摘要
Among practical metal additives,boron(B) has a high volumetric heating value,making it a promising choice as a fuel additive.Although B can theoretically yield a large amount of energy upon complete combustion,its combustion is retarded by the initial presence of B oxide,which coats the surfaces of B particle.To improve the ignition and combustion properties of B powder,LiOH and NH4F were used as precursors to synthesize uniformly LiF-coated B composites(LiF-B) in situ.The LiF-B mixture was also prepared for comparison using a physical method.X-ray diffraction(XRD),Fourier-transform infrared(FTIR),scanning electron microscope(SEM),and energy-dispersive X-ray spectroscopy(EDS) were used to characterize the morphologies and compositions of the products.The thermal and combustion properties of the samples were characterized by thermal gravity-differential thermal gravity(TG-DTG),differential scanning calo rimetry(DSC) and closed bomb experiment.The XRD,FTIR,SEM and EDS results demonstrated the successful preparation of the coated LiF-B sample.The TG-DTG and closed bomb experiment results indicated that the addition of LiF decreased the ignition temperature of B powder,and increasing its reaction efficiency.DSC results show that when LiF-B was added,the released heat of underwater explosive increased by 6727.2,7280.4 and 3109.6 J/g at heating rates of 5,10,and 15℃/min,respectively.Moreover,LiF-B decreased the activation energy of secondary combustion reaction of explosive system as calculated through Kissinger’s method by 28.9%,which indicated an excellent catalytic effect for the thermal decomposition of underwater explosive.The results reveal that LiF can improve the combustion efficiency of B powder,thereby increasing the total energy of explosives.The mechanical sensitivity increased slightly after adding LiF-B to the underwater explosive.Co mpared to the underwater explosive with added B,the mechanical sensitivity of the explosive with added LiF-B was significantly lower.
基金
This work was supported by the National Natural Science Foundation of China(Grant No.:3020050321328).
