ساخت و مشخصه يابي بالك نانو كامپوزيت هيدروكسي آپاتيت-تيتانيا به روش تف جوشي دو مرحله اي

چكيده انگليسي :

Fabrication and Characterization of Dense Bulk Nanostuctured Hydroxyapatite TitaniaComposite via Two Step Sintering Method Ali Farzin a farzin@ma iut ac ir Department of Materials Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor Mehdi Ahmadian ahmadian@cc iut ac ir AbstractHydroxyapatite HA has been extensively studied and clinically applied for both its bioactive and properties inmedicine and for its biological and chemical similarity to the organic phase of bone and teeth HA is too brittleto be used as bulk material under loaded conditions For a successful application of HA ceramics in load bearingareas of human body it is necessary to improve its mechanical properties One way to overcome this restrictionof HA is to use HA as a matrix in a composite and other bioactive reinforcement ceramic or metal In recentyears most of researches about HA have focused to develop HA based bioceramic composite Recently it hasbeen reported that Titania and HA represent a good combination for functionally graded materials providing agradient of bioactivity and good mechanical properties Moreover Titania is able to enhance osteoblast adhesionand induce cell growth The methods of manufacturing nanostructured composites are different and can theyinclude spark plasma sintering hot pressing and Two Step Sintering Two step sintering TSS has beenapplied in the present work to suppress the accelerated grain growth of Hydroxyapatite HA and Titania TiO2 nanoparticles in the HA TiO2 composites in the last sintering stage Two step sintering method is a clearexample of a multivariable process that demands important resource and time consuming efforts in order tooptimize firing schedules Most of researchers apply this process based on try and error method When thenumber of factors and parameters settings is high the experimental plan yields an undue number ofexperiments Nevertheless experimental planning may be optimized based on partial factorial experimentalplans Among the existing methods the Taguchi approach is particularly attractive for simplicity and clarity ofuse it This work presents an integrated approach to assess optima two step sintering schedules of HA 15wt TiO2 that combines predictions of the sintering kinetics based on conventional sintering data withTaguchi fractional experimental plans It was shown by application of Two Step Sintering method the finalgrain size of HA 15wt TiO2 maintainlower than 100nm while by application of conventional sintering itreaches higher than 100nm X Ray Diffraction XRD Scanning Electron Microscopy SEM TransmissionElectron Microscopy TEM Fourier Transform Infra Red FTIR and Archimedes method were used tocharacterize powders and bulks prepared by TSS method To find how important the temperatures at sinteringsteps might be several TSS regime were conducted The results showed that the temperatures were critical atboth sintering stages The optimum regime consisted of heating the green bodies up to 1150 C in the first step ofsintering and then holding at 1050 C for about 25h in the second step This yielded the finest microstructurewith no exaggeration in grain growth The results of soaking of dense bulk prepared by optimum regime of TSSon the Simulated Body Fluid SBF were shown the specimens prepared by optimum TSS regime is bioactive Results of cell culture confirmed that the products from specimens prepared by optimum TSS regime dissolutionsignificantly promoted cell growth The nanostructured HA Titaniacomposite prepared by optimum TSS regimespecimen resulted no pernicious TCP phase Key words Two step sintering Nanostructured composite HA Titania Grain growth Biomedicalapplication Cell growth

فرزين، علي

ساخت و مشخصه يابي بالك نانو كامپوزيت هيدروكسي آپاتيت-تيتانيا به روش تف جوشي دو مرحله اي

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