Papers by Keyword: Surface Oxides

Abstract: Surface oxides of medium manganese steel treated under different hot-dip galvanizing processes were analyzed by X-ray photoelectron spectroscopy, scanning electron microscope microscopy and energy dispersive spectrometer techniques. Combined with thermodynamic calculation, the effects of dew point and alloying elements on the formation of oxides were investigated. It was shown that many oxides such as Cr₂O₃ and Al₂O₃, which deteriorate galvanizing performance largely, were formed at lower dew point, and that the formation of Cr and Al oxides could be effectively inhibited at higher dew point. It was also shown that the formation of MnO could be controlled by regulating the rate of Al/Mn in the composition of experimental steel, thus reducing the surface defect.

Abstract: Study of microstructure of high Cr-alloyed sintered austenitic stainless steel was performed in few stages XPS analysis of powder surface, theoretical prediction of microstructure by Thermo-Calc and JMatPro software and metallographic observation of sintered material. XPS analysis showed presence of thin iron oxide layer on the surface of powder particles and oxide islands formed by Si, Mn and Cr. Theoretical prediction made by Thermo-Calc and JMatPro calculations showed presence of austenite with chromium carbides and carbonitrides in equilibrium state. Both predictions are in good agreement. Metallographic observation of sintered material showed that microstructure contains small austenitic grains with size of 3-5 μm with fine carbides (1-2 μm) and carbonitrides distributed mostly on grain boundaries. Metallographic study of material confirmed theoretical predictions.

Abstract: The cutting tool material of 9SiCr4 is widely applied in the manufacturing. The paper studied the microstructure and surface oxides on 9SiCr4 by SEM and XRD. through the studying of microstructure, paper find that basal body- Fe is distributed with the lamellar shape on 4-9 μm, and FeC3- called cementite again and Si distributed with small spherical or elliptical particle shape on 0.5-1μm, and Cr distributed with large spherical or elliptical particle shape on 3-5μm and W distributed with large rod shaped on length 1.5μm and width 0.5μm. Moreover, Surface oxides of 9SiCr4 are NaNO3, Na3H (CO3).2H2O, Fe2O3 and Fe3O4.

Abstract: An efficient surface modification technique for fabricating tin dioxide/carbon composite nanotubes has been developed. This technique combines with implantation of acidic groups, interaction between surface oxides and metal ions or hydration molecules, and thermal. To functionalize multi-layered carbon nanotubes (CNTs), gaseous oxidation at 300°C was used to build functional oxygen groups including carboxyl, carbonyl and hydroxyl group, on ends or sidewalls of CNTs. X-ray photoelectron spectroscopy clearly indicated that the atomic ratio of attached tin-oxide on the oxidized CNTs gradually increases with the oxidation level, i.e., surface O/C atomic ratio. This evidence reflected that the surface oxides act as an adsorption center that strongly interacts with metal ions or hydration molecules in aqueous phase.