Calcium aluminate cement(CAC)is widely used as a binder for refractory materials,and thus the improvement in compressive strength is of vital importance for CAC applied at high temperature.For this purpose,nano-Ca_(10...Calcium aluminate cement(CAC)is widely used as a binder for refractory materials,and thus the improvement in compressive strength is of vital importance for CAC applied at high temperature.For this purpose,nano-Ca_(10)(PO_(4))_(6)(OH)_(2)additive with a ratio of 0.5–1.5 mass%was added with the water-cement ratio to be 0.4.X-ray diffraction and isothermal calorimetry analysis demonstrate that nano-Ca_(10)(PO_(4))_(6)(OH)_(2)additive can shorten the hydration process and promote the formation of main hydrates of CaAl2O4·10H2O(CAH10)and Ca2Al2O5·8H2O(C2AH8).In addition,scanning electron microscopy results suggest that nano-Ca_(10)(PO_(4))_(6)(OH)_(2)can protect CAH10 and C2AH8 from being destroyed during the calcination,guaranteeing that these thin lamellar crystals are intertwined to form the denser microstructure.Benefited from above effects,nano-Ca_(10)(PO_(4))_(6)(OH)_(2)can obviously improve the compressive strength of the CAC mortar samples cured for 7 d after calcination at 1100°C,while the improving effect is dependent upon its contents.Especially,compared with the one without the additive,the compressive strength of the sample with 1.0%nano-Ca_(10)(PO_(4))_(6)(OH)_(2)is increased by 14%.展开更多
Zn(CF_(3)SO_(3))_(2)as an electrolyte has been widely used to improve the electrochemical performance for ZIBs due to that the bulky CF_(3)SO_(3)-can reduce the solvation effect of Zn^(2+)and promote the ionic diffusi...Zn(CF_(3)SO_(3))_(2)as an electrolyte has been widely used to improve the electrochemical performance for ZIBs due to that the bulky CF_(3)SO_(3)-can reduce the solvation effect of Zn^(2+)and promote the ionic diffusion.Herein,we found that Zn(CF_(3)SO_(3))_(2)electrolyte can induce different electrochemical mechanisms from ZnSO_(4)electrolyte.Compared to the ZnSO^(4)electrolyte,the HNaV_(6)O_(16)·4H2_(O)electrode with Zn(CF_(3)SO_(3))_(2)electrolyte exhibits a high capacity of 444 mAh·g^(-1)at 500 mA·g^(-1)with a capacity retention of 92.3%after 80 cycles.Even,at a high rate of 5 Ag-1,the HNaV_(6)O_(16)·4H_(2)O electrode delivers an initial discharge capacity of 328 mAh·g^(-1)with a capacity retention of 93.7%after 1000 cycles.Differing from the mechanism with ZnSO4 electrolyte,the excellent cycle stability of HNaV_(6)O_(16)·4H_(2)Oelectrode can be attributed to the in-situ phase transformation to ZnxV_(2)O_(5)·nH_(2)O based on the co-intercalation of Zn^(2+)/H^(+).展开更多
基金The authors express their appreciation to the National Natural Science Foundation of China(Nos.51904021 and 51974021)the Fundamental Research Funds for the Central Universities(Nos.FRF-TP-19-008A1 and FRF-TP-19-004B2Z)+1 种基金China Postdoctoral Science Foundation(2019M660458 and 2020T130052)Beijing Excellent Talents Foundation for financial support.
文摘Calcium aluminate cement(CAC)is widely used as a binder for refractory materials,and thus the improvement in compressive strength is of vital importance for CAC applied at high temperature.For this purpose,nano-Ca_(10)(PO_(4))_(6)(OH)_(2)additive with a ratio of 0.5–1.5 mass%was added with the water-cement ratio to be 0.4.X-ray diffraction and isothermal calorimetry analysis demonstrate that nano-Ca_(10)(PO_(4))_(6)(OH)_(2)additive can shorten the hydration process and promote the formation of main hydrates of CaAl2O4·10H2O(CAH10)and Ca2Al2O5·8H2O(C2AH8).In addition,scanning electron microscopy results suggest that nano-Ca_(10)(PO_(4))_(6)(OH)_(2)can protect CAH10 and C2AH8 from being destroyed during the calcination,guaranteeing that these thin lamellar crystals are intertwined to form the denser microstructure.Benefited from above effects,nano-Ca_(10)(PO_(4))_(6)(OH)_(2)can obviously improve the compressive strength of the CAC mortar samples cured for 7 d after calcination at 1100°C,while the improving effect is dependent upon its contents.Especially,compared with the one without the additive,the compressive strength of the sample with 1.0%nano-Ca_(10)(PO_(4))_(6)(OH)_(2)is increased by 14%.
基金This study was financially supported by the National Natural Science Foundation of China(No.51772193)China Postdoctral Science Foundation(No.2019T250254).
文摘Zn(CF_(3)SO_(3))_(2)as an electrolyte has been widely used to improve the electrochemical performance for ZIBs due to that the bulky CF_(3)SO_(3)-can reduce the solvation effect of Zn^(2+)and promote the ionic diffusion.Herein,we found that Zn(CF_(3)SO_(3))_(2)electrolyte can induce different electrochemical mechanisms from ZnSO_(4)electrolyte.Compared to the ZnSO^(4)electrolyte,the HNaV_(6)O_(16)·4H2_(O)electrode with Zn(CF_(3)SO_(3))_(2)electrolyte exhibits a high capacity of 444 mAh·g^(-1)at 500 mA·g^(-1)with a capacity retention of 92.3%after 80 cycles.Even,at a high rate of 5 Ag-1,the HNaV_(6)O_(16)·4H_(2)O electrode delivers an initial discharge capacity of 328 mAh·g^(-1)with a capacity retention of 93.7%after 1000 cycles.Differing from the mechanism with ZnSO4 electrolyte,the excellent cycle stability of HNaV_(6)O_(16)·4H_(2)Oelectrode can be attributed to the in-situ phase transformation to ZnxV_(2)O_(5)·nH_(2)O based on the co-intercalation of Zn^(2+)/H^(+).
