreased with increasing the MA time Characterization of nanocomposite WC 20wt Fe Co with different percents of iron and cobalt in bindershowed that sample with equal ratio of iron to cobalt had the highest value of relative density hardness rupture strength and fracture toughness equivalent with 98 2 1241 HV30 2079 6 MPa and 21 7 MPa m respectively Sintering of compacted nanocomposites resulted in evolution of undesirable eta phase Etaphase could be almost eliminated by addition of carbon to the powder mixture prior to milling Byelimination of eta phase Hardness and fracture toughness of optimal sample reached to1357HV30 and 24 9MPa m respectively Keywords Cemented carbide Tungsten carbide Transverse rupture strength fracture toughness eta phase

علي سعيدي، محمد حسين فتحي

مريم كرباسي

احمد منشي، مرتضي شمعانيان