Classifications

• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06D—MEANS FOR GENERATING SMOKE OR MIST; GAS-ATTACK COMPOSITIONS; GENERATION OF GAS FOR BLASTING OR PROPULSION (CHEMICAL PART)
  • C06D5/00—Generation of pressure gas, e.g. for blasting cartridges, starting cartridges, rockets
  • C06D5/06—Generation of pressure gas, e.g. for blasting cartridges, starting cartridges, rockets by reaction of two or more solids
• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B23/00—Compositions characterised by non-explosive or non-thermic constituents
• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B35/00—Compositions containing a metal azide

Definitions

• the compo- 149/75 149/77 sition is useful as a source of gas to inflate bags used Int. I as restraint Systems f the protection of automobile [58] Field of Search 149/6, 35, 37, 75, 40,
• This invention relates to a composition of matter suitable for generating gases.
• Pyrotechnic compositions containing an alkali metal azide, oxidizing compound and a fuel such as boron or silicon are disclosed in US. Pat. No. 3,122,462. When used as sources of gas, however, these pyrotechnic compositions, depending upon the proportions of the ingredients, may exhibit a high burning rate, approaching detonation.
• a gas generating composition suitable for inflating an automobile restraint system has now been found which avoids the disadvantages of prior art propellant and pyrotechnic compositions.
• the novel composition contains an alkali metal or alkaline earth metal azide, an oxidizing compound and an oxide of silicon, aluminium, titanium, tin or zinc with or without admixture with silicon, aluminum, titanium, tin or zinc metal, said oxide, and metal if present, being in amount sufficient to react with metallic oxides produced during the decomposition of the azide.
• the composition produces nitrogen gas at a rate suitable for inflation of an automobile restraint bag and the solid products of gas forming reaction are non-toxic and non-corrosive.
• the gas generating composition of this invention comprises l an azide of an alkali metal or an alkaline earth (2) an oxidizing compound in proportion sufficient to react completely with said azide with the liberation of nitrogen gas therefrom, and (3) an oxide selected from the group consisting of silicon oxide, aluminum oxide, titanium oxide, tin oxide and zinc oxide, with or without admixture with a metal selected from the group consisting of silicon, aluminum, titanium, tin
• compositions containing only oxide as ingredient (3) burn more slowly than compositions having only metal as ingredient (3).
• (3) is a mixture of silica and silicon
• variation of the proportions of these two components provides a range of burning rates extending from about 1 10 milliseconds with silica only to about 1 1 milliseconds with silicon only, depending on the size and configuration of the propellant mass.
• the ingredients of the gas generating composition may be mixed together in the form of solid particles and ignited by means of a hot wire or a squib.
• the composition may be employed in two separate portions, a first portion comprising the azide and the oxidizing compound, and a second portion comprising the metallic oxide. The second portion will then be placed as a sheath about the first portion, or be placed in the outlet zone of the vessel carrying the gas generating composition.
• the gas generating composition will be enclosed in a vessel that communicates with the inflatable bag of the restraint system.
• a baffle and/or filtering device will be positioned in the gas duct between the gas generating vessel and the inflatable bag for the purpose of restricting the flow of solid products into the bag.
• reaction of the gas generating composition can be represented by the equation:
• Suitable azide ingredients of the gas generating compositions of this invention are lithium azide, sodium azide, potassium azide, rubidium azide, cesium azide, calcium azide, magnesium azide, strontium azide and bar- .ium azide.
• Oxides suitable as ingredients of the gas generating compositions include silicon dioxide (silica) aluminum oxide, titanium dioxide, tin oxide, and zinc oxide.
• Metals suitable as ingredients of the compositions include silicon, aluminium, titanium, tin and zinc.
• the proportions of the azide and oxidizing compound are chosen so that the azide will be completely reacted to form gaseous nitrogen.
• Azides are toxic materials and it is undesirable to inject unreacted azide into the inflatable restraint bag.
• the proportion of oxide and when present the metal is chosen so that the metallic residue of the reaction between the azide and the oxidizing compound will react to form the non toxic solid compounds.
• the oxide is silica and the metal silicon, the compounds formed will be silicates. In the case of other oxides and metals there will be formed oxygen-containing compounds such as aluminates, titanates, etc.
• the ingredients of the gas generating composition are employed in particulate form. Although particle size is not apparently critical, it is convenient to employ material in the particle size less than 100 mesh Tyler screen size.
• EXAMPLE 1 Three 40 gram charges of a composition containing sodium azide, silicon dioxide and potassium perchlorate in the molar proportions 814:1 were placed in canisters and ignited in a field test using a No. 8 electric blasting cap to initiate ignition. The material burned in slightly less than 1 second.
• EXAMPLE 2 One gram charge of the above formulation was ignited by an S1 19 squib. Material required about 3 seconds for complete combustion.
• EXAMPLE 3 Three 40 gram charges of a composition containing sodium azide, silicon and potassium perchlorate in molar proportions 8:4:3 were placed in canisters and ignited in a field test using a No. 8 electric blasing cap to initiate ignition. The material burned extremely quickly at a rate only fractionally less than a detonation.
• EXAMPLE 5 Two 5 gram charges of the material in Example 3 were placed in canisters and ignited in a closed high pressure vessel. Ignition was achieved by means of a hot wire. A peak pressure of approximately 900 psi. was achieved in 22 milliseconds after the initiation of combustion.
• EXAMPLE 6 Two 20 gram charges of the material in Example 3 were placed in canisters and ignited in a closed high pressure vessel. Ignition was by means of a hot wire. A peak pressure of approximately 9,000 p.s.i. was achieved in l 1 milliseconds after initiation of combustion.
• EXAMPLE 7 Five 20 gram charges of material in Example 1 were placed in canisters and ignited in a closed pressure vessel by means of a hot wire. A peak pressure of 2,500 p.s.i. was achieved in a combustion time of milliseconds. Some ignition delay was observed using the hot wire method of ignition. The above figure of 110 milliseconds is actual burn time, and does not include the delay period.
• EXAMPLE 8 Three 20 gram charges of a composition containing sodium azide, aluminum and potassium chlorate in the molar proportions 2:2:1 were placed in canisters and ignited in a closed high pressure vessel. ignition was by means of a hot wire. The samples had an average combustion time of 14 milliseconds. The residue of combustion was extracted with water and the water extract analyzed for sodium and aluminum. The atomic ratio Al/Na is given in table 1. it can be seen that the conversion of aluminum into sodium aluminate NaA1O is on average 52 percent efficient, since complete conversion would provide a Al/Na ratio of 1.0.
• EXAMPLE 9 Three 20 gram charges of a composition containing sodium azide. alumina (A1 0 and potassium perchlorate in the molar proportions 8:4:l were placed in canisters and ignited in a closed high pressure vessel. Ignition was by means of a hot wire. The samples had an average combustion time of milliseconds. The residue was analyzed as in Example 8. The results are given in Table 1. It can be seen that the conversion into sodium aluminate is on average 48 percent efficient.
• Silanox 101 fumed silica having a silane coating
• Silanox 101 has a surface area of 225 sq. meters/gram and a pH of 2. precipitated silica coated with polysiloxane.
• fumed silica coated with a silane acts as a desensitizer.
• a gas generating composition as claimed in claim 1 wherein the azide is selected from the group consisting of lithium azide, sodium azide, potassium azide, rubidium azide, cesium azide, calcium azide, magnesium azide, strontium azide and barium azide.
• a gas generating composition as claimed in claim 1 wherein the oxidizing compound is an inorganic perchlorate selected from the group consisting of lithium perchlorate, sodium perchlorate, potassium perchlorate, rubidium perchlorate, magnesium perchlorate, calcium perchlorate, strontium perchlorate, barium perchlorate, ferric perchlorate and cobalt perchlorate.
• a gas generating composition as claimed in claim 1 including as ingredient fumed silica coated with a water repellent.

Landscapes

• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Combustion & Propulsion (AREA)
• Air Bags (AREA)
• Emergency Lowering Means (AREA)
• Feeding, Discharge, Calcimining, Fusing, And Gas-Generation Devices (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Investigating Or Analyzing Materials By The Use Of Fluid Adsorption Or Reactions (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=10366188

Family Applications (1)

Country Status (10)

Cited By (40)

Families Citing this family (8)

Citations (4)

• 1972
  • 1972-07-24 GB GB3448172A patent/GB1391310A/en not_active Expired
• 1973
  • 1973-06-28 CA CA175,211A patent/CA997933A/en not_active Expired
  • 1973-07-02 US US375654A patent/US3883373A/en not_active Expired - Lifetime
  • 1973-07-17 NO NO2911/73A patent/NO136091C/no unknown
  • 1973-07-18 BE BE133624A patent/BE802514A/xx unknown
  • 1973-07-20 NL NL7310133A patent/NL7310133A/xx not_active Application Discontinuation
  • 1973-07-23 IT IT26931/73A patent/IT995049B/it active
  • 1973-07-23 FR FR7326881A patent/FR2193801B1/fr not_active Expired
  • 1973-07-23 SE SE7310254A patent/SE409451B/xx unknown
  • 1973-07-24 JP JP8281173A patent/JPS532156B2/ja not_active Expired

Patent Citations (4)

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