Development of Microarc Oxidation/Sputter CeO2 Duplex Ceramic Anti-Corrosion Coating for AZ31B Mg Alloy.

A duplex CeO2/MAO coating was deposited on AZ31B magnesium alloy through microarc oxidation and reactive radio frequency magnetron sputtering. The microstructure and chemical composition of the proposed coating were investigated through scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The CeO2/MAO coating was approximately 580 nm in thickness and showed fewer micropores and defects than those the MAO coating presented. The properties of corrosion resistance were assessed using the polarization test, electrochemical impedance spectroscopy, and the neutral salt spray test. The CeO2/MAO duplex coating had the lowest corrosion current density of 3.25×10-9 A/cm² and the highest polar resistance, approximately four orders of magnitude higher than that of the uncoated sample. Electrochemical measurements suggested that CeO2 coating can serve as a strong physical barrier between the corrosion medium and the Mg alloy.

Effect of Al Content on Microstructure and Mechanical Property of Nanocomposite TiAlSiN Thin Films.

TiAlSiN thin films exhibit high hardness due to the multicomponent and multiphase structures. Effects of Si on TiAlSiN microstructure and mechanical properties have been well studied. However, there is insufficient information on the effects of Al. Thus, in this work, Al-contained nanocomposite nc-TiN/a-SiNx thin films with Al up to 10 at.% were prepared by magnetron co-sputtering Ti, Al and Si3N4 targets in Ar/N2 gas atmosphere. The effects of Al on TiAlSiN microstructure and mechanical property were well studied. Adjusting Al/(Ti+Al) target power ratio tuned chemical composition, microstructure and consequently mechanical properties. With increase of Al/(Ti+Al) target power ratio from 0 to 0.2, Al content increased from 0 to 10 at.%. X-ray photoelectron spectroscope results showed that aluminum nitride was formed. X-ray diffraction results confirmed that the nanocrystalline phase TiN was with Si and Al in its structure, or (Ti, Al, Si) N. The matrix was amorphous silicon nitride containing aluminum nitride. Nanoindentation hardness of the thin films remained at about 28 GPa till Al addition was increased to 3.1 at.%.

Effects of CeO² on Microstructure and Corrosion Performance of the Coatings Prepared by Pulse Micro Arc Oxidation on AZ31B Mg Alloy.

To improve corrosion performance of coatings on AZ31B magnesium alloy, the nano-CeO² additives were included in Na²SiO³ based electrolyte during process of pulse micro arc oxidation (MAO). The MAO-CeO² coating was successfully prepared to characterize its structure, micro morphology and composition. The XRD results indicated that MAO-CeO² coatings were consisted of Mg²SiO4, MgSiO³, MgF² and CeO². The intensity of CeO² peaks increases with increasing nano-CeO² particles in electrolyte. The number of cracks on MAO-CeO² coatings exhibited a V-shaped trend with increase in nano-CeO² content. Meanwhile, the influence of nano-CeO² on corrosion behavior of MAO-CeO² coatings is investigated by salt spray test and electrochemical measurement. The corrosion current density of coatings presented same trend and corrosion potential is further studied. The MAO-CeO² coatings formed in electrolyte with 10 g/L nano-CeO² showed best corrosion performance which has the lowest corrosion current density of 0.58 nA/cm² and the highest corrosion potential of - 1269 mVSCE.

ZIF-67-Derived CoSe/NC Composites as Anode Materials for Lithium-Ion Batteries.

As a typical metal selenide, CoSe is a kind of foreground anode material for lithium-ion batteries (LIBs) because of its two-dimensional layer structure, good electrical conductivity, and high theoretical capacity. In this work, the original CoSe/N-doped carbon (CoSe/NC) composites were synthesized using ZIF-67 as a precursor, in which the CoSe nanoparticles are encapsulated in NC nanolayers and they are connected through C-Se bonds. The coating structure and strong chemical coupling make the NC nanolayers could better effectively enhance the lithium storage properties of CoSe/NC composites. As a consequence, the CoSe/NC composites deliver a reversible capacity of 310.11 mAh g-1 after 500 cycles at 1.0 A g-1. Besides, the CoSe/NC composites show a distinct incremental behavior of capacity.

Application of tetrahydrofuran dispersant in microemulsion for fabricating titania mesoporous thin film.

A new strategy was used to fabricate titania mesoporous thin film by incorporating tetrahydrofuran (THF) into the CTAB/n-butyl alcohol/cyclohexane/water reverse microemulsion as a micelle disperser. Highly dispersed and congregated TiO(2) particles in the microemulsion with and without THF were observed by transmission electron microscopy (TEM), respectively. The photographs observed by field-emission scanning electron microscopy (FE-SEM) show that a uniform titania mesoporous thin film with monodisperse TiO(2) spherical nanoparticles of ca. 20 nm was obtained using the microemulsion with THF.

[Determination of UV-Vis reflective spectra of long after-glow phosphorescent material].

The long after-glow phosphorescent materials were fabricated by using "wet" method. The component materials were dissolved in water solution so that their homogeneous mix was reached at molecular level. The approach that metal nitrates and organic reductants would react spontaneously and get into combustion at a moderately low ambient temperature through oxido-reduction reaction was introduced into our fabrication of long after-glow phosphorescent samples. The ambient temperature to generate the combustion could go down to 500 degrees C, and the reaction completed within 1-2 minutes, producing a fluffy resultant with small crystal structure and even composition, which is easy to grind, and with low bulk density for its powder. UV-Vis reflective spectrophotometer was used to determine and analyze the characteristics of the sample before and after its absorption of light. The result shows that the properties of the samples fabricated from both "wet" and "dry" techniques are similar except their bulk densities, and the UV-Vis reflective spectrum was able to clearly describe the spectral characteristics of long after-glow phosphorescent materials.