Comparison of Microstructural and Mechanical Properties of Hydroxyapatite-ZrO2 Composites with Commercial Inert Glass Addition

Hydroxyapatite(HA) is very popular bioceramic for hard tissue restorations. But, bulk HAs are not suitable for load bearing applications. So, HA material can be reinforced with a second phase (i.e polymers, metals and ceramics) to make a stronger composite material. The aim of this study is to compare the microstructural and mechanical properties of HA-ZrO2 composites with the addition of 5 and 10 wt % commercial inert glass (CIG), separately. The green samples were produced according to BS 7253 at 350 MPa. Then, they were sintered at between 1000 and 1300 degrees C for 4 h. Microstructural properties of the obtained composites were characterized using SEM (Scanning electron microscopy) + EDS; phase analysis was done by X-ray diffractometer (XRD), mechanical properties were measured by compression and hardness tests. According to the results of ongoing bioactivity and biocompatibility studies, these two composites will possibly be good candidates for orthopedical applications

INVESTIGATION OF INDENTATION FRACTURE TOUGHNESS (K-IC) AND WEIBULL PARAMETERS OF 0.25Li(2)O.2SiO(2)-0.75BaO.2SiO(2) GLASS-CERAMIC

In the present study, mechanical properties of 0.25Li(2)O.2SiO(2)-0.75BaO.2SiO(2) glass-ceramic were investigated. The transformations temperatures were determined by DTA instrument. The optimum nucleation temperature was found to be 540 degrees C. This suggested the crystallization temperatures as 675, 720 and 800 degrees C. After carrying out crystallization heat treatments, Vickers indentation test was applied. In order to determine the indentation fracture toughness (KIC), crack half-length, 'c' of the samples was measured. To calculate KIC, Young's modulus, E and the measured hardness, Hv were used. Using KIC and probability of fracture, 'P', ln ln[1/(1-P)]-ln KIC graph was drawn based on the Weibull distribution equation. Consequently, Weibull modulus,, m` and scale parameter, 'K-0' were determined and compared with each other

Sintering effects of mullite-doping on mechanical properties of bovine hydroxyapatite

In this study, sintering effects on microstructural behavior of bovine derived hydroxyapatite doped with powder mullite are considered in the temperature range between 1000 C-omicron and 1300 C-omicron. Results show that maximum values of both compressive strength and microhardness are achieved in the samples sintered at 1200 C-omicron for all mullite additions of 5, 7.5, 10 and 12.5 wt. Moreover, above 1000 C-omicron, decomposition of HA and new phase formations such as whitlockite and gehlenite play a major role in both compressive strength and microhardness properties which increase up to 10 wt mullite reinforcement. (C) 2017 Elsevier B.V. All rights reserved

Production and Characterization of Alumina-Titania Biocomposite

Alumina is a biomaterial of choice for more than 20 years due to its high hardness accompanied by low friction, wear and inertness to in vivo environment. It has been reported that titanium oxidized to the rutile phase is bioactive. This is a property discovered for certain ceramics such as Bioglass and sintered hydroxylapatite (HA). But the combination of alumina and titania forming tialite (Aluminium titanate-50 mol % Al2O3 and 50 mol % TiO2) is a new challenge. In this work we made firstly the beneficiation of the Seydisehir alumina by leaching it in the acidic solution the Aqua Regia followed by preparation of batches containing 2,5 wt %, 3,5 wt % and 4,5 wt % of MgO as the sintering aid, 1 wt % of SiO2 and the balance; the alumina and titania powder mixture (1:1 mole). After sintering these batches at 1600 degrees C for about 12 h, their mechanical properties (the compression and hardness testings) and phase ratios (the XRD analysis) were analyzed and compared with the control group containing the laboratory scale alumina instead of the Seydisehir alumina. Following the characterization (the SEM and the EDS analysis) of the substrate material, the comparison of two different materials was carried out

Microstructural and mechanical properties of hydroxyapatite-zirconia composites

This work focuses on the improvement of the mechanical properties of hydroxyapatite (HA) through the addition of 3 mol% yttria partially stabilized zirconia (PSZ). Enamel-derived HA (EHA) from freshly extracted human teeth and commercial HA (CHA) were chosen as the matrix. The effects of addition up to 10 wt% of PSZ and of sintering temperature (1000 degrees-1300 degrees C) on the density, microhardness, and compression strength were evaluated. For EHA-PSZ composites, the density and mechanical properties were generally enhanced by adding 5 wt% PSZ, especially after sintering at 1200 degrees C, whereas CHA-PSZ composites showed lower strength values at sintering temperatures of 1200 degrees and 1300 degrees C with respect to EHA-PSZ composites. This may be due to the lower stability of CHA-PSZ composites with higher amounts of calcium zirconate formed over 1100 degrees C when compared with EHA-PSZ composites