ساخت كامپوزيت دوگانه Al-TiC-B4C از روش ريخته گري كوبشي و ارزيابي خواص آن

چكيده انگليسي :

Fabrication of Al TiC B4C Hybrid Composite by Squeeze Casting and Evolution of its Properties Younes Mazaheri Rodbali y mazahri@ma iut ac ir February 26 2012 Department of Material Science and Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiM Meratian Associate professor Supervisor meratian@cc iut ac irR Emadi Associate professor Supervisor remadi@cc iut ac irAbstractIn this study fabrication of Al TiC 1Al B4C 1Al TiC B4C composites containing different percents ofTiC and B4C powders by casting techniques was studied The density of TiC 4 93 g cm3 is higherthan A1 2 71 g cm3 and as a result TiC particles deposit in melt These particles tend toagglomeration which can be dissolved by intense stirring during the melting process Furthermorecasting techniques suffers from poor wettabilty and distribution of the reinforcement particles in thematrix The oxide film prevents the Al melt from achieving intimate contact with the ceramics such asTiC and its breakdown at high temperatures is vital to achieve wetting To overcome these problems addition of alloying element to melt injection of reinforcement to melt in the form of Al B4Cp cpcomposite powders and heat treatment of reinforcement particles and using of the Na3AlF6 wereinvestigated After completion of the injection and distribution TiCp in melt aluminium meltcomposites were solidified under a vertical pressure of 100MPa Before pouring melt composites in diethe slag was separated from surface melt The volume fraction of porosity and its size and distributionin a cast metal matrix composite play an important role in controlling the material s mechanicalproperties Porosity cannot be fully avoided during the casting process but it can decrease with extraprocessing such as squeeze casting Microstructural characterization of the samples was investigated byscanning electron microscopy SEM energy dispersive spectroscopy EDS and X ray diffractometer XRD The results showed that heat treatment of B4C powders and using of the flux with TiC powdersimprove the wettability and distribution of reinforcement particles in the solidified matrix Heattreatment of ceramic particles decreases absorbed gases from the particle surface and enhances thewetability Also the flux removes the oxide film from the molten metal surface and facilitatesspontaneous incorporation of the particles into the melt Evaluation of mechanical properties includedhardness tensile properties and wear behavior was performed The results of mechanical propertiesshowed that the hardness yield and ultimate tensile strength of composite samples improved incompare with pure Al Also comparison of composites showed the better mechanical properties for Al 7 5 TiC 7 5 B4C hybrid composite Also the surface of samples revealed low friction coefficientsand wear rates for Al 7 5 TiC 7 5 B4C hybrid composite which were significantly lower than thoseobtained for other samples The wear mass loss of the pure Al Al 10TiC Al B4C Al 5vol TiC 5 B4C and Al 7 5vol TiC 7 5vol B4C composites after 1000m sliding distance were 82 5 36 21 25 2 13 8 mg respectively Scanning electron microscopy tests revealed different wear mechanisms onthe surface of the warn test specimens Key WordsCasting Hybrid Composite Wettability mechanical properties Wear

مظاهري رودبالي، يونس

ساخت كامپوزيت دوگانه Al-TiC-B4C از روش ريخته گري كوبشي و ارزيابي خواص آن

ترشوندگي , خواص مكانيكي , سايش