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4D micro-scale, phase-contrast X-ray imaging and computed tomography of HMX-based polymer-bonded explosives during thermal runaway

DOI: 10.1016/j.combustflame.2020.12.025 DOI Help

Authors: G. R. Parker (Los Alamos National Laboratory) , D. S. Eastwood (University of Manchester) , M. Storm (Diamond Light Source) , K. Vitharana (University of Manchester) , E. M. Heatwole (Los Alamos National Laboratory) , I. Lopez-pulliam (Los Alamos National Laboratory) , R. M. Broilo (Los Alamos National Laboratory) , P. M. Dickson (Los Alamos National Laboratory) , A. Martinez (Health and Safety Laboratory) , Christoph Rau (Diamond Light Source) , N. K. Bourne (University of Manchester)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Combustion And Flame , VOL 226 , PAGES 478 - 489

State: Published (Approved)
Published: April 2021
Diamond Proposal Number(s): 15068 , 16650 , 18198

Abstract: High-resolution synchrotron x-ray radiography with computed tomography is used to observe the evolution of porosity created by thermal exposure in two HMX-based polymer-bonded explosive compositions; LX-04 and BX-63. The measurements were made in situ, over an extended period of time, during which the samples were heated on a slow-rate thermal trajectory. The tests ended with thermal-runaway to ignition after which the samples were consumed by combustion. The primary means of damage appears to be from mechanical debonding of the HMX-binder interface with secondary contribution from chemical decomposition. Confinement and binder properties affect the amount of porosity and permeability that develops. Additionally, observations were made describing the emergence and structure of an internal ignition volume, the formation and transport of a pre-ignition melt layer, and how the early stages of combustion were affected by material morphology, mechanical confinement and melt. The contact angle between molten HMX and the fluoropolymer, Viton A, is also presented. For the first time we have time-resolved x-ray images of ignition in sufficient detail to verify the mechanism of cookoff in polymer-bonded explosive compositions.

Journal Keywords: Radiography; Auto-ignition; Explosive behavior; Damage; Porosity; Convective burn

Subject Areas: Chemistry

Instruments: I13-2-Diamond Manchester Imaging