Modification Behavior of Trace Rare Earth on Impurity Phases in Commercial Purity Aluminum

Modifying effect and mechanism of trace rare earth on Fe(Si) rich impurity phases in commercial purity aluminum were studied with the aids of SEM, EDAX, TEM, etc. It is found that Ce rich mixed rare earth (RE) is an effective modifying agent, which makes the coarse Fe rich impurity phases transform into complex compounds of tiny, sphere/short stick form, thus improving mechanical properties of this material; its modifying mechanism is in that RE gathering in front of solid/liquid interface enters into the impurity phases, forming complex (AlFeSiRE) compounds; or is adsorbed in the impurity phases surface, impeding the growth of impurity phases; however, excessive RE will result in the increasing of RE compounds (secondary phases), and plasticity reduction of this material. Therefore, its addition amount should be less than 0 07% (mass fraction).

Influence of Impurities of Zircon Sand on the Microstructure of Fused Zirconia Grains for Continuous Casting of Steel Refractories

Certain impurities of zircon sands, especially alumina, titania, calcia and yttria cannot be completely re- moved in the production of fused zirconia and may have an influence on the corrosion resistance and other product properties of refractories for continuous casting of steel. In this paper, we present our findings on how impurities in raw materials end up in different stabilised zirconia refractory grains, in particular calcia-, magnesia- and yttria-stabilised zirconia. The microstructure （and phase composition） is affected by both the raw materials and the fusion conditions （furnace type and cooling technology）.

Structural evolution of layered oxide cathodes for spent Li-ion batteries:Degradation mechanism and repair strategy

Sustainable development has long been recognized as one of the most critical issues in today’s energy and environment-conscious society.It has never been more urgent to recycle and reuse the end-of-life cathode materials.Here,this work systematically investigates the structure-critical degradation mechanism of polycrystalline LiNi_(x)Co_(y)Mn_(1−x−y)O_(2)(NCM),combining experimental characterization and DFT simulations.Targeting the key degradation factors,a synergistic repair strategy based on deep mechanochemical activation and heat treatment was successfully proposed to direct regenerate the degradedNCMmaterial.Studies indicate the induction and promotion of synergistic repair technique on the reconstruction of particlemorphology,the recovery of the chemical composition and crystal structure,and the favorable transformation of the impurities phase in the failed materials.In particular,the synergistic repair process induces a gradient distribution of LiF and further enables partial fluorine doping into the NCM surface,forming abundant oxygen vacancies and increasing the content of highly reactive Ni2+.Benefiting from the comprehensive treatment for the multi-scale and multi-form degradation behaviors,the repaired material exhibits a capacity of 176.8 mA h g^(-1)at 0.1 C,which is comparable to the corresponding commercial material(172.8 mA h g^(-1)).The satisfactory capacity of the recovered cathode proves that it is an effective direct renovating strategy.

Thermal stability of LiFePO_4/C-LiMn_2O_4 blended cathode materials

Safety is important to lithium ion battery materials. The thermal stability of LiFePOa/C-LiMn204 blended cathode materials is characterized by using TG, XRD, and SEM etc. The results show that LiFePO4/C-LiMn2O4 possesses a worse thermal stability than pure spinel LiMn2O4 and pure olivine LiFePO4/C. When LiFePO4/C-LiMn2O4 blended cathode materials are sintered at 500℃ under Ar atmosphere, the sintered cathode materials emit O2, and appear impurity phases （Li3PO4, Fe2O3, Mn3O4）. It is deduced that some chemical reactions take place between different materials, which leads to a worse discharge specific capacity. LiFePO4/C-LiMn2O4 blended cathode materials, therefore, need to be managed and controlled strictly for the sake of ther- mal stability and safety.