Metal additives play an essential role in explosive and propellant formulations. Boron(B) is widely used in propellant applications owing to its high energetic content. The addition of B to explosives and propellants ...Metal additives play an essential role in explosive and propellant formulations. Boron(B) is widely used in propellant applications owing to its high energetic content. The addition of B to explosives and propellants increases their energy density, making them more efficient and powerful. Nevertheless, B forms oxide layers on its surface during combustion, slowing down the combustion rate and reducing rocket motor efficiency. To overcome this issue, other metal additives such as aluminum(Al), magnesium(Mg),and titanium(Ti) are revealed to be effective in boosting the combustion rate of propellants. These additives may improve the combustion rate and therefore enhance the rocket motor’s performance. The present study focused on preparing and investigating the ignition and combustion behavior of pure hydroxyl-terminated polybutadiene(HTPB)-B fuel supplemented with nano-titanium and nanomagnesium. The burn rates of HTPB-B fuel samples were evaluated on the opposed flow burner(OFB)under a gaseous oxygen oxidizer, for which the mass flux ranges from 22 kg/(m^(2)·s) to 86 kg/(m^(2)·s). The addition of Ti and Mg exhibited higher regression rates, which were attributed to the improved oxidation reaction of B due to the synergetic metal combustion effect. The possible combustion/oxidation reaction mechanism of B-Mg and B-Ti by heating the fuel samples at 900℃ and 1100℃ was also examined in a Nabertherm burnout furnace under an oxygen atmosphere. The post-combustion products were collected and further subjected to X-ray diffraction(XRD) and field emission scanning electron microscopy(FE-SEM) analyses to inspect the combustion behavior of B-Ti and B-Mg. It has been observed that the B oxide layer at the interface between B-Ti(B-Mg) is removed at lower temperatures, hence facilitating oxygen transfer from the surroundings to the core B. Additionally, Ti and Mg decreased the ignition delay time of B, which improved its combustion performance.展开更多
Paraffin-based fuel has a great potential for several innovative missions,including space tourism,due to its safety,low environmental impact,high performance and low cost.Despite the fact that liquefying solid fuels i...Paraffin-based fuel has a great potential for several innovative missions,including space tourism,due to its safety,low environmental impact,high performance and low cost.Despite the fact that liquefying solid fuels increases the regression rate of hybrid rocket motors,incorporating energetic materials into solid fuel can still improve the performance.The objective and scope of this study is to increase the performance characteristics of the paraffin-based fuel by using magnesium diboride(MgB_(2))and carbon black(CB)additives.The cylindricalport fuel grains were manufactured with various additives percentages in mass(wt%:CB-2%and MgB_(2)-10%)and tested using a laboratory-scale ballistic hybrid motor under gaseous oxygen.The mechanical performance results revealed that adding CB and MgB_(2) improved the ultimate strength and elastic modulus of paraffin-based fuels.The addition of these fillers increased the hardness of fuel by developing a strong interaction in the paraffin matrix.Thermogravimetry(TG)results showed that CB inclusion improved the thermal stability of the paraffin matrix.The average regression rates of fuels loaded with CB and MgB_(2) were 32%and 52%higher than those of unmodified paraffin wax,respectively.The characteristic velocity efficiency was found in the range of 68%e79%at an O/F ratio of 1.5e2.6.The MgB_(2) oxidation/combustion in the paraffin matrix was described by a four-step oxidation process ranging from 473 K to 1723 K.Finally,a combustion model of MgB_(2) in the paraffin matrix was proposed,and four-step oxidation processes were discussed in detail.展开更多
基金the Hindustan Institute of Technology and Science for their support.
文摘Metal additives play an essential role in explosive and propellant formulations. Boron(B) is widely used in propellant applications owing to its high energetic content. The addition of B to explosives and propellants increases their energy density, making them more efficient and powerful. Nevertheless, B forms oxide layers on its surface during combustion, slowing down the combustion rate and reducing rocket motor efficiency. To overcome this issue, other metal additives such as aluminum(Al), magnesium(Mg),and titanium(Ti) are revealed to be effective in boosting the combustion rate of propellants. These additives may improve the combustion rate and therefore enhance the rocket motor’s performance. The present study focused on preparing and investigating the ignition and combustion behavior of pure hydroxyl-terminated polybutadiene(HTPB)-B fuel supplemented with nano-titanium and nanomagnesium. The burn rates of HTPB-B fuel samples were evaluated on the opposed flow burner(OFB)under a gaseous oxygen oxidizer, for which the mass flux ranges from 22 kg/(m^(2)·s) to 86 kg/(m^(2)·s). The addition of Ti and Mg exhibited higher regression rates, which were attributed to the improved oxidation reaction of B due to the synergetic metal combustion effect. The possible combustion/oxidation reaction mechanism of B-Mg and B-Ti by heating the fuel samples at 900℃ and 1100℃ was also examined in a Nabertherm burnout furnace under an oxygen atmosphere. The post-combustion products were collected and further subjected to X-ray diffraction(XRD) and field emission scanning electron microscopy(FE-SEM) analyses to inspect the combustion behavior of B-Ti and B-Mg. It has been observed that the B oxide layer at the interface between B-Ti(B-Mg) is removed at lower temperatures, hence facilitating oxygen transfer from the surroundings to the core B. Additionally, Ti and Mg decreased the ignition delay time of B, which improved its combustion performance.
文摘Paraffin-based fuel has a great potential for several innovative missions,including space tourism,due to its safety,low environmental impact,high performance and low cost.Despite the fact that liquefying solid fuels increases the regression rate of hybrid rocket motors,incorporating energetic materials into solid fuel can still improve the performance.The objective and scope of this study is to increase the performance characteristics of the paraffin-based fuel by using magnesium diboride(MgB_(2))and carbon black(CB)additives.The cylindricalport fuel grains were manufactured with various additives percentages in mass(wt%:CB-2%and MgB_(2)-10%)and tested using a laboratory-scale ballistic hybrid motor under gaseous oxygen.The mechanical performance results revealed that adding CB and MgB_(2) improved the ultimate strength and elastic modulus of paraffin-based fuels.The addition of these fillers increased the hardness of fuel by developing a strong interaction in the paraffin matrix.Thermogravimetry(TG)results showed that CB inclusion improved the thermal stability of the paraffin matrix.The average regression rates of fuels loaded with CB and MgB_(2) were 32%and 52%higher than those of unmodified paraffin wax,respectively.The characteristic velocity efficiency was found in the range of 68%e79%at an O/F ratio of 1.5e2.6.The MgB_(2) oxidation/combustion in the paraffin matrix was described by a four-step oxidation process ranging from 473 K to 1723 K.Finally,a combustion model of MgB_(2) in the paraffin matrix was proposed,and four-step oxidation processes were discussed in detail.
