Equipped With Energy Dispersive Spectroscopy Research Articles

Reaction Mechanisms and Tensile Properties of the Composites Fabricated by Al-B2O3 System

The aluminum matrix composites (AlB2+α-Al2O3)/Al were fabricated by in situ reaction synthesis from an Al-B2O3 system. The reaction pathways, apparent activation energies and tensile properties were analyzed by using differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), and equipped energy dispersive spectroscopy (EDS). The results showed that there are two-step reactions in the Al-B2O3 system. The first-step is 15Al+7B2O3→7α-Al2O3+AlB12+2B and the second-step is 2B+AlB12+6Al→7AlB2. Their corresponding apparent activation energies are 352 and 444 kJ/mol, respectively. The tensile strength and elongation rate of the composites are 190.5 MPa and 6.6%, respectively.Compared with ordinary aluminum base material, the performance is superior. There are many dimple and cracked α-Al2O3 reinforcements in tensile fracture surface layer.

Effect of MnO on Mineral Composition of CaO-SiO<sub>2</sub>-MgO-Al<sub>2</sub>O<sub>3</sub>-Cr<sub>2</sub>O<sub>3</sub> System

The chromium leaching from stainless steel slag highly depends on the occurrence of chromium. The effect of MnO on the mineral composition of stainless steel slag was investigated through CaO-SiO2-MgO-Al2O3-Cr2O3 synthetic slags. The experiments were performed in a conductive furnace, and the samples collected during tests were analyzed using X-ray Diffrac-tion (XRD) and Scanning Electron Microscope (SEM) equipped Energy Dispersive Spectroscopy (EDS). The results show that the addition of MnO significantly reduces the solidus temperature of oxide systems from 1204oC to 950oC, promotes the spinel precipitation and increases the size of spinel crystals. The fraction of chromium contained in non-spinel mineral phases decreases and the amount of larnite dissolved into spinel phase slightly reduces with the content of MnO increasing. In addition, the amorphous phase forms when the content of MnO is up to 6 wt%. Hence, the addition of MnO is beneficial to suppress chromium leaching from slag.

Synthesis and characterization of LiCo1/3Mn1/3Fe1/3PO4/C nanocomposite cathode of lithium batteries with high rate performance

Olivine structured LiCo1/3Mn1/3Fe1/3PO4/C nanocomposites were prepared by a combination of spray pyrolysis at 300 °C and wet ball-milling followed by heat treatment at 500 °C for 4 h in a 3%H2 + N2 atmosphere. The formation of a solid solution between LiCoPO4, LiMnPO4, and LiFePO4 at this composition was confirmed by X-ray diffraction analysis. Scanning electron microscopy and transmission electron microscopy with equipped energy dispersive spectroscopy verified that the LiCo1/3Mn1/3Fe1/3PO4/C nanocomposites were agglomerates of LiCo1/3Mn1/3Fe1/3PO4 primary particles with a geometric mean diameter of 107 nm and a uniform chemical composition, and carbon was well distributed on the surface of the agglomerates. The LiCo1/3Mn1/3Fe1/3PO4/C nanocomposite cathode exhibited a high discharge capacity of 159 mAh g−1 at 0.05 C in the potential range of 2.0–5.0 V, corresponding to 94% of theoretical capacity. The capacity retention was 87% after 50 cycles at a charge–discharge rate of 1 C. Furthermore, the rate capability test showed that the high capacity still was retained even at 5 C and 20 C rate with 106 and 72 mAh g−1, respectively.

Preparation of LiCoPO 4/C nanocomposite cathode of lithium batteries with high rate performance

LiCoPO 4/C nanocomposites could be successfully prepared by a combination of spray pyrolysis and wet ball-milling followed by heat treatment. X-ray diffraction analysis confirmed that the LiCoPO 4/C nanocomposites were well crystallized in an orthorhombic structure with Pmna space group. Scanning electron microscopy and transmission electron microscopy with equipped energy dispersive spectroscopy verified that the LiCoPO 4/C nanocomposites were the agglomerates of LiCoPO 4 primary particles with a geometric mean diameter of 87 nm, and the carbon was well distributed on the surface of the agglomerates. The LiCoPO 4/C nanocomposites were used as cathode active materials for lithium batteries, and the electrochemical tests were carried out for the cell Li|1 M LiPF 6 in EC:DMC = 1:1|LiCoPO 4/C at various charge–discharge rates. The cells delivered first discharge capacities of 142 and 109 mAh g −1 at 0.05 and 20 C, respectively. Furthermore, the discharge capacity after 40 cycles corresponded to 87% of initial one at 0.1 C rate. The excellent rate capability of the cells is mainly due to the well distributed carbon on the LiCoPO 4 agglomerates, and a much smaller lithium ion diffusion distance in the electrode.

Effect of Pretreatment Conditions on Particle Size of Bimetallic Pt–Au Catalysts Supported on ZnO/Al<SUB>2</SUB>O<SUB>3</SUB> and Its Activity for Toluene Oxidation

Bimetallic Pt-Au catalysts supported on ZnO/Al2O3 were prepared by incipient wetness impregnation (IW-IMP) method with different pretreatment conditions such as flow velocity, calcination temperature, and heating rate under H2 during the calcination procedure, and characterized by X-ray diffraction (XRD), CO chemisorption, and scanning transmission electron microscopy (STEM) equipped energy dispersive spectroscopy (EDS). Furthermore, catalytic activity for complete oxidation of toluene was measured using a flow reactor under atmospheric pressure. Finally, relationship between the particle sizes with pretreatment conditions and catalytic activity for toluene on the bimetallic Pt-Au catalysts was discussed. In these results, nanosized bimetallic Pt-Au particles on ZnO/Al2O3 could be prepared by IW-IMP method. Relationship between the Pt and Au particle size and activity for toluene oxidation was clearly observed.

Effect of La2O3 on microstructure, mechanical and tribological properties of Ni-W coatings

In this paper, a Ni-W-La2O3 composite coating was prepared by the electrodeposition method. Microhardness tester and environmental scanning electron microscope equipped energy dispersive spectroscopy were employed to investigate the microhardness and the surface morphology of the composite coatings respectively, and the high temperature friction behavior and corrosion resistance of the coatings against molten glass were investigated by using a high temperature tribometer. The results show that La2O3 can refine the microstructure effectively, and make the element distribution uniform, which leads to the increase of average microhardness. La2O3 particulates can reduce the friction coefficient between the composite coating and glass during the sliding process at about 973 K largely, and the corrosion resistance of the La2O3 added Ni-W coatings is effectively improved compared with that of the non-added one, furthermore the mechanism of friction-reducing and anti-corrosion is also discussed.

Preparation and characterization of the bimetallic Pt–Au/ZnO/Al 2O 3 catalysts: Influence of Pt–Au molar ratio on the catalytic activity for toluene oxidation

The bimetallic Pt–Au catalysts supported on ZnO/Al 2O 3 with different Pt/Au molar ratios were prepared by impregnation (IMP) method using a mixed solution of Pt and Au precursor. These were characterized by X-ray diffraction (XRD), CO chemisorption, temperature programmed reduction (TPR), and transmission electron microscopy (TEM) equipped energy dispersive spectroscopy (EDS). Catalytic activity for complete oxidation of toluene was measured using a flow reactor under atmospheric pressure. In the results, the aggregation of Au particles depended on the molar ratio in the bimetallic Pt–Au catalyst, and Pt particles was well dispersed homogeneously even by the IMP method. The Pt 75Au 25 and Pt 67Au 33 catalysts concurrently coated with Pt and Au precursors by IMP method showed higher activity than monometallic Pt and Au catalyst for toluene oxidation. Also, in order of the catalytic activity for toluene was very good agreement compare with the TPR results. The Au particles might promote the toluene oxidation over the bimetallic catalyst concurrently coated with Pt and Au particles. Therefore, the size of Pt and Au particles and catalytic activity were confirmed to be correlated to molar ratio of Pt and Au loaded.

Tribological and anti-corrosion properties of Ni–W–CeO 2 coatings against molten glass

Composite plating was used to prepare Ni–W infused rare earth oxide CeO 2 composite coatings. The high temperature friction behavior and corrosion resistance of the coatings against molten glass were investigated by using a high temperature tribometer. A microhardness tester and an environmental scanning electron microscope equipped energy dispersive spectroscopy were employed to investigate the microhardness and the surface morphology of the composite coatings respectively. The results show that the brittle fracture, high temperature tribological properties and the corrosion resistance of Ni–W infused CeO 2 coatings are superior to those of a standard Ni–W coating. CeO 2 particles decrease the friction coefficient from nearly 0.5 to about 0.25 during the composite coatings sliding against the molten glass at about 973 K, and proper quantities of CeO 2 decrease the variation of the friction coefficient value. Furthermore, CeO 2 can improve the corrosion resistance of the Ni–W coatings at high temperature effectively.