US1757713A - Coated phosphide and process for making - Google Patents

Description

Patented May 6, 1930 .PAENT FF C FE LIX HIEBLER, F HANOVER, GERMANY COATED PHOSPHIDE AND PROCESS FOR MAKING A He Drawing.- Application filed July 23, 1927, Serial No. 208,048, and in Germany August 14, 1925.

This invention relates to a calcium phosphide which when immersed into water will first develop no gas at all or only small quantities of gas and properly develop a gas only after the lapse of some time, so that the maximum development of flames and smoke will be retarded as compared with the commercially obtainable calcium phosphide. This retarded ignition is brought about according to this invention by providing proper envelopes for the pieces of calcium phosphide.

There are several processes known, which consist of imbedding and impregnating calcium carbide. In most of these processes envelopes are employed which are insoluble in Water or impermeable for the same, such as parafine, petroleum, linseed oil and other drying or non-drying oils. Some of the known processes employ mixtures with fatty bodies or metal sheets or the like.

I In all these cases, however, a retardation of the starting point of the development of acetylene after the admission of water is not produced, but there will be merely a protection against the undesirable action or water and against further action of the water upon the carbide after interruption of the development of the acetylene. Accordingly, the

envelopes which are used in this case are preferably removed before use, that is to say, before the water commences to exert its action. This may, for instance, be done by scratching off said envelopes or destroying the same,

for instance, by crushing the masses which have previously been pressed in forms. Also said envelopes may be destroyed by chemical action, as for instance, by saponiiying the oil by means of lye or an alkali.

It is further essential in all these processes, that always only a art of the filling of carbide is made accessi le to the water in order to act on the same, so that after removal of the Water the remainder of the filling will be maintained in an undecomposed state and in a condition whereby the carbide is pro tected against the decomposing action of the water. Y

A further especial advantage, which is aimed at in these known processes, is claimed to reside in the fact that the development of gas is quickly accomplished and takes place in a manner which is as much as possible uniform. In case the development of gin does not innncdiately take place during inn inersion of the mass into water by reason of the insolubility of the impregnating agents. such for instance, as linseed oil and petroleum, there will even be brought about an immediate development of acetylene by special steps, as, for instance, by crushing the pieces of the mass or by adding min-impregnated pieces of carbide to the same.

In contradistinction to this, the present invention consists essentially in providing an envelope for the calcium phosphide. whereby a quite different and surprising effect is obtained.

Calcium phosphide is extensivelv used in the firing of torpedoes for the purposes of military training in order to indicate the location of the torpedo after firing, whereby the water which enters the calcium phosphide will generate self-igniting phosphinc.

The development of gas with the heretofore used calcium phosphide is accomplished in such a way, that a short time after the entrance of the water there will be developed a maximum of flames and smoke.

With the products which are commercially obtainable at the present time this maximum of flames and smoke is generated in every case in less than five minutes. Such a calcium phosphide has practically been fully satisfactory for firing within small ranges. Since, however, the ranges of torpedo firing have been considerably increased, said ranges being many times those formerly employed, the commercially obtainable calcium phosphidc has become entirely insufficient for this case. The attempts which have becnmadc to obtain a maximum development of flames and smoke after a period of about ten minutes or even longer, were based on either mechanical means or on a chemical process, for instance by using especially selected calcareous substances, but have never resulted in success. I

By the present invention, a retarded ignition and more particularly a retardation of the moment when a maximum development of flames and'smoke takes place, is successful- I mum development of flames and smoke.

The/new process according to this invention may be illustrated by the following example: I

A quantity of 2 kg. of pieces of calcium phosphide is heated in a rotary furnace to gether with 0.6 kg. of bichromate of potassium to a temperature of about 600, the drum of the furnace being thereu on constantly rotated and properly coole In this manner a calcium hosphide will be obtained which is provided with a firmly adhering coating of olive-green color and after immersion will develop a maximum production of flames and smoke after a time of about twelve minutes. If instead of 600 g. a smaller quantity of bichromate of potassium is taken, the maximum production of flames and smoke will take place after a shorter time. p

in addition to this, one will be enabled to determine and fix in advance thetime of the maximum production of flames and smoke with an accuracy which is suficient for all practical purposes, by selecting for the envelope substances having a difierent solubility. The melting points of the substances used must also be considered, as, if the melting point is too high, it is impossible to reduce a proper film.

is suitable substances for the envelope there may be employed compounds of any desired constituency which are soluble in water, provided that these substances in fused condition do not decompose phosphides. Especially fused salts, such as silicates of alkali metals, borax-glass, water soluble p rophosphates, especially alkali metal pyrop 0sphates, bichromate or potassium and common salt have been found suitable for this purpose.

I claim:

l. The process of regulating the development of gas with phosphides, which consists in enclosing the phosphide in an envelope capable of preventing the access of water to said phosphide until a relatively long period of time has elapsed after the immersion of said enevelope into the water.

2. The process of regulating the development of gas with phosphides, which consists in enclosing the phosphide m an envelope formed of a material which is soluble in water, but capable of preventing the access of water to said phosphide until a relatively long period of time has elapsed after the immersion of said envelope into the water.

3. The process of regulating the develop in treating the hosphide with a mass of fused salts there y to form an envelope enclosing the phosphide and capable of preventing the access of water thereto until a relatively long period of time has elapsed after the immersion of said envelope into the water.

4. The process of regulating the development of gas with phos hides, which consists in treating pieces of p osphide with a filmproducing material which is soluble in water thereby to form an envelope enclosing the phosphide and capable of preventing the access of water to said phosphide until a relatlvely long period of time has elapsed after the immersion of said envelope into the ment of gas with phosphides, which consists