Several types of ceramic membranes have been developed for a half of century. Alumina is the most extensive advantage among different type of ceramic membranes. Many types of alumina powder with difference particle size distributions were used as a starting material for extrusion process. The ceramic dough compositions for extrusion were studied. The sheet of alumina supports were fired at various sintering temperatures contained approximately 40% porosity after sintering at 1400℃ for 2 hour.
Al_2O_3-30wt%TiC composites doped with 0.5wt%MgO and 0.3-1.0wt% Y_2O_3 additives are pressureless-sintered at different conditions such as temperatures, soaking times, and heating rates under an argon atmosphere. The physical, mechanical properties, and cutting performance of sintered composites were compared with commercial one. In this work, the Al_2O_3-30wt%TiC composites doped with 0.5wt%MgO and 0.3wt% Y_2O_3 sintered at 1800℃ obtained highest density of 97% of theoretical.
In this research, the photocatalyst of titanate layer compounds, K_2Ti_4O_9 and H_2Ti_4O_9, were prepared and characterized to compare their photodecomposition of methylene blue dye. Silver loading photocatalysts were prepared by reduction under blacklight irradiation. The photodecomposition activities of methylene blue dye were in the order of K_2Ti_4O_9/Ag>K_2Ti_4O_9>H_2Ti_4O_9/Ag>>H_2Ti_4O_9.
A mixed oxide synthesis route has been investigated for the synthesis of zirconium titanate, ZrTiO_4. The formation of ZrTiO_4 phases have been investigated as a function of calcination temperature by XRD. The crystal structure, particle size distribution, morphology and phase composition of the calcined powders were determined via XRD and SEM. It has been found that with increasing calcination temperature up to 1150℃, the result showed that anatase-TiO_2. The yield of the ZrTiO_4 phase increase significantly up to 1350℃, when a single phase of ZrTiO_4 was formed, revealing that the rutile-TiO_2 had completely reacted with the ZrO_2 phase. It seemed that the pure wolframite phase of ZrTiO_4 powders was successfully obtained from calcinations conditions of 1350℃ for 4 h with heating/cooling rates of 5℃ minute^(-1).
Solid solution perovskite structure of lead zirconate-lead nickel niobate ceramics, (1-x)PbZrO_3-xPb(Ni_(1/3)Nb_(2/3))O_3 (PZ-PNN) with x=0-0.5, were synthesized via the columbite precursor method. The formation of the perovskite phase in the calcined powders has been investigated as a function of calcination conditions by TG-DTA and XRD techniques. The morphology evolution was determined by scanning electron microscopy (SEM) technique.
Biomorphic TiC/C ceramic was produced by vacuum-infiltrating carbon perform with TiO_2 sol and subsequently synthesis by carbothermal reduction process. Carbon preforms were pyrolyzed from rubber wood, sadao-chang wood and coastal pine wood. The effect of infiltrating time to the TiC/C products were analyzed. By observing the resulted products by SEM and XRD found that TiC/C were formed with retaining morphology of the original template structure.
In this work, Lead zirconate titanate ceramics (Pb(Zr_<0.52>Ti_<0.48>)O_3: PZT) were prepared by conventional mixed oxide method. The optimum temperature for calcinations the formation of phase pure perovskite was found to be about 750℃ for 2 h with heating rate of 10℃/min. Phase formation was examined by X-ray diffraction (XRD). The sintering procedures were carried out at 1150 and 1200℃ for 6 h with heating rate of 3, 5 and 10℃/min. Influence of heating rate on physical properties and microstructure were investigated. The results show that at percent of linear shrinkage and densification were decreased with increased heating rate. However, the average grain size of PZT ceramics was not much influence by heating rate.
In this work, the effect of calcinations temperature on microstructure and phase formation of Ba(Zr_xTi_<1-X>)O_3 powders was investigated. The BZT powders were prepared via the solid state reaction method under various calcinations temperatures. The pure perovskite phase of the BZT powders was obtained with calcinations condition at 1,300℃ for 4 h. The TGA and DTA results were corresponding to XRD investigation. The microstructure of the powders exhibit an almost-spherical morphology and have a porous agglomerated form.
Ni-Cu/Gd-doped ceria composite anode powder was prepared via sol-gel route. The acid/alkoxide ratio (0.6-4) and water/alkoxide (>25) were found to be suitable for obtaining homogenous gel with an increasing chance of gel formation as the amount of water increases. XRD results of the powder fired at 900℃ showed the (Ce, Gd)O_2, (Cu, Ni)O, NiO and CuO phases.
Al_2O_3-ZrO_2 (AZ_x), with x=5, 15, 25, 35, 45 and 50 mol% ZrO_2 content, were prepared by Co-precipitation method. Synthesized powders were characterized thermal reaction by differential thermal analysis technique (TG-DTA) and were investigated phase formation using x-ray diffraction. It was indicated that the reaction was happened at temperature between 850℃ to 1100℃. AZ_x powders were successfully obtained for calcination conditions of 1000℃ for 2 h. Moreover, morphology and particle size evolution have been determined via SEM technique. It is showed that particles are agglomerated and basically irregular in shape.
Nanocrystal stabilized tetragonal zirconia (t-ZrO_2) powders were prepared through a soft combustion route, with yittrium^<3+> as stabilizing agent and niobium^<5+> for conducting properties. The precursor solutions were prepared from zirconyl nitrate, yttrium nitrate and niobium nitrate. Glycine was used as the fueling agent. The mixed solutions were soft combusted at low temperature and then calcined to produce nanocrystalline powders. Nb-Doped t-ZrO_2 was produced with average particle size ranging from 15 to 30 nm with a band gap of 2.17 eV.
This paper presents the study of the effect of sintering temperature on microstructure and mechanical strength of zirconia sintered part prepared using powder metallurgy process. Three different sintering cycles were applied to the zirconia compacted powder during the sintering process. The results showed that sintering temperature asserts influence in the formation of interparticle bonding in the sintered parts. Examination of the polished surface indicated that higher sintering temperature results in stronger interactions between the particles. Therefore the sintered parts prepared under higher sintering temperature (1500℃) achieved greater strength compared to the sintered parts prepared under 1300℃ operating temperature.
The oxidation behavior of porous reaction-bonded silicon nitride has been investigated in the temperature range 900-1400℃ for up to 3 hours by the Simultaneous Thermal Analysis technique. The mechanism of oxidation is complex and depends critically on the temperature. At low temperatures in excess oxygen, a protective silica film is formed by passive oxidation. The low P_<o2> in pores beneath the film leads to active oxidation of both the silicon nitride and silicon oxynitride which may be formed during fabrication process. A model for the roles of the silica film and the silicon oxynitride was proposed and discussed.
Ni^<2+> ions occupy the tetrahedral(4), trigonal bipyramid(5) and octahedral(6) sites in glasses and glass-ceramics. The color changes depending on coordination number, typically pink for tetrahedral site, brown for trigonal bipyramidal and tetrahedral sites and green to blue for octahedral site, respectively. The broad NIR emission peaking at around 1220 nm was observed only for octahedral Ni^<2+> ions. This emission is due to 3^T_2(F)→3^A_2(F) transition.
The origin of coloration and luminescence of Se-, Te-and Bi-doped glasses and glass-ceramics were investigated. NIR luminescence was observed at around 1100 nm and 1200 nm in Bi-doped and Te-doped glasses and glass-ceramics, respectively. On the contrary, no NIR luminescence could be observed in Se-doped glass. It is suggested that the origin of coloration and NIR luminescence in these hosts is most likely to be caused by molecular Se_2 (Se_2^->, Te_2 <Te_2^-> and Bit <Bi_2^->.
Glass-ceramics were prepared by using hydrometallurgical zinc waste and waste glasses (clear and amber cullet) as raw materials. The mixtures were melted at 1450℃ for 1 hour. The proportion of Zn-waste in the mixtures varied from 20 to 60 wt%. The obtained glasses were ground and pressed into a bar shape and then sintered at 750℃ and 850℃ for 2 hours. Their physical and mechanical properties were determined. It was found that the density of the glass-ceramics increased with an increase in the proportions of Zn-waste.
The changes of glass structure and optical absorption of Mn^<3+>, Cu^<2+>, Ni^<2+> and Co^<2+> ions in industrial soda-lime-silica glasses were studied. The glasses containing 11-19 mol% Na_2O were melted under air atmosphere in an electric furnace at 1450 ℃ for 8 h. Glass composition, properties, structure changes and optical absorption were investigated. The results showed that increasing Na_2O content caused the highly basic of glasses. As well as the degree of disconnectivity in the network, the molar polarizability of oxide (-II) species were slightly increased. The optical densities of each transition ions such as Mn^<3+>, Cu^<2+>, Ni^<2+> and Co^<2+> ions were increased at constant wavelength when the structures of glass were disconnected.
In this research, TiO_2 photocatalyst was immobilized on borosilicate glass powder. The immobilization was carried on by mixing TiO_2 and borosilicate powder and then calcined at 600 to 800℃ for 1 h. XRD and SEM analysis showed uniform coating of TiO_2 on glass powder surface. The TiO_2-coated glass powder showed good photocatalytic activity for methylene blue decomposition.
The production of biodiesel from potential tropical plant oil such as physic nut (Jatropha curcas L.) may lead to large amount of associated waste cake which has to be properly managed. Conversion of this waste biomass to valued added raw material such as activated carbon through pyrolysis process is an environmentally sound option. In the work reported here, preliminary tests were conducted to investigate the influences of different pyrolysis parameters on the properties of pyrolysed chars. Chars were characterized by thermogravimetric (TG) analyzer for the proximate analyses and the pyrolysis kinetic studies. The determination of surface areas and pore size distributions of obtained chars was also carried out. The optimum conditions for pyrolysis which yield maximum BET surface area were established. Results showed that it was feasible to prepare chars with high BET surface areas from Physic nut waste.
In this work, locally incinerator bottom ash (IBA) with particle size less than 290μm was processed using conventional powder production technique involving milling, compacting and sintering. Ball milling was used in order to reduce the particle size of the ash. Uniaxial compaction process was carried out to form a green parts. Then green samples were sintered at three different temperatures of 1000℃, 1050℃ and 1100℃. Characterizations were made at every single process involved; powder, green and sintered parts. From this study, it showed that the sintered product of the finer ash promotes better green and sintered quality. The sintered densities seem to be increased along temperature increment which contribute to better mechanical properties, hardness and compression strength.
The aim of this research is using latex from para-rubber mixed in concrete block to develop strength and thermal insulation properties. The concrete blocks are formed under TIS standard . The compressive strength and water absorption are tested by TIS standard  while the bending strength and coefficient of thermal conductivity are evaluated by ASTM standard [2, 3]. From the results, the water absorption of concrete block is reduced. When the latex to cement ratio is increased, the bending strength increases while the compressive strength decreases. For the insulation property, it indicates that the concrete blocks with para-rubber is an excellent insulation. This means latex from para-rubber could be an admixture which improves concrete block properties for strength and thermal insulation.
This paper reveals the successful application of Cr_3C_2-NiCr coating on the Ni-based superalloy Superni 718 (18.5Fe-19Cr-5.13Ta-3.05Mo-0.9Ti-0.5 Al-0.18Mn-0.18Si-0.15Cu-0.04C-bal Ni (Wt%) by the high velocity oxy-fuel (HVOF) process using LPG gas as a fuel. The combined techniques of optical microscopy, X-ray diffraction (XRD), scanning electron microscopy/energy-dispersive analysis (SEM/EDAX) and electron probe microanalysis (EPMA) have been used to characterise the microstructure, porosity, coating thickness, phase formation and microhardness properties of the coating-substrate composite.
Mechanical alloying (MA) of Ni-74.9mol%Al-3.1mol% Si powder mixtures was performed for relatively short milling times by planetary ball mill. The MA powders were coated on ductile cast iron (JIS-FCD450) by vacuum hot pressing at a relatively low temperature (873K) to investigate potential for mechanochemical activation of MA on surface coating. At the optimal milling time, the coated layer was well-reacted with high density (almost no pores) and high hardness (max. 1110HV).
The fabrics coated with TiO_2 particle have been easily prepared by dipping in the TiO_2 sol at low temperature. SEM and EDS observation confirms that the TiO_2 films were uniformly coated on the fabric surface. Some roughness and cracking were also observed. The TiO_2-coated fabrics can absorb the UV light, especially in the range of 300-350 nm.
Tribo-properties of hard coated tools were evaluated under using cold-forming oils for steel by ball penetration test. Diamond-like carbon including Si (DLC-Si) is a special target of hard coatings for better properties of anti-galling and low friction, but it cannot show good performance under a dry condition for the severe test. Using pure mineral oil, VC, TiN and DLC-Si indicated large ball penetrating load. When oil containing phosphoric esters of 30% was applied, DLC-Si reduced the load by nearly 30% for VC and TiN, but some scratches were observed on the DLC-Si surface. Applying oil containing phosphoric esters and phosphoric acid, DLC-Si performed low friction without scratches on the surface. Also the load of DLC-Si was smaller than those of TiN and VC. The combination of DLC-Si and high performance oil was so effective.
The 5-Axis Laser Aided Manufacturing Process (LAMP) system is the process in which the material deposition and material removal processes are integrated. The system exploits the additional rotation axes in order to reduce the support structures. Therefore, the hybrid system has the capability to build complicated geometry with a single setup. The strategy to decompose the 3D model into cells and the algorithm to arrange the deposition sequence of those cells are discussed in the paper. Once the sequence is determined, the cells are sliced into non-uniform layers. The gap problems between deposition tracks on each layer are eliminated by using the algorithm to generate the "Spiral-like" tool path for deposition process.
This research compared the corrosion behavior of the Ni plated and the unplated Hastelloy C-276 and stainless steel 316 EAS coatings produced by Electric Arc Spraying in 2M NaOH solution at 25℃ using electrochemical technique. The results can be summarized that Ni platings of a few microns thick as a sealant can improve the corrosion resistance of the EAS coatings. The as-sprayed Hastelloy C-276 coating exhibits higher corrosion rate than the as-sprayed stainless steel 316 coating. The corrosion behavior can be improved further by smoothening of the EAS coating surfaces before plating. The corrosion resistances of the smoothened Hastelloy C-276 coatings, both plated and unplated, are superior to those of the stainless steel 316 coatings.
In this study, ITO and TiO_2 films were deposited on sodalime glass, NaCl(100) and silicon(111) wafer. Microstructure of the deposited films, before and after post-annealing at 400℃ and 500℃, was analyzed by XRD. It has been found that; i) ITO: as deposited plane (222) was recognized only on silicon and glass substrates. After annealing, planes (211), (400), (440), and (622) were also observed on all substrates. The relative ratios of (400)/(222) on silicon and NaCl substrates were higher than on glass. ii) TiO_2: as deposited no indication of preferred plane were found. After annealing, planes (101), (004), (200), (105) and (211) and (622) were observed on silicon while only plane (101) on NaCl, and no structure observed on glass.
In the present work, the effect of the structural and magnetic properties of the electrodeposited Ni-Fe thin films on copper substrate in continuous and pulse mode under potentiostatic control without and with the presence of ultrasonic filed was investigated. The influence of ultrasonic filed improved the efficiency of film deposition and the coercivity of the as prepared films decreases with the increase in the Nickel content.
In this study, a silicon carbide layer was synthesized by 40 keV 12^C^+ implantation of a ptype (100) Si wafer to a dose of 6.5×10^<17> cm^<-2> at 400℃. The implanted sample was subsequently annealed at 1000℃ in a vacuum furnace. As a non-destructive technique, glancing incidence X-ray diffraction analysis (GIXRD) was used to probe the crystallinity of the synthesized layer. The results indicated that 3C-SiC was formed during implantation and the subsequent annealing had greatly enhanced its crystalline quality.
Pure and Pb-doped (Pb=0.3) Bi_2Sr_2Ca_2Cu_3O_<10+x> (Bi-2223) thick films (〜5-30 μm) were electrophoretically deposited on high purity silver foil using ethanol as the suspending liquid. The deposition was done at applied voltage of 400 V/cm and current of 〜0.02 mA/cm^2 for a period of 10 minutes. Short sintering time of 1 hour at 820℃ was performed to reduce film porosity and allow vacancy diffusion of the deposited grains. X-ray diffraction and surface image analysis of the film shows c-axis orientation and excellent grain alignment, respectively. These results indicate texturing of the deposited films.
The mechanism for the hydrothermal growth of ZnO nanoblades and nanoflowers is presented. ZnO nanostructures were grown on a copper strip substrate using zinc acetate dihydrate and ethanolamine as precursors at 65℃. The mechanism of growth was deduced as a function of substrate's exposure time to the reaction mixture. The growth was found to be nucleation driven and the presence of a seed structure promotes the formation of a nanoflower. Nanoblades grow due to the supersaturation of ZnO on the substrate surface.
Growth rate of DLC films were investigated using magnetic field enhanced nanopulse plasma chemical vapor deposition method. Maximum growth rate of DLC film by this magnetron CVD method is approximately fifty-fold larger than that of conventional plasma CVD method. High growth rate area of DLC film corresponds to the magnetic field distribution region that the field is parallel to the substrate 15 to 20 mm above the substrate.