Papers by Author: Sawet Intarasiri

Abstract: Natural opal, an amorphous, hydrous form of silica (SiO₂-n-H₂O), has been one of the favored precious gemstones for many centuries. Though beautiful, opal is very fragile and is damaged quite easily. Thus, opals of all varieties have been synthesized experimentally and commercially. The objective of this project was to synthesize and to compare crystalline opals. In this work, the development of powder sintered glass ceramics process based on soda lime silica glass waste with metal oxide powder enable jewelry applications. The substantial viscous flow of the glass led to dense products for rapid treatments at relatively low temperatures (900–1,000°C), whereas glass/metal powder interactions resulted in the formation of color agent crystals, provide enhancing optical properties. Several techniques were applied for characterization of the ingots. The chemical analysis was performed by Energy Dispersive X-ray Fluorescence (ED-XRF). The mineralogical compositions of the samples were determined by X-ray diffraction analysis. Raman spectroscopy was applied for optical characterization. The results were compared with a natural common opal. The present investigation demonstrated that the common opal with both color and colorless appearance can be synthesized by the technique, as the crystalline phase of opal structure was identified by XRD measurement. There is a great potential for such materials with novel functionalities for artificial gemstone application, i.e. opal forming.

Abstract: Sawdust is a waste from furnitureindustry which is mostly left in the garbage or burn for landfill in hugequantities every year. Efforts to find utilization of this material haveresulted mostly in low value. However, sawdust waste can be considered as analternative to fabricate fiber reinforced polymer composites for furniturefunction. This study was undertaken to determine the physical and mechanicalproperties of wood plastic composites, which were made under laboratoryconditions by hot pressing of high-density polyethylene (HDPE) with teakwoodsawdust as filler. Seven levels of mixed flour, 10, 20, 30, 40, 50, 60 and 70%,based on the composition by weight was added to the HDPE powder with palm oilas coupling agent. A flat pressing technology, the simplest method for capableof large dimension wood plastic panel production, was used to manufacturetesting specimens in dimensions 5.8 x 7.3 cm². Investigation of themechanical property of the composites material, according to the Americansociety for testing and materials (ASTM) method, was done by impact strengthtester. The measurement results were found that impact strength was decreased uponthe increasing of the sawdust up to 30 % mixing then gradually increased. However,by increasing mixed flour content, water resistance of the panels wasnegatively influenced. The best appearance of composites material in comparisonwith the natural woods was ~30% sawdust powder mixing. The woodplastic panels were utilized for construction of a Thai spirithouse as an outdoor decoration.

Abstract: t was known that historical objects were highly heterogeneous. Due to the complex nature of materials and objects, extremely sensitive, spatially resolved, multi-elemental and versatile analytical instruments were needed. The techniques employed should be as a noninvasive as possible and able to give complementary information from macroscopic to nanometer scales. In this work, X-ray based spectroscopy including energy dispersive X-ray fluorescence spectroscopy (EDS), Proton-induced X-ray emission spectroscopy (PIXE), and micro-beam X-ray fluorescence spectroscopy (µ-XRF) were used to analyze chemical composition of the Lanna-style glass. Microstructure was also studied. It can be concluded that these techniques in combination are powerful for the investigation of heterogeneous glassy materials.

Abstract: The Thai amulets that created in an image of Lord Buddha meditation were made to explain the Dharma of Buddha and believed to bless every life in this world for good karma. Phra Somdej Wat Rakhang amulet is the top of the five most famous Thai amulets. There are many molds with various compositions. In this work, it was the first time that X-ray fluorescence spectrometry methods; scanning electron microscope cooperated with energy dispersive X-ray fluorescence spectrometer (SEM/EDS) and particle induced X-ray emission spectroscopy (PIXE) were carried out to analyze their compositions. Two samples were collected from different molds. Results revealed C, Ca and Si were main composition. The differences in their compositions have been used to identify and characterize for each molds.