Studies On Technique And Its Application Of X-ray Diffraction Testing For Polymer Bonded Explosive

With the developing of military weapons, the requirements of weapon's performances is becoming higher and higher. PBX cylinder is the core component of many kinds of weapons which heavily influent the further developing of weapons. The test for determining residual stress distribution has very realistic value to enhance PBX cylinder qualities and search for optimum chemical match and processing parameters. Until now, there is only a few technologies used to test residual stress. So it's valuable to do further searches on test of residual stress in PBX cylinders.In this paper, the ingredients of PBX, manufacture technology and PBX cylinder forming theory are introduced. Moreover, the causes of residual stress and existing manners are also discussed. Comparing the advantages and disadvantages of several stress test methods and considering the characters of PBX, we find out two effective and secure ways– XRD and supersonic measurement– to test residual stress in PBX cylinders. Through the analyzing the basic theories of residual stress, computing, using XRD to carry out serial tests for PBX cylinders prepared by different forming parameters, we get the following results:⑴Analyzing the test methods used in home and abroad, combing the technical requirements of PBX cylinders for residual and Chemical and physic properties of PBX, we draw a conclusion that XRD, supersonic measurement, cloud interferrometry, laser interferometry are suitable to test PBX residual stress. The IR Prestige-21 test result shows PBX's inferred transmission ratio is low due the property to the material. Finally, we conclude that the two effective ways to test residual stress are XRD interferomety and supersonic interferomety.⑵Comparing XRD test results of JOB-9003 PBX cylinders that are mold under different pressures with HMX test results, we find that diffraction peaks shift slightly. This phenomenon means interplanar distance changes because of residual stress. This phenomen on provides a reliable foundation for experiments.⑶Theoretically, we deduce the formula to compute residual stress in PBX based on XRD test datum. The computed results show us 2θis linear with Sin2Ψ. We can compute the macro residual stress in cylinders by slope coefficient M and constant K. We modify the test method based on the computed results. The test results show the residual stress in PBX cylinders are a kind of positive tensile stress around several mega Pa.⑷Stress test experimental datum of PBX cylinders that are molded under different pressures indicate the following results:①PBX cylinder residual stress changes with the molding pressure. Residual stress climbs up with the increase of molding pressure. But the relationship between residual stress and molding pressure is not linear. Under the pressure of 150 MPa, residual stress reaches the max.②Residual stresses appear to be drag stresses in all parts of PBX cylinders. The residual stress values remain around several MPa except borderland. Borderland residual stress is dramatic smaller than the central area and the difference reaches several tens of MPa, in some areas even more than one hundred MPa.③Residual stress has declined after 19 months. So the residual stress declines with time.⑸We treat PBX cylinders under different heat-treatment conditions, then test the residual stress, and the results indicate:①Heat-treatment can release the residual stress and enhance PBX cylinder's quality and performances.②There is no significant difference of stress releasing efficiency between PBX cylinders that are heat treated for 120 hours and 14 hours. So, there is no significant improvement of stress releasing efficiency by a longer heat treatment when a certain long heat treat time is reached.③If the PBX cylinders are heat treated by the second time, the residual stress declines slightly. So the heat treatment is more efficient to decline stress at the first time.The research work in this paper is partly supported by State Science and China Academy of Engineer Physics union fund. Our research results have reference value for the assessment of PBX residual stress and molding technology.