Beta-SiC/SiO2 core-shell nanowires were obtained in a mullite boat after the reaction between silicon nanopowder and CH4 gas at 1623 K (1350°C), without adding metal catalysts from outside. The as-grown nanowires were characterized by X-ray diffractometry, scanning electron microscopy, transmission electron microscopy, scanning TEM, and infrared-ray spectroscopy.The results showed that the typical nanowires consisted of single crystalline β -phase SiC core of 50-70 nm in diameter and a uniform wrapping layer of low crystallinity SiO2 of ~15 nm in thickness, and their lengths were up to several tens of micrometers. The nanowires axes lay along the [111] direction of β -SiC. Oxygen from the experimental setup or the raw powder should be a key factor to synthesize the core/shell nanowires.
High-yield SiC/SiO2 core-shell nanowires were synthesized without adding metal catalysts from outside through a simple thermal evaporation of silicon powders during decomposition of methane gas. The influence of three parameters, size of Si raw powder (50 nm and 5 μ m), reaction temperature (1573, 1623 and 1673 K), and soaking time (1, 3 and 6 h), was investigated.The typical synthesized nanowires from different conditions possess the diameter of no thicker than 100 nm with several tens micrometers in length. It was addressed that the condition using the smaller size Si powder, which contained the highest amount of oxygen, at higher temperature lead to more complete reaction to obtain a large quantity of nanowires. The synthesized nanowires at higher reaction temperature and longer soaking time possessed larger core than those nanowires prepared at lower reaction temperature and shorter soaking time. Oxidation of larger size Si powder improved yield of nanowires. Based on these results, it was suggested that the typical nanowires should be grown via the oxide-assisted growth mechanism.
The paper is focused on the influence of alternative fillers on rubber compounds properties. Three different types of powder fillers, drinking water treatment sludge (DWTS), perlite and calcium carbonate, were mixed into rubber compound mixtures. The mixtures were composed of STR20, EPDM, zinc oxide, steric acid, paraffin wax, 2-mercaptobenzothiazole (MBT), sulphur, Wingstay L, and filler. The mixtures were mixed in a Kneader type mixer at temperature of 70°C and then continuously mixed using a two-roll mill at temperature of 70°C. The relationships between type and the amount of filler versus properties of rubber compounds were demonstrated. The results showed that tensile and elongation at break of rubber compounds gradually decreased with increasing the amount of filler. Rubber compounds filled with small particle size filler possessed higher tensile strength and elongation at break than those filled with large particle size filler. Values of DIN abrasion loss of rubber compounds prepared under proper mixing condition were not more than 300 mm3. Under appropriate condition, the rubber compounds with DWTS, perlite and calcium carbonate provided sufficiently high shore A hardness (not less than 50 Shore A hardness). Finally, alternative fillers such as DWTS and perlite were expected to replace calcium carbonate in normal formula.
Fast pyrolysis with three typical modified zeolite catalysts was evaluated to produce bio-oil from Jatropha waste. Jatropha waste was pyrolyzed in a stainless-steel reactor at 600 under N2 gas flow. The aromatic hydrocarbon selectivity in the bio-oil was in the order: PtPd/ZSM(30) (73.7 %) PtPd/Beta(22.5) (68.6 %) PtPd/USY(20) (48.7 %), where the weight ratio of Jatropha/catalyst was 1. In addition, catalyst regeneration was carried out to study the catalyst efficiency. The analysis of fresh and regenerated catalysts by XRD, NH3-TPD, and TG/DTG, as well as product selectivity and surface properties showed that coke deposition and removal were associated with the zeolite structure and surface acid property. Due to pore size regulation, H-ZSM-5 with 10-membered ring (10 MR) could promote the pyrolysis reaction on the outside surface rather than in the inside channels. In USY zeolite with 12 MR, the reaction could occur inside the channels, but the moderate acid nature resulted in only slightly developed coke formation, which could be removed, at least partly, after regeneration. In beta zeolite with 12 MR, the total amount of surface acidity was more than twice that of USY, which undergoes more condensed coke formation, and was more difficult to remove by regeneration than the coke over USY. Thus, under these pyrolysis conditions, PtPd/ZSM(30) seems to be a better candidate for pyrolysis of Jatropha waste compared to PtPd/Beta(22.5) and PtPd/USY(20).
This paper is about Interlocking Stabilized Soil Blocks (ISSB) as developed in Thailand. ISSB are seen as an eco-friendly building material for home building and structures such as water tanks and sanitation facilities. For several decades the Thai R&D Institute TISTR has worked on developing and testing ISSB, which in other countries are called compressed stabilized earth blocks or CSEB. The composition of building blocks and the quality of building structures determine together the structural quality of the house or building. If there is a need for earthquake- and storm resistance, the building blocks and the structures must have specific features. Building stacked houses is an important issue given the growing scarcity of land for housing and the increasing land prices. ISSB is not only applied in Thailand, but also in Cambodia for low-cost housing and in Nepal for home reconstruction after the 2015 earthquake. ISSB or CSEB is also applied in other countries as an alternative building material and technology to replace the use of fired bricks and concrete building blocks for housing. Reducing the use of cement in the materials and structures is important for environmental reasons, but in ISSB/CSEB the use of cement as a stabilizer cannot always be avoided. This is surely the case in areas where earthquakes, heavy storms and floods can occur. Although this paper focuses mainly on technical aspects of sustainable housing and construction, there is also a focus on social sustainability, meaning a strong involvement of local communities in the production of sustainable building materials for walls, newly developed construction technologies, and mutual house and facility construction.
Reflective pigment was prepared by using Fe2O3 and Al2O3 as starting materials. Fe2O3 and Al2O3 powders were mixed at 0.8:2, 1:2 and 1.2:2 mole ratio using ball milling. The mixed powders were dried and calcined at temperature of 1500°C, 1600°C and 1700°C for various soaking time at 2, 8 and 20 h. Phase data were analyzed by x-ray diffractometry. It was found that (Al1-x, Fex)2O3 presented as a new phase in calcined powders at temperature of 1500°C to 1700°C for 2 h. The other new phase such as FeAl2O4 was detected in calcined powders at temperature of 1700°C for 8 and 20 h. From the experimental results indicated that complete reaction was occurred when higher calcination temperature and longer soaking time were used, resulting in spinel structure (FeAl2O4) generated. Then, the synthesized powders were mixed with exterior paint by mass ratio of 0:100, 10:90, 20:80, 30:70 and 40:60, respectively. The mixed paints were sprayed on metal sheets. Then the coated metal sheets were exposed under 200 watts lamb and measured the temperature difference between the exposed side and opposite side. The result showed that at the ratio of 30:70 exhibited the highest temperature difference of 14°C approximately. From the result, we concluded that spinel structure (FeAl2O4) is a candidate for near-infrared (NIR) reflective pigment of exterior paint.
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