US3033718A

US3033718A - Gas-producing charge

Info

Publication number: US3033718A
Application number: US501442A
Authority: US
Inventors: Ralph F Preckel
Original assignee: Hercules Powder Co
Current assignee: Hercules Powder Co
Priority date: 1955-04-14
Filing date: 1955-04-14
Publication date: 1962-05-08
Anticipated expiration: 1979-05-08

Description

3,033,718 A -RRQDUs i -GHARG Ralph F. Preckel, Cumberland, Md, ass'ignor to Hercules Powder company, Wilmington, Del., a corporation of Delaware "NoDrawing; FildApr. 14, 1955,- se No. 501,442

invention relates "to production V of I smokeless powders and more particularly to the production of smokelesspowders having peculiarly desirableballistics for applications in jet-actuated devices.

It is well known that there is a definite and direct relationship between the pressure at which a smokeless powderpropellantburns and its burning rate. The relationshipmay be mathematically expressedas r=cP or as g1=l71 lo'g B+log cywhere ris the burning rate, P is and nareconstants characteristic of a given propellant.

Thus, when a plot of log r against-log P isrnade for the conventional propellant, -a straight line of slope n is obtained showing an increase in burning rate for each increasein. pressure. Such arelationship is not disadvanta'geous in the conventional gun propellant and in fact is used to advantage in progressive powders where it is' highly desirable to generate increased pressures after the projectile or shot charge has begun to move along the barrel. However, this relationshippresents a serious problem in formulation of propellants for jet actuated devices since once the desired'operating pressure is reached, total- 1y different considerations obtain, p

his highly desirable, once the operating pressure of a jet actuated device is reached, that the pressure genemitted by theburningpropellantbe maintained as nearly constant as' possible. Accordingly, if this result is to be attained, the slope n of the line representing the pressureburning rate relationship of the particular propellant must desirably approachzero in the zone of useful rocket pressure. In the prior art rocket powders, in all of which the slope iii-has -a value of- 0.7 or over, any fracturing or slivering of the propellant charge leads to a pressure buildup because of an increase in linear burning rate resulting from the increase in pressure due to the increase in burningsurface.

powder, the higher will bethe pressure rise encountered.

The higher the n value of the particular Therefore, the results of sucha fracturing or slivering vary from a highly undesirable thrust fluctuation with conse-v manufacture ofcharges and nozzles for jet devices. A

propellant having a very low n value within the range of useful rocket pressures, however, would allow for considerable tolerances without appreciable deviation from the specified ballistics.

A second serious problem confronting producers of propell-ants for jet-actuated. devices is thediminution of the Y temperaturecoefiicient of equilibrium pressure at the desired operating pressursarpressureran e. The temperature colfic'ient of equilibrium pressure is a measure of the pressure variation to be expected'on account of temperaturevariation alone, using a given propellant. It is obtained'by firingidentical samples of propellant under identical-conditions except forchanges in temperature and pressure. Tlliejcoefiicient may beexpressed as.

the pressure at which the burning'rate is measured, and c v 7 3,033,718 Patented May s, issz where AP is the experimental difference in pressure under conditions of equilibrium burning due tothe temperature change At; and Fis the rnean of the low temperature and high temperature pressures. 1

The advantage of having a low temperature coefficient of equilibrium pressure is obvious. If the coeflicient is low, the jet actuated device may be designed for an unusually low range of service pressure over the wide temperature range ordinarily specified for such devices in field use. Since existing propellants generally have ternperature coeilicients of equilibrium pressure of about 0.8% C. or more, service pressure may change by 100% or more in going from the lowest expected temperature to the highest expected temperature. It is, therefore, highly desirable to lower the temperature coeihcient of equilibrium pressure below that of existing rocket propellants and thereby hold variation in service pressures due to temperature change to a minimum. If the coefiicient could be lowered from 0.8% C. to 0.4%/ C. or less, service pressure variation would be diminished by at least onehalf.

As a result of the advantages set forth above for a pro pellant having alow 11 value and a low temperature coefiicient of equilibrium pressure, the combination of those two ballistic characteristics would allow additionally for important economies in the inert weight of jet-actuated devices. This is clearly seen if the equation is examined which relates the ratio between the mass of propellant (m) and the mass of .the jet device without propellant (M), the gas velocity of the burning propellant (V), and thehighest theoretically obtainable velocity of the jet device (V ;)--as follows:

With propellants now available, the highest ratio of m/M has been about 1, where mass of propellant and mass of jet device are about equal. If it is possible, by use of a new propellant which will not build up excessive pressures, to decrease M by 10% and increase theamount of propellant to give the same total initial weight, V would be increased by a factor March 7, l955,'of which the present application is a continuation-impart, gas-producing compositions are disclosed and claimed which are characterized by the desirably low it value and/or the desirably low temperature coeflicient of equilibrium pressure. Such gas-producing. compositions can be produced by uniformly incorporating in a singleor double-base smokeless powder'an amount, not exceeding 10%, of atleast one aromatic compound of lead. If the smokeless powder to which one of these ballistic modifiers is added is. a single-base powder, it should preferably comprise from -95 of nitrocellulose and from 5-15 of-nonvolatile, nonxplosive plasticizer. If the propellant used is a multiple-base formula, it should preferably comprise from 40-85% of nitrocellulose, from 10-35% of explosive liquid nitric ester and from 5-30% of asubstantially nonvolatile, nonexpiosive plas'ticiz'cr. Up to and including 10% of one or more of the ballistic modifiers selected from the group consisting of aromatic compounds of lead may be employed without adversely aifecting the ballistics of the gas-producing compositions of the invention. However, it is preferred to employ only sufiicient of the additive to effect the desired modification in ballistics. In most cases, it has been found that J about 4% of aromatic lead compound, based on the weight of the smokeless powder employed, is ample. While lead salicylate, lead acetyl salicylate and lead 2,4- dihydroxy benzoate are the preferred modifiers, a substantial effect has been obtained from the incorporation of lead or any aromatic compound of lead.

In copending application Serial No. 492,802, filed March 7, 1955, it is disclosed that lowered n values and coefiicients of equilibrium pressure can also be obtained by incorporating lead, inorganic lead compounds, or allphatic lead compounds in smokeless powder compositions having a heat of explosion not exceeding 900 calories per gram. In accordance with copending application Serial No. 492,801, filed March 7, 1955, it may be desirable to employ a mixture of an aromatic lead compound and lead or nonaromatic lead compound. Mixtures of aromatic lead compounds and lead Z-ethylhexoate were found particularly desirable since lead Z-ethylhexoate is a liquid and assists in obtaining the necessary uniform admixture of modifier throughout the composition. Moreover, it was found that especially where the heat of explosion of the composition does not exceed 900 calories per gram, the incorporation of lead or nonaromatic lead compound with the aromatic lead compound will often extend the pressure range of low n value in the low pressure direction.

Gas-producing compositions characterized by a low 11 value and a low temperature coefiicient of equilibrium pressure have proved greatly advantageous in jet and rocket applications. Actually, the only difiiculty which has been encountered lies in the fact that each specific formulation of smokeless powder and ballistic modifier has been characterized by a specific burning rate at specific pressures and that the plateau area of low It value wherein a substantially constant burning rate and pressure are obtained is a peculiar characteristic of a given composition. Consequently, in order to obtain either a higher rate of burning in a particular pressure region of low It value or to move the region of low it value to a higher pressure range, it has been necessary to design a specific charge formula. Such a procedure obviously requires a considerable amount of experimentation in order to obtain the desired ballistics even though the desired increase in burning rate or shift in the region of low 11 value may be small.

The object of the present invention, therefore, is a gasproducing composition which is characterized by a low n value.

Another object of the invention is a gas-producing composition which is characterized by both a low n value and by a low temperature coeificient of equilibrium pressure.

A further object of the invention is such a gas-producing composition in which the burning rate is substantially increased in a region of low it value within the range of useful rocket pressures.

An additional object of the invention is a means by which the burning rate of a gas-producing composition having a low It value and a low temperature coefficient of equilibrium pressure in the range of useful rocket pressure can be substantially increased without inordinately increasing the n value.

Generally described, the present invention is a gas-pro ducing composition comprising a smokeless powder having uniformly incorporated therein and intimately admixed therewith within each particle thereof an amount not exceeding of at least one aromatic compound of lead, and an amount of finely-divided carbon not substantially exceeding the amount of the lead compound.

The burning rates in the plateau or low n value region in useful rocket pressure ranges of powders modified by incorporation of an aromatic lead compound have generally ranged from about 0.20 to 0.35 inch/second. By the addition to composition thus modified of finely-divided carbon in amounts not substantially exceeding the amount of the lead compound employed, it is possible to increase plateau burning rates in the range of useful rocket pressure far above the plateau burning rates of the same compositions to which no carbon has been added. It has been found that a preferred range of carbon addition exists for each aromatic lead ballistic modifier chosen. Within this range, the plateau burning rate is strongly dependent on the carbon concentration and at optimum concentration, n values of between 0.0 and 0.2 are readily obtained. In fact, negative n values are often obtained. Furthermore, there is also an optimum carbon content which will give the maximum burning rate attainable while still retaining an acceptably low slope in the desired pressure ranges. Carbon concentrations which achieve these preferred and optimum conditions are naturally functions of each particular basic formula of gas-producing composition. Generally, carbon concentrations of 1% or less and lead or lead compound concentrations of 5% or less are preferred. In all cases, however, the amount of carbon must not exceed the amount of lead and/or lead compound employed. The upper limit of aromatic lead compound ballistic modifier or combination of aromatic and nonaromatic lead compounds is 10%. Lead ,B-resorcylate, lead salicylate and lead acetyl salicylate are the preferred modifiers. When a nonaromatic lead compound is desired in admixture with the aromatic lead compound, lead 2-ethylhexoate is also preferred in'the present invention due to its desirable physical characteristics.

While the finely-divided carbon may vary in particle size, the smaller particle sizes are most effective. The greatest increase in plateau burning rate which has been obtained has been with a carbon black having an average particle size of 0.01 micron or below.

Having generally described the invention, the following examples are presented for purposes of illustration.

In Table I ballistic data are set forth to illustrate the efiect of carbon black addition to gas-producing compositions of the invention containing the indicated percentage of various ballistic modifiers selected from the group consisting of aromatic lead compounds. In these examples, the following nominal compositions were employed. The indicated amounts of carbon are additive.

EXAMPLES 1-10 Percent Nitrocellulose (12.6% N) 58.5. Nitroglycerin 27.0. Triacetin 8.5. Ethyl centralite 2.0. Ballistic modifier (As indicated). Carbon black (Excello, 0.03 micron) (As indicated).

EXAMPLES 11-14 Nitrocellulose (12.6% N) 50.0. Nitroglycerin 34.2. Diethylphthalate 9.2. Nitrodiphenylamine 2.0. Ballistic modifier (As indicated). Carbon black (Carbolac 1, 0.011 micron) (As indicated).

EXAMPLES 15-17 Nitrocellulose (12.6% N) 58.5. Nitroglycerin 35.3. Triacetin 1.7.: Nitrodiphenylamine 2.5. Ballistic modifier (As indicated).

Carbon black (Excello, 0.03 micron) (As indicated).

EXAMPLES 18-19 Carbon black (Excello, 0.03 micron) (As indicated).

Percent 7 0 6 2 4. 3 0 1 7 3 9 9 n "M 3 4 5 5 5 3 5 4 3 5 MEN. 8 8 8 W 8 8 8 8 mm 8 8 M 8 0 m 1 m w X(. e m 5 n n 1 .w r ew a A 2 a a u a m u z n u 4 w mm O 0 0 0 0 0 0 0 0 0 0 "0 0 0 m x o n u v u men o eudmmm u n 0 h 0. e 5 0 6 1 7 36 61-3 29 76 6083 522 760 m 0 53%. cnuls 51mg 0 843 021 90 6303 0431 A n 000 0 0O 0 0. 0 000 03%00 09 0 0 001 .0 0100 00 U 0 0 n uO 10n u 0O O000 000m 0000 H 1 w 00 .1 00 0 00 000 000 0550 0000 0000 0000 050 0000 000 00 0000 moo 00 5 5 .2 5045 A 6 00 22 0500 50 0000 00 a 1 2 3 2'4 L1 4 23 1 L 1n 1 191 4 LL4 LA 1 1 4 13 3 113 13 low m e506 5. we. KM MSJWM seam cco L. we. nice .io L6 chin. in. ice 0750 00 075 300 3522 5595 .0400 O we 529 00 00 14 0000 965 4100 3500 31 307 300 1806 3895 3914 3 19 393 3606 397 28 261 8 147 1374 L2 Om LL 2 3 1 1 L l L LL L L1 1 11 1 1 EXAMPLES 24-25 EXAMPLES 26-27 (As'indicated).

' (As indicated).

(in/sec.) (in/sec.) terval(p.s.i.)

0 00 Q0Q00QQ0000Q00Q0000QQQ00Q00000000000000QQQQQQ000000000000000000000000000 Nitrocellulose (12.6% N) 58.5. Nitroglycerin 5 Triacetin 6.0. Nitrodiphenylamine 2.5. Ba 'stic modifier (As indicated). Carbon black (Carbolac 1, 0.011

micron 10 Nitrocellulose (12.6% N) 95.0. Nitrodiphenylamine 1-.0. Ballistic modifier (As indicated).

Carbon black (Carbola'c 1, 0.011

IIllCl'OIl Interpolated burning rate (p.s.i.)

Pressure At 25 C. At 50 0. Pressure in Percent Table I (As indicated).

.5 EXAMPLES 20-21 10.0. amine (As indicated).

EXAMPLES 22-23 (As indicated).

micron micron Nitroce1lu1ose.(12.6% N) 58.5. Nitroglycerin 27.0. Triacetin Nitrodiphenyl Ballistic mddifier (As indicated). Carbon black (fCarbolac 1, 0.011

Nitrocellulose (12.6% N). 58.5. :Nitroglycerin. s,.. 28.5.

Triacetin Ethyl centralite 2.5. Ballistic modifier ----r---- Carbon black ('Molacco, 0.083

duce the" desired up to by wen,

Table IICont1nued hiterpolated burning rate Graphical 'n. Tempera- Av ragq J ur e particle co'eflicient Heat of Ex Type of size of of eq uiexplosion carbon black carbon Pressure At 0. M 5020. Pressure librium" (cal/g.)

black (p.s.i.) (in/sec.) (in/sec.) (p.s.i.) n pressure v (microns) (Percent/ O 31. ,Excello-- 0.030 500 0.39 a 044' 300- 860 0.9 V 0.4 839 1; 500 0.09 0. 76 v 2,000 0.74 0.80 H 2,500 0.77 0.84 32;. P-33 0.140 500 0.36 0.44 300- 800 1.2 0.35 830 From the foregoing examplesand from thedisclosure of the copending application, Serial No. 492,801, it is :evident that While aromatic lead cornpounds are, generally operable in lowering the n valuezand the temperature eoefficient of equilibrium pressure in smokeless'powder compositions, some of the specific compounds are more, effective than others. In likemanner, while'the addition of finely-divided carbon will raise the burning rate in the plateau region or 'all these compositions, some combinatiofis of ballistic modifier and carbon are more-desirable than others. From" the combined viewpoints of fefiectiveness and economy, combinations of lead salicylate or 'lea'd act'yl s'alicylatc'ahd carbon are preferred. The exai'nples'fiifthef illustrate that desirable ballistic effects maybe o'btaifi'edby e of a nonaromatic lead ojmpou'r'id along with "the aromatic lead compound and carbon.

nivinea carbon will usually profig rate'increase in the plateau region. In fact, 6p results are generally encountered when the finely-divided carbon constitutes between 10 and 33% byvveignt'oftne lead and/or lead compound employed; 'Grareranieants' of carbon"rn'ayfbefernployed ht 6f the gas-producing composition as 1 ngas the amount or carb'on never substantially exceeds the amount of ballistic modifier. If the amount of carbo'n plo'yed does exceed the amount of plateaupr'oduciri'g' agent, platcauballis'tics' are detrimentally affected. Furthermore, increasing the carbon content of a particular powder composition brings about a corres'ponding increase in brittleness in the powder, In addition it Will be appreciated that addition of unnecessary aniount's'fnf either the" plateau-producingmodifier or the carhonffiefs a cooling of the powder which lowers potentialaiid' ignitiljility. Consequently, it islundesirable to r'npldy more ofeithe'r are-diner thanfis necessary to gbtaiii the desired niodificati n in ballistics. e

The "composition o'f'th'e ir'ive'n onfiia'y beprepared by conventional solventless process; water-'wetfiitreeenui and the other ingredients are adrfiiiie d' in asehrader'bewrwith water. The resulting slurry or paste is dried to 10% 'w'ater'a'nd is colloided and dried Between liot'c'olldiding rolls" which may be even-speed or 'difierential-spee'd rolls as desired. The fesultingcolloide'd, dfy sheets are thencut into disks or car et r'oll'safetlifi extruded'te' desired grain size. Flake p mer-may be refined by suitably shredding the" sheet. The resulting grains are normally glazed, usually/With graphit'efto lower static generation and to improve flowingcharacteristics.

The compositions of'the' i'iivehtion may also be made by the solvent process. the usual solvent process, the

hydrated nitrocellulose along with additional ingredients into green grains, usually by extrusion into cords and cutting the cords to the desired length; The green grains are then subjected to solvent removal steps. The greater:

portion of the solvent isnorrnally removed by passing a warm inert gaseous medium such as air or flue gets over ,the grains. The re'mainderof the solventwhich can be practically removed is then usually leached out by a water treatment. -Water is then removed by an air dry step and the dry grains are normally given a glaze, usually of graphite, to lower staticgeneration' and to improve flowing characteristics.

As is'well known to the art, eolloiding solvent can be removed from powder grains of large diameter .and web only with extreme diificulty This difficulty increases as the web thickness is increased. It is therefore desirable to prepare grains of the multiple base formulations of this invention-by solventless extrusion or by a suitablecaSting process. It is preferred to extrude grains up to about 5 or'6- inches in diameter and to cast all larger grains.

Casting of the larger grains is prefe'rred becausethe cost and massive nature of extrusion presses large enough to produce grains of over 5 or 6 inches in diameter become prohibitive. I I

- In the usual casting process, tiny singleor double-base powder grains, prepared-by either the solvent or solventless techniques, are introduced into a mold together with suitable plasticizers; Theplasticizers cause the grains to coalesce into a unitary mass 0t plastics composition. The preferred casting process is that disclosed in the' copending application of; Gordon W. McCurdy, Serial No.-

28,218, filed May 20, 1 948.

The single-base formulations given in the examples 6 are preferably made by a conventional solvent process,

extruded and cut to the desired granulation. Such a process limits the possible size of the single-base grains to a diameter or web thicknesswhich will allows'ufiicient removalof the colloidingsolvent. Grains or solventcolloided powder having large diameter and web are, of course, operable and as long as the heat of explosion does not exceed about 900 calories per gram, addition of the disclosed modifiers according to this inventionwill efiect the desired-modification in ballistics. It is, of course well known that thechange in ballistics during storage causedby gradual migration and evaporationIof the colloiding solvent is the reason why large grains of solvent-colloided powder are not manufactured. As improved processes and means for solvent removal are developed,- it will perhaps be possible to produce corresporid'ingly larger grains of solvent-'colloided powder which are 'ballistically' stable.

It is not preferred to -produce, single-base grains by solventless extrusion or by casting because, in order to keep the powder in the single base category, the plasticizer employed re bring aboiit colloidin'g and/er consolidation must be of lower potential than the nitrocellulose. The necessary amount of plasticizer, therefore, so lowers the potential that such powders have only a limited application. Nevertheless, incorporation of the disclosed modifiers in single-base grains prepared by solventless extrusion or by casting still results in a low 11 value and a low temperature coefficient of equilibrium pressure.

If the gas-producing charges of this invention are made by solventless extrusion, the ballistic modifier or modifiers are preferably added at some time prior to dehydration of the water slurry and the additive system is mixed to a stage of homogeneity. The slurry is then dehydrated, the moist mass is rolled into colloided sheets, the sheets are made into rolls and the rolls are extruded in the conventional manner. However, it is often found advantageous to add the ballistic modifiers during the rolling operation, rather than to the water slurry. If the well-known Schrader process is employed, the modifiers may be added to the hydrated nitrocellulose in the mixing bowl in any preferred order. A portion of the water is evaporated prior to rolling. The Schrader' process is preferred when water-soluble plasticizers are employed.

If the charges of this invention are prepared by solvent extrusion, the ballistic modifier or modifiers are preferably added to the dehydrated nitrocellulose after it has been broken up in a mixer. The modifiers may be introduced with the plasticizer or plasticizers or may be added before or after introduction of the plasticizer as may be desired in the particular formulation.

If the grains are made by casting, the ballistic modifier is homogeneously incorporated during the preparation of the casting powder as above described.

In order to produce the "plateau type ballistics of the invention, the modifiers must be uniformly incorporated with the other ingredients of the composition; that is, the modifier must be intimately admixed with the other ingredients within each particle of the composition whether the charge is a loose charge of individual grains or consists of a single grain of any desired size. The glazing or coating of a single grain or a plurality of grains in a loose charge will not produce the desired modification in the pressure-burning rate relationships. Thus, powder grains coated or glazed with a lead compound to render them free-flowing are not operable in the invention.

The heat of explosion of an explosive composition may be experimentally determined in the known manner by actually exploding a sample of the substance in a bomb calorimeter under conditions which insure complete combustion of the constituents of the composition, and measur-ing the heat liberated. However, in the case of smokeless powder compositions, which contain at most only small portions of inorganic material, it is usually desirable to determine the heat of explosion by calculation. The calculation of heats of explosion is especially desirable in order to accurately predeterrnine the calorific value of a proposed composition prior to its formulation. In this calculation, use is made of a simple relation; namely, the heat of explosion per gram of powder is equivalent to the sum of the products of the weight fraction of a given constituent by the contribution to the heat of explosion of the constituent. This contribution of the constituent is for convenience termed the partial calorific potential" or the partial heat of explosion, and is usually designated as K Thus, the heat of explosion of the composition is derived by the equation:

Heat of explosion=EX K Where X, is the weight fraction of the powder component i.

For compositions consisting principally of carbon, hydrogen, oxygen, and nitrogen, K is quickly and accurately determined according to the following equations:

' where O, is the number of gram-atoms of oxygen per gram of the powder component i, C, is the number of gram-atoms of carbon per gram of the powder component i, H, is the number of gram-atoms of hydrogen per gram of the powder component i, H.C. is the heat of combustion at 25 C. and constant volume, and AB is the heat of formation per gram of the powder component i from its elements.

Partial heat of explosion" for inorganic substances such as the ballistic modifiers of the invention are not quite as readily calculated but may, nevertheless, be determined according to methods disclosed by De Pauw in Z. P. ges. Schiessund Sprengstotfwesen, 32, 11, 36, 60 (1937); or by Hirschfelder and Sherman in Simple Calculation of Thermochemical Properties for Use in Ballistics, O.S.R.D. Report No. 1300, declassified and issued as P3274215.

Actually, it is unnecessary to experimentally determine the K, values for the various constituents of the smokeless powders in accordance with the invention since tables of the partial heats of explosion for these materials are available as published data. The following is a listing of the K, values of the normally used smokeless powder components and many of the operable ballistic modifiers in accordance with the invention.

Substance (i): Partial heat of explosion (cal./g.) Acetone -l938 Carbon black --3330 Diamylphthalate 2190 Dibutylphthalate 2055 Diethanol nitramine dinitrate 1294 Diethylene glycol dinitrate 1030 Diethylphthalate -1746 Dinitrotoluene Diphenylamine 2684 Diphenylurea 2227 Diphenylurethane 2739 Ethyl alcohol 1749 Ethyl centralite -2398 Ethyl urethane 1639 Graphite 3377 Lead Lead acetate --282 Lead phthalate acetate 462 Lead diacetylacetonate -868 Lead anthranilate 864 Lead azide 365 Lead benzoate 950 Lead m-aminobenzoate 796 Lead dichlorobenzoate 736 Lead 2,4-dimethoxybenzoate 766 Lead Z-ethylhexoate -1336 Lead 4-ethoxy-2-hydroxybenzoate 87() Lead p-hydroxybenzoate 826 Lead bromide 137 Lead carbonate (basic) -47I Lead chloride -151 Lead chromate 977 Lead citrazinate 752 Lead tetraethyl 1725 Lead fluoride 127 Lead gallate 573 Lead gentisate 674 Lead hydroxide 189 Lead iodide 91 Lead linoleate 1982 Lead pyromellitate 250 Lead trimesate 460 Lead molybdate 403 Lead tetrachloronaphthalate 534 Lead naphthenate 2048 Lead l-hydroxy-2-naphthoate 1ll7 Lead 3-hydroxy-2-naphthoate 1117 Lead oleate 2010 Lead oxalate 58 ful rocket pressures.

Substanceti); Partial heat of explosion cal./ g.) Lead oxide (PbO)'-. r 67 Lead oxide (Pb O 139 Lead oxide (Pb02) 302 Lead n-butylphthalatet; -974 Lead fi-resorcylate uia" '-704 Lead tetraphenyl ad- -'1725 Lead salicylate 752 I Lead .acetylsalicylate 857 Lead aminosalicylate -746 Lead thiosalicylate -874 Lead stearatc -2s00 Lead phthalate stearate 1543 Lead sulfate -150 Lead sulfide 222 Lead tartrate t 172 Lead o-toluate 1057 Nitrocellulose Y 13.25% N .L- 1041 13.15% 1027 13.00% 1007 12i60% .951 12.20% a y 895 12.00% N 867 11.50% N 797 Nitroglycerin -a 1785 Nitroguanidine 720 Triacetin -1284 Water The advantages of the gas-producing compositions of this invention over presently available formulations are readily apparent; The compositions of this invention are characterized by distinguishing properties which have heretofore been found highly desirable but unobtainable; namely, a lower temperaturecoefiicient of equilibrium pressure and a constant or-more nearly constant burning rate over a wide pressure range within the zone of use- Furthermore, by varying the carbon concentration inthe gas-producing compositions of the invention within the prescribed limits, the burning rate of the plateau region, or region oflow n'value, may be greatly increased without shifting the plateau out of the zone of useful rocket pressures.

What I claim and desire to protect by Letters Patent is:

l. A gas-producing composition consisting essentially spasms of a s'mokelesspowder having uniformly incorporated;

therein and intimately admixed therewith within each particle thereof an amount not exceeding 10% of at least one aromatic compound of lead and an amount of finelydivided carbon not substantially exceeding that of the lead compound and said gas-producing composition having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship.

2. A gas-producing composition consisting essentially of a smokeless powder having uniformly incorporated therein and intimately admixed therewith within each particle thereof an amount not exceeding 10% of lead fl-resorcylate and an amount of finely-divided carbon not substantially exceeding the amount of lead B-resoroylate' and said gas-producing composition having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship. 1

3. A gas-producing composition consisting essentially of a smokeless powder having uniformly incorporated therein and intimately admixed therewith within each particle thereof an amount not exceeding 10% of lead salicylate and an amount of finely-divided carbon'not substantially exceeding. the amount of lead salicylate and said gasproducing composition having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship.

4. A gas-producing composition consisting essentially of a smokeless powder having uniformly incorporated therein and intimately admixed therewith within each particle thereof an amount not exceeding 10% of lead 14 acetyl salicylate and an amount of finely divided carbon not substantially exceeding the amount of lead acetyl Salicylate and said gas-producing composition having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship. 5. A gas-producing composition consisting essentially of a smokeless powder having uniformly incorporated,

therein and intimately admixed therewith withinfeach particle thereof an amount not exceeding 10% of a mixture of lead salicylate and lead 2-ethylhexoatedand an. amount of finely-divided carbon not substantially exceeding the amount of the said mixture and said gas-' producing composition having a value of less than 0.7 for the slope n of the line representing the pressureburning rate relationship.

6. A gas-producing composition consisting essentially producing composition having a value of less than 0.7

for the slope n of the line representing burning rate relationship. I

7. A gas-producing composition consisting essentially of the pressure- 'a smokeless powder containing -95% of nitrocellulose and having uniformly incorporated therein and intimate ly admixed therewith within each particle thereof an amount not exceeding 10% of at least one aromatic compound of lead and an amount of finely-divided carbon not substantially exceeding that of the lead :com-

pound and said gas-producing composition having a value of lessthan 0.7"for the slope n of the line represent ng the pressure-burning rate relationship.

I 8. A gas-producing composition consisting essentially'of I a smokeless powder containing 85-95% of nitrocellulose and having uniformly incorporated therein and intimately admixed therewith within each particle thereof an amount not exceeding 10% of lead ,B-resorcylate and an amount of finely-divided carbon not substantially exceeding the amount of lead'fi-resorcylateand said gasproducing composition having a value of less than 0.7 for the slope h of the line representing the pressureburning rate relationship. p

9. A gas-producing composition consisting essentially of a smokeless powder containing 85-95% of nitrocellulose and having uniformly incorporated therein and intimately' admixed therewith within each particle thereof an not exceeding 10% of lead salicylate and an amount of finely-divided carbon not substantially exceeding the amount of lead salicylate and said gas-producing composition'having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship.

10. A gas-producing composition consisting essentially of a smokeless powder containing 85-95% of nitrocellulose and having uniformly incorporated therein and intimately admixed therewith within each particle thereof an amount not exceeding 10% of lead acetyl salicylate and an amount of finely-divided carbon not substantially exceeding the amount of lead acetyl salicylate and said gas-producing composition having a value of less than 0.7 for the slope n of the line representing the pressureburning rate relationship.

11. A gas-producing composition consisting essentially of a smokeless powder containing 85-95% of nitrocellulose and having uniformly incorporated therein and intimately admixed therewith within each particle thereof an amount not exceeding 10% of'a mixture of lead salicylate and lead 2-ethylhex0ate'l and an amount of finely-divided carbon not substantially exceeding the amount of the said mixture and said gas-producing composition having a value of less than 0.7 for the slope n 1.5 of the line representing the pressure-burning rate relationship.

12. A gas-producing composition consisting essentially of a smokeless powder containing 85-95% of nitrocellulose and having uniformly incorporated therein and intimately admixed therewith within each particle thereof an amount not exceeding of a mixture of lead acetyl salicylate and lead Z-ethylhexoate and an amount of finely-divided carbon not substantially exceeding the amount of the said mixture and said gas-producing composition having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship.

13. A gas-producing composition consisting essentially of a smokeless powder containing nitrocellulose and at least one explosive nitric ester and having uniformly incorporated therein and intimately admixed therewith within each particle thereof an amount not exceeding 10% of at least one aromatic compound of lead and an amount of finely-divided carbon not substantially exceeding that of the lead compound and said gas-producing composition having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship.

14. A gas-producing composition consisting essentially of a smokeless powder containing nitrocellulose and at least one explosive nitric ester and having uniformly incorporated therein and intimately admixed therewith within each particle thereof an amount not exceeding 10% of lead fi-resorcylate and an amount of finely-divided carbon not substantially exceeding the amount of lead B-resorcylate and said gas-producing composition having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship.

15. A gas-producing composition consisting essentially of a smokeless powder containing nitrocellulose and at least one explosive nitric ester and having uniformly incorporated therein and intimately admixed therewith within each particle thereof an amount not exceeding 10% of lead salicylate and an amount of finely-divided carbon not substantially exceeding the amount of lead salicylate and said gas-producing composition having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship.

16 16. A gas-producing composition consisting essentially of a smokeless powder containing nitrocellulose and at least one explosive nitric ester and having uniformly incorporated therein and intimately admixed therewith within each particle thereof an amount not exceeding 10% of lead acetyl salicylate and an amount of finely-divided carbon not substantially exceeding the amount of lead acetyl salicylate and said gas-producing composition having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship.

17'. A gas-producing composition consisting essentially of a smokeless powder containing nitrocellulose and at least one explosive nitric ester and having uniformly incorporated therein and intimately admixed therewith within each particle thereof an amount not exceeding 10% of a mixture of lead salicylate and lead 2-ethylhexoate and an amount of finely-divided carbon not substantially exceeding the amount of the said mixture and said gasproducing composition having a value of less than 0.7 for the slope n of the line representing the pressureburning rate relationship.

18. A gas-producing composition consisting essentially of a smokeless powder containing nitrocellulose and at least one explosive nitric ester and having uniformly incorporated therein and intimately admixed therewith within each particle thereof an amount not exceeding 10% of a mixture of lead acetyl salicylate and lead 2-ethylhexoate and an amount of finely-divided carbon not substantially exceeding the amount of the said mixture and said gas-producing composition having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship.

References Cited in the file of this patent UNITED STATES PATENTS 1,357,865 Henning Nov. 2, 1920 2,385,135 Holmes Sept. 18, 1945 2,498,388 Ball Feb. 21, 1950 2,982,638 Cooley May 2, 1961 FOREIGN PATENTS 621,685 Great Britain Apr. 14, 1949

Claims

1. A GAS-PRODUCING COMPOSITION CONSISTING ESSENTIALLY OF A SMOKELESS POWDER HAVING UNIFORMLU INCORPORATED THEREIN AND INTIMATELY ADMIXED THEREWITH WITHIN EACH PARTICLE THEREOF AN AMOUNT NOT EXCEEDING 10% OF AT LEAST ONE AROMATIC COMPOUND OF LEAD AND AN AMOUMT OF FINELYDIVIDED CARBON NOT SUBSTANTIALLY EXCEEDING THAT OF THE LEAD COMPOUND AND SAID GAS-PRODUCING COMPOSITION HAVING A VALUE OF LESS THAN 0.7 FOR THE SLOPE N OF THE LINE REPRESENTING THE PRESSURE-BURNING RATE RELATIONSHIP.