Numerical investigation on thermomechanical behavior of alumina–calcium hexaluminate refractories for purging plug

Alumina–spinel refractories used in slit-type purging plugs are susceptible to cross-sectional damage,resulting in a serious mismatch between their service life and that of ladle.Alumina–calcium hexaluminate refractories have gradually become the new trend in purging plug materials with the development of refining technology.The thermomechanical damage of slit-type purging plugs with alumina–calcium hexaluminate refractory was investigated by the thermo-solid coupling simulation.Combined with the polynomial fitting and design of experiments methods,the influence of thermophysical parameters on temperature and thermal stress of alumina–calcium hexaluminate refractories for purging plugs was systematically analyzed.The results show that the maximum thermal stress of the purging plugs appears during the stages of steel transporting and stirring,and the vulnerable parts are located above Y=0.323 m.The thermal conductivity and the coefficient of thermal expansion of the material are the most sensitive parameters to the temperature and thermal stress inside the structure,respectively.The addition of more calcium hexaluminate can relieve the stress concentration and large deformation around the slits.Consequently,when the content of calcium hexaluminate is 47 wt.%and in the form of aggregate-binder,the temperature and thermal stress distribution inside the refractory are optimal,which can effectively improve the service life of the slit-type purging plug.

A facile method to fabricate high-quality perovskite nanocrystals based on single crystal powder

Although great advancements have been successfully achieved in ligand-assisted reprecipitation strategy(LARP)towards lead halide perovskite nano crystals(NCs)syn thesis,it still remains challe nging to develop bright and stable iodide-based perovskite NC via facile LARP.Herein,striki ngly bright MAPbl3 NCs with photoluminesce nee qua ntum yield(PLQY)as high as 79%are synthesized via replacing the raw material(MAI and Pbh)with MAPbl3 crystal powder during LARP procedure.It has been found that crystal powder derived MAPbl3 NCs are more iodide-rich compared with that based on raw material,which is favorable to passivate the surface trap state.Accordingly,femtosecond transient absorption spectroscopies and space charge limited current measurements have corroborated that the trap density is much less in crystal powder resulted MAPbl3 NCs.Further analyses indicate stronger solvation with reduced precursor colloid size has been observed in crystal powder derived precursor solution probably due to the formation of MAPbl3-DMF.This work has provided a facile but valid method to enhance the photoluminesce nee of perovskite NC via modulati ng the beginning precursor solution.

A core-shell catalyst design boosts the performance of photothermal reverse water gas shift catalysis

Photothermal reverse water gas shift(RWGS)catalysis holds promise for efficient conversions of greenhouse gas CO_(2) and renewable H_(2),powered solely by sunlight,into CO,an important feedstock for the chemical industry.However,the performance of photothermal RWGS catalysis over existing supported catalysts is limited by the balance between the catalyst loading and dispersity,as well as stability against sintering.Herein,we report a core-shell strategy for the design of photothermal catalysts,by using Ni1_(2)P_(5) as an example,with simultaneously strong light absorption ability,high dispersity and stability.The core-shell structured Ni1_(2)P_(5)@SiO_(2) catalyst with a relatively small Ni1_(2)P_(5) particle size of 15 nm at a high Ni1_(2)P_(5) loading of 30 wt%exhibits improved activity,nearly 100%CO selectivity,and superior stability in photothermal RWGS catalysis,particularly under intense illuminations.Our study clearly reveals the effectiveness of the core-shell strategy in breaking the limitation of supported catalysts and boosting the performance of photothermal CO_(2) catalysis.