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The hollow structure commonly used in aerospace field is generally formed by the SPF/DB, but its disadvantages lead to surface groove and complex internal structure difficult to form. In this paper, the method of milling combined with diffusion bonding is used to improve the defect. Diffusion bonding of TC4 titanium alloy hollow structure was carried out at temperature ranging from 800 °C to 900 °C for 10 ~ 30 min. The interfacial bonding ratio, deformation ratio, microstructures, microhardness and mechanical properties of the diffusion bonded joints were investigated. The results show that joints with high bonding quality can be obtained when bonded at 850 °C and 900 °C for 20 ~ 30 min. The joint bonding ratio is more than 92%, the tensile strength is 952 MPa, and the deformation ratio is maintained at about 10%. The microhardness of the TC4 alloy hollow structural joint increases with the increase in bonding temperature, showing a trend of "high in the middle and low on both sides", and it has a peak value (HV472) when bonding time is prolonged up to 30 min. The findings indicate that qualified workpiece can be obtained by the process.

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Ultra-fine 2,2’,4,4’,6,6’- Hexanitrostilbene (HNS-IV) was obtained by HNS-II by vibration cavity comminute. This method uses only alcohol and deionized water, which can be viewed as a green technology. The morphology, particle size, specific surface area, thermal decomposition property and the threshold energy for slapper detonator were compared between HNS-IV and HNS-II in this paper. Results show that after HNS pulverizing, the particle size decreased from 27.18μm to 1.44μm, the specific surface area increased from 0.73m2•g−1 to 9.10m2•g−1. DSC analysis shows that the decomposition peak temperature Td decreases and the melting temperature Tm increases after pulverizing. It is speculated that in the explosive reaction with very high heating rate, the enthalpy of decomposition will be increased by pulverizing, which will be more conducive to detonation growth and explosive reaction. According to the calculation of thermal decomposition kinetics, the decomposition and activation energy Ea of HNS decreases after pulverizing, and the thermal decomposition reaction rate of HNS-IV increases when the temperature is less than 409.6°C. The initiation threshold test of the impact plate shows that the 50% initiation threshold energy of HNS- II is 1.242J, and the 50% initiation threshold energy of HNS-IV is 0.558J, and the initiation threshold for slapper detonatorer is significantly reduced by 55%. This means that the ultra-fine HNS-IV is very suitable as the main ingredient in the booster in the EFI initiation.

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