Study on Preparation and Properties of PVC Film Modified by Rare Ea rth

The transparent PVC films were prepared by tape casting. In the process of prepa ration, rare earth nitrate, as a kind of modifier, was added to th e solution of PVC and THF. These PVC films were tested after being crosslinked b y ultraviolet light. It is found that the mechanical and physical properties of all the PVC films modified by rare earth nitrate are greatly enhanced.

On the modification of hypereutectic Al-Si alloys using rare earth Er

Hypereutectic Al-17.5Si （wt pct） and Al-25Si （wt pct） alloys with various content of rare earth Er were prepared by conventional casting technique. The effect of Er on the microstructure and properties of the hypereutectic Al-Si alloys was investigated using optical microscopy, scanning electron microscopy as well as friction and wear tests. It was found that optimal amount of Er exists in modifying the hypereutectic Al-Si alloys. An appropriate addition of Er improved the anti-wear properties, and reduced the friction coefficient of the hypereutectic Al-Si alloys studied. The primary silicon crystals in the hypereutectic Al-Si alloys were refined with the suitable addition of Er element. The modification mechanism was also discussed in this paper.

Rare earth modified Ni-Si catalysts for hydrogen production from methane decomposition

Different rare earth （RE=La, Ce, Pr, Nd, Sm, Y） and Cu modified nickel catalysts for hydrogen production from meth-ane decomposition were synthesized by a sol-gel process and method. The catalysts were characterized or analyzed through Brumauer-Emmett-Teller （BET）, X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM） techniques. And the hydrogen production performance was also evaluated by a fixed-bed and micro-reaction technique with CH4→C＋H2 as a probe reaction. The results showed that rare earth modification had played a great role for nickel catalysts, for example, smaller nickel particles, good thermal stability, high activity, etc. La was the best additive among rare earth modification. The SEM of rare earth modified catalysts showed ordered flower-like structure and rare earth modification made the nickel particles move to the surface of catalysts. In addition, the SEM of nano-carbons was also changed by rare earth modification with long, narrow nano-carbon fibers or tubes obtained. Solid carbon formation was prevented by rare earth modification.

Study on Cerium Oxide Modified Natural Rubber

The action of CeO2powders in natural rubber was studied. The effects of particle size, content and surface modification of CeO2powders on the properties of natural rubber was discussed. The results showed that the scorch and curing time of rubber decreased, the physic mechanical properties and aging resistance of natural rubber vulcanizates enhanced after filled with CeO2powders. Especially tear strength and abrasion resistance increased much, and was raised 25% and 20% respectively. The surface of modified CeO2powders had hydrophobic organize layer which could increase interface cohesion with the rubber and dispersity in rubber resulting in exerting reinforcement effect. The modified CeO2powders improve the physic mechanical properties of rubber much compared with the unmodified CeO2powders.

Cu-Mn catalysts modified by rare earth lantnaum for low temperature water-gas shift reaction

The Cu-Mn catalysts doped with different amounts of lanthanum（La） for water-gas shift reaction（WGSR） were prepared, and characterized by X-ray diffraction（XRD）, temperature-programmed reduction（TPR）, temperature-programmed reduction of oxidized surfaces（s-TPR）, temperature-programmed desorption of CO_2（CO_2-TPD）, infrared spectrum（FT-IR） and X-ray photoelectron spectroscopy（XPS）. Catalytic activities were tested for a water-gas shift reaction. The results showed that the introduction of 0.5 mol.% La could significantly improve the catalyst activity for low-temperature shift reaction compared with the undoped catalyst, which might be from the introduction of La making the Cu and Mn components distribute uniformly and the synergistic effect between Cu and Mn increasing the dispersion of Cu on the surface of the catalyst. The apparent CuO phases besides Cu_（1.5）Mn_（1.5）O_4 were found in the samples with at least 3.0 mol.% La content, and the basic sites increased with the increasing of La contents at a decreased rate. With excessive La doping, La particles would aggregate and cover some active sites, resulting in that Mn could not effectively inhibit the gathering together and growing up of Cu crystalline grain, and decreased the dispersion of Cu on the surface, which resulted in the poor activity of the catalyst for WGSR.

Effect of combinative addition of mischmetal and titanium on the microstructure and mechanical properties of hypoeutectic Al-Si alloys used for brazing and/or welding consumables

Effects of mischmetal（RE） and/or Ti modifier on the microstructure including α-Al dendrites, eutectic Si phases and other secondary phases of Al-Si brazing and/or welding alloys were investigated by differential scanning calorimetry（DSC）, optical microscopy（OM）, scanning electron microscopy（SEM）. The DSC results showed that an addition of RE decreased the eutectic temperature and caused supercooling, promoting the nucleation of eutectic Si crystals. In addition, the maximum temperature of the first endothermic peak varied with the different RE contents, which had a good correlation with the microstructural modification of the eutectic Si phase. The α-Al dendrites were well refined by increasing the cooling rate or adding 0.08 wt.% of Ti. When 0.05 wt.% RE was added to the Al-5Si-0.08 Ti alloy, the morphology of eutectic Si phase was transformed from coarse platelet to fine fibers and the mechanical properties of the resulting welding rod were well improved. Whereas, when excess RE was added, a large number of β-Fe phases appeared and the aspect ratios of β-Fe phases increased. The morphologies and chemical components of two kinds of RE-containing intermetallic compounds（IMCs） were also discussed.

Surface characteristics of Y3Al5O12：Ce^3＋ phosphor with greatly enhanced photoluminescence after chemical defect-selective etching

The surface of a commercial Y3Al5O12：Ce^3＋ phosphor was modified by 99% NH_4F＋CH_3COOH solution in a supersonic bath with water temperature of 80 oC for 4 h. The scanning electron microscopy（SEM） results showed that the edge angles were not as sharp as the unmodified particles and the flat surfaces turned rough with many micro-structures covered. Positron lifetime measurements quantitatively showed that surface defects were removed away by more than 50%. As a result, the photoluminescence determinations showed that the backscatter loss was reduced by 4.2% and the emission power was enhanced by 5.6% after the surface modification. The conversion efficiency was greatly improved from 47.3% to 51.1%, as presented by the fluorescence images. Therefore, it would be greatly helpful for the improvement of efficiency, transparency and stability of pc-LED. Moreover, this method was significantly suitable for mass production due to its easy operation and low cost.

Cerium based shells with palladium cores encapsulated:an efficient catalyst for carbon monoxide oxidation

Pd@Zr/Ce O2 core-shell catalyst prepared by hydrothermal method was applied in CO oxidation reaction, exhibiting high CO oxidation activity at low temperature.XRD（X-ray diffraction） analysis demonstrated that the remarkable enhancement of catalytic performance was found to depend on the presence of more oxygen vacancies in the core-shell structure, which contributed higher content of and ready release of active oxygen species at low temperature, confirmed by H2-TPR（temperature programed reduction） results.Interestingly, introducing a small amount of zirconium（0.5 wt.%） exhibited a significant improvement of catalytic activity because the introduction of Zr further improved the amount of crystal defects and promoted the migration of oxygen species.