8775

8136

كارشناسي ارشد

مواد

اصفهان: دانشگاه صنعتي اصفهان، دانشكده مواد

1392

شانزده،73ص.: مصور،جدول،نمودار(رنگي)

ص.ع.به فارسي و انگليسي

رحمت اله عمادي

احمد منشي

3/2/93

علي سعيدي، مهدي احمديان

مهندسي مواد

ID8136

Formation of SiC nao whiskers in MgO C refractories Maryam Bakhtiari mary bakh67@yahoo com 2014 Department of Materials Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisor Dr Rahmatollah Emadi remadi@cc iut ac ir AbstractThese days MgO C refractories are wide spread in steel making furnaces because of theproperties like thermal shock resistance and corrosion resistance Oxidation of carbon isone of the most important problems of these refractories and this results increasing ofporosity and decreasing the strength and corrosion resistance Using reinforcement like SiC and B4C as antioxidant prevents oxidation of carbon and increase the strength at hightemperatures The aim of this research is formation of insitu SiC nano whiskers in MgO Crefractories SiC by having unique characterization improves the properties of theserefractories It is prospected that the produced composite will have good resistant tothermal shock The formation of these insitu whiskers accomplish at usage temperatureand is not an expensive additive Some of these whiskers decomposes to Si and C duringusage Si acts as an antioxidant and prevents from oxidation of C Also C has it s goodeffects on MgO C refractories Initial materials including fused magnesia sinteredmagnesia flake graphite and calcinated alumina were mixed by binder and additives suchas Ferrosilicon SiC and B4C were added to this mixture The powder was pressed by 4MPa pressure and the samples were tempered at different temperatures and times Phasestructure and morphology were detected by XRD and SEM Bulk density BD ColdCrushing Strength CCS tensile strength with Brazilian test Apparent porosity AP and water absorption were investigated Also the reaction between steel s slag and therefractory was observed Some of the samples were coked and heated to 1650 degreecentigrade and formation of insitu nano whiskers was studied The results show that byadding Ferrosilicon to samples at 1650 degree centigrade insitu SiC nano whiskers havebeen produced Formation of whiskers improves the physical mechanical and corrosionproperties of these refractories At 250 degree centigrade by adding 3wt Ferrosilicon tosamples Strength 1 5 times increased and at 1650 degree centigrade by adding 5wt Ferrosilicon to samples strength 1 9 times increased In samples with 3wt SiC at lowtemperature 1 5 times and at high temperature 1 8 times strength has been increased Insamples with 1wt B4C at 250 degree centigrade strength has been increased 1 4 times Keywords MgO C refractories insitu SiC nano whiskers Physical mechanical and corrosion properties

رحمت اله عمادي

احمد منشي

علي سعيدي، مهدي احمديان