Showing papers on "Friction sensitivity published in 2013"

On the Reliability of Sensitivity Test Methods for Submicrometer-Sized RDX and HMX Particles

Abstract: Submicrometer-sized RDX and HMX crystals were produced by electrospray crystallization and submicrometer-sized RDX crystals were produced by plasma-assisted crystallization. Impact and friction sensitivity tests and ballistic impact chamber tests were performed to determine the product sensitivity. Rather than reflecting the quality of the particles, we found the sensitivity tests to be unreliable for submicrometer particles. The used impact test was not accurate enough, while in the friction and ballistic impact chamber tests the submicrometer-sized crystals were distributed among the grooves of the porcelain plate or among the grains of the sandpaper used in these tests. These observations stress the need for revisiting the current standards used for determining the hazardous properties like friction and impact sensitivity of energetic materials in the case, where the sample consists of submicrometer-sized crystals. Recommendations were suggested to develop new test methods that only use the interactions between the particles and therefore allow the application of sensitivity tests for submicrometer/nano-sized energetic materials. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Friction coefficients and grasp synthesis

Abstract: We propose a new concept called friction sensitivity which measures how susceptible a specific grasp is to changes in the underlying friction coefficients. We develop algorithms for the synthesis of stable grasps with low friction sensitivity and for the synthesis of stable grasps in the case of small friction coefficients. We describe how grasps with low friction sensitivity can be used when a robot has an uncertain belief about friction coefficients and study the statistics of grasp quality under changes in those coefficients. We also provide a parametric estimate for the distribution of grasp qualities and friction sensitivities for a uniformly sampled set of grasps.

Decreasing the Friction Sensitivity of TATP, DADP and HMTD

Abstract: The influence of water and WD-40 oil content on the sensitivity to friction of three primary explosives, triacetone triperoxide (TATP), diacetone diperoxide (DADP) and hexamethylene triperoxide diamine (HMTD), has been investigated. All of these explosives belong to a group of improvised explosives. The possibility of desensitization of these explosives by the addition of other substances was studied. Sensitivity curves were obtained for the solid organic peroxides with various liquid contents. The sensitivity decreases significantly with only a small quantity of liquid − up to about 20% of the liquid. Further increase in the liquid content has a negligible further impact on the sensitivity to friction. Water and WD-40 oil were compared as desensitizating agents.

Investigation on the Friction Sensitivity of a Matchhead Composition Influenced by the Surface Roughness of Contact Materials

Abstract: Fire and explosions in the processing of matchhead compositions are reported due to the friction sensitivity of materials used. This investigation is aimed at investigating the influence of different types of contact materials and their surface roughness on the friction sensitivity of a matchhead composition. The friction sensitivity of the matchhead composition was found to be dependent on the contact materials and their roughness. The results demonstrated that the contact materials and their surface roughness imparted variations to the sensitivity, ranging from 108 to 360 N. The sensitivity response of the energetic mixture was quicker in case of aluminum plate-aluminum pin combinations than those when steel plate-steel pin and brass plate-brass pin combinations were used. For the first time, the experimental investigation identified a new value based on the material’s surface roughnesses called critical surface roughness, at which the matchhead composition ignited at a minimum frictional load. The matchhead composition was found to be highly hazardous at the critical surface roughness values of 1.09, 1.01, and 1.05 μm for aluminum, brass, and steel surfaces, respectively. Based on the experimental results this paper also discusses mechanism of ignition caused by the frictional load.

Preparation and Study of Nano Octahydro-1,3,5,7tetranitro-1,3,5,7-tetrazocine

Abstract: Nano octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine(HMX) was prepared by the use of pulverized machine HLG-50.The size distribution was traced by the nano laser particle size analyzer,and the particle size was characterized by SEM.The contaminants were detected by the use of FT-IR,Raman spectra,XRD and ICP-AES.The thermal decomposition of nano HMX was described by the TG/DSC simultaneous thermal analyzer.The friction,impact and shock sensitivities were tested to indicate the stability.The result shows that the diameters of the most particles are less than 100 nm and the impurities in the product were absolutely few.The peak temperature of its thermal decomposition decreased a little compared with the raw materials.The friction sensitivity reduced by a large margin,particularly the impact and the shock sensitivities decreased 132.6% and 60.0%,respectively.The stability increased so much that there would be a good application.By the way,the mechanism of reduced sensitivity was discussed.

Novel friction sensitivity instrument

Abstract: The utility model provides a novel friction sensitivity instrument which is accurate in measurement. The novel friction sensitivity instrument comprises a base, as well as a movable bracket, a load arm and balance weights which are located on the base, wherein a handle capable of adjusting the movable bracket, and a switch are further arranged on the base; and a porcelain plate is arranged on the movable bracket, an adjusting rod is arranged at the free end of the porcelain plate, and a load controller is arranged on the load arm. According to the novel friction sensitivity instrument provided by the utility model, load control equipment is installed on the basis of the original available friction sensitivity instrument, so as to accurately control the load of the friction sensitivity instrument, thus ensuring the accuracy of the friction sensitivity instrument during the measurement process and the correctness of the measurement result.

Otrzymywanie i badanie właściwości 4,4',5,5'-tetranitro-2,2'-bi-1H-imidazolu (TNBI)

Abstract: The known synthesis methods of 4,4’,5,5’-tetranitro-2,2’-bi-1H-imidazole (tNBI) are reviewed. two novel nitration methods of 2,2’-biimidazole to tNBI were presented. solid products of reactions were analyzed using 1H, 13c NMR and IR spectroscopy. Thermal stability has been studied by Dta. friction sensitivity of main product was examined. Heat of combustion was measured and standard enthalpy of formation was calculated. Detonation velocity of tNBI for the density of 1.72 g/cm3 was measured.

Preparation, Characterization and Performances of Ultrafine CL-20/Cr_2O_3 Composite Energetic Materials

Abstract: In order to reduce the mechanical sensitivity of CL-20,ultrafine CL-20/Cr2O3composite energetic materials with the mean particle diameter of 1~2μm was prepared,by sol-gel method and supercritical drying technologyIts pattern,particle size and complex methods were characterized by SEM and FT-IR,and its impact sensitivity and its friction sensitivity were studiedTest results indicated that its characteristic droop is higher 2302% and its P(friction sensitivity) is decreased 30% than that of raw materials

An Efficient Synthesis of GUDN as Green Oxidizer

Abstract: N-Guanylurea dinitramide (GUDN) is an energetic material with low sensitivities and good performance for use as propellants or insensitive munitions explosives. The efficient synthesis and characterization of high energy density material of GUDN is reported. GUDN was characterized spectroscopically as well as elemental analysis. In addition, the heats of formation were calculated with the Gaussian 09 suite of programs. For initial safety testing, the impact sensitivity and the friction sensitivity were tested following BAM procedure.

Sensitivity Characteristics of Double Base Propellants Containing Super Thermites

Abstract: Super thermites Al/PbO,Al/CuO and Al/Bi2O3 were prepared by ultrasonic dispersion method using nano-Al,micro-Al,nano-PbO,nano-CuO and nano-Bi2O3 as the raw materials.On the bases of results of compatibility evaluation between super thermites and some double-base(DB) propellant components,these super thermites were applied in DB propellant.According to the national military standard methods,the mechanical sensitivity of different MIC-DB propellants was reviewed.Electrostatic spark sensitivity tester was employed to evaluate the risk of different MIC-DB propellants v.s.electrostatic response.The thermal sensitivity of several MIC-DB propellants was studied by 5s explosion temperature method.The results show that the effect of impact sensitivity of thermites on DB propellants is smaller,the friction sensitivities of several MIC-DB propellants are slightly larger,and the type of thermites has little effect on the friction sensitivity of MIC-DB propellants.The electrostatic spark sensitivity of all MIC-DB propellants is relatively low.The thermal sensitivity of several MIC-DB propellants is affected by the size of nano-Al and the category of super thermites.In comparison with the MIC-DB propellants with micro thermites,the heat-resistance of nano-MIC-DB propellants is larger.

친환경 산화제 gudn의 효율적 합성

Abstract: N-Guanylurea dinitramide (GUDN) is an energetic material with low sensitivities and good performance for use as propellants or insensitive munitions explosives. The efficient synthesis and characterization of high energy density material of GUDN is reported. GUDN was characterized spectroscopically as well as elemental analysis. In addition, the heats of formation were calculated with the Gaussian 09 suite of programs. For initial safety testing, the impact sensitivity and the friction sensitivity were tested following BAM procedure.