Stoichiometric MgAl2O4 spinel nanoparticles were synthesized by microwave assisted combustion reaction from aluminium nitrate nanohydrate(Al(NO3)3.9H2O) and Sol-Gel prepared magnesium hydroxide(Mg(OH)2) in the presenc...Stoichiometric MgAl2O4 spinel nanoparticles were synthesized by microwave assisted combustion reaction from aluminium nitrate nanohydrate(Al(NO3)3.9H2O) and Sol-Gel prepared magnesium hydroxide(Mg(OH)2) in the presence of urea((NH2)2CO) as a fuel,in about 20 min of irradiation.X-ray diffraction(XRD) studies reveal that mi-crowave assisted combustion synthesis route yields single-phase spinel nanoparticles with larger crystalline size(around 75 nm) than other conventional heating methods.Scanning electronic microscope(SEM) images show nanoparticles with spherical shape and homogenous morphology.The surface area measurements(SBET) show crystals with 2.11 m2/g and 0.0033 mL/g pore volume.展开更多
5.0 vol.% graphene nanoplatelets(GNPs) and aluminum powders were mixed to prepare GNPs/Al composites via high-energy ball milling(HEBM). The mixed powders were subjected to spark plasma sintering(SPS) and subsequent h...5.0 vol.% graphene nanoplatelets(GNPs) and aluminum powders were mixed to prepare GNPs/Al composites via high-energy ball milling(HEBM). The mixed powders were subjected to spark plasma sintering(SPS) and subsequent hot extrusion. The microstructure and mechanical properties of extruded composites were investigated by X-ray photoelectron spectroscopy(XPS), transmission electron microscopy(TEM) and tensile tests. In the extruded composites, 5.0 vol.% GNPs were dispersed homogeneously and no serious GNP-Al interfacial reaction occurred. As a result, the yield strength and ultimate tensile strength of the extruded GNPs/Al composites reached 462 and 479 MPa, which were 62% and 60% higher than those of the extruded Al matrix, respectively. The enhanced mechanical properties were attributed to the effective load transfer capacity of dispersed GNPs. This demonstrated that it may be promising to introduce dispersed high-content GNPs via HEBM, SPS and hot extrusion techniques and GNP-Al interfacial reaction can be controlled.展开更多
A novel kind of waterborne epoxy coating pigmented by nano-sized aluminium powders on high strength steel was formulated. Several coatings with different pigment volume content (PVC) were prepared. The coating morphol...A novel kind of waterborne epoxy coating pigmented by nano-sized aluminium powders on high strength steel was formulated. Several coatings with different pigment volume content (PVC) were prepared. The coating morphology was observed using scanning electron microscopy (SEM), and the electrochemical properties were investigated by electrochemical impedance spectroscopy (EIS). Immersion test and neutral salt spray test were also conducted to investigate the corrosion resistance of the coating. It is demonstrated that the critical pigment volume content (CPVC) value is between 30% and 40%. The coating with PVC of 30% exhibits good corrosion resistance in 3.5% (mass fraction) NaCl solution.展开更多
The explosive characteristics of aluminum powder have great significance in preventing and controlling aluminum-dust explosion accidents, especially the nano-aluminum powder. The explosion characteristics of 100 nm an...The explosive characteristics of aluminum powder have great significance in preventing and controlling aluminum-dust explosion accidents, especially the nano-aluminum powder. The explosion characteristics of 100 nm and 75 μm aluminum powders were investigated by using a 20 L spherical explosion cavity and a horizontal pipe whose cross-section area is 80 mm × 80 mm and length is 8 m. The results show that the maximum explosion pressure and its rising rate of 100 nm aluminum powder gradually increase with increasing concentration of aluminum-powder at the beginning. When aluminum-powder concentration is I kg/m3, the maximum explosion pressure reaches its maximum, and then gradually decreases. While when the concentration is 1.25 kg/m3, the maximum rate of pressure rise obtains its maximum, and then decreases. After 100 nm aluminum powder is exploded in pipes, the peak overpressure of blast wave first decreases and then increases to the maximum at a distance of 298 cm from the ignition source, and then gradually decreases. The most violent concentration is about 0.4 kg/m3 which is lower than 0.8 kg/m3 of 75 μm aluminum powder, so 100 nm aluminum powders are more easily exploded. The change laws of maximum explosion pressure, maximum rate of pressure rise and blast-wave peak overpressure of 100 nm aluminum powders with concentration are similar to those of 75 ktm aluminum powders, but these values are much higher than 75 Bm aluminum powders under the same concentration, so the aluminum-powders explosion of 100 nm will produce more harms. In the process of production, storage and transportation of aluminum powder, some relevant preventive measures can be taken to reduce the loss caused by aluminum-dust explosion according to nano-aluminum dust.展开更多
Nano-sized silica-alumina particles were in-situ synthesized in supersolubilizing reverse micellae.Both the most probable pore diameters and the particle sizes were distributed in nano-scale SiO2-Al2O3 particulates.Th...Nano-sized silica-alumina particles were in-situ synthesized in supersolubilizing reverse micellae.Both the most probable pore diameters and the particle sizes were distributed in nano-scale SiO2-Al2O3 particulates.The influence of SiO2/Al2O3 mass ratio and the surfactant content on the particle size and morphology,pore structure,and acidity was characterized by the low temperature nitrogen adsorption/desorption (BET),SEM,TEM and NH3-TPD methods.The test results indicated that the most probable pore diameter of SiO2-Al2O3 nanoparticles was around 10 nm,the specific surface area was about 223-286 m2 /g,the pore volumes were about 0.48-0.63 cm 3 /g,and the particle sizes of porous SiO2-Al2O3 calcined at 550 ℃ were distributed always in the range between 10 nm to 50 nm.The calcined SiO2-Al2O3 nano-powders showed their acidity being stronger than the porous γ-Al2O3 support.展开更多
文摘Stoichiometric MgAl2O4 spinel nanoparticles were synthesized by microwave assisted combustion reaction from aluminium nitrate nanohydrate(Al(NO3)3.9H2O) and Sol-Gel prepared magnesium hydroxide(Mg(OH)2) in the presence of urea((NH2)2CO) as a fuel,in about 20 min of irradiation.X-ray diffraction(XRD) studies reveal that mi-crowave assisted combustion synthesis route yields single-phase spinel nanoparticles with larger crystalline size(around 75 nm) than other conventional heating methods.Scanning electronic microscope(SEM) images show nanoparticles with spherical shape and homogenous morphology.The surface area measurements(SBET) show crystals with 2.11 m2/g and 0.0033 mL/g pore volume.
基金financial supports from National Key R&D Program of China (2017YFB0703103)Key Area R&D Program of Guangdong Province,China (2019B010942001)。
文摘5.0 vol.% graphene nanoplatelets(GNPs) and aluminum powders were mixed to prepare GNPs/Al composites via high-energy ball milling(HEBM). The mixed powders were subjected to spark plasma sintering(SPS) and subsequent hot extrusion. The microstructure and mechanical properties of extruded composites were investigated by X-ray photoelectron spectroscopy(XPS), transmission electron microscopy(TEM) and tensile tests. In the extruded composites, 5.0 vol.% GNPs were dispersed homogeneously and no serious GNP-Al interfacial reaction occurred. As a result, the yield strength and ultimate tensile strength of the extruded GNPs/Al composites reached 462 and 479 MPa, which were 62% and 60% higher than those of the extruded Al matrix, respectively. The enhanced mechanical properties were attributed to the effective load transfer capacity of dispersed GNPs. This demonstrated that it may be promising to introduce dispersed high-content GNPs via HEBM, SPS and hot extrusion techniques and GNP-Al interfacial reaction can be controlled.
基金Project(51001007) supported by the National Natural Science Foundation of ChinaProject(2011ZE51057) supported by the Aero Science Foundation of China
文摘A novel kind of waterborne epoxy coating pigmented by nano-sized aluminium powders on high strength steel was formulated. Several coatings with different pigment volume content (PVC) were prepared. The coating morphology was observed using scanning electron microscopy (SEM), and the electrochemical properties were investigated by electrochemical impedance spectroscopy (EIS). Immersion test and neutral salt spray test were also conducted to investigate the corrosion resistance of the coating. It is demonstrated that the critical pigment volume content (CPVC) value is between 30% and 40%. The coating with PVC of 30% exhibits good corrosion resistance in 3.5% (mass fraction) NaCl solution.
基金supported by the Major State Basic Research Development Program of China (No. 2011CB201205)the Open Fund Program of the State Key Laboratory of Explosion Science and Technology (No. KFJJ10-19M)
文摘The explosive characteristics of aluminum powder have great significance in preventing and controlling aluminum-dust explosion accidents, especially the nano-aluminum powder. The explosion characteristics of 100 nm and 75 μm aluminum powders were investigated by using a 20 L spherical explosion cavity and a horizontal pipe whose cross-section area is 80 mm × 80 mm and length is 8 m. The results show that the maximum explosion pressure and its rising rate of 100 nm aluminum powder gradually increase with increasing concentration of aluminum-powder at the beginning. When aluminum-powder concentration is I kg/m3, the maximum explosion pressure reaches its maximum, and then gradually decreases. While when the concentration is 1.25 kg/m3, the maximum rate of pressure rise obtains its maximum, and then decreases. After 100 nm aluminum powder is exploded in pipes, the peak overpressure of blast wave first decreases and then increases to the maximum at a distance of 298 cm from the ignition source, and then gradually decreases. The most violent concentration is about 0.4 kg/m3 which is lower than 0.8 kg/m3 of 75 μm aluminum powder, so 100 nm aluminum powders are more easily exploded. The change laws of maximum explosion pressure, maximum rate of pressure rise and blast-wave peak overpressure of 100 nm aluminum powders with concentration are similar to those of 75 ktm aluminum powders, but these values are much higher than 75 Bm aluminum powders under the same concentration, so the aluminum-powders explosion of 100 nm will produce more harms. In the process of production, storage and transportation of aluminum powder, some relevant preventive measures can be taken to reduce the loss caused by aluminum-dust explosion according to nano-aluminum dust.
基金the financial support of Liaoning Province National Science Fund (No.20072009)
文摘Nano-sized silica-alumina particles were in-situ synthesized in supersolubilizing reverse micellae.Both the most probable pore diameters and the particle sizes were distributed in nano-scale SiO2-Al2O3 particulates.The influence of SiO2/Al2O3 mass ratio and the surfactant content on the particle size and morphology,pore structure,and acidity was characterized by the low temperature nitrogen adsorption/desorption (BET),SEM,TEM and NH3-TPD methods.The test results indicated that the most probable pore diameter of SiO2-Al2O3 nanoparticles was around 10 nm,the specific surface area was about 223-286 m2 /g,the pore volumes were about 0.48-0.63 cm 3 /g,and the particle sizes of porous SiO2-Al2O3 calcined at 550 ℃ were distributed always in the range between 10 nm to 50 nm.The calcined SiO2-Al2O3 nano-powders showed their acidity being stronger than the porous γ-Al2O3 support.
