WO1995018780A1

WO1995018780A1 - Non-azide gas generant compositions containing dicyanamide salts

Info

Publication number: WO1995018780A1
Application number: PCT/US1995/000040
Authority: WO
Inventors: Reed J. Blau; David A. Flanigan
Original assignee: Thiokol Corporation
Priority date: 1994-01-10
Filing date: 1995-01-04
Publication date: 1995-07-13
Also published as: AU1521595A

Abstract

Gas generating compositions for inflating automobile air bags and similar devices are provided. The gas generating compositions use dicyanamide salts as a primary fuel. The dicyanamide salts are selected from the group consisting of alkali metal, alkaline earth metal, metalloidal, and transition metal dicyanamides, and complexes thereof. If desired other fuels, in addition to the dicyanamide salts may be incorporated into the compositions. Such fuels may include organic fuels, preferably with high nitrogen contents or nitrides. The compositions also include oxidizer-effective quantities of oxidizers. Typically, such oxidizers will be selected from the group consisting of metal nitrates, metal perchlorates, metal chlorates, and transition metal oxides. In some cases it may be desired to include a second oxidizer in addition to those listed above. Examples of such additional oxidizers will include transition metal oxides such as Fe2O3, MnO2, and CuO, and Co2O3.

Description

NON-AZIDE GAS GENERANT COMPOSITIONS CONTAINING DICYANAMIDE SALTS

Field of the Invention The present invention relates to novel gas generating compositions for inflating automobile air bags and similar devices. More particularly, the present invention relates to the use of dicyanamide salts, and derivatives thereof, as primary fuels in gas generating pyrotechnic compositions.

Background of Invention Gas generating chemical compositions are useful in a number of different contexts. One important use for such compositions is in the operation of "air bags." Air bags are gaining in acceptance to the point that many, if not most, new automobiles are equipped with such devices. Indeed, many new automobiles are equipped with multiple air bags to protect the driver and passengers.

In the context of automobile air bags, sufficient gas must be generated to inflate the device within a fraction of a second. Between the time the car is impacted in an accident, and the time the driver would otherwise be thrust against the steering wheel, the air bag must fully inflate. As a conse¬ quence, nearly instantaneous gas generation is required. There are a number of additional important design criteria that must be satisfied. Automobile manufacturers and others set forth the required criteria which must be met in detailed specifications. Preparing gas generating compositions that meet these important design criteria is an extremely difficult task. These specifications require that the gas generating composition produce gas at a required rate. The specifications also place strict limits on the generation of toxic or harmful gases or solids. Examples of restricted gases include carbon monoxide, carbon dioxide, NOx, SOx, and hydrogen sulfide. The automobile manufacturers have also specified that the gas be generated at a sufficiently and reasonably low tempera¬ ture so that the occupants of the car are not burned upon impacting an inflated air bag. If the gas produced is overly hot, there is a possibility that the occupant of the motor vehicle may be burned upon impacting a just deployed air bag. Accordingly, it is necessary that the combination of the gas generant and the construction of the air bag isolates automo¬ bile occupants from excessive heat. All of this is required while the gas generant maintains an adequate burn rate. In the industry, burn rates in excess of 0.5 inch per second (ips) at 1,000 psi (pounds per square inch) , and preferably in the range of from about 1.0 ips to about 1.2 ips at 1,000 psi are generally desired. As used herein, 1 pound equals 453.593 grams and 1 inch equals 0.0254 meters.

Another related but important design criteria is that the gas generant composition produces a limited quantity of particulate materials. Particulate materials can interfere with the operation of the supplemental restraint system, present an inhalation hazard, irritate the skin and eyes, or constitute a hazardous solid waste that must be dealt with after the operation of the safety device. The latter is one of the undesirable, but tolerated in the absence of an acceptable alternative, aspects of the present sodium azide materials.

In addition to producing limited, if any, quantities of particulates, it is desired that at least the bulk of any such particulates be easily filterable. For instance, it is desirable that the composition produce a filterable, solid slag. If the solid reaction products form a stable material, the solids can be filtered and prevented from escaping into the surrounding environment. This also limits interference with the gas generating apparatus and the spreading of potentially harmful dust in the vicinity of the spent air bag which can cause lung, mucous membrane and eye irritation to vehicle occupants and rescuers.

Both organic and inorganic materials have also been proposed as possible gas generants. Such gas generant composi- tions include oxidizers and fuels which react at sufficiently high rates to produce large quantities of gas in a fraction of a second. At present, sodium azide is the most widely used and accepted gas generating material. Sodium azide nominally meets industry specifications and guidelines. Nevertheless, sodium azide presents a number of persistent problems. Sodium azide is relatively toxic as a starting material, since its toxicity level as measured by oral rat LD₅₀ is in the range of 45 mg/kg. Workers who regularly handle sodium azide have experienced various health problems such as severe headaches, shortness of breath, convulsions, and other symptoms. In addition, sodium azide combustion products can also be toxic since molybdenum disulfide and sulfur are presently the preferred oxidizers for use with sodium azide. The reaction of these materials produces toxic hydrogen sulfide gas, corrosive sodium oxide, sodium sulfide, and sodium hydroxide powder. Rescue workers and automobile occupants have complained about both the hydrogen sulfide gas and the corrosive powder produced by the operation of sodium azide-based gas generants.

Increasing problems are also anticipated in relation to disposal of unused gas-inflated supplemental restraint systems, e.g. automobile air bags, in demolished cars. The sodium azide remaining in such supplemental restraint systems can leach out of the demolished car to become a water pollutant or toxic waste. Indeed, some have expressed concern that sodium azide, when contacted with battery acids following disposal, forms explosive heavy metal azides or hydrazoic acid.

Sodium azide-based gas generants are most commonly used for air bag inflation, but with the significant disadvantages of such compositions many alternative gas generant compositions have been proposed to replace sodium azide. Most of the proposed sodium azide replacements, however, fail to deal adequately with each of the selection criteria set forth above.

It will be appreciated, therefore, that there are a number of important criteria for selecting gas generating compositions for use in automobile supplemental restraint systems. For example, it is important to select starting materials that are not toxic. At the same time, the combustion products must not be toxic or harmful. In this regard, industry standards limit the allowable amounts of various gases produced by the opera¬ tion of supplemental restraint systems.

It would, therefore, be a significant advancement in the art to provide compositions capable of generating large quantities of gas that would overcome the problems identified in the existing art. It would be a further advancement to provide gas generating compositions which are based on sub¬ stantially nontoxic starting materials and which produce substantially nontoxic reaction products. It would be another advancement in the art to provide gas generating compositions which produce limited particulate debris and limited undesir¬ able gaseous products. It would also be an advancement in the art to provide gas generating compositions which form a readily filterable solid slag upon reaction. Such compositions and methods for their use are disclosed and claimed herein.

Summary and Objects of the Invention The present invention is related to the use of composi- tions which include dicyanamide salts as fuels in gas gener¬ ants. The gas generant compositions are particularly adaptable for use in automobile air bag systems and avoid the toxicity problems of conventional azide gas generants. The compositions of the present invention are tailorable to provide burn rates and gas outputs sufficient to operate such automobile air bag systems.

The compositions are composed of one or more fuels, one or more oxidizers, and other optional components, such as binders. The primary fuel components are dicyanamide compounds, including alkali metal, alkaline earth metal, metalloidal, or transition metal derivatives or complexes of dicyanamides, or mixtures thereof. One preferred dicyanamide salt is sodium dicyanamide (NaN(CN)₂) .

If desired, other fuels, in addition to the dicyanamide salts, may be incorporated into the compositions. Such fuels may include organic fuels, preferably with high nitrogen contents. Examples of this type of fuel include aminotetra- zoles, azobitetrazoles, bitetrazoles, and alkali metal, alkaline earth, and transition metal salts thereof. The compositions may also include nitrides as fuels. Examples of these materials include boron nitride, silicon nitride, titanium nitride, phosphorous nitride, iron nitride, ternary nitrides and complex nitride phases.

The compositions also include oxidizer-effective quanti¬ ties of oxidizers. It is presently preferred that the oxidizer be present in amounts ranging from about 50% to about 200% of the stoichiometric amount necessary to oxidize the fuels present in the composition.

Typically, such oxidizers will be selected from the group consisting of metal nitrates, metal perchlorates, metal chlorates, and transition metal oxides. In some cases it may be desired to include a second oxidizer in addition to those listed above. Examples of such additional oxidizers include transition metal oxides such as Fe₂θ₃, Mn0₂, and CuO, and Co₂0₃.

The present compositions can also include additives conventionally used in gas generating compositions, propel- lants, and explosives such as binders, burn rate modifiers, slag formers, release agents, and additives which effectively remove NO_x. Typical binders include lactose, boric acid, silicates including magnesium silicate, polypropylene carbon¬ ate, polyethylene glycol, zinc bisaminotetrazolate, amino- tetrazole, polypropylene carbonate, alumina and other conven¬ tional polymeric binders. Typical burn rate modifiers include Fe₂0₃, K₂Bι₂Hi₂, Bi₂Mo0₆, and graphite carbon fibers. A number of slag forming agents are known and include, for example, clays, talcs, silicon oxides, alkaline earth oxides, hydroxides, oxalates, of which magnesium carbonate, and magnesium hydroxide are exemplary. A number of additives and/or agents are also known to reduce or eliminate the oxides of nitrogen from the combustion products of a gas generant composition, including alkali metal salts and complexes of tetrazoles, aminotetra- zoles, triazoles and related nitrogen heterocycles of which potassium aminotetrazole, sodium carbonate and potassium carbonate are exemplary. The composition can also include materials which facilitate the release of the composition from a mold such as graphite, molybdenum sulfide, or boron nitride. As mentioned above, these compositions are particularly adaptable for use in automobile air bag systems. Such systems typical include a collapsed, inflatable air bag, and a gas generating device connected to said air bag for inflating said air bag, said gas generating device containing the gas generat¬ ing compositions described herein. Such devices are well known and conventional in the art. In more general terms, the compositions of the present invention can be used in connection with gas generating devices of various types. The essential components of such devices include the gas generating composi¬ tions of the present invention and means for igniting the composition. The present compositions are particularly useful for generating large quantities of a nontoxic gas, such as nitrogen gas. Significantly, the present compositions avoid the use of azides, produce no sodium hydroxide by-products, generate no sulfur compounds such as hydrogen sulfide and sulfur oxides, and still produce a nitrogen containing gas. The compositions of the present invention also produce only limited particulate debris, provide good slag formation and avoid, if not substan¬ tially avoid, the formation of nonfilterable particulate debris. At the same time, the compositions of the present invention achieve a relatively high burn rate, while producing a reasonably low temperature gas. Thus, the gas produced by the present invention is readily adaptable for use in deploying supplemental restraint systems, such as automobile air bags.

Detailed Description of the Invention

The present invention is related to the use of dicyanamide salts as fuels in gas generating compositions. It is observed that such compositions are capable of reacting with an appro¬ priate oxidizer to yield significant quantities of non toxic gases. The decomposition takes place at a rate sufficient to qualify such materials for use as gas generating compositions in automobile air bags and other similar types of devices. Basic Compositions

As mentioned above, the primary fuel component is a dicyanamide. Suitable dicyanamide compounds include alkali metal, alkaline earth metal, metalloidal, transition metal dicyanamides, complexes, and mixtures thereof. More particu¬ larly, these salts or complexes include those of transition metals such as copper, cobalt, iron, titanium, and zinc; alkali metals such as potassium and sodium; alkaline earth metals such as strontium, magnesium, and calcium; boron; aluminum; and nonmetallic cations such as ammonium, hydroxylammonium, hydrazinium, guanidinium, aminoguanidinium, diaminoguanidinium, triaminoguanidinium, or biguanidinium.

The fuel is combined with a suitable oxidizer, such as metal nitrates, metal perchlorates, metal chlorates, and transition metal oxides. The oxidizer is present in the composition in an amount in the range of from about 50% to about 200% of the stoichiometric amount necessary to oxidize the fuel present in the composition, including said dicyana¬ mide. In one example of the compositions of the present inven¬ tion 68.74% (all percentages are weight percent unless other¬ wise indicated) strontium nitrate was combined with 31.26% sodium dicyanamide. This composition was formulated by mixing via water slurry, and then drying the resulting mixture under vacuum. The dried mixture was then pressed into pellets. An alternative example combined 69.50% strontium nitrate, 27.50% sodium dicyanamide, and 3.00% lactose as a binder. Pellets of the mixture were made by the procedure outlined above.

The compositions were found to be stable and relatively safe to handle. When the compositions were burned, minimal quantities of steam were produced. Very low levels of carbon monoxide were observed. However, the burn rate was relatively high, as was the overall gas output. Specifically, the burn rate for the second formulation was 1.04 inches per second at 1,000 psi.

The properties observed for these compositions were adequate to inflate automotive air bags in the required time frame. This was confirmed further by igniting 25 3/8 inch diameter pellets weighing a total of 15.26 grams in a standard gas generating test fixture. The combustion chamber reached a maximum pressure of 1,750 psi at 0.025 seconds.

Compositions Employing Multiple Fuels

As discussed above, it is also possible to provide gas generating compositions which employ fuels other than dicyan¬ amide salts alone. In these compositions a second fuel component is added.

One type of additional fuel includes high nitrogen content organic materials. Examples of these materials include aminotetrazoles, azobitetrazoles, bitetrazoles, and alkali metal, alkaline earth, and transition metal salts thereof. The relative percentage of dicyanamide salt to organic fuel can vary widely depending on the desired performance.

The addition of a tetrazole component to the composition enhances significantly the crush strength of pellets formed using these compositions. Upon combustion, an increase in the nitrogen content of the generant gases, relative to carbon dioxide, is observed. Presently, restrictions have been placed on the levels of carbon dioxide that can be produced from gas generants used in the automotive industry. Even a small percentage of a dicyanamide salt added to a composition containing a tetrazole, or tetrazole salt, enhances the burn rate of the composition. Thus, compositions containing both dicyanamide salts and tetrazoles often exhibit enhanced performance over compositions containing only one of the fuels.

An example of such a composition includes 61.85% strontium nitrate, 9.69% sodium dicyanamide, 25.46% zinc aminotetrazo- late, and 3.00% lactose. This composition had a flame tempera¬ ture of 2316°K and burn rate of 0.83 ips. This burn rate was significantly higher than the 0.49 ips rate obtained for a formulation where zinc aminotetrazole was the sole fuel. Table I illustrates six (6) exemplary formulations which incorporate both a dicyanamide and an organic fuel. All values are weight percent. Table II provides performance data for each formulation.

TABLE I

Code Sr(N0₃)₂ Zn(AT)₂ NaN(CN)₂ Cu(II) Co(II) [ATH]* Oxide Oxide

1 58.48 34.88 6.65 — —

2 48.73 29.06 5.54 — 16.67

3 40.53 28.24 5.41 25.82 —

4 29.14 19.57 7.46 43.82

5 42.49 [12.64] 13.23 31.54 -

6 24.52 [9.86] 10.31 55.30 -

*Zn(AT)₂ is zinc bis(aminotetrazole) , [ATH] is aminotetrazole, the percentages shown in brackets.

Each of the formulations were mixed via water slurry and dried under vacuum. The formulations were found to be rela¬ tively safe. For burn rate analyses, the formulations were pressed into 3-4 gram 0.5 inch diameter pellets using a Carver Model M hydraulic press held at 6,000 lb gauge pressure for 40 seconds. Pellet strength was measured on pellets with a 0.37 inch diameter, a 0.19 inch maximum height, and a 0.13 inch cylinder height that were formed at 3,400 lb gauge pressure for 20 seconds. The load at failure as measured on an Instron tensiometer ranged from 30 pounds to 60 pounds.

The pellets were burned. The gases produced for samples 1-4 range from about 60% (volume percent) to about 62% nitro- gen, from about 24% to about 29% carbon dioxide, and about 11% to about 15% water vapor. The gases produced for samples 4 and 6 ranged from about 56% to about 57% nitrogen, from about 32% to about 33% carbon dioxide, and about 11% water vapor. Performance date for these formulations is summarized in Table II. TABLE II

*Gas yields are based on a comparison with convention sodium azide gas generating compositions

It will be appreciated that the ballistic data indicate that the formulations have characteristics within the range necessary for usable automobile gas generant compositions.

In an alternative set of embodiments, a second fuel is selected from the group consisting of nitrides. Nitrides of the following types are usable: binary nitrides including boron nitride (BN) , silicon nitride (Si₃N₄) , titanium nitride (TiN) , phosphorus(V) nitride (P₃N₅) , and iron nitride (Fe₅N₂) ; ternary nitrides such as Mg₂PN₃; and complex nitride phases such as Zn₇[Pι₂N₂₄]Cl₂. Gas generants containing nitrides as the sole fuel are difficult to ignite and combust efficiently. Further¬ more, their overall gas yield is low. The addition of dicyan- amide salts enhances significantly ignition and combustion efficiency, in addition to increasing the overall gas yield. Synergistically, the nitrides enhance the nitrogen content of the gases produced upon combustion. In addition, they increase the filterability of the slag produced. Examples of such compositions were formulated and include:

(1) 70.0% strontium nitrate, 17.97% sodium dicyan¬ amide, 10.02% boron nitride, and 2.00% lactose.

(2) 67.26% strontium nitrate, 17.20 percent sodium dicyanamide, 13.55% silicon nitride, and 2.00% lactose. (3) 63.78% strontium nitrate, 14.31% sodium dicyan¬ amide, 19.90% titanium nitride, and 2.00% lactose.

Each of those formulations was mixed via water slurry, dried under vacuum, and pressed into pellets. Performance of these compositions was compared to that for a formulation containing sodium dicyanamide only. That formulation (formulation 4) comprised 69.50% strontium nitrate, 27.50% sodium dicyanamide, and 3.00% lactose. The data obtained is as follows:

TABLE III

Code Flame temp Gas Yield Burn rate Crush (°K) (ips) strength (pounds)

1 2382 0.91 0.52 35

2 2520 0.89 0.68 15

3 2465 0.86 0.55 15

4 2076 0.99 1.04 14

Once again, gas yields are as compared to conventional sodium azide compositions.

Compositions Employing Multiple Oxidizers

It has been found advantageous in certain applications to add a mixture of transition metal oxides as additional oxidiz¬ ing species. Examples of these materials include Fe₂0₃ Mn0₂ CuO, and Co₂0₃.

Formulations employing this approach are described in Table IV. All amounts are expressed in weight percent. TABLE IV

Code Sr(N0₃)₂ Zn(AT)₂ NaN(CN)₂ Cu(II) Fe(III) Oxide Oxide

1 49.80 30.77 5.87 6.24 7.87

2 48.70 29.87 5.69 - 15.74

3 49.80 31.68 6.04 12.48 -

These formulations were mixed in the same manner described above and tested for burn rate and flame temperature. The data are set forth in Table V.

TABLE V

Code Flame Temp. Burn Rate (°K) (ips)

1 2070 1.15

2 2032 0.724

3 2108 0.782

It is noteworthy that the composition containing two oxidizers displays an enhanced burn rate when compared to compositions containing a comparable quantity of only one of the oxidizers.

The present invention is further described in the follow¬ ing non-limiting examples.

Example 1 A gas generating formulation containing sodium dicyan¬ amide, strontium nitrate, and lactose was prepared. Strontium nitrate powder (34.75 grams, 69.50%) , sodium dicyanamide powder (13.75 grams, 27.50%) and lactose powder (1.5 gram, 3.00%) were slurried in approximately 25 ml of water to make a thin paste. The resulting paste was dried in vacuo (1 mm Hg) at 170°F with occasional stirring until completely dry. The dry composition was then pressed into pellets. The pellets were tested for burning rate, density and mechanical crush strength. Burning rate was found to be 1.04 ips at 1,000 psi, with a burn rate exponent of 0.32 over the range of 400 to 1,800 psi. The crush strength was found to be 23 pounds load at failure. The density of the composition was found to be 1.96 grams/cc.

Example 2 A sodium dicyanamide containing composition having strontium nitrate oxidizer was prepared according to the process of Example 1. The composition was tested by combusting a multiple pellet charge in a ballistic test device. The test device comprised a combustion chamber equipped with a conven¬ tional 0.25 gram BKN0₃ igniter. The combustion chamber included a fluid outlet to a 13 liter tank filled with argon. The test fixture was configured such that the environment of an automobile air bag was approximated.

In this experiment, 25 3/8 inch diameter pellets weighing a total of 15.26 grams were ignited and allowed to undergo combustion. The combustion chamber reached a maximum pressure of 1750 psi at 0.025 seconds. The maximum tank pressure was 95 psia. Gases in the tank were found to be 78.0% argon, 13.9% nitrogen, 7.5% carbon dioxide, 0.4% oxygen, 0.2% N0_X, and less than 0.1% carbon monoxide.

Example 3 A gas generating formulation containing sodium dicyan¬ amide, strontium nitrate, boron nitride and lactose (35 grams total weight) was prepared. Strontium nitrate powder (24.50 grams, 70.01%), sodium dicyanamide powder (6.29 grams, 17.97%), boron nitride powder (3.51 grams, 10.02%), and lactose powder (0.70 grams, 2.00%) were slurried in approximately 10 ml of water to make a thin paste. The resulting paste was dried in vacuo (1 mm Hg) at 170 °F with occasional stirring until completely dry. The weight of the slag after ignition of a small amount of powder suggested complete combustion of the boron nitride. Pellets were tested for burning rate, density, and mechanical crush strength. The burn rate was found to be 0.52 ips at 1,000 psi for 3 gram, 1/2 inch diameter pellets having a density of 2.1 grams/cc. The predicted flame temperature is 2382 °K and predicted volume-corrected gas yield relative to a commercially available azide-formulation is 0.91. The crush strength was found to be 35 pounds load at failure for 3/8 inch diameter pellets with a 0.19 inch maximum height.

Example 4

A 35 gram mix of gas generating formulation containing strontium nitrate (23.54 grams, 67.26%), sodium dicyanamide (6.02 grams, 17.20%), silicon nitride (4.74 grams, 13.55%), and lactose powder (0.70 grams, 2.00%), was slurried, dried, prepared for analysis and analyzed similarly to the formulation in Example 4.

The composition yielded the following data. The weight of the combustion residue suggested complete oxidation of the silicon nitride. The burn rate was found to be 0.68 ips for pellets with a density of 2.1 grams/cc, whereas the crush strength was found to be 15 pounds load at failure. The predicted flame temperature is 2530 °K and predicted volume- corrected gas yield is 0.89.

Example 5

A 35 gram mix of gas generating formulation containing strontium nitrate (22.32 grams, 63.78%), sodium dicyanamide (5.01 grams, 14.31%), titanium nitride (6.97 grams, 19.90%), and lactose powder (0.70 grams, 2.00%), was slurried, dried, prepared for analysis and analyzed similarly to the formulation of Example 4 yielding the following data. The weight of the combustion residue suggested complete oxidation of the titanium nitride.

The burn rate was found to be 0.55 ips for pellets with a density of 2.3 grams/cc whereas the crush strength was found to be 15 pounds load at failure. The predicted flame temperature is 2465 °K and predicted volume-corrected gas yield is 0.86. Summary In summary, the present invention provides composition for use as gas generants. The compositions of the present inven¬ tion overcome significant limitations of the existing art. The present invention provide non-azide gas generant compositions which still burn at a relatively high rate and provide a significant gas output. In addition, the compositions of the present invention substantially avoid the formulation of toxic or dangerous gaseous or solid reaction products. The present invention may be embodied in other specific forms without departing from its essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. What is claimed is:

Claims

1. A solid gas generating composition comprising a fuel and an oxidizer therefor, said fuel selected from the group consisting of alkali metal, alkaline earth metal, metalloidal, and transition metal dicyanamides, and complexes and mixtures thereof.

2. A solid gas generating composition as defined in claim 1 wherein said dicyanamide comprises sodium dicyanamide.

3. A solid gas generating composition as defined in claim 1 wherein said oxidizer is selected from the group consisting of metal nitrates, metal perchlorates, metal chlorates, and transition metal oxides.

4. A solid gas generating composition as defined in claim 1 wherein said oxidizer is present in the composition in an amount in the range of from about 50% to about 200% of the stoichiometric amount necessary to oxidize said fuel.

5. A solid gas generating composition as defined in claim 1 wherein said fuel further comprises an organic fuel in addition to said dicyanamide fuel, said organic fuel selected from the group consisting of aminotetrazoles, azobitetrazoles, bitetrazoles, and alkali metal, alkaline earth, and transition metal salts thereof.

6. A solid gas generating composition as defined in claim 1 wherein said fuel further comprises a nitride in addition to said dicyanamide fuel.

7. A solid gas generating composition as defined in claim 6 wherein said nitride is selected from the group consisting of boron nitride, silicon nitride, titanium nitride, phosphorous nitride, and iron nitride.

8. A solid gas generating composition as defined in claim 6 wherein said nitride is selected from the group consisting ternary nitrides and complex nitride phases.

9. A solid gas generating composition as defined in claim 1 wherein said oxidizer further comprises a second oxidizer component selected from the group consisting of transition metal oxides.

10. A solid gas generating composition as defined in claim 9 wherein said transition metal oxide is selected from the group consisting of Fe₂0₃, Mn0₂, and CuO, and Co₂0₃.

11. A solid gas generating composition as defined in claim 1 further comprising up to about 50% by weight binder.

12. A solid gas generating composition as defined in claim 11 wherein said binder is selected from the group consisting of lactose, zinc bisaminotetrazolate, aminotetra- zole, polypropylene carbonate, and alumina.

13. A solid gas generating composition as defined in claim 1 wherein said dicyanamide salts and complexes comprise transition metal salts and complexes.

14. A solid gas generating composition as defined in claim 1 wherein said dicyanamide salts and complexes comprises salts and complexes of non metallic cations.

15. A solid gas generating composition as defined in claim 14 wherein said non metallic cations are selected from the group consisting of ammonium, hydroxylammonium, hydrazinium, guanidinium, aminoguanidinium, diaminoguanidinium, triaminoguanidinium, and biguanidinium.

16. A solid gas generating composition comprising a first fuel, a second fuel, and an oxidizer therefor, said first fuel being selected from the group consisting of alkali metal, alkaline earth metal, metalloidal, or transition metal dicyanamides or a complex or mixture thereof.

17. A solid gas generating composition as defined in claim 16 wherein said second fuel is selected from the group consisting of aminotetrazoles, azobitetrazoles, bitetrazoles, and alkali metal, alkaline earth, and transition metal salts thereof.

18. A solid gas generating composition as defined in claim 16 wherein said second fuel is selected from the group consisting of nitrides.

19. A solid gas generating composition as defined in claim 18 wherein said nitrides are selected from the group consisting of boron nitride, silicon nitride, titanium nitride, phosphorous nitride, and iron nitride.

20. A solid gas generating composition as defined in claim 18 wherein said nitrides are selected from the group consisting ternary nitrides and complex nitride phases.

21. A solid gas generating composition comprising a fuel and first and second oxidizers therefor, said fuel comprising an alkali metal, alkaline earth metal, metalloidal, or transition metal dicyanamide or a complex thereof.

22. A solid gas generating composition as defined in claim 21 wherein said first oxidizer is selected from the group consisting of metal nitrates, metal perchlorates, metal chlorates, and transition metal oxides.

23. A solid gas generating composition as defined in claim 21 wherein said second oxidizer is selected from the group consisting of transition metal oxides.

24. A solid gas generating composition as defined in claim 23 wherein said transition metal oxide is selected from the group consisting of Fe₂0₃, Mn0₂, and CuO, and Co₂0₃.

25. A solid gas generating composition as defined in claim 21 wherein said oxidizer is present in the composition in an amount in the range of from about 50% to about 200% of the stoichiometric amount necessary to oxidize said dicyanamide.

26. An automobile air bag system comprising: a collapsed, inflatable air bag; and a gas generating device connected to said air bag for inflating said air bag, said gas generating device containing a gas generating composition comprising a fuel and an oxidizer therefor, said fuel selected from the group consisting of alkali metal, alkaline earth metal, metalloidal, and transition metal dicyanamides, and complexes thereof.

27. A gas generating device comprising: a gas generating composition comprising a fuel and an oxidizer therefor, said fuel selected from the group consisting of alkali metal, alkaline earth metal, metalloidal, and transition metal dicyanamides or a complex thereof; and means for initiating the reaction of the composition.

28. A gas generating device as defined in claim 27 wherein said initiating means comprises an igniter.

29. An automobile air bag system comprising: a collapsed, inflatable air bag; a gas-generating device connected to said air bag for inflating said air bag, said gas-generating device containing a gas-generating composition comprising a fuel and an oxidizer therefor, said fuel selected from the group consisting of alkali metal, alkaline earth metal, metalloidal, and transition metal dicyanamides or a complex thereof; and means for igniting said gas-generating composition.

30. A method of inflating an air bag comprising reacting a fuel and an oxidizer to produce gases, said fuel selected from the group consisting of alkali metal, alkaline earth metal, metalloidal, and transition metal dicyanamides, and complexes thereof.

31. A method of inflating an air bag as defined in claim 30 wherein said dicyanamide comprises sodium dicyanamide.

32. A method of inflating an air bag as defined in claim 30 wherein said oxidizer is selected from the group consisting of metal nitrates, metal perchlorates, metal chlorates, and transition metal oxides.

33. A method of inflating an air bag as defined in claim 30 wherein said oxidizer is present in the composition in an amount in the range of from about 50% to about 200% of the stoichiometric amount necessary to oxidize said dicyanamide.

34. A method of inflating an air bag as defined in claim 30 wherein said fuel further comprises an organic fuel in addition to said dicyanamide fuel, said organic fuel selected from the group consisting of aminotetrazoles, azobitetrazoles, bitetrazoles, and alkali metal, alkaline earth, and transition metal salts thereof.

35. A method of inflating an air bag as defined in claim 30 wherein said fuel further comprises a nitrides in addition to said dicyanamide fuel.

36. A method of inflating an air bag as defined in claim 35 wherein said nitrides are selected from the group consisting of boron nitride, silicon nitride, titanium nitride, phosphorous nitride, and iron nitride.

37. A method of inflating an air bag as defined in claim 35 wherein said nitrides are selected from the group consisting ternary nitrides and complex nitride phases.

38. A method of inflating an air bag as defined in claim 30 wherein said oxidizer further comprises a second oxidizer component selected from the group consisting of transition metal oxides.

39. A method of inflating an air bag as defined in claim 38 wherein said transition metal oxide is selected from the group consisting of Fe₂0₃, Mn0₂, and CuO, and Co₂0₃.

40. A method of inflating an air bag as defined in claim 30 further comprising up to about 50% by weight binder.

41. A method of inflating an air bag as defined in claim 40 wherein said binder is selected from the group consisting of lactose, zinc bisaminotetrazolate, aminotetrazole, polypro¬ pylene carbonate, and alumina.