US1769229A - Electrode and contact element - Google Patents

Description

' not become brittle,

Patented July 1, 1930 AMBROSE J. HANDELL, 0] WESTII'IELD, NEW JERSEY ELECTRODE AND CONTACT ELEMENT Io Drawing. Application filed May 19,

This invention relates to electrode and contact elements which are subject to electrlc arcs, such as the contact elements of timing devices and circuit makin and breaking devices and the electrodes 0 spark plugs.

Heretofore the most satisfactory materials obtainable for the manufacture of such elements were platinum and alloys of platinum with other metals of the platinum grou The extremely high cost and scarcity of suc metals render their use prohibitive on any large scale. Among the base metals, tungsten is fairl satisfactory for contact points but is altogether unsatisfactory for spark plug electrodes because it oxidizes very rapidly at even moderately high temperatures and is also quite expensive in the ductile condition. The spark plug electrodes have been heretofore commonly manufactured from pure nickel, various alloys of nickel and manganese, and Monel, which is an alloy of mckel, copper, manganese and iron. These materials have been fairly satisfactory heretofore but with the developement of the modern high speed internal combustion motor, the service conditions have become more and more severe, so that the necessity of a bet ter electrode material has been imperative.

Among the qualities, which are desirable in an alloy for such elements, the following may be mentioned 1. Ability to withstand the cutting and abrading action of an electric spark or high voltage are, while the metal is at a high temperature.

2. Resistance to oxidation at high temperatures, and to corrosion by products of combustion.

3. Ability to withstand deterioration by changes in internal structure under the conditions of service, so that the electrode does but remains tough and ductile.

4. High thermal conductivity and high or fairly high electrical conductivity.

5. Small tendency to absorb carbon under the service conditions or ability to remain strong and tough whether or not carbon is absorbed.

6. Sufficient strength, toughness, mallea- 1925. Serial No. 81,458.

bilit and ductility to allow working into the nished form by ordinary methods, and hardness not too great to allow easy machining of the finished material.

I have discovered that by the addition of suitable proportions of silicon or silicon and certain other elements to nickel, an element may be produced which exhibits far greater durability in such service than any other base metal alloy previously known.

Increased ability to withstand the cutting and abrading action of the spark is con ferred upon nickel by additions which increase the hardness and strength at hi h temperatures, and the resistance to oxidation. Not all additions which produce this effect are suitable, however, because many of them have a bad effect upon the other properties, such as thermal and electrical conductivity, ductility, etc. Even small additions of silicon have a powerful hardening effect, and greatly promote the resistance to oxidation, and these effects are retained at high temperatures.

Additions of chromium and tungsten will harden nickel, but in order to produce the effeet of a given addition of silicon, so much more chromium or tungsten must be added that the thermal conductivity of the resultant alloy is lowered very much more, and the electrical resistance is very much increased. This effect is so pronounced that the usefulness of the alloys is practically destroyed.

Alumium has a similar eflect in hardening nickel and promoting resistance to oxidation, but the accompanying bad efiects are not so pronounced as for chromium or tungsten. The hardening effect of zirconium is great, but the resistance to oxidation obtained by addition of zirconium is not so high, and the high cost of zirconium is a great disadvantage. The same remarks apply to titanium and vanadium. Therefore, while small amounts of any or all of these metals may be 7 added, to the alloy, amounts to be added must 95 not be excessive, and they will not serve to replace all of the silicon. If sufficient silicon is present, none of these metals need be added.

Addition to nickel of suflicient silicon, or of 100 silicon plus the other metals mentioned, to produce the required resistance to cutting and abrasion, to oxidation, and to deterioration of structure at hi h temperatures will lower the ductility ant? toughness considerably, as compared to pure nickel. These latter ualities can be greatly improved by the furt er addition to the alloy of a suitable proportion of manganese, without harm to the previously mentioned qualities, and this effect of the manganese is so valuable that while manganese is not an absolutely essential constituent, the alloys containing a certain amount of man anese are decidedly preferable to those wh ch contain no manganese, or only trifling amounts. Too much manganese should not be added. as it will cause a lowering of the thermal conductivity, and thereby automatically raise the operating temperature of the electrodes when in service, which will of course mean increased severity of the working conditions and conse uently a shorter life.

etals such as copper and iron should not be present it they can be avoided. These metals are of little or no value in promoting the desirable qualities, and they will reduce the thermal conductivity markedl if more than trifling amounts are present. 11 also has the bad effect in these alloys of reducing the resistance to oxidation, and when much is present, of causing brittleness, nullifying the beneficial efiect of the manganese addition.

The percenta es of the various constituents of the alloy w ich have been found b experiment to be preferable and desirab e are the following Silicon should be present in amounts pref erably not to exceed approximately 6 to 7%. Above these percentages the alloy becomes so hard as to be practically unworkable by ordinary methods, which of course destroys its usefulness for this purpose, although m castings, much larger amounts might be used. The referable addition is from 3 to 5% in which range the alloy is strong, quite tou h and ductile, and exhibits all the good ua ities previously enumerated. Addition 0 silicon in amounts less than three per cent is of very marked benefit, but with the smaller additions the benefit to be obtained is of course also less.

Manganese should preferably be present in amounts of approximately 2%, and not great- 1y to exceed approximately 5%. The beneficial effect on the toughness and ductilit of an addition of manganese is very marked, but if more than about 5% is present the thermal conductivity is lowered considerably, without compensating increase of toughness and ductility. If less than about of 1% or so is present, the effect is small. while with additions of about 2%, the beneficial effects are very pronounced, without any marked decrease in thermal or electrical conductivity,

as compared with alloys containing little or no manganese.

Any or all of the elements, aluminum, chromium, tungsten, zirconium, titanium, and vanadium may be used to replace a portion of the silicon, but they should not be used to re lace all or a major portion of the silicon. eir combined total should not exceed the total of the silicon resent, and the total of these elements lust e silicon should not much exceed the mentioned as the practical limit for silicon, for although their efiects on the ductility are less, their efiects on the thermal conductivity and electrical resistance are greater.

Iron is of no benefit to the alloy, and should be kept as low as possible, because of its bad effects on the resistance to. oxidation, the toughness and the thermal and electrical conductivities. It should preferably be present only in such amounts as are unavoidable when working with commercial materials.

The bad effects of copper are much less pronounced, but as cop r is of no benefit, it also should be kept as ow as possible.

Elements such as sul hur, carbon, phosphorus, etc., should be ept as low as possible, because of their bad effects on the mechanical roperties.

The ba ance of the alloy should be nickel. I am aware that cobalt may be substituted for nickel, in this alloy, but the high price of cobalt, as compared with that of nickel makes it, at the present time, an undesirable substitute for nickel, and it ofiers no compensating advantage over nickel. When mckel is used the amount of cobalt present should be small, and when cobalt is used the amount of nickel present should be small, for when large amounts of these elements are present simultaneously, the thermal and electrical conductivities of the resultant alloy are considerably lowered, which is an undesirable efiect.

Commerical nickel frequently contains a small amount of silicon, usually less than of 1 rcent, and it is necessa tiona silicon to the commercia nickel so that the silicon content will be at least of 1 percent or more.

It will be understood that by the term nickel, I intend cobalt to be considered as an equivalent substitute and that the electrode and contact elements are formed of an allo of nickel with an added quantity of si icon and referably also man anese with optionally t e addition of smal quantities of other substances, all as specified in the ap nded claims.

t will be obvious that the specific instances, which have been given herein, are intended solely for the purpose of explaining the-nature of the invention, and that, therefore, various changes in the details and proto add addi- III portions may be made b those skilled in the art within the princip e and scope of the invention, as expressed in the appended claims.

I claim 1. Electrode and contact elements subject to electric arcs, such as for timing devices, spark plugs, and circuit making and breaking devices, said elements bein formed of an alloy comprising a base of nickel with an added quantity of substances selected from the group consisting of silicon, alumium, chromium, tungsten, zirconium, titanium, manganese, and vanadium, the substances added from said group including at least silicon, and constituting between 1 and 5% of the alloy.

2. Electrode and contact elements subject to electric arcs, such as for timing devices, spark plugs, and circuit making and breaking devices, said elements being formed of an alloy comprising a base of nickel with an added quantity of substances selected from the group consisting of silicon, aluminum, chromium, tungsten, zirconium, titanium, manganese, and vanadium, the substances added from said group includin at least silicon, the silicon constituting atdeast 40% of the added substances.

3. Electrode and contact elements subject to electric arcs, such as for timing devices, spark plugs, and circuit making and breaking devices, said elements being formed of an alloy comprising a base of nickel with an added quantity of substances selected from the group consisting of silicon, aluminum, chromium, tungsten, zirconium, titanium, ma anese, and vanadium, the substances added rom said group including at least silicon, and constitutlng less than 10% of the alloy.

4. Electrode and contact elements subject to electric arcs, such as for timing devices, spark plugs, and circuit making and breaking devices, said elements being formed of an alloy comprising a base selected from the group comprising nickel and cobalt with an added quantity of silicon in an amount between 2 to 5%.

5. Electrode and contact elements subject to electric arcs, such as for timing devices, spark plugs, and circuit making and breaking devices, said elements being formed of an alloy comprising a base selected from the group comprising nickel and cobalt with an added quantity of silicon and manganese, the silicon addition varying between of 1% and 10%, and the manganese varying between nothing and 5%.

6. Electrode and contact elements subject to electric arcs, such as for timing devices, spark plugs, and circuit making and breaking devices, said elements being formed of an alloy comprising a base selected from the group comprising nickel and cobalt with an AMBROSE J. MANDELL.