Preparation Process And Performance Test Of PTFE Based Aluminum Alloy Active Materials

The invasion coupling enhancement effect of PTFE based active materials is of great significance to improve the efficient destruction ability of warheads,active fragments prepared using them not only have excellent kinetic energy penetration,but also can undergo chemical reactions and release energy to produce greater coupling damage effects on targets,making them the most important research direction in the field of efficient damage.However,the current PTFE based active materials cannot meet the requirements of high density,high strength and high energy release efficiency of the warhead.In view of the low density,high preparation process temperature and poor energy release efficiency of current PTFE based active materials,this paper proposes to introduce high-density metal systems such as Zr,Ni and Zn,fiber reinforced toughening systems such as Al fiber and carbon fiber,and energetic binder systems such as GAP and NC into the formulation of Al/PTFE,the low-temperature preparation process of isostatic pressing is carried out,the enhanced toughening mechanism of the preparation process is studied by discrete element simulation,and through mechanical properties,thermal properties and sensitivity tests,the influencing factors of the introduction of different system materials on PTFE based active materials are revealed.The main research contents and results of this paper are as follows:（1）In this paper,a total of ten PTFE based active material formulations are prepared,including Al/PTFE,Al/Zr/Ni/PTFE,Al/Zr/Zn/PTFE,Al/Zr/PTFE,Mg/Zn/Al/PTFE,Al/PTFE/CF,Al/Zr/PTFE/CF,Al fiber/Al/PTFE,NC/Al/PTFE and GAP/Al/PTFE.Among them,the formula of the high-density metal system is determined according to the complete reaction radio,the Al fiber and CF are added to the Al/PTFE according to the total 5 wt%,respectively.And the energetic binder is prepared by coating according to the 5 wt%of Al.Through the electron densitometer and SEM electron microscope,it is found that the density of high-density metal system is greater than 3 g·cm^-3.The surface of Al powder coated by NC and GAP obviously has a coating layer,and the surface roughness of CF increased after surface treatment.According to the thermal deformation temperature of PTFE,the preparation process parameters are determined as follows:200℃for 1 hour and 280 MPa for5 minutes.Subsequently,the above ten kinds of Al/PTFE active materials are prepared by three processes of formula material mixing,compression molding and warm isostatic pressing.（2）Based on EDEM conducted simulation and simulation research on two preparation processes such as mold compression molding and warm isostatic pressing.The simulation results show that due to pressure relief and rebound effect,density of Al/PTFE prepared by compression moding decreased from 2.07 g·cm^-3 at pressure retaining to 1.84 g·cm^-3 after pressure relief,and density of Al/PTFE prepared by warm isostatic pressing decreased from2.22 g·cm^-3 at pressure retaining to 2.09 g·cm^-3 after pressure relief.From bulk density,it can be seen that porosity of active material prepared by warm isostatic pressing is smaller than that by compression molding.The Al/PTFE prepared by two preparation processes is divided into four areas from top to bottom and density of different regions is obtained.The results showed that density of grain prepared by molding is larger in middle and smaller at both ends,and density distribution of grain prepared by isostatic pressing process is evenly distributed.According to porosity and density distribution,it can be seen that superiority of preparation process such as warm pressure molding.The pressing force-time curve drawn from the simulation result data shows that the pressing force and time in the simulation are consistent with the actual process parameters used,reflecting the reliability of the simulation results.（3）Ten kinds of Al/PTFE are tested for compressing stretching mechanical performance,and stress-strain curve is drawn based on the test results.The results show that:The compression process of Al/PTFE has transformed from elastic stage to failure stage,compressive strength is 16.8 MPa.The tensile process has undergone elastic stage,cold pull phase,enhanced stage and failure stage,tensile strength is 1.9 MPa.Compared with Al/PTFE,the compression stretching performance of Al/Zr/PTFE/CF is the best,compression strength is 27.1 MPa,and stretch strength is 6 MPa.The compression process of high-density metal system has gone through elastic stage,strengthening stage,and failure stage.The tensile process has experienced elastic stage,strain softening stage,cold pull phase,and failure stage.The compression process of fiber reinforced system is consistent with that of high-density metal system,and stretching process of the two formulations containing carbon fibers is consistent with that of the Al/PTFE active materials.The stretching process of the Al fiber/Al/PTFE changes from the elastic stage to failure stage.The compression and tensile processes of the energetic binder system are consistent with those of Al/PTFE active materials.Then,the SHPB of Al/PTFE,Al/Zr/PTFE,Al/Zr/PTFE/CF are tested.Under the condition of high strain rate loading,the maximum stress of Al/PTFE is 40 MPa and that of Al/Zr/PTFE is 42.4 MPa.The maximum stress of Al/Zr/PTFE/CF is 47.4 MPa.（4）The TG-DSC test results show that the introduction of other system materials can improve the exothermic energy of Al/PTFE,and it is found that the starting temperature of the reaction between Al and PTFE in the Al/Zr/Ni/PTFE formulation is delayed by about20℃,and the reaction of Al/Zr/Ni alloy powder is initiated during the reaction stage,with an exothermic energy of 73.79 J·g^-1.In the Mg/Zn/Al/PTFE,the exothermic peak of the reaction between Mg and PTFE masks the endothermic peak of the decomposition of PTFE.The mechanical sensing test results show that the impact sensitivity of Al/PTFE active material powder is 8%,and the introduction of Al/Zr/Ni alloy powder,Al fiber and NC has improved the impact sensing of PTFE based active material powder.The introduction of CF and GAP reduces the impact sensitivity of PTFE based active material powder.The others formula powder is zero.In contrast to the impact sensitivity,the probability of the Al/PTFE formula powder is more likely to explode,and its explosion probability is 20%.The introduction of other materials reduces its friction sensitivity,and most of the formula powder friction is zero.