Sibel Daglilar

Effect of Yttria-doping on Mechanical Properties of Bovine Hydroxyapatite (BHA)

Sintered bodies of hydroxyapatite, derived from calcinated bovine bone (BHA) and doped with 0.5 and 1 wt% Y2O3, were prepared. Measurements of density, compression strength, and microhardness, along with scanning electron microscopy (SEM) and X-ray diffraction (XRD) were carried out. The experimental results showed that BHA doping with yttria favors formation of glassy phase, which advances sintering and results in a dense and reinforced BHA matrix. The best mechanical properties were achieved after sintering at 1200°C for compressive strength (82MPa) and 1300°C for microhardness (672HV). These results are better than pure BHA or composites of hydroxyapatite with Y2O3-stablized zirconia, qualifying yttria (as dopant of BHA) for further in vitro and in vivo experimentation.

MAGNETIC CORE SHELL STRUCTURES: from 0D to 1D assembling

Material research and development studies are focused on different techniques of bringing out nanomaterials with desired characteristics and properties. From the point of view of materials development, nowadays scientists are strongly focused on obtaining materials with predefined characteristics and properties. The morphology control seems to be a determinant factor and increasing attention is devoted to this aspect. At this moment it is possible to engineer the materials features by using different methods and materials combination for both medical and industrial applications. In the applications of chemistry and synthesis, biology, mechanics, optics solar cells and microelectronics tailoring the adjustable parameters of stoichiometry, chemical structure, shape and segregation are evaluated and opens new fields. Because of the magnetic features of nanoparticles and durable particle size, less than 100 nm, this study is aiming to describe their uses in practical applications. Thats why the whole hydrodynamic magnetic core shell topic will be reviewed on this paper. Additionally, the properties acting in general sight in solid-state physics are utilized for material selection and for defining issue connecting the core, shell structure and their producing properties. Here, in the study of core/shell nanoparticle various physical and chemical synthesis routes and the effect of electrospun method are briefly discussed. Starting from a real void of the scientific literature, the existent data related to the 1D magnetic electrospun materials are reviewed. The perspectives in the medical, environmental or energetic sector is great and bring some real advantages related to the 0D core@shell structures because both mechanical and biological properties are dependent on the morphology of the materials.

Production and Performance of Al-Ti-C Grain Refiners with Addition of K2TiF6 and Elemental Carbon

Abstract AlTiC master alloys were improved greatly and used as a new type in grain refinement of aluminum and aluminum alloys. In the present work, Al-Ti-C grain refiners with different Ti/C ratios were in-situ produced by the addition of K2TiF6 and elemental carbon powder mixture to the commercial pure aluminum. The effects of casting temperature and Ti/C ratio on the grain refinement process were investigated by the so-called Alcoa Cold Finger test and respective optimum conditions were determined. The results indicate that the produced Al-Ti-C master alloys contain TiC and TiAl3 particles within the aluminum matrix. The proper conditions for evaluating the efficiency of the produced Al-Ti-C master alloy to obtain a minimum grain size are: Temperature of 1300 °C, holding time of 20 minutes, and a Ti/C 0.60 wt.-%

Electrospun Poly(ε-Caprolactone)/Bovine Hydroxyapatite (BHA) Composite Nanofibers for Bone Tissue Engineering

Tissue engineering applications have opened a different future-promising era for critical injuries, defects and diseases. Bone tissue engineering is the part of tissue engineering which aims to stir up new practical bone re-formation via the interactive combination of biomaterials and cells. Poly (e-caprolactone) (PCL) is a unique semi crystalline polymer material which handles several important features such as biocompatibility, high biomedical durability and degradation properties. Bovine hydroxyapatite (BHA) is another biocompatible material which provides to get ultimate mechanical behavior in composite designs. Because of their high biocompatibility, PCL and BHA were integrated the electrospinning system together. The system was revised for multi-feeding needle equipment. Eight dissimilar tissue scaffolds were produced and investigated for this recent work.

Mechanical Behavior of PCL Nanofibers

The biomedical applications of Poly (e-caprolactone) (PCL) have an extensive usage area such as tissue engineering, regenerative medicine, cartilage defects and biomedical implants. Because of the PCL’s high biocompatibility and excellent mechanical features some implants have been designed for getting remarkable results. Clinically approved fibers ranging from 500 nm to 750 nm were produced by electrospinning method. The mechanical properties of the fiber scaffolds were performed via tensile testing and results were measured by special programme. Five different fiber scaffolds which they produced in various compositions have been used for this research.

Autocatalytic Ni-P and Ni-B Deposition on SiC Ceramic Particles

Ceramic particles like SiC have attracted great attention because of their usability as reinforcement for composite materials. Autocatalytic (electroless) nickel deposition is a unique process for the enhancement of the surface properties of ceramic particles. In this study, deposition of nickel phosphorus (Ni-P) and nickel boron (Ni-B) layer on SiC particles via autocatalytic plating in hypophosphite and borohydride baths was investigated. SiC powders were sensitized and activated respectively in order to ensure catalytic properties. Electroless nickel coating was carried from two different nickel ion sources (nickel chloride, nickel sulphate) following the pre-treatments of particle surfaces. Coated powders morphologies were characterized by transition electron microscope (SEM). X-ray diffraction and energy dispersive spectroscopy (EDS) analysis were used to investigate the chemical analysis of coating layers. The results showed that a better uniformity and bonding were obtained for Ni-P coatings with the Ni source of NiSO4.6H2+O as compared to NiCl2.6H2+O. For Ni-B coatings, the Ni2+ source of NiC12.6H2O has provided better quality and continuous coating layer on SiC surfaces.

Effect of Laminar Cooling Parameters on Martensite Volume Fraction and Mechanical Properties of Hot Rolled Dual Phase Steel

In this study, effect of rolling and coiling temperature in thermo mechanical controlled process (TMCP), on the microstructure and mechanical properties of dual phase (DP) steel according to martensite volume fraction (MVF) rate was investigated. By using various finishing mill exit temperature and cooling conditions that is controlled laminar cooling system, the microstructural evolution of coil improves the mechanical properties with lower costs and higher productivities, in comparison to the heat treatment after rolling. The main part of the paper contains the result of tensile, yield and microstructure properties of DP600 steel produced on hot strip rolling plant and run- out table line. The results show that a higher MVF and an increasing cooling rate after the last deformation raised strength of the DP600 steel. The yield strength and ultimate tensile strength increase by decreasing coiling temperature.

Production of Al-Ti-C Grain Refiners with the Addition of Elemental Carbon and K 2 TiF 6

Al−Ti−B grain refiners are widely used as aluminum grain refiners. Despite the problems in application, Al−Ti−C refiners have an increasing demand in recent years. In the present work, Al-Ti-C grain refiners with different Ti:C ratios were produced by in-situ method with the addition of elemental carbon into the Al-Ti master alloy (master alloy method) and the addition of K2TiF6 and elemental carbon powder mixture into the commercially pure aluminum (flux method). The effects of production method and Ti:C ratio on the grain refinement process were investigated using Alcoa Cold finger Test and so optimum conditions were determined. The best performance was accomplished with the refiner produced at 1300°C with the master alloy method.