Abstract: The effect of slurry solids content was studied for a novel direct foaming method based on slurry boiling to produce porous alumina ceramics. Slurries with solids contents of 30 to 45 wt. % were produced by conventional processing methods. The physical properties of slurry density and surface tension were measured, as well as thermal properties such as specific heat and latent heat, which were obtained using differential scanning calorimetry (DSC). Samples were fabricated by boiling the slurries on a hot plate until the liquid was completely evaporated. The resultant porous samples were presintered at 1000 °C and were examined to determine the pore size and structure. The measured pore diameter of samples obtained from this experiment were compared with theoretical calculations of departing bubble diameter from a heated surface proposed by Fritz, and Cole & Rohsenow. It was found that the pore size had a relationship with slurry solids content depending on the thermal gradient. The pore size, at a position away from the heated surface, increased as the solids content increased. However, the pore size at the heated surface did not vary significantly with solids content. The results showed that a direct foaming method based on slurry boiling is capable of producing porous alumina and that solids content of the slurry may be utilized to somewhat control pore size and structure.
Abstract: The aim of this research was to find a way to reduce energy costs by using thermal image techniques for investigating the thermal efficiency of ceramic furnaces. The case study was “Ban Nam Jo Ceramic”. The researchers collected the information by performing an in-depth interview at the research area, collecting preliminary data and using the thermal camera in the technical analysis part. The researchers also measured the temperature and volume of gas in the furnace. After that, those data were used to calculate the energy balance and the thermal efficiency of ceramic kilns. The data showed that the first measured furnace had calculated thermal efficiency of 9.99%. After the maintenance, the thermal efficiency increased to 16.64%. Furthermore, the volume of liquid petroleum gas decreased by 40%, and the damage in products after firing decreased by 3 %.
Abstract: The aim was to investigate the relation between micromorphology of porosity and electrical resistance of dental luting cements. Five dental luting cements were evaluated: zinc phosphate, glass ionomer, and three types of resin luting cements. Porosity of the specimen was analyzed by micro-CT and electrical resistance of cement was measured at voltage of 125 V up to 30 days and solubility of each specimen was calculated. It showed that the resin luting cements provided the highest electrical resistance regardless of amount of porosity. Zinc phosphate and glass ionomer had high porosity and the lowest resistance (14 and 3 kΩ, respectively). It was found that the electrical resistance of luting cement was not directly affected by the amount of porosity, but it seems to be related to pore connection. There is no correlation between electrical resistance and percentage of porosity but the morphology of porosity may have an influence on the electrical property of luting cement. Models of pore connection were proposed to explain the electrical resistance of luting cement.
Abstract: In this report, metakaolin based-geopolymer foams reinforced with carbon fibers have been prepared for thermal insulating purpose. Potassium silicate and potassium hydroxide solutions were used as activating agents while hydrogen peroxide was used as a pore former. In order to improve chemical interfacial adhesion with the matrix, the carbon fiber was pre-oxidized using 3 M of nitric acid solution for 10, 30, 50 and 70 min. It was found that variation in treatment time did not cause significant difference in neither mechanical nor thermal conductivity. However, both flexural strength and fracture toughness were significantly improved when the geopolymer foams were reinforced with carbon fibers while thermal conductivity was increased by about two times. The prepared geopolymer foams showed promising results to serve the designed purpose. Keywords: metakaolin based-geopolymer foam, carbon fiber reinforcement, oxidation treatment, mechanical and thermal properties.
Abstract: The aim of this study is to decolorize the high iron content (more than 0.1 %wt Fe2O3) glass. The contained 0.13 wt% iron oxide (Fe2O3) soda-lime silicate is prepared by high iron content sand with 0.17 wt% of Fe2O3. Iron oxide in soda-lime glass presents in two forms, Fe2+ (green) « Fe3+ (yellow). In principle, high iron content sand is not suitable to produce tableware. Therefore, the glass manufactures require high purity of sand because they want to control the amount of iron oxide as low as possible, which usually tableware glass contains only small amount of iron oxide (0.01 - 0.04 wt% Fe2O3) to avoid iron effect (green color). The soda-lime silicate glasses is decolorized by three different agents, Neodymium oxide (Nd2O3), Manganese oxide (MnO2), and Tin oxide (SnO2) 0.125 0.25 0.50 1.00 and 2.00 %wt respectively. The glasses are melted twice in the platinum crucible and investigated of the optical properties by UV-Vis spectrophotometer. The results of the color in CIE L*a*b* system are found that glass containing MnO2 and SnO2 slightly changes to white shade, but still presents in green. However, the result of contained 1.00 and 2.00 %wt SnO2 glasses is nearly cleared, the result of contained Nd2O3 glasses are satisfied, and the contained 0.25 %wt Nd2O3 glass is showed very clear. Anywise the color of glasses containing 1.00 and 2.00 %wt Nd2O3 turned to blue. The reaction of glasses containing Mn and Sn occur according to the mechanism of chemical decolorization. The reactions was described by the following equation, Fe2+ + Mn3+ g Fe3+ + Mn2+ and Fe2+ + Sn5+ f Fe3+ + Sn4+, but the reactions are limited and strongly depending on the redox equilibrium. For Nd2O3, the reaction presents according to physical decolorization, because the color of Nd2O3 is stable in melted glass and it can dismissed the color of Fe2O3 directly. Therefore, this method can apply for the tableware glass production with high iron content sand.
Abstract: Upconversion luminescence materials have recently received attentions because of theirs light conversion ability from infrared into visible and ultraviolet light. In this work, alkaline yttrium fluoride doped by ytterbium and thulium (AYF4: 20%Yb3+, 0.5%Tm3+) were synthesized by molten salt method at 400 °C for 2 hours with different eutectic molten salts, i.e. NaNO3-KNO3, NaNO3-LiNO3, KNO3-LiNO3, and NaNO3-KNO3-LiNO3. Pure hexagonal NaYF4 microrods were successfully synthesized using eutectic NaNO3-KNO3 molten salt. Under 980 nm laser diode excitation, upconversion luminescence in both visible and ultraviolet region was clearly observed. On the other hand, for the use of other eutectic molten salts containing LiNO3, the mixed phases of tetragonal LiYF4 and orthorhombic Y6O5F8 were obtained. These powders emitted only visible light with 10 times lower intensity than the hexagonal NaYF4 microrods synthesized using NaNO3-KNO3.
Abstract: The development of Dan Kwian pottery products is a research that uses participatory action research methodology and qualitative research method. By selecting a specific sampling in area 7, Dan Chai Community, Dan Kwian District, Muang, Nakhon Ratchasima Province, Thailand. The objective of this research three reasons: 1) the study form and evolution of Dan Kwian pottery products. 2) the development of Dan Kwian pottery products to form individually. 3) To study the satisfaction of entrepreneurs and consumers towards Dan Kwian pottery products. The research found that the model of Dan Kwian pottery products in the past to convey the wisdom of the grandparents emphasize the usefulness rather than beauty. At present, the style of Dan Kwien pottery products has been designed in a popular fashion and computer aided design. The pottery have a variety of uses and beauty than in the past. The Dan kwian pottery product was development pattern to form a new identity. The five models was selected: two cat models, one peacock model, one owl model and one cart model to from fifty models. The researcher was introduced five new pottery products to assess the satisfaction of four entrepreneurs and thirty consumers. It was found that the pattern of the pottery is unique has average of entrepreneurs was 4.75, while the consumer has average of 4.13. The uniqueness of skin color has average of entrepreneurs was 4.75, while the consumer has average of 4.00. The beauty of the new pottery has average of entrepreneurs was 5.00, while the consumer has average 4.27. The useful for function of the pottery has average of entrepreneurs was 5.00, while the consumer has average of 4.70.
Abstract: This research aims to development of Dan-Kwian ceramic jewelry from past to present. In terms of design, the raw materials and decorative techniques used in designed and developed Dan-Kwian ceramic jewelry for unique contemporary beauty. As a result, developed from the original by adopting simple shapes of geometry to be used for modern purposes, the emphasis is on creating different sizes in jewelry, which are large, medium and small. And highlight the color of clay body to light, medium and dark. The raw materials used to create Dan-Kwian ceramic jewelry prototype is Dan-Kwian clay mixed with kaolin and compound clay. At difference mixing ratio to determine the shade, then design and create masterpieces. Test fired with electric furnace at 800 and 1200°C, emphasize the natural brown and orange color of clay body. Decorated with smoked technique with rice husk in clay pot using charcoal stove owing to create a black color in the finished workpiece. Then, put it to sort the appropriate of each set. After that, design a piece of 5 different styles, in which the set consists of necklaces, bracelets and earrings. The most popular set of Dan-Kwian ceramic jewelry from the producer group is the first set inspired by the sphere, which can be prepared easily. Outstanding, the attraction is that the sphere in the center can be rotated. And the dark color in the center contrasted with the light outer circle. Overall, the five set are well received by the producer group. Make a way to see how to produce for sale, by selling it with existing products.
Abstract: The high purity nanosilica materials could preparation from different synthesis route. In this research, rice husk ash was extracted into silica powder, by chemical extraction method. Then, chemical composition analysis with XRF technique. In addition, the extracted silica nanoparticles were analyzed by XRD technique. Physical structure of nanoscale particles by SEM imaging. The results showed that the chemical composition of rice husk ash consists mainly of silica. While, the extracted silica nanoparticles had a high silica content of 99.9999%. In addition, silica extracted with silica nanoparticles was confirmed by XRD at position 2θ ≈ 22° and the crystalline extracts were amorphous to the physical characteristics of the SEM images. In the future, nanosilicon powder may be used to synthesize lithium-ion batteries.