US2640770A - Igniting composition and method of preparing same - Google Patents

Description

' affected by moisture. to eliminate all water-soluble ingredients and to Patented June 2, 1953 UNITED STATS TENT OFFICE IGNITING COIVIPOSITION AND METHOD OF PREPARING SAME Sidney J. Magram, Baltimore, and John J. Blissel, Kingsville, Md.

No Drawing. Application May 29, 1951, Serial No. 228,962

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to us of any royalty thereon.

This invention relates to a composition which is particularly useful as a first fire or igniting composition. That is, it is the material present in munitions which is ignited by a primer and which in turn ignites the munition filling and thus produces th required effects of the muniions.

Munitions with which this invention deals particularly are those used to obtain incendiary effects, as for example, magnesium bombs containing Thermit type fillings, Thermit incendiary bombs, Thermit grenades, smoke shells, floats, pots, and. grenades.

An object of this invention is to provide a first fire igniting composition or starter which meets all the requirements for a satisfactory starting material. More specifically, the objects will appear as follows.

The first fire or igniting composition must be invariably ignited by the primer. This means that the mixture must have a suificiently low ignition temperature. It has been found that the ignitability of gasless Thermit-type starters depends on several factors, such as the nature of the oxidizable metal powder and the oxidizing agent, the particle size of the first fire ingredients, and the composition of the mixture. To ensure ignition of the starter mixture it is preferred that the particle size of the starter mix be such that in their ignitability, depending on their method of manufacture.

The first fire or igniting composition must deendab1y ignite the filling. In accordance with this invention, it was found that a starter that;

produces slag and evolves little or no gas would be more reliable in this. case than a starter evolving gases and building up pressure in a confined space.

The first fire or igniting composition should remain unaffected by prolonged surveillance. It

has been found that to obtain this object it is.

necessary to employ ingredients which are not It is, therefore, advisable utilize only materials that show little or no moisture absorption in a humid atmosphere.

, :..-.been. found that the iron oxide should be finely- The materials comprising the first fire must be available in quantities suflicient to supply all the required munitions.

The first fire or igniting composition must be safe enough to manufacture and load into bombs. This means that it should be sufficiently insensitiv to friction, impact, sparks and heat to be handled with the ordinary precautions for handling sensitive pyrotechnic mixtures.

The number of constituents should be a minimum required for proper functioning.

Heretofore, no starter or igniting material has been developed which has all of these properties. Nor has any such composition been proposed previously which is stable during storage. It is the object of this invention to provide a starting or igniting mixture which will satisfy all of the foregoing requirements.

While starters or igniters evolving little or no gas have been known in which combinations of manganese have been used in combination with various other metallic oxides, these compositions deteriorate in a humid atmosphere because the metallic powder slowly reacts with water in the air to form a coating of an oxide or hydrated oxide over the particles of metallic powder.

It has been found that a starter or igniting composition can be obtained which meets all the requirements set out above by employing a combination of iron oxide and a powdered metal selected from the group consisting of titanium and zirconium.

Such a starter has excellent stability in moist atmospheres and has the desired functioning properties of sensitivity to ignition and development of high temperature for ignition of Thermit-type compositions, which have ignition temperatures well above1000 C.

The most satisfactory type of iron oxide should have a high degree of purity, and be free from gas-forming and hygroscopic impurities. It has been discovered that the percentage of moisture absorption by various fine ferric oxides is fairly high at 100% humidity, but at humidity it is less than 0.2%. By heating ferric oxide to approximately 1000 0., the moisture absorption at humidity is practically eliminated. However the ferric oxide is converted to a powder which no longer forms a compact cake under pressure. The desired binding properties are destroyed, Since the moisture absorption was low at 80% humidity, it is practical to use the untreated iron oxide and determine by surveillance in tropical storage whether it is satisfactory.

In order to obtain good binding qualities it has which is free from appreciable quantities of metals which can react with moisture to form metallic oxides, since the oxides are inert and only consume heat in a pyrotechnic mixture.

In Table II are listed, with results, some first fire starter or igniting mixtures that were tested in a primer testing machine. This machine, briefly described, has, on top, a depression where a primer holder may be placed. Screwed on top of this is a cylinder holding the firing pin, By dropping an iron cylinder on top of the firing pin, this pin is made to hit the primer which, in turn, flashes on to the first fire. Metal spaces are available to adjust the distance from the primer to the surface of the first fire {starter} The primer was approximately 2-in. away in these tests. The starters g. samples in most instances) were tested in small steel cups, because the melting of the cup could be used as a rough visual indication of the temperature and heat evolved from each starter.

It has also been observed that the iron oxidemetal powder of this invention when compacted under a dead load of 2,900 lb. in a hydraulic press made a hard pellet, and that the composition was still capable of being ignited by the primer.

As an example of a filling used in magnesium bombs with which the igniting materials of this invention have been found to be particularly effective is a composition known as Therm-64C. This mixture has the following ingredients:

Ingredient: Parts by weight Aluminum 16.0103 Iron oxide, scale 44.0105 Aluminum, grained 9.0:04 Barium nitrate 290:0.4

Sulfur :01

andmeth-ods of preparing the same, without de- 7 parting from the scope of the invention, it is intended that all matter contained in the above description shall be considered as illustrative and that the claims be given a construction as broad as is consistent with the state of the prior art.

We claim:

1. An igniting composition consisting of about parts by weight of ferric oxide and about 30 parts by weight of titanium.

2. A method of preparing an igniting composition paste which comprises mixing about 30 parts by weight of titanium with water, mixing the ingredients to form a smooth paste, adding about 70 parts by weight of ferric oxide, blending the mixture, and then drying said mixture.

SIDNEY J. MAGRAM. JOHN J, BLISSEL.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,389,695 Petinot Sept. 6, 1921 1,417,075 La Cour et a1 May 23, 1922 2,131,041 Hale Sept. 27, 1938 2,392,353 Aitchison Jan. 8, 1946 2,424,937 Linzell July 29, 1947 2,452,091 Woodberry et al. Oct. 26, 1948 2,478,918 Hale et a1 Aug. 16, 1949 FOREIGN PATENTS Number Country Date 232,554 Great Britain Feb. 5, 1925 352,118 Great Britain July 9, 1931

Claims (2)

1. AN IGNITING COMPOSITION CONSISTING OF ABOUT 70 PARTS BY WEIGHT OF FERRIC OXIDE AND ABOUT 30 PARTS BY WEIGHT OF TITANIUM.

2. A METHOD OF PREPARING AN IGNITING COMPOSITION PASTE WHICH COMPRISES MIXING ABOUT 30 PARTS BY WEIGHT OF TITANIUM WITH WATER, MIXING THE INGREDIENTS TO FORM A SMOOTH PASTE, ADDING ABOUT 70 PARTS BY WEIGHT OF FERRIC OXIDE, BLENDING THE MIXTURE, AND THEN DRYING SAID MIXTURE.