Narumon Lertcumfu

Characterization of Metakaolin-Based Materials for Dye Adsorption from Aqueous Solution

The properties of metakaolin-based materials were investigated. The studied materials were prepared by mixing metakaolin and aluminum oxide in alkaline solution. The obtained samples were cast into plastic molds and then left at 27°C for 24 h. The properties of the materials were investigated using XRD, FTIR, and SEM. The obtained results suggested that reaction of the mixed materials occurred. The adsorption properties of the materials, including removal efficiency, distribution coefficient, and uptake capacity were determined. The obtained results revealed that the studied materials exhibited high adsorption capacity, which is good for the adsorbent applications.

Effects of Sintering Temperatures on Structural, Electrical and Mechanical Properties of BNKT Piezoelectric Ceramics

This research investigated the effects of sintering temperatures on the structural, dielectric, ferroelectric, piezoelectric and mechanical properties of lead-free Bismuth Sodium Potassium Titanate (BNKT) piezoelectric ceramics. The BNKT ceramics were prepared by solid-state mixed oxide method and sintering at temperature ranging from 1100 to 1150°C for 2 h. All ceramics sample showed highly density and reach a maximum at sintering temperature 1125°C of 5.81 g/cm3. X-ray diffraction patterns exhibited pure perovskite structure with coexisting of rhombohedral-tetragonal phases for all compositions. The microstructure was characterized by Scanning Electron Microscope (SEM), from SEM image the ceramics showed cubic-like grain shape. The average grain size increased with increasing sintering temperature. The dielectric permittivity showed the optimum sintering at 1125°C with reach a maximum dielectric constant of 4,194. Furthermore, at sintering temperature 1125°C present highest strain (Smax = 0.14%) with a large normalized strain coefficient (d*33 = Smax/Emax) of 233 pm/V.

Processing and Properties of Biphasic Calcium Phosphates Bioceramics Derived from Biowaste Materials

Properties of biphasic calcium phosphates bioceramics derived from biowaste materials were investigated. The hydroxyapatite (HA) powder was synthesized from bovine bone via thermal treatment while β-tricalcium phosphate (β-TCP) powder was synthesized from mussel shells via solid state solution. Pure HA and β-TCP were successful obtained. The HA and β-TCP were mixed together and sintered at 1100 - 1350°C. The effects of the sintering temperature and the ratio of HA/ β-TCP on the properties of the studied samples were investigated. The sintering temperature at 1250°C presented the maximum value of density and hardness. X-ray analysis of BCP ceramics sintered at 1250°C presented multiple phases of calcium phosphate. Average grain sizes of the studied samples decreased as the ratio of HA increased.

Influence of Sintering Temperature on Structure and Electrical Properties of Modified-BNKT Lead-Free Piezoelectric Ceramics

In this research, the effects of sintering temperature on phase structure, densification, microstructure, and electrical properties of modified-BNKT ceramics were investigated. Conventional sintering of lead-free 0.97Bi0.5(Na0.80K0.20)0.5TiO3-0.03(Ba0.70Sr0.30)O3 or 0.97BNKT-0.03BSrT ceramic was investigated to clarify the optimal sintering temperature for densification and electrical properties. All ceramics were prepared by a conventional mixed oxide and sintered at various temperatures from 1100 to 1150°C. XRD pattern indicated all ceramics exhibited a single perovskite without any secondary phases. The maximum density of 5.80 g/cm3 with relative density of 99.32% were observed for the ceramic sintered at 1125°C. Grain size tended to increase with increasing the sintering temperature. The good dielectric (Td = 121 °C, Tm = 320 °C and e¢max = 4982) and ferroelectric properties (Pr = 16.66 µC/cm2, Ec = 17.85 kV/cm and Rsq = 0.74) were obtained for the ceramic sintered at optimum sintering temperature of 1125°C.

Electrical properties of sodium potassium niobate/mullite ceramic composites

ABSTRACT In the present study, the composites between KNN and mullite were fabricated via a solid-state reaction technique. KNN was calcined at 900°C and mullite which synthesized from kaolinite (Ranong, Thailand) was calcined at 1300°C. Effects of KNN content on the composites properties such as densification and electrical properties including dielectric, ferroelectric and piezoelectric properties have been investigated. It was found that the densification behavior of the composites was improved by KNN added. The addition of KNN also resulted in improvements of electrical properties such as remanent polarization, dielectric constant, and piezoelectric coefficient of the materials.

Fabrication and Properties of Mullite Ceramics from Ranong Kaolin

In the present study, mullite powders were prepared from fired Ranong kaolin powder at high temperatures. Differential thermal analyses and X-ray diffraction (XRD) technique were used to understand kaolin–mullite reaction sequence and phase formation of the starting material after a heat treatment, respectively. It was found that phase of mullite started to occure at ∼1000 °C. Microstrural study by a scanning microscope, indicated that there was a change in microsture after the heat treatment, i.e. grain shape changed from equiaxed to needle grains shape . The AC conductivity decreased with decreasing the sintering temperature and 1500 °C ceramic presented a very high frequency stabilty of conductivity, suggesting that this martial can be used as an electrical insulator for wide frequency range.

Influence of Curing on Calcined Kaolin-Based Geopolymer

The object of this work was to use calcined kaolin-based geopolymer as an alternative material to replace ordinary Portland cement (OPCs) by applying geopolymerization processes. Geopolymer slurry was prepared from calcined kaolin and alkali activators, which consisted of 10 M NaOH and Na2SiO3 solution. The fresh slurry was cast into plastic molds and then cured at room temperature for 24 h. Reaction temperatures were measured (for 24 hours after casting). Compressive strength of the geopolymer was tested after curing at room temperature and after microwave heating. The mechanical properties increased with added plaster for microwave curing of 5 min. It is believed that this process can increase the efficiency of the production line for geopolymer.

Dielectric and Mechanical Properties of Mullite/Modified BaTiO3 Composites

Composites between mullite and modified BT were prepared by a conventional technique. The samples were calcined at 1300 °C for 2 h. The composites were sintered at 1250 °C for 2 h. The dielectric and mechanical properties the samples were investigated. The mechanical properties were found to improve after sintering at a suitable temperature. Addition of the BT produced an improvement in dielectric constant due to the BT has high piezoelectric properties. A higher dielectric constant for a sample contained higher amount of the BT was related with a higher polarization in the samples.

Effects of Calcium Carbonate Synthesized from Cockle Shell on Characteristics of Calcium Phosphate Biphasic

Calcium phosphate is a biomaterial which exhibits excellent biocompatibility, bioactivity and biodegradability for bone replacement and other medical applications. In the present work, multiphasic calcium phosphate compounds consisting of hydroxyapatite (HAp) and tri-calcium phosphates (TCP) were prepared by a solid state reaction method. Effects of calcium carbonate (CaCO3: ±3-5 wt%) on the properties of the studied powders were investigated where calcium carbonate powder was synthesized from a natural product (cockle shell). The phase formation and morphology of the powders were characterization by many techniques such as XRD, SEM and dynamic light scattering techniques. The results showed that amount of calcium carbonate additive affected on the properties of the studied samples.

Effect of Metal Oxide Nanoparticles Addition on Physical Properties of Hydroxyapatite

In the present study the effects of metal oxide nanoparticles addition on the microstructure, physical properties of the HA ceramics were investigated. Many techniques were used for the analysis. X-ray diffraction analysis revealed a co-exist phases between hydroxyapatite and tricalcium phosphate in the sintered samples. Addition of NiO resulted an increase in the lattice parameters of the tricalcium phosphates due to the bigger radii atom (Ni) substitution for the small radii atom (Ca). Energy dispersive spectroscopy suggested that most of NiO particles located at grain boundary, resulting in an improvement of hardness of the samples