A novel design of micro-aluminum(μAl)powder coated with bi-/tri-component alloy layer,such as:Ni-P and Ni-P-Cu(namely,Al@Ni-P,Al@Ni-P-Cu,respectively),as combustion catalysts,were introduced to release its huge energ...A novel design of micro-aluminum(μAl)powder coated with bi-/tri-component alloy layer,such as:Ni-P and Ni-P-Cu(namely,Al@Ni-P,Al@Ni-P-Cu,respectively),as combustion catalysts,were introduced to release its huge energy inside Al-core and promote rapid pyrolysis of ammonium perchlorate(AP)at a lower temperature in aluminized propellants.The microstructure of Al@Ni-P-Cu demonstrates that a three-layer Ni-P-Cu shell,with the thickness of~100 nm,is uniformly supported byμAl carrier(fuel unit),which has an amorphous surface with a thickness of~2.3 nm(catalytic unit).The peak temperature of AP with the addition of Al@Ni-P-Cu(3.5%)could significantly drop to 316.2℃ at high-temperature thermal decomposition,reduced by 124.3℃,in comparison to that of pure AP with 440.5℃.It illustrated that the introduction of Al@Ni-P-Cu could weaken or even eliminate the obstacle of AP pyrolysis due to its reduction of activation energy with 118.28 kJ/mol.The laser ignition results showed that the ignition delay time of Al@Ni-P-Cu/AP mixture with 78 ms in air is shorter than that of Al@Ni-P/AP(118 ms),decreased by 33.90%.Those astonishing breakthroughs were attributed to the synergistic effects of adequate active sites on amorphous surface and oxidation exothermic reactions(7597.7 J/g)of Al@Ni-P-Cu,resulting in accelerated mass and/or heat transfer rate to catalyze AP pyrolysis and combustion.Moreover,it is believed to provide an alternative Al-based combustion catalyst for propellant designer,to promote the development the propellants toward a higher energy.展开更多
After widely screening, a kind of bacteria was obtamed, which is casy to culture and hasstrong ability of reducing Au3+ to Au0. It was used to prepare the highly dispersive Au/a-Fe2O3catalyst by in situ reducmg the Au...After widely screening, a kind of bacteria was obtamed, which is casy to culture and hasstrong ability of reducing Au3+ to Au0. It was used to prepare the highly dispersive Au/a-Fe2O3catalyst by in situ reducmg the Au3+ ions impregnated on a-Fe2O3 supporter to Au0 particles.with a mean size of 5 nm, under the condition of 28℃ and pH 4.5. The reductive degree ofAu3+ was up to 100%. This catalyst showed good catalytic property for the oxidation of carbonmonoxide, the percent conversion of 1.5% CO, balanced withe air was up to 100% under thecondition of 25~28℃and GHSV 500mL·h-1·g-1, and the percent conversion of 100% lastedfor 75 h at 25 ℃.展开更多
DDP-coated Sn nanoparticles were prepared by ultrasonic irradiation method. The nanoparticles were found to be well dispersed and coated with the surfactant DDP. The tetragonal phase of the as-prepared nanoparticles w...DDP-coated Sn nanoparticles were prepared by ultrasonic irradiation method. The nanoparticles were found to be well dispersed and coated with the surfactant DDP. The tetragonal phase of the as-prepared nanoparticles was characterized by selected area electron diffraction (SAED) and X-ray diffraction (XRD). In addition, the powder was found to have an excellent antiwear property by tribological test.展开更多
基金supported by the National Natural Science Foundation of China,China(Grant Nos.U20B2018,U21B2086,11972087)。
文摘A novel design of micro-aluminum(μAl)powder coated with bi-/tri-component alloy layer,such as:Ni-P and Ni-P-Cu(namely,Al@Ni-P,Al@Ni-P-Cu,respectively),as combustion catalysts,were introduced to release its huge energy inside Al-core and promote rapid pyrolysis of ammonium perchlorate(AP)at a lower temperature in aluminized propellants.The microstructure of Al@Ni-P-Cu demonstrates that a three-layer Ni-P-Cu shell,with the thickness of~100 nm,is uniformly supported byμAl carrier(fuel unit),which has an amorphous surface with a thickness of~2.3 nm(catalytic unit).The peak temperature of AP with the addition of Al@Ni-P-Cu(3.5%)could significantly drop to 316.2℃ at high-temperature thermal decomposition,reduced by 124.3℃,in comparison to that of pure AP with 440.5℃.It illustrated that the introduction of Al@Ni-P-Cu could weaken or even eliminate the obstacle of AP pyrolysis due to its reduction of activation energy with 118.28 kJ/mol.The laser ignition results showed that the ignition delay time of Al@Ni-P-Cu/AP mixture with 78 ms in air is shorter than that of Al@Ni-P/AP(118 ms),decreased by 33.90%.Those astonishing breakthroughs were attributed to the synergistic effects of adequate active sites on amorphous surface and oxidation exothermic reactions(7597.7 J/g)of Al@Ni-P-Cu,resulting in accelerated mass and/or heat transfer rate to catalyze AP pyrolysis and combustion.Moreover,it is believed to provide an alternative Al-based combustion catalyst for propellant designer,to promote the development the propellants toward a higher energy.
文摘After widely screening, a kind of bacteria was obtamed, which is casy to culture and hasstrong ability of reducing Au3+ to Au0. It was used to prepare the highly dispersive Au/a-Fe2O3catalyst by in situ reducmg the Au3+ ions impregnated on a-Fe2O3 supporter to Au0 particles.with a mean size of 5 nm, under the condition of 28℃ and pH 4.5. The reductive degree ofAu3+ was up to 100%. This catalyst showed good catalytic property for the oxidation of carbonmonoxide, the percent conversion of 1.5% CO, balanced withe air was up to 100% under thecondition of 25~28℃and GHSV 500mL·h-1·g-1, and the percent conversion of 100% lastedfor 75 h at 25 ℃.
文摘DDP-coated Sn nanoparticles were prepared by ultrasonic irradiation method. The nanoparticles were found to be well dispersed and coated with the surfactant DDP. The tetragonal phase of the as-prepared nanoparticles was characterized by selected area electron diffraction (SAED) and X-ray diffraction (XRD). In addition, the powder was found to have an excellent antiwear property by tribological test.
基金Research Project from Department of Science and Technology of Shandong Province(2012GGA01012)Scientific ResearchFoundation for the Returned Overseas Chinese Scholars of State Education Ministry(2004-527)
