Papers by Author: P. Kantha

Abstract: The aim of this work was to analyze the effect of using rice husk ash (RHA) and bovine bone as raw materials of glass-ceramics based on the SiO₂-Na₂O-CaO-P₂O₅ system on their physical, mechanical properties and bioactivity. All of the investigated compositions were prepared by melting the glass mixtures at 1300°C for 3 h. The resulting glass samples were heated at different temperatures ranging from 600 to 1000°C with fixed dwell-time for 2 h for crystallization. Phase identification of the prepared glass ceramics was carried out by X-Ray diffraction (XRD) and scanning electron microscope (SEM) techniques. In addition, in vitro test was carried out in stimulated body fluid (SBF). Differential thermal analysis (DTA) showed that the glass transition occurred at 505°C and crystallization at 700°C. The main crystalline phase form in most glass ceramics is a sodium calcium silicate. The optimum heat treatment temperature, at which the maximum mechanical value (620 HV) could be obtained, is around 1000°C. After incubation in SBF for 7 days, all of the samples show good bioactivity in vitro, as evident by the formation of bone like apatite phase.

Abstract: The aim of this study was to investigate the effect of BaZr_0.05Ti_0.95O₃ (BZT) addition on the microstructure, physical, dielectric and piezoelectric properties of hydroxyapatite (HA), and develop new biomaterials which have potential applications in the support for cellular growth and in the system for bone regeneration. In this case the BaZr_0.05Ti_0.95O₃- HA composites (HABZT) were prepared by conventional sintering method. The BZT were added to HA with ratio 0, 10, 20 and 30 %wt. Then the mixed powders were pressed and subsequently sintered at the temperature ranging from 1150 to 1350°C. The result showed that the dielectric and piezoelectric properties were improved by the addition of BZT. Moreover, the bioactivity of the HA improved with addition of BZT especially at 10% as evident by the formation of bone like apatite layers on the surface of all BCZT composites after soaking in simulated body fluid (SBF) for 15 days. The results confirmed the possibility of using these bioactive composites for treatment within the human body.

Abstract: In this research, it is interesting to fabricate glass ceramics containing lead free ferroelectric crystals. The new lead free ferroelectric phase of interest is orthorhombic Bi2GeO5 which are precipitated in the BiO1.5-GeO2-BO1.5 system and studied in the region of 60 mol% BiO1.5:20 mol% GeO2: 20 mol% BO1.5. The glasses were prepared by conventional melt-quenching method. The glasses were melted separately in Pt and Al2O3 crucible in an air atmosphere. It is found that the as-received glasses were easily obtained from Al2O3 crucible while that from Pt crucible devitrification of Bi2GeO5 crystals were observed in some glasses, giving rise to an instability and difficulty in obtaining good based glasses by using this Pt crucible. The glass ceramics prepared from Pt crucible crystallized into two phases of the expected Bi2GeO5 and second phase Bi4Ge3O12 while Bi2GeO5 phase only observed in the glass ceramics prepared from Al2O3 crucible. Crystallinity and phases of the glass ceramics have a significant effect on their dielectric properties.