Magnesium oxysulfate （MgSO4·5Mg（OH）2·2H2O） flake powders with an average diameter of 2 ~tm and a thickness of 0.052 μm were prepared using magnesium sulfate and sodium hydroxide as raw materials by hydr...Magnesium oxysulfate （MgSO4·5Mg（OH）2·2H2O） flake powders with an average diameter of 2 ~tm and a thickness of 0.052 μm were prepared using magnesium sulfate and sodium hydroxide as raw materials by hydrothermal synthesis process. The composition, morphology and structural features of the hydrothermal products were examined with X-ray powder diffraction （XRD）, scanning electron microscopy （SEM） and Fourier transform infrared spectroscopy （FTIR）. The experimental results indicate that in the conditions of n（NaOH）/n（MgSO4） of 1.25, the dosage of w（Na3PO4） crystal additives of 1.0% w（MgSO4）, stirring for 5 h at 180 ℃, the morphology of MgSO4·5Mg（OH）2·2H2O products is flaky and laminar, which is a kind of complex magnesium singlecrystal. The recycling of MgSO4 mother liquor was also investigated to make a full use of the materials and reduce disposal. The results prove that there is no adverse effect on the yield and purity of the products.展开更多
A series of dynamic behavior tests on Nanjing flake-shaped fine sand were performed by using the WFI cyclic triaxial apparatus made in England. The dynamic behaviors of Nanjing flake-shaped fine sand under different s...A series of dynamic behavior tests on Nanjing flake-shaped fine sand were performed by using the WFI cyclic triaxial apparatus made in England. The dynamic behaviors of Nanjing flake-shaped fine sand under different static deviator stress levels and cyclic stress ratios were studied. Through comparing the effective stress path under cyclic loading with static loading, the processes of liquefaction of saturated Nanjing flake-shaped fine sand with development of dynamic pore-water pressure, including the initial compact state, compression state and dilative state, were investigated. The variation of the shear stiffness with the number of cycles and cyclic strain was investigated by analyzing the secant shear modulus in each unload-reload loop of dynamic stress-strain relationship. And by means of the exponential function, the empirical equations of the relationship between secant shear modulus Gsec, shear modulus ratio Gsec/Gmax and cyclic strain ε were established based on series of test results. The results show that according to different combinations of static deviator stress and cyclic stress, two kinds of failure patterns with deviator stress reversal or no deviator stress reversal are observed in the samples tested in this series, including cyclic mobility and the failure of accumulation residual strain. In addition, the degradation of dynamic shear modulus is due to the development of vibration pore-water pressure and it is observed that the shear modulus reduces with the progressive number of cycles.展开更多
To achieve aluminum particles with ultrafine granularity and high reactivity,the mechanical ball-milling method was adopted and three kinds of coatings,including stearic acid(SA),viton and dinitrotoluene(DNT),were add...To achieve aluminum particles with ultrafine granularity and high reactivity,the mechanical ball-milling method was adopted and three kinds of coatings,including stearic acid(SA),viton and dinitrotoluene(DNT),were added.The effects of milling time and different coatings on granularity and reactivity of ultrafine aluminum particles were studied.The structures of prepared ultrafine aluminum were characterized by scanning electron microscopy,X-ray particle diffraction and the thermal properties were analyzed by TG/DSC.Besides,the reactivity of prepared ultrafine aluminum particles was comprehensively analyzed and judged according to several thermodynamic parameters,the maximal oxidation rate,the oxidation degree of aluminum and the enthalpy change.The results revealed that aluminum particles prepared by the mechanical ball milling method were all flake-like and the particle sizes were below5 mm with nanometer-scale thickness.And the crystal form of aluminum was found to be unchanged.Besides,the ultrafine flake aluminum coated with stearic acid after milling for 5 h showed the highest reactivity with 56.1% of oxidation degree before 660℃,0.945 mg/℃ of maximal oxidation rate and 20491 J/g of enthalpy change.展开更多
Magnesium potassium phosphate cement(MKPC)coatings exhibit potential for carbon steel protection but face challenges in practical application due to the preparation process and properties.This study develops flake gra...Magnesium potassium phosphate cement(MKPC)coatings exhibit potential for carbon steel protection but face challenges in practical application due to the preparation process and properties.This study develops flake graphite(FG)-modified MKPC coatings via spraying process,investigating the effects of FG size and dosage on phase composition,microstructure,mechanical properties,corrosion protection,and thermal conductivity.Results show that a low FG dosage(5 wt%)synergistically optimizes multifunctional performance.Compared to unmodified MKPC,FG2-1 exhibited exceptional impact resistance,associated with a 57%reduction in corrosion current density(icorr),a 356.3% increase in low-frequency impedance modulus(Z_(0.01 Hz))and a 37% increase in thermal conductivity.However,the coating with a high FG dosage(15 wt%)degraded performance due to defect accumulation and reduced crystallinity of KMgPO_(4)·6H_(2)O.This work advances the rational design of multifunctional inorganic coatings for extreme service environments requiring coupled corrosion protection and thermal management.展开更多
基金Project(50704036) supported by the National Natural Science Foundation of ChinaProject(08JJ3027) supported by the Natural Science Foundation of Hunan Province, China
文摘Magnesium oxysulfate （MgSO4·5Mg（OH）2·2H2O） flake powders with an average diameter of 2 ~tm and a thickness of 0.052 μm were prepared using magnesium sulfate and sodium hydroxide as raw materials by hydrothermal synthesis process. The composition, morphology and structural features of the hydrothermal products were examined with X-ray powder diffraction （XRD）, scanning electron microscopy （SEM） and Fourier transform infrared spectroscopy （FTIR）. The experimental results indicate that in the conditions of n（NaOH）/n（MgSO4） of 1.25, the dosage of w（Na3PO4） crystal additives of 1.0% w（MgSO4）, stirring for 5 h at 180 ℃, the morphology of MgSO4·5Mg（OH）2·2H2O products is flaky and laminar, which is a kind of complex magnesium singlecrystal. The recycling of MgSO4 mother liquor was also investigated to make a full use of the materials and reduce disposal. The results prove that there is no adverse effect on the yield and purity of the products.
基金Project (2007CB714200) supported by National Basic Research Program of ChinaProject (90715018) supported by Key Research Project of National Natural Science Foundation of China
文摘A series of dynamic behavior tests on Nanjing flake-shaped fine sand were performed by using the WFI cyclic triaxial apparatus made in England. The dynamic behaviors of Nanjing flake-shaped fine sand under different static deviator stress levels and cyclic stress ratios were studied. Through comparing the effective stress path under cyclic loading with static loading, the processes of liquefaction of saturated Nanjing flake-shaped fine sand with development of dynamic pore-water pressure, including the initial compact state, compression state and dilative state, were investigated. The variation of the shear stiffness with the number of cycles and cyclic strain was investigated by analyzing the secant shear modulus in each unload-reload loop of dynamic stress-strain relationship. And by means of the exponential function, the empirical equations of the relationship between secant shear modulus Gsec, shear modulus ratio Gsec/Gmax and cyclic strain ε were established based on series of test results. The results show that according to different combinations of static deviator stress and cyclic stress, two kinds of failure patterns with deviator stress reversal or no deviator stress reversal are observed in the samples tested in this series, including cyclic mobility and the failure of accumulation residual strain. In addition, the degradation of dynamic shear modulus is due to the development of vibration pore-water pressure and it is observed that the shear modulus reduces with the progressive number of cycles.
基金supported by the Natural Science Foundation of China (Project No51606102)the Fundamental Research Funds for the Central Universities (No. 30916011315)+3 种基金the Qing Lan Project, the Weapon Research Support Fund (No. 62201070827)a Project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutionsthe Shanghai Aerospace Science and Technology Innovation Fund (SAST2015020)Basic Product Innovation Technology Research Project of Explosives
文摘To achieve aluminum particles with ultrafine granularity and high reactivity,the mechanical ball-milling method was adopted and three kinds of coatings,including stearic acid(SA),viton and dinitrotoluene(DNT),were added.The effects of milling time and different coatings on granularity and reactivity of ultrafine aluminum particles were studied.The structures of prepared ultrafine aluminum were characterized by scanning electron microscopy,X-ray particle diffraction and the thermal properties were analyzed by TG/DSC.Besides,the reactivity of prepared ultrafine aluminum particles was comprehensively analyzed and judged according to several thermodynamic parameters,the maximal oxidation rate,the oxidation degree of aluminum and the enthalpy change.The results revealed that aluminum particles prepared by the mechanical ball milling method were all flake-like and the particle sizes were below5 mm with nanometer-scale thickness.And the crystal form of aluminum was found to be unchanged.Besides,the ultrafine flake aluminum coated with stearic acid after milling for 5 h showed the highest reactivity with 56.1% of oxidation degree before 660℃,0.945 mg/℃ of maximal oxidation rate and 20491 J/g of enthalpy change.
基金National Key Research and Development Program of China(2024YFB3714804)National Natural Science Foundation of China(52171277)+1 种基金Baima Lake Laboratory Joint Funds of the Zhejiang Provincial Natural Science Foundation of China(LBMHZ24E020001)Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering(2022SZ-TD006).
文摘Magnesium potassium phosphate cement(MKPC)coatings exhibit potential for carbon steel protection but face challenges in practical application due to the preparation process and properties.This study develops flake graphite(FG)-modified MKPC coatings via spraying process,investigating the effects of FG size and dosage on phase composition,microstructure,mechanical properties,corrosion protection,and thermal conductivity.Results show that a low FG dosage(5 wt%)synergistically optimizes multifunctional performance.Compared to unmodified MKPC,FG2-1 exhibited exceptional impact resistance,associated with a 57%reduction in corrosion current density(icorr),a 356.3% increase in low-frequency impedance modulus(Z_(0.01 Hz))and a 37% increase in thermal conductivity.However,the coating with a high FG dosage(15 wt%)degraded performance due to defect accumulation and reduced crystallinity of KMgPO_(4)·6H_(2)O.This work advances the rational design of multifunctional inorganic coatings for extreme service environments requiring coupled corrosion protection and thermal management.
