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Effect of annealing treatment on the characteristics of bovine bone
A. Niakan,S. Ramesh,C.Y. Tan,J. Purbolaksono,Hari Chandran,W.D. Teng 한양대학교 세라믹연구소 2015 Journal of Ceramic Processing Research Vol.16 No.2
The effect of annealing on the properties of bovine bone was investigated over the temperature range of 400 ℃ to 1300 ℃ at a ramp rate of 10 ℃/minute. The XRD results indicated that annealing at between 600 ℃ and 1100 ℃ resulted in phase pure hydroxyapatite (HA). However, decomposition of HA to form tri-calcium phosphate was observed for samples annealed above 1000 ℃. Thermo-gram analysis of bovine bone revealed the existence of organic combinations that was completely removed from the structure during heat treatment above 600 ℃. Annealed bovine bone between 800 ℃-1000 ℃ exhibited features of interconnecting pore structure, suitable for biomedical application. The study revealed that proper heat treatment through the control of annealing temperature represent a viable method to produce a HA structure from bovine bone.
S.M. Kwa,S. Ramesh,L.T. Bang,Y.H. Wong,W.J. Kelvin Chew,C.Y. Tan,J. Purbolaksono,H. Misran,W.D. Teng 한양대학교 세라믹연구소 2015 Journal of Ceramic Processing Research Vol.16 No.2
The sintering of yttria-tetragonal zirconia polycrystals (Y-TZP) is commonly carried at a predefined temperature using a long holding time of 2 hours. This often has resulted in grain coarsening which affects the mechanical properties of the sintered body and low temperature degradation (LTD) behaviour of the ceramic when exposed to moist environment. In this research, the effect of using a short holding time of 1 min. during sintering coupled with small amounts (0.5 and 1 wt%) of manganese oxide, MnO2 as dopant on the mechanical properties and LTD behaviour of 3 mol% Y-TZP were investigated. The results showed that the mechanical properties improved significantly with the addition of 0.5 wt% MnO2 for the 1-min. and 12-min. holding time samples when compared to 2 hours holding time sintered at the same temperature of 1350 ℃. Nevertheless, regardless of the holding time employed, the 1 wt% MnO2 addition was not effective in improving the mechanical properties and ageing resistance of Y-TZP ceramic.
Properties of hydroxyapatite synthesize by wet chemical method
S. Ramesh,S. Adzila,C.K.L. Jeffrey,C.Y. Tan,J. Purbolaksono,A.M. Noor,M.A. Hassan,I. Sopyan,W.D. Teng 한양대학교 세라믹연구소 2013 Journal of Ceramic Processing Research Vol.14 No.4
The sintering behavior of a commercial HA and synthesized HA was investigated over the temperature range of 700 o C to 1400 o C in terms of phase stability, bulk density, Young’s modulus and Vickers hardness. In the present research, a wet chemical precipitation reaction was successfully employed to synthesize a submicron, highly crystalline, high purity and single phase stoichiometric HA powder that is highly sinteractive particularly at low temperature regimes below 1100 o C. It has been revealed that the sinterability of the synthesized HA was significantly greater than that of the commercial HA. The temperature for the onset of sintering and the temperature required to achieve densities above 98% of theoretical value were approximately 150 o C lower for the synthesized HA than the equivalent commercial HA. Nevertheless, decomposition of HA phase upon sintering was not observed in the present work for both powders.