Papers by Author: Mohamad Hasmaliza

Abstract: Dolomite is a raw carbonate mineral rich in contents with calcium, magnesium and oxide compounds also including other minor impurities from other compounds. It could be easily found in sedimentary rock which is most likely known as dolostone associated with limestone and chalk carbonates. This mineral has been used in a variety of industries including agricultural, metallurgy, constructions, biomass and others. Currently, there are abundant sources of local dolomite minerals but have very limited applications when compared to other types of carbonate minerals. This was contributed by the lack of basic technical information on dolomite properties and no extensive research has been done to evaluate the new potential of this mineral. Therefore, this paper made a brief review on the important characteristics, properties and thermal behavior of dolomite and based on these findings discussed the dolomite's suitability and potential to be used as bioceramics and in biomedical applications.

Abstract: In this study, a composite of bioactive glass and cordierite (BG/cordierite) was proposed to increase the strength of bioactive glass (BG). Both BG and cordierite were separately synthesized with the method of glass melting and used to fabricate BG/cordierite with sintering temperature in the range from 600 to 1000 °C. The BG/cordierite were characterized using X-ray diffraction (XRD), density, bulk density, porosity and hardness test. The XRD pattern shows amorphous phase and crystalline phase such as combeite, wollastonite and larnite appeared after sintering. The highest hardness value show by BG/cordierite with sintering temperature 950 °C (BG/C950) with 251 Hv.

Abstract: Formation of crystal structures in glass ceramic is influenced by the heat treatment of parent glass. Most of research often studied on the important of sintering temperature and its soaking time. In this study, the effect of soaking time (3, 4 and 5 hours) during melting process (1550 °C) on crystal structures of Lithium Aluminosilicate (LAS) glass ceramic was conducted. All samples were then sintered at 900 °C for 30 minutes. The amorphous phase was identified prior to sintering process and transformed into crystalline phase for all samples after sintering process in XRD analysis. Major crystalline phase of high quartz solid solution and β-spodumene (LiAlSi₂O₆) were observed and higher intensity peak is found as the soaking time is longer. The microstructure of the sintered samples was observed under SEM and the particles were displayed an evidently growth of the grain as function to the soaking time. The functional groups of Si-O-Si and Si-O(Si, Al) bonding were appeared in fourier-transform infrared spectroscopy (FTIR) analysis corresponding to the silicates and aluminosilicate bonding. The results achieved present 5 hours soaking time during melting process was the optimum soaking time for melting LAS glass at 1550 °C.

Abstract: In this work, the piezoelectric material system of Pb (Zr_0.52Ti_0.48)O₃ ceramics were synthesized by conventional solid state via high energy planetary mill reaction. This process were chosen in order to skip the calcinations and implement a single firing process which very effective to reduce the possibility of PbO loss. The effect of sintering parameters on structural behavior of pure PZT ceramic was discussed in detail. Comprehensive studies have been carried out in order get optimum parameter for sintering process, thus improved the performance of the pure PZT ceramics. Grain size properties of Pb (Zr_0.52Ti_0.48)O₃ ceramics increased with increasing the sintering temperature and duration. However longer sintering condition (1200 °C, 3 hours) causes excessive PbO loss which leads to presence new phases in XRD analysis, promote grain growth behavior with inhomogenous microstructure and tend to have more pores.