Classifications

• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B45/00—Compositions or products which are defined by structure or arrangement of component of product
• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B33/00—Compositions containing particulate metal, alloy, boron, silicon, selenium or tellurium with at least one oxygen supplying material which is either a metal oxide or a salt, organic or inorganic, capable of yielding a metal oxide
• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B45/00—Compositions or products which are defined by structure or arrangement of component of product
  • C06B45/18—Compositions or products which are defined by structure or arrangement of component of product comprising a coated component
  • C06B45/30—Compositions or products which are defined by structure or arrangement of component of product comprising a coated component the component base containing an inorganic explosive or an inorganic thermic component

Definitions

• the invention relates to nanostructured reactive substances according to the Preamble of claim 1.
• silicon atoms are exposed on the surface of the silicon structures and can react with the oxygen in the pores.
• the energy released by the oxidation reaction causes, among other things, the further removal of hydrogen from the surface of the silicon structures and thus the exposure of silicon atoms, which in turn now react with the oxygen in the environment.
• Partial oxidation of the surface of the silicon structures stabilizes the system. Since liquid oxygen has to be introduced for the reaction, it only takes place at cryogenic temperatures up to ⁇ 90K. The reaction is triggered spontaneously. The reactive system is therefore not stable and cannot be handled in practice.
• the invention is based on the object of a safely manageable nanostructured Propose reactive substance based on fuel and oxidant Nanometer size scale is stable and separated from each other Exposure to energy can be brought together for an explosive reaction.
• a mixture of fuel (silicon) and oxidant on a nanometer scale enables almost direct contact between the fuel and the Oxidizing agent, only separated by a barrier layer. After breaking the barrier layer the fuel and oxidant are spatially close together and can be below React energy release.
• the silicon-oxygen bond is e.g. B. about 18 KJ / mol stronger than the carbon-oxygen bond, which explains the increased energy density.
• the reactive substance according to the invention can be safely handled in the temperature range from - 40 ° C to + 100 ° C and also in the event of unwanted external influences such as impact, fall, Light, heat, electromagnetic fields, scoring or sawing in silicon process lines.
• the reactive substance can be integrated on chips or other components and is suitable for Detonator or igniter for impulse, gas, light, flame and shock wave generating media.
• the invention is suitable as a pulse element for projectiles, for position control of satellites and control of missiles, missiles and projectiles as well as for ignition of explosives and ignition of other charges, such as propellant charges, pyrotechnic charges.
• the reactive substance is also suitable as a chip-integrated, ultra-fast heating element for mass spectroscopic application or for the destruction of EPROMS.
• the reactive substance has a high energy density and energy release rate compared to conventional reactive materials.
• the energy release rate can be freely selected in a simple manner by choosing a suitable geometric structure and / or structure size. It can be set from burn-up to detonation. If the reactive substance is used as an explosive, the energy density is up to a factor of 5 greater than with TNT.
• Porous silicon will by electrochemical etching of crystalline silicon (e.g. silicon wafers, wafers) produced and represents a sponge-like structure, consisting of a silicon framework and pores (holes).
• the mean size, the pores and the remaining after etching Silicon structures, as well as the porosity can be selected by appropriate choice of parameters of the starting material used (substrate doping, etching current density, concentration or composition of the etching solution).
• pores and silicon structures in the range from approximately 1 nm to 1000 nm can be achieved.
• the porosity can be set over a range of 10% -98%. Since the pore network of the porous silicon samples is accessible from the outside (the environment), oxidizing agents can be introduced into the pores. The substances listed below appear suitable.
• the silicon-hydrogen bond is on the surface of the nanostructured framework relatively weak and thus the mixture present on the nanometer size scale is made Fuel (silicon) and oxidizing agent in the pores are relatively unstable.
• Fuel silicon
• oxidizing agent in the pores are relatively unstable.
• To increase the Stability requires additional passivation of the surface of the Silicon scaffold. This can e.g. through oxidation (thermal Treatment of the samples in an oxygen atmosphere) of the porous silicon sample after the Manufacture.
• a barrier or buffer layer is formed (suboxide layer consisting of a submonolayer of oxygen).
• the strength of the passivation can vary according to the duration of the thermal treatment (completeness of the oxidation of the surface) can be set. See the exemplary embodiment for details.
• the barrier layer increases the stability 'of the in the reactive state (filling the pores with oxidizing agent) brought samples.
• the introduced barrier layer can also act as a diffusion barrier for Slowly running oxidation processes act, which lead to a degradation of the reactive mixture.
• the hydrogen-covered surface of the silicon structures in porous silicon Air is not stable to oxidation. Forms in a period of about a year a submonolayer of silicon oxide on the surface of the silicon structures.
• the reactive samples are ignited by supplying energy and breaking the barrier layer on, whereby a direct contact of the fuel (silicon) with the oxidizing agent is achieved.
• Possible ignition mechanisms are shock, temperature increase (e.g. through Current flow or laser pulse), pulsed laser radiation (which, for example, resonates with a Silicon-hydrogen or silicon-oxygen surface bond is located).
• One advantage of this implementation is that, in contrast to porous silicon, there are no "connecting bridges" between the nanometer-sized silicon structures (solid framework) that can easily break when impacted, form free silicon bonds and thus lead to an unintended reaction.
• the compactible body in contrast to porous silicon, can also be shaped geometrically freely.
• Porous silicon with LiNO 3 as an oxidizing agent in the pores :
• Porous silicon is produced by electrochemically etching a silicon wafer (surface (100), specific conductivity 8 ohm centimeters) with an etching solution of hydrofluoric acid (HF 49 percent by weight in water) and ethanol (1: 1 by volume).
• the etching current density is 50 mA / cm 2 .
• the etching time is 30 minutes.
• the sample is annealed at 200 ° C in air for 1600 minutes
• the surface of the silicon structures is covered with a submonolayer (an atomic layer passivated under the surface of the silicon structures).
• the surface of the However, silicon structures remain covered with hydrogen.
• One more way consists of annealing at 700 ° C for 30 seconds. The will also Removed hydrogen from the surface of the silicon structures.
• the stability of the reactive samples filled with oxidizing agents can be slight or strong can be increased compared to the samples without tempering.
• a saturated solution of lithium nitrate LiNO 3 in methanol is applied to the sample.
• This saturated solution is drawn into the pores by capillary action.
• the solvent is evaporated.
• the application of the solution can be repeated several times in order to fill the pores as completely as possible with LiNO 3 .
• Metal contacts are then evaporated onto the porous silicon sample, to which a voltage is applied in order to trigger the reaction between silicon and the oxygen from the LiNO 3 .

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Crystallography & Structural Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Silicon Compounds (AREA)
• Fuel Cell (AREA)

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• 2002
  • 2002-02-06 DE DE10204895A patent/DE10204895B4/de not_active Expired - Fee Related
• 2003
  • 2003-02-05 EP EP03002476A patent/EP1334955A3/fr not_active Withdrawn
  • 2003-02-06 US US10/360,429 patent/US6803244B2/en not_active Expired - Fee Related

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