US2490571A

US2490571A - Pyrophoric alloy of zirconium, lead, and titanium, and sparking device containing the same

Info

Publication number: US2490571A
Application number: US67935A
Authority: US
Inventors: Robert J Anicetti
Original assignee: Metal Hydrides Inc
Current assignee: Metal Hydrides Inc
Priority date: 1948-12-29
Filing date: 1948-12-29
Publication date: 1949-12-06
Anticipated expiration: 1966-12-06

Description

Dec. 6, 1949 R. J. ANlcETTI 29490571 PYROPHORIC ALLOY OF ZIRCONIUM, LEAD AND TITANIUM AND SPARKING DEVICE CONTAINING THE SAME Filed Dec. 29, 1948 Egfr I will] Patented Dec. 6, 1949 PYROPHORIC ALLOY OF ZIRCONIUM, LEAD, AND TITANIUM, AND SPARKING DEVICE CONTAINING THE SAME Robert J. Anicetti, Richland, Wash., assignor to Metal Hydrides Incorporated, Beverly, Mass., a corporation of Massachusetts Application December 29, 1948, Serial No. 67,935

(Cl. 'l5-134) 6 Claims.

This invention relates to sparking devices, such as cigarette lighters, industrial igniting appliances, etc., having a pyrophoric material which produces sparks by impact with a hard body. The invention is based upon my discovery that an alloy comprising lead and zirconium in certain proportions is highly pyrophoric.

It has been known in the art that cerium possesses marked pyrophoric properties but is too soft for industrial use. However when alloyed with minor amounts of iron or certain other metals, it has been used extensively in industry as the pyrophoric material for cigarette lighters, etc. The properties of cerium and zirconium differ radically. For example, unlike cerium, zirconium is a very hard metal. It has found many uses in industry in the form of ferrozirconium. Ferro-zirconium is not suitable for use in industry as a pyrophoric material. However, alloys of cerium and iron have been used extensively for this purpose. Although many other pyrophorie materials have been discovered, so far as I am aware, none of these other materials have possessed characteristics such that it has been able to replace, either Wholly or in part, the expensive cerium alloys for use in industry as a pyrophoric material. Alloys of zirconium with various other metals have been produced but prior to my invention alloys of lead and zirconium have not been produced in proportions Which exhibit pyrophoric properties.

Pyrophoric materials suitable for use in the practice of the invention contain lead, titanium and zirconium in proportions between about 20 to 75 per cent lead, about 5 to 40 per cent titanium and between about 25 to 80 per cent zirconium by weight.

, It is extremely surprising and unexpected to discover that zirconium and lead from alloys in proportions which possess marked pyrophoric properties. Prior highly skilled investigators had failed to produce satisfactory alloys of lead and zirconium in any proportions. Bulletin No. 186 of the Bureau of Mines (1921) states that all attempts to produce an alloy by smelting together zirconium and lead did not give satisfactory results. Hugh H. Cooper, at the meeting of the Electrochemical Society on May 5, 1923, referring to his work with various alloys of zirconium stated, Few alloys with lead were made and these seemed to disintegrate when exposed to the air for some time. The United States patent to Petinot No. 1,335,982, dated April 6, 1920, describes the production of alloys of zirconium and lead by the reduction of calcium zirconate with carbon in the presence of molten lead.

While certain alloys of zirconium and lead possess marked pyrophoric properties, the binary alloys of titanium and lead in the same proportions do not possess these properties although zirconium and titanium are known to be substantial equivalents in many instances. Similarly, binary alloys of thorium and lead do not possess these properties.

However, I have discovered that the addition of titanium in an amount up to about 40 per cent by weight to zirconium and lead in the proportions stated provides a pyrophoric alloy having improved properties for many industrial uses. It also lowers the melting point of the zirconiumlead alloy. I have obtained best results using from about 10 to 30 per cent titanium. My presently preferred materials contain between about 30 to 60 per cent lead with or without titanium and 25 to 65 per cent by weight of zirconium. The titanium imparts hardness to the zirconiumlead alloy. It also improves the friction characteristics of the alloy when zirconium and lead are present in certain proportions.

I have discovered that the pyrophoric material of lead and zirconium may be diluted with one or more other metals, such as calcium, antimony, manganese, copper, tin, aluminum, magnesium, calcium, etc. Manganese appears to impart hardnessv to the material and is beneficial in a manner similar to titanium. It may be employed in amount up to about 40 parts by weight. When magnesium is used in amounts between about 0.1 to 0.5 part by weight, it increases the brilliance of the sparks. In general, the combined amounts of lead and zirconium form the predominating portion of the pyrophoric material.

This application is a continuation-in-part of my applications Serial No. 777,889, filed October 4, 1947, Serial No. 643,960, filed January 28, 1946, and Serial No. 67,089, led December 23, 1948, all of which applications are now abandoned; and also of my application Serial No. 746,329, led May 6, 1947. In that application I have claimed the improvement in a sparking device having a sparking element oi pyrophoric material in which the sparking element consists essentially of zirconium and lead in the proportions of 20 to 75 per cent of lead and 25 to 80 per cent by weight of zirconium. I also disclosed that improved properties are imparted to the pyrophoric material of zirconium and lead by including therein up to 20 per cent by Weight of titanium. I have now discovered that such properties are imparted to such pyrophoric material of zirconium and lead to a greater or less degree by including titanium therein in amounts between about 5 per cent and 40 per cent by weight. My presently preferred material for use in sparking devices consists essentially of about 35 per cent of lead, 35 per cent of zirconium and 30 per cent by weight of titanium.

One method for producing a suitable pyrophoric material is described in my copending application,.Serial No. 746,328, led May 6, 1947,

now abandoned. Thus, a mixture of small pieces of lead, preferably a powder, and zirconium or zirconium hydride with r Without titanium or titanium hydride or other materials is loaded into a crucible and the letter placed in a high frequency electric induction furnace. After adjusting the cover, the furnace is connected with a vacuum system and the air and moisture is evacuated, preferably, while raising the temperature to assure removal of gases. gas, such as argon or helium, is admitted and the charge is heated gradually until the charge becomes molten. Preferably, a temperature between 1350" C. and 1600 C. is used but a temperature as low as 1000 C. may be used in some cases depending upon the composition -of the charge. After :the charge is liquified, heating is stopped and the liquid mass either frozen in the Crucible or a detachable plugis removed from the bottom of the crucible and the liquid mass allowed to escape by bottom pouring into molds in the lower part of the furnace and frozen in the molds while maintained in an inert environment.

I have obtained best results using zirconium metal of which 70 per cent was 325 mesh and 30 per cent 100-1-325 mesh or zirconium hydride of which 85 per cent was 325 mesh and 15 per cent was -100-,'325 mesh. When titanium is a component, I prefer to employ titanium metal or titanium hydride of comparable particle sizes. The zirconium metal and zirconium hydride which I have used was prepared by reducing zirconium oxide by heating with either calcium hydride or magnesium and thereby converting the calcium hydride and magnesium to metal oxides, the latter being removed by leaching. The titanium and titanium hydride was prepared by similarly reducing titanium oxide by heating with calcium hydride. These materials had the following approximate analysis in which the amounts are per cent by weight:

Zr 98.5 96.5 97.0 97.0 H2 0.10 0.3 1.9 1.9 3.3 0.2 C 0.10 0.10 0.1 0.05 0.1 0.2 N 0.80 0.06 0.8 0.05 0.8 0.8 Ca 0.30 0.05 0.4 0.05 0.3 0.5 Mg. 0.3 0.05 0.3

Example I Lead ingots measuring about 1 x 1" x 1% and having an aggregate weight of 1.1 pounds were placed in a clay-graphite Crucible having a detachable plug in its bottom. Zirconium metal powder Iweighing 0.67 pound and titanium powder weighing 0.23 pound were placed in the crucible andpermitted to fall in the spaces between the lead ingots. The particle size of the zirconium ypowder was about 70 per cent 325 mesh and 30- per cent 100 to 325 mesh. The particle size of the titanium powder was comparable to that of the zirconium. The crucible then was placed in a high frequency electric induction furnace and, 'after adjusting the cover, the furnace was evacuated to remove air and moisture. Argon was then admitted land the charge heated to 1400 C. which required about 30 minutes. The charge was held at that temperature for about 5 minutes and the source of heat was then shut olf. Then the plug in the bottom of the crucible was pushed out with a long graphite rod causing the liquid mass in the crucible to flow into a split gang Then an inert mold positioned in the cooler bottom portion of the furnace.

The mol-d was permitted to cool substantially to normal room temperature and then was removed from the furnace. The solid rods had an analysis of 33.5 per cent zirconium, 11.5 per cent titanium and 55 per cent lead and possessed good sparking characteristics.

The same method of producing the alloy is applicable when the hydrides of the metals are used except that the evolved hydrogen (between about 600 C. and 1200 C.) is removed through a pet cock and is burned as it escapes. It is desirable to maintain apressure within the furnace slightly above atmospheric pressure and, to assure this, additional inert gas, such as argon or helium, may be admitted if necessary.

Another method for producing a suitable .pyrophoric material comprises forming an intimate mixture comprising lead, preferably a powder of -50 mesh, and finely divided zirconium or zirconium hydride with or without .titanium or titanium hydride. 'Ihis mixture is placed in dies of desired shape and size and pressed under a pressure, preferably, between 40 and 50 thousand pounds per square inch. The self-sustaining rods or briquettes thus formed may be placed in suitable heating trays, such as graphite trays, and the `trays placed in a high frequency electric induction furnace. The furnace is then placed under vacuum and heated rapidly to a temperature between about l C. to about 1250 C. but in no case above the melting point of the alloy desired and then immediately cooled substantially to normal room temperature. Alternatively, the furnace may be evacuated to remove air and moisture and an inert gas, such as argon or helium, admitted to create a pressure slightly above atmospheric pressure. Instead of heating the self-sustaining rods in an electric induction furnace, they may be placed in the retort of a gas or oil fired type of furnace and heated in the presence of an inert gas under pressure slightly greater than atmospheric to a temperature between 700 C. and 1000 C., but preferably between 900 C. to 1000 C. for one-half to one and onehalf hours. In the latter case, a higher temperature may be used if desired.

Eample II The following are illustrative pyrophoric materials in which the amounts are per cent by weight:

This invention will be more clearly understood from the following description in conjunction with the accompanying drawings, in which:

Figure 1 is a sectional elevational view of a cigarette lighter embodying the invention:

Figure 2 is a perspective view of another appliance embodying the invention and particularly adapted for lighting gas burners; and

Figure 3 is an enlarged front elevational view, partly in section, of the appliance shown in Figure 2.

Figure l of the accompanying drawing illustrates a cigarette lighter embodying the invention. This device comprises a hollow receptacle I providing a completely closed chamber II to retain a low-boiling combustible liquid. The top wall I2 of the receptacle is provided with an opening in which a short tube I3' is securely tted. A wick positioned within the chamber I I has one end portion I4 projecting through the tube I3. The bottom wall I5 is provided with a threaded hole I'6 through which the combustible low boiling liquid may be introduced into the chamber II. The hole i6 normally is closed by a threaded plug I1.

A tube I8 extends between and is tightly tted in aligned holes in the bottom and top walls of the receptacle I0. Spaced bearing members are secured to the top wall I2 and rotatably support a stud shaft 2I passing through and fixed in the center of a knurled hardened steel disc 22. The arrangement is such that the disc 22 is positioned directly over the upper end of the tube I8 and adjacent to the end portion I4 of the wick and is rotatably supported in a plane passing through the end portion I4 of the wick and the axis of the tube. A rod 23 of a pyrophoric material of the composition previously described is slidably positioned within the tube I8. One end of the rod 23 normally is held in contact with the knurled edge of the disc 22 by a coil spring 24 extending between the other end of the rod and a plug 25 threaded in the bottom end of the tube I8.

When the disc 22 is rotated, its knurled edge impacts the rod 23 and causes sparks to be thrown on the wick I4 to ignite the combustile liquid carried by the wick.

Another type of appliance embodying the invention is illustrated in Figures 2 and 3. This device is particularly adapted for igniting the gas in gas stove burners, bunsen burners, etc., and comprises a wire W of spring steel which is shaped to form a coil 26 intermediate its length with the remaining portions of the

wire forming arms

21 and 28 extending in the same general direction from the coil but tending to spring apart when held near one another. The arm 28 is shaped to form an oiset end portion 29 having aligned portions 38 and 3| connected by a straight portion 32. The end of the member 3| is offset to provide a stop 33. A thin rectangular block 34 of hardenedsteel having a knurled surface 9 is held upon the member 32 by engagement of the members and 3l with the

grooves

35 and 36 in the opposite'gedges of the block. The free end portiton 31 (Fig. 3) of the arm 21 extends parallel to the member 30 and is threaded to receive an internally threaded sleeve 38. A rod 39 of a pyrophoric material of the composition previously described is held securely in the sleeve 38 so as to extend outwardly therefrom in engagement with the knurled top surface 9 of the block 34. The rod 39 normally is held against the stop 33 by the spring action of the

arms

21 and 28.

By grasping the

arms

21 and 28 between the iingers of one hand, they may be moved toward and away from one another to cause the rod 39 to impact the knurls on the surface 9 and throw sparks over a gas burner and ignite the gas.

The

rods

23 and 39 are formed of a pyrophoric material comprising lead, titanium and zirconium in the proportions of 20 to 75 per cent of lead, 25 to 80 per cent of zirconium and from about 5 to 40 per cent of titanium, with or without other diluting metals. The rod 23 has a diameter of about 2.4 mm. while the rod 39 has a diameter of about gif of an inch. In these and other types of industrial sparking devices, the dimensions and shape of the body of pyrophoric material may be different. It may be produced in any desired manner, such as by the methods previously described.

I claim:

1. In a sparking device having a sparking element of pyrophoric material, the improvement wherein the sparking element consists essentially of lead, zirconium and titanium, the lead and zirconium being in the proportions of 20 to 75 per cent lead and 25 to 80 per cent zirconium by weight, the titanium being 5 to 40 per cent by weight of the whole material.

2. In a sparking device having a sparking element of pyrophoric material, the improvement wherein the sparking element consists essentially of lead, zirconium and titanium in the proportions of 30 to 60 per cent of lead, 25 to 65 per cent of zirconium and 5 to 40 per cent by weight of titanium.

3. In a sparking device having a sparking element of pyrophoric material, the improvement wherein the sparking element consists essentially of about 35 per cent of lead, 35 per cent of zirconium and 30 per cent by weight of titanium.

4. An air stable pyrophoric material in solid massive form which is suitable for industrial appliances, such as cigarette lighters, consisting essentially of lead, zirconium and titanium, the lead and zirconium being in the proportions of 20 to '75 per cent lead and 25 to 80 per cent ziressentially of about 35 per cent by weight of zirconium, 35 per cent by weight of lead and 30 per cent by weight of titanium.

ROBERT J. ANICETTI.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,006,849 Hofman Oct. 24, 1911 1,102,575 Faehr July 7, 1914 1,335,982 Petinot Apr. 6, 1920 1,562,540 Cooper Nov. 24, 1925 OTHER REFERENCES Cooper, article in Trans. Amer. Electrochem. Soc., vol. 43, 1923, pages 220, 222, 224, 225 (complete article, pages 215-230, inclusive).

Certificate of Correction Patent No. 2,490,571 December 6, 1949 ROBERT J. ANICETTI It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 1, line 39, for the Word from readform; column 3, line 5, for letter read latter and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent OHice.

Signed and sealed this 21st day of March, A. D. 1950.

[SEAL] THOMAS F. MURPHY,

Assistant Commissioner of Patents.