طراحي،ساخت،مشخصه يابي و مدل سازي تيتانات باريم متخلخل با پوشش هيدروكسي آپاتيت نانو ساختار

چكيده انگليسي :

Design Preparation Analysis and Modeling of Porous BaTiO3 with Nanostructured Hydroxyapatite Coating Hoda Zarkoob hd zarkoob@yahoo com March 13 2010 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisors Prof Saeed Ziaei Rad szrad@cc iut ac ir Prof Mohammadhossein Fathi fathi@cc iut ac ir Abstract In recent years based on noticeable interests in the field of bone tissue remodeling many researches have been carried out These researches are due to finding the deformation mechanisms in bone tissue and investigating the electro active materials that when placed in bone graft structures have the ability to simulate the undergoing mechanisms As the deformation mechanism of bone could have its origins in bone s piezoelectricity for simulating this mechanism in a bone graft material a porous matrix made of a piezoelectric ceramic was chosen as a candidate to use Barium Titanate BaTiO3 is a popular piezoelectric ceramic proven to have biocompatibility Therefore porous barium Titanate BT was used as the basic structure The porous BT was then coated with Hydroxyapatite HA to enhance its biological properties Barium Titanate Nano powder which is used for making porous BT prepared with the sol gel method The morphology and the grain size of the prepared BT powder were investigated with Transmission Electron Microscopy TEM BT ceramic was foamed via a direct foaming method using polyurethane spray foam The whole surface of the foam voids was coated with HA due to the application of dip coating method The related HA is produced with the so called sol gel method and expected to have nano structure so it would resemble bone tissue in nano structural properties The morphology and composition of the foam and its coating was investigated with Scanning Electron Microscopy SEM Transmission Electron Microscopy TEM and X ray diffract Tacnique XRD After preparing the BT porous samples with HA coating the samples were polarized within a 2 3 kV mm electric field and its piezoelectric coefficient d33 was measured with a piezometer Using TEM micrographs of Barium Titanate powder the grain size of the prepared powder was estimated to be between 70 nm 100 nm The experimental pattern obtained from XRD analysis of porous sample with HA coating shows that the phase structure of prepared sample was constituted of Barium Titanate and Hydroxyapatite Also crystallite size of the HA coating was measured using XRD pattern of the coating and Scherer s equation It was estimated that the HA coating had nano structure and its crystallite size is in the range of 20 nm 30 nm In order to study the mechanical behavior of BT foams uniaxial compression test was done on porous samples with and without HA coating The compression stress strain diagram of the prepared samples drew with the result gained from the uniaxial compression test The porous structure was modeled in a commercial finite element package with crushable foam material model In order to investigate the effect of porosity coating polarizing and getting under stress in bioactivity ten different groups of porous compact samples with without HA coating polarized non polarized with without stress of the samples were prepared The samples were immersed in SBF solution for a period of one month The morphology of the soaked samples were studied using SEM Also changes in Ca2 and PO4 3 ions during one month of immersing were studied by means of inductively coupled plasma ICP analysis The results of uniaxial compression test show that the coating magnifies the pressure strength of the structure 5 times in compare with non coated samples and enhances the mechanical properties Also the theoretical results gained from modeling the uniaxial compression test in the finite element software demonstrate a reasonable correspondence with the experimental data The results show that crushable foam material model was a good candidate for modeling the mechan

زركوب، هدا

طراحي،ساخت،مشخصه يابي و مدل سازي تيتانات باريم متخلخل با پوشش هيدروكسي آپاتيت نانو ساختار

سراميك پيزوالكتريك , فوم شكست پذير