Modern mining explosives employ solutions of ammonium nitrate, where the solution is the oxidising component of a fuel/oxidiser mixture. This thesis is primarily concerned with the shock response of water and of aqueous solutions of ammonium nitrate. Of particular interest are the temperatures induced through shock compression. An experimental facility, using a single stage gas gun in the 'plate impact' configuration, is described, along with associated experimental diagnostics. Measurements of, and improvements to, the tilt at impact are reported. The problem of shock temperature is discussed, including a brief review of the relevant literature. It is demonstrated that direct measurement of shock temperature is a complex issue that is not yet fully understood, whereas determination of temperature from an equation of state is an established technique. In a series of experiments, plate impact techniques were utilised to determine the Hugoniot and, through shock/reload experiments, the equation of state of water and aqueous solutions of ammonium nitrate. In-situ manganin gauges were used to measure stresses in the liquids and, from the arrival times of the shock wave, determine the shock velocity. Linear shock velocity-particle velocity Hugoniots for the liquids were determined, up to particle velocities of 1km/s, with uncertainties on the intercept and slope of these Hugoniots of 5%. A Mie-Grûneisen equation of state was used to describe the shock/reload experiments. Approximate calculations of shock temperature are reported. Increasing ammonium nitrate concentrations resulted in greater calculated temperatures. It was demonstrated that the liquids investigated in this thesis show a temperature dependence of the Grûneisen parameter, ?, which cannot be accommodated in the model. The present work is believed to be the first demonstration of this effect in shock compressed liquids. The data presented provide constraints on future theoretical development of equations of state.

The object of this study was to investigate the micro-structural response of DP 600 subjected to high strain rate, ballistic impact tests. The ballistic tests were conducted using normal impact of a hardened steel penetrator into a 2 mm thick sheet of DP 600. The average strain rates produced from this test method are on the order of 10^5 s-1. Multiple methods were used to investigate the micro-structure before and after high strain rate deformation including optical microscopy, electron microscopy, and X-ray diffraction. A large variation in material response was observed between tests conducted at 0.8 x 10^5 and 2.5 x 10^5 s-1.

For roughly fifteen years the military has sought to use the properties of ceramics for armor applications. Current high-performance ceramics have extremely high compressive strengths and low densities. One ceramic that has been shown to be highly resistant under ballistic impact is silicon carbide (SiC). It has been found that even within the silicon carbides, those manufactured by certain methods and those with certain microstructural properties have advantages over others. In order to understand the microstructural reasons behind variations in ballistic properties, plate impact tests were conducted on two sintered silicon carbides with slightly different microstructures. Two variations of a silicon carbide with the trade name Hexoloy SA were obtained through Saint Gobain. Regular Hexoloy (RH) and Enhanced Hexoloy (EH) are pressureless sintered products having exactly the same chemistries. EH went through additional powder processing prior to sintering, producing a final product with a slightly different morphology than RH. Samples of each were characterized microstructurally including morphology, density, elastic wavespeeds, microhardness, fracture toughness, and flexure strength. The characterization revealed differences in porosity distribution and flexure strength. It was determined that the porosity distribution in EH had fewer large pores leading to an 18% increase in flexural strength over that for RH. The focus of the mechanics of materials community concerning dynamic material behavior is to pin down what exactly is happening microstructurally during ballistic events. Several studies have been conducted where material properties of one ceramic type are varied and the dynamic behavior is tested and analyzed. Usually, from one variation to the next, several properties are different making it hard to isolate the effect of each. For this study, the only difference in the materials was porosity distribution. Plate impact experiments were conducted at the Army Research Laboratory (ARL) using the gas gun facilities within the Impact Physics Branch. A VISAR was utilized to measure free surface velocities. Tests were performed on each material to determine the Hugoniot Elastic Limit (HEL) and spall strength. Spall strength was measured as a function of impact stress, and pulse duration.

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This work presents a systematic study of the mechanochemical processes leading to chemical reactions occurring due to effects of high-strain-rate deformation associated with uniaxial strain and uniaxial stress impact loading in highly heterogeneous metal powder-based reactive materials, specifically compacted mixtures of Ti/Al/B powders. This system was selected because of the large exothermic heat of reaction in the Ti+2B reaction, which can support the subsequent Al-combustion reaction. The unique deformation state achievable by such high-pressure loading methods can drive chemical reactions, mediated by microstructure-dependent meso-scale phenomena. Design of the next generation of multifunctional energetic structural materials (MESMs) consisting of metal-metal mixtures requires an understanding of the mechanochemical processes leading to chemical reactions under dynamic loading to properly engineer the materials. The highly heterogeneous and hierarchical microstructures inherent in compacted powder mixtures further complicate understanding of the mechanochemical origins of shock-induced reaction events due to the disparate length and time scales involved. A two-pronged approach is taken where impact experiments in both the uniaxial stress (rod-on-anvil Taylor impact experiments) and uniaxial strain (instrumented parallel-plate gas-gun experiments) load configurations are performed in conjunction with highly-resolved microstructure-based simulations replicating the experimental setup. The simulations capture the bulk response of the powder to the loading, and provide a look at the meso-scale deformation features observed under conditions of uniaxial stress or strain. Experiments under uniaxial stress loading reveal an optimal stoichiometry for Ti+2B mixtures containing up to 50% Al by volume, based on a reduced impact velocity threshold required for impact-induced reaction initiation as evidenced by observation of light emission. Uniaxial strain experiments on the Ti+2B binary mixture show possible expanded states in the powder at pressures greater than 6 GPa, consistent with the Ballotechnic hypothesis for shock-induced chemical reactions. Rise-time dispersive signatures are consistently observed under uniaxial strain loading, indicating complex compaction phenomena, which are reproducible by the meso-scale simulations. The simulations show the prevalence of shear banding and particle agglomeration in the uniaxial stress case, providing a possible rationale for the lower observed reaction threshold. Bulk shock response is captured by the uniaxial strain meso-scale simulations and is compared with PVDF stress gauge and VISAR traces to validate the simulation scheme. The simulations also reveal the meso-mechanical origins of the wave dispersion experimentally recorded by PVDF stress gauges.