No abstract
Dental resin composite cements were prepared with simply mixing method of Part A and Part B. The material components in Part A were composed of Bis-GMA, TEDGMA, 4-META, SiO2 nanopowders and BPO. The components in Part B were Bis-GMA, TEDGMA, 4-META, SiO2 nanopowders and 2,2¢-(4-methylphenylimino) diethanol. Before using SiO2 nano-filler in the formulation of Part A and Part B, it had to be coated with methacryloxypropyltrimethoxysilane (MPS) which served as a silane coupling agent. Therefore, the optimum amount of MPS (1, 1.2, 1.5 and 2%) and SiO2 nano-filler (20, 27.27 and 33.33 wt%) used to fabricate the composites were investigated. The homogeneous mixture of Part A and Part B at mass fraction of 1:1 was formed into the bar shape with dimension of 25 mm x 2.0 mm x 2.0 mm and then cured under light source for 20 s. Then flexural strength was measured using the universal testing machine. Depth of cure was tested using mould which was perforated in cylindrical shape of 6 mm in depth and of 4 mm in diameter. The result showed that composite with 27.27 wt% of salinized SiO2 nanopowders by 1.5% of MPS showed the highest flexural strength of 65 MPa and depth of cure of more than 5 mm which were accepted according to ISO 4049. This study could be concluded that using a proper amount of MPS to silanize SiO2 nanopowders and using an optimum amount of SiO2 nanopowders significantly improved the flexural strength of dental resin composite cements.
The PSZTM ceramics from Pb0.94Sr0.06(Zr0.52Ti0.48)O3doped with 0.1 mol% Mn were prepared by a solid state reaction and. Two different methods were used to calculate the amount of Mn-dopant into PSZT powder. One was calculated rely on B-site precursor represented byBmethod. The other was computed based on the amount of calcined PSZT calledCmethod. This study was to investigate the effect of the two different calculating formulations of Mn doped PSZT ceramics by B and C methods on phase formation, microstructure, physical and electrical properties. The results were observed that phase identification showed the formation of perovskite structure in both cases. Besides, the mechanical quality factor (Qm) of the PSZTM ceramics derived fromBmethod was two times higher than those fromCmethod. Nevertheless, the dielectric constant (K), piezoelectric coefficient (d33) and planar coupling coefficient (kp) of the PSZTM ceramics fromBmethod were slightly lower than those of derived fromCmethod. This could be drawn the conclusion that PSZTM with 0.1 mol% Mn prepared byBmethod can be used as hard-type piezoelectric material.
The effect of manganese doping on microstructure, piezoelectric and electromechanical properties of Pb0.94Sr0.06(Zr0.52Ti0.48)O3 (PSZT) ceramics has studied. The PSZT ceramics doped MnCO3 concentration in the region of 0-1.0 mol% were prepared by a solid-state reaction and conventional sintering process. Phase identification showed the formation of single phase perovskite structure in all compositions. Microstructure and fracture behavior were observed by scanning electron microscopy (SEM). The fracture behavior demonstrated the change of fracture type from trangranular to mix of trans-and inter-granular type with increasing the amount of MnCO3. Dielectric constant (K), d33 and kp were increased when higher amount of MnCO3 was doped. In addition, the mechanical quality factor (Qm) was highest at 0.1 mol% MnCO3 doping in PSZT ceramics.
Nowadays, the concept of harvesting energy from the environment, for example, thermal, wind, sun, vibration and human activities is much of interest. PZT is one of the materials which show an ability to harness vibration energy and then change to electrical energy. Therefore, the PZT (Pb(Zr0.53Ti0.47)O3) doped with 0.02 mol% BYF (Bi(Y0.7Fe0.3)O3) piezoelectric ceramics has been studied to improve the figure of merit (d33*g33). The PZT and BYF powder systems were prepared by solid state reaction with calcination temperature of 800 and 850 °C for 2 h, respectively. XRD results showed that both powders exhibited pure perovskite phase for PZT and single phase of BYF without pyrochlore phase. Then, the two calcined powders (PZT and BYF) were mixed according to the composition of 0.02 mol% BYF doped PZT by two different milling techniques called conventional ball-milling (CBM) and high energy ball-milling (HBM) for 10 h. The result showed that average particle size obtain from HBM was 1 µm which was smaller than from CBM shown up to a few microns in bimodal mode. The PZT-BYF-HBM ceramics showed higher physical and electrical properties but lower K value. Thus promoting to higher g33 which was equal to 36.89 * 10-3(Vm/N) and FOM was 11,632*10-15(m2/N), while PZT-BYF-CBM had g33 of 26.86* 10-3(Vm/N) and FOM at 8,016*10-15(m2/N), respectively.
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