Abstract: The atomic oxygen oxidant—Peroxy-monosulfuric acid was prepared by the method of electrolysis under the condition of with and without ultrasonic. The influence of electrolysis time, electrolyte concentration, electrolytic voltage and the additive concentration on the concentration of oxidant were investigated. The result indicated that with the usage of ultrasonic, combination the cavitation effect and the chemical effect enhanced the concentration of electrolysis oxidant; with the electrolytic time of 3 hours, the electrolytic tension of 6V, the sulfuric acid weight concentration of 35%, the additive concentration of 0.5g/L, the ultrasonic frequency of 40kHz and the power of 150W, the oxidant concentration could reach to 0.9177mol/L. This research is helpful for decreasing the production cost of atomic oxygen oxidant.
Abstract: This study focused on the adsorption characteristics of hazardous heavy metals using reactive inorganic agents in synthetic wastewater. Basic properties of five reactive agents were analyzed by zeta potential, particle size, XRF and SEM. Zeta potential of five adsorbents was 45, 7, 14, -2 and 45 mV, respectively. Average particle size was in the range of 1.4 to 9㎛. By XRF analysis, main components were Na, Al, Si, S and Fe in reactive agents and no great differences in Mg, K, Ca and Ti components. As, Zn, Ni, Cu, Cr, Cd and Pb were used as target heavy metals. Adsorption capacity of Pb and Cu was in the order: TN 315Ny-T3>TN820L>TN315NY.
Abstract: Spherical carbon nanoparticles were synthesized by sol-gel polymerization of resorcinol and formaldehyde in the presence of CTAB(cetyltrimethylammonium bromide) and subsequent carbonization at 900°C. It is found that the amount of CTAB, water and catalyst showed a significant impact on the morphology and size of carbon nanoparticles. According to the BET surface area and capacitance, the nanoparticles were divided into two groups. The carbon nanoparticles with surface area of 725-758 m2/g showed capacitance between 120-140 F/g, while those with surface area of 596-649 m2/g showed capacitance only 60-80 F/g. Difference in the pore size of 1.5 nm to 3.0 nm probably contributed to the difference of capacitance.
Abstract: Tungsten is one of the most promising candidates for the plasma facing materials (PFM) in fusion experiment devices. In this study, tungsten coatings were fabricated on copper alloy substrates via air plasma spraying technology. The in-flight behaviors of tungsten particles in the spraying process were investigated. The microstructure and some properties of the as-sprayed coatings, including surface roughness, bonding strength, microhardness and thermal property, were evaluated. The results showed that the temperature and velocity of the in-flight tungsten particles increased by enhancing the spraying power. Un-melted particles and microcracks were found for the coatings prepared under the low (32.7kW) and high (47.6kW) spraying powers, respectively. The highest bonding strength and microhardness were obtained for the coating prepared under a medium spraying power (42.5kW) by reason of its good in-flight behaviors. The thermal conductivity of tungsten coatings was 32.2 W٠K-1٠m-1 at room temperature, which was much lower than that of bulk tungsten.
Abstract: In-filled CoSb3 skutterudites (InzCo4Sb12) were prepared and the filling effects on the thermoelectric and transport properties were examined. Seebeck coefficient and Hall coefficient confirmed that all the samples showed n-type conductivity. Temperature dependence of the electrical resistivity suggested that InzCo4Sb12 is a highly degenerate semiconducting material. The thermal conductivity was considerably reduced by In filling and the lattice contribution was dominant.
Abstract: Sn-doped CoSb3 skutterudites were prepared by encapsulated induction melting and their electronic transport properties were examined. The Sn dopant generated excess charge carriers, which increased in concentration with increasing Sn doping content. However, the carrier mobility decreased with increasing doping content, indicating a decrease in the hole mean free path by impurity scattering. The Seebeck coefficient decreased and the electrical resistivity decreased slightly with increasing the carrier concentration due to the reduced carrier mobility by impurity scattering. The lattice thermal conductivity was dominant in the Sn-doped CoSb3 skutterudites.
Abstract: In our previous studies, 10-40wt%Ni/Al2O3 membrane was prepared by uniaxial pressing and sintered at 900 to 1400°C for 2 h. It was found that 10wt%Ni/Al2O3 membrane sintered at 1400°C showed the highest physical and mechanical properties. Thus, this work we focused on the effect of different pressing processes on the properties of Ni/Al2O3 membrane with longer soaking time. Firstly, 10-40wt%Ni and Al2O3 powders were mixed by dried ball-milling. Then, the mixture powder was pressed to form a bar shape by two different processes; uniaxially pressing (No CIP) and uniaxially pressing followed by cold isostatic pressing (CIP) at 250 MPa for 5 min. All Ni/Al2O3 specimens from two pressing routes were sintered at 1400°C for 4h under air atmosphere and reduced at 900 °C under H2 (99.99%). From the results, it was found that the densification process affected to physical and mechanical properties of Ni/Al2O3. The CIPed - 10wt%Ni/Al2O3 membrane sintered at 1400°C for 4 h showed the highest relative density and flexural strength of 76% and 106 MPa with the lowest pore size (78 nm) and 17% porosity. The addition of nickel content gradually decreased physical and mechanical properties of Ni/Al2O3.
Abstract: . La1-xCexCoO3 (x=0, 0.2, and 0.4) perovskite-type mixed oxides using polyvinyl alcohol (PVA) as complexing agent at two molar ratio of metal ion to PVA (1:1 and 1:2) were successfully prepared by sol-gel process. The precursor included lanthanum (II) nitrate hexahydrate, cerium (II) nitrate hexahydrate, and cobalt (II) nitrate hexahydrate where polyvinyl alcohol was added as complexing agent. The suitable condition of Cerium (Ce) substitution and PVA molar ratio were established for further application in hydrocarbon conversion to high value added products. TGA thermogram of as-prepared precursor showed that PVA absolutely decomposed at temperature higher than 500°C. XRD patterns of calcined catalyst showed both LaCoO3 rhombohedral and CeO2 cubic structures that confirmed the formation of mixed crystal structure. Nevertheless, Co3O4 slightly appeared with low peak intensity which came from the oxidation reaction of as-prepared catalyst during calcinations. XRD showed that PVA did not effect to crystal structure of synthesized catalyst. Higher PVA content added in the precursor cause the reduction of crystal growth of catalyst in calcinations step. In contrast, morphology of catalyst is directly related with PVA content such that the spongy and sheet-like structure were formed with increasing PVA content which prevented the agglomeration of particles. The results showed that PVA content play an important role in morphology of perovskite-type mixed oxide catalysts but did not affected to their crystal structures.
Abstract: Recent search for novel thermoelectric materials has revealed a new class of compounds with half-Heusler structure as good candidates for higher performance thermoelectric conversion [1-2], since the structure was first found . The unit cell of the half-Heusler with a space group F4¯ 3m consists of 4 interpenetrating cubic lattices. The crystallographic sites (0,0,0) and (1/4, 1/4, 1/4) are occupied by two different transition metals, the (1/2, 1/2, 1/2) site is occupied by Sn, Sb, or Bi, and the site (3/4, 3/4, 3/4) is empty [4,5]. Candidates with this structure for the investigation would be categorized into the combination of (Ti/Zr/Hf)(Co/Ni/Pt)(Sb/Sn/Bi) [4-6].