US3914009A

US3914009A - Electrical contact device and method of preparation thereof

Info

Publication number: US3914009A
Application number: US417177A
Authority: US
Inventors: Enrique Chia; Herbert M Hanegan; Paul S Keith
Original assignee: Southwire Co LLC
Current assignee: Southwire Co LLC
Priority date: 1971-11-19
Filing date: 1973-11-19
Publication date: 1975-10-21
Anticipated expiration: 1992-10-21

Abstract

An electrical contact device having an electrical conductivity of at least 57% based on the International Annealed Copper Standard and unexpected properties of increased thermal stability, ultimate elongation, bendability, ductility, creep resistance, tensile and yield strength, and fatigue resistance when compared to conventional aluminum alloy connectors. The electrical contact device contains substantially evenly distributed iron aluminate inclusions in a concentration produced by the addition of more than about 0.20 weight percent iron to an alloy mass containing less than about 99.78 weight percent aluminum, from about 0.07 to about 0.35 weight percent magnesium, from about 0.01 to about 0.25 weight percent silicon, from about 0.0002 to about 0.20 weight percent copper, and up to about 0.15 weight percent conventional impurities normally found within a commercial aluminum alloy. The substantially evenly distributed iron aluminate inclusion are obtained by casting an alloy consisting essentially of less than about 99.78 weight percent aluminum, more than about 0.20 weight percent iron, from about 0.07 to about 0.35 weight percent magnesium, from about 0.01 to about 0.25 weight percent silicon, from about 0.0003 to about 0.20 weight percent copper, and up to about 0.15 weight percent typical impurities to form an aluminum alloy bar, billet, or shape, subsequently forming into a contact device without intermediate anneals and annealing the formed contact device. After annealing, the contact device has the aforementioned novel and unexpected properties of increased thermal stability, ultimate elongation, tensile strength, electrical conductivity of at least 57% of the International Annealed Copper Standard, and increased bendability, fatigue resistance, creep resistance, ductility, and high yield strength.

Description

United States Patent [191 Chia et al.

[4 Oct. 21, 1975 1 1 ELECTRICAL CONTACT DEVICE AND METHOD OF PREPARATION THEREOF [75] Inventors: Enrique Chia; Herbert M. Hanegan;

Paul S. Keith, all of Carrollton, Ga.

[73] Assignee: Southwire Company, Carrollton,

22 Filed: Nov. 19, 1973 21 Appl. No.: 417,177

Related US. Application Data [63] Continuation-impart of Ser. No. 200,576, Nov. 19,

1971, abandoned.

[52] US. Cl 339/278 C; 29/193; 29/527.7; 29/630 C; 75/138; 148/2 [51] Int. Cl. H01R 3/02 [58] Field of Search... 29/193, 630 C, 527.5, 527.7; 75/138; 148/2, 32; 164/76, 57; 339/278 C OTHER PUBLICATIONS R. H. Harrington, The Effects of Single Addition Metals on the Recrystallization, Electrical Conductivity and Rupture Strength of Pure Aluminum, Transactions of the American Society for Metals, Vol. 41, pp. 443-459, 1949.

Primary ExaminerC. W. Lanham Assistant ExaminerV. K. Rising Attorney, Agent, or FirmVan C. Wilks; Herbert M. Hanegan; Stanley L. Tate [57] ABSTRACT An electrical contact device having an electrical conductivity of at least 57% based on the International Annealed Copper Standard and unexpected properties of increased thermal stability, ultimate elongation, bendability, ductility, creep resistance, tensile and yield strength, and fatigue resistance when compared to conventional aluminum alloy connectors. The electrical contact device contains substantially evenly distributed iron aluminate inclusions in a concentration produced by the addition of more than about 0.20 weight percent iron to an alloy mass containing less than about 99.78 weight percent aluminum, from about 0.07 to about 0.35 weight percent magnesium, from about 0.01 to about 0.25 weight percent silicon, from about 0.0002 to about 0.20 weight percent copper, and up to about 0.15 weight percent conventional impurities normally found within a commercial aluminum alloy. The substantially evenly distributed iron aluminate inclusion are obtained by casting an alloy consisting essentially of less than about 99.78 weight percent aluminum, more than about 0.20 weight percent iron, from about 0.07 to about 0.35 weight percent magnesium, from about 0.01 to about 0.25 weight percent silicon, from about 0.0003 to about 0.20 weight percent copper, and up to about 0.15 weight percent typical impurities to form an aluminum alloy bar, billet, or shape, subsequently forming into a contact device without intermediate anneals and annealing the formed contact device. After annealing, the contact device has the aforementioned novel and unexpected properties of increased thermal stability, ultimate elongation, tensile strength, electrical conductivity of at least 57% of the International Annealed Copper Standard, and increased bendability, fatigue resistance, creep resistance, ductility, and high yield strength.

26 Claims, 5 Drawing Figures US. Patent Oct. 21, 1975 ELECTRICAL CONTACT DEVICE AND METHOD OF PREPARATION THEREOF CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of copending application Ser. No. 200,576, filed Nov. [9, 1971 now abandoned.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a diagramatic representation of one embodiment of the present invention illustrating a Butt Splice.

FIG. 2 is a diagramatic representation of the present invention embodied as a Stacking Pin.

FIG. 3 is a diagramatic representation of the present invention embodied as a Ring Tongue Terminal.

FIG. 4 is a diagramatic representation of the present invention embodied as a Flanged Spade Terminal.

FIG. 5 is a diagramatic representation of the present invention embodied as a Rectangular Blank Tongue Terminal.

DESCRIPTION OF THE PREFERRED EMBODIMENTS This invention relates to an electrical contact device suitable for use as an electrical conductor and more particularly concerns an electrical contact device having an acceptable electrical conductivity and improved thermal stability, elongation, bendability, and tensile strength.

Contact devices as used herein are understood to include single and multiple circuit connectors, tubes, bus bars, ferrules, fasteners, terminals, splices, receptacles, pins, tabs, sockets, jacks, plugs, and other like contact devices for conducting electricity.

The use of various aluminum alloys as conductors of electricity is well established in the art'. Such alloys characteristically have conductivities of at least 57% of the International Annealed Copper Standard (hereinafter sometimes referred to as IACS) and chemical constituents consisting of a substantial amount of pure aluminum and small amounts of conventional impurities such as silicon, vanadium, iron, copper, manganese, magnesium, zinc, boron and titanium. The physical properties of prior electrical contact devices have proven less than desirable, i.e., their thermal stability has rendered such contact devices generally unsuitable for many applications. Generally desirable percent elongations have been obtained only at less than desirable percent elongations. In addition, the bendability, ductility, creep resistance, and fatique resistance of prior aluminum alloy contact devices have been so low that they have been generally unsuitable for many oth erwise desirable applications.

Thus, it becomes apparent that a need has arisen within the industry for an electrically conductive contact device suitable for use with aluminum conductors which has both improved thermal stability, improved percent elongation and tensile strength, and also possesses the ability to withstand numerous bends at one point and to resist fatiguing during use. Therefore, it is an object of the present invention to provide an electrical conductor device of acceptable conductivity and improved physical properties and suitable for use with aluminum conductors such that said conductors may be used in new applications. Another object of the present invention is to provide an electrical contact device having novel properties of increased thermal stability ultimate elongation and tensile strength, improved bendability, ductility, creep resistance, yield strength and fatigue resistance, and acceptable electrical conductivity. These and other objects, features and advantages of the present invention will become apparent to those skilled in the art from a consideration of the following detailed description of the following detailed description of the invention.

In accordance with this invention, the present electrically conductive contact device is prepared from an alloy comprising less than about 99.78 weight percent aluminum, more than about 0.02 weight percent iron, from about 0.07 to about 0.35 weight percent magnesium, from about 0.0] to about 0.25 weight percent copper, and up to about 0.15 weight conventional impurities normally found in a commercial aluminum alloy.

Preferably, the aluminum content of the present alloy comprises from about 97.25 to about 99.72 weight percent, with particularly superior results being achieved when from about 97.90 to about 99.35 weight percent aluminum is employed.

The iromgontent of the present alloy advantageously comprises l fi o'm about 0.02 weight percent to about 2.00 weighti percent, with particularly superior results being achieved when from about 0.05 weight percent to about Weight percent iron is employed.

Preferably from about 0.20 to about 0.15 weight percent silicon is employed in the present alloy, with particularly superior results being achieved when from about 0.04 to about 0.10 weight percent silicon is employed.

The magnesium content of the present alloy advantageously comprises from about 0.07 to about 0.25 weight percent, with particularly superior results being achieved when from about 0.10 to about 0.20 weight percent magnesium is employed.

Preferably the copper content of the present alloy comprises from about 0.005 to 0.15 weight percent, with particularly superior results being achieved when from about 0.01 to about 0.10 weight percent copper is employed.

The present electrical contact device is prepared by initially melting and alloying aluminum with the necessary amount of iron, magnesium, copper, or other constituents to provide the requisite alloy for processing. Typical impurities or trace elements are also present within the melt, but only. in trace quantities, such as less than about 0.05 weight percent each with a total content of trace impurities generally not exceeding about 0.15 weight percent. Preferably the individual trace elements are present in an amount of from about 0.0004 about 0.04, and the total content of trace elements are present in an amount of from about 0.002 to about 0.l0 weight percent. Of course, when adjusting the amount of trace elements due consideration must be given to the conductivity of the final alloy since some trace elements affect conductivity more severely than others. Typical trace elements include vanadium, manganese and zinc.

Magnesium, iron, and copper are the major constituents added to the melt to produce the alloy of the present invention. Normally about 0.10 weight percent magnesium, about 0.01 weight percent copper, and about 0.50 weight percent iron are added to the typical aluminum conponent used to prepare the present alloy.

Of course, the scope of the present invention includes the addition of more or less magnesium, iron, and copper together with the adjustment of the content of all alloying constituents.

After alloying, the melted aluminum composition can be continuously cast into a continuous bar or conventionally cast into a bar, billet or shape. Where the alloy is continuously cast the bar is'hot-worked in substantially that condition in which it is received from the casting machine. A typical hot-working operation comprises rolling the bar in a rolling mill substantially immediately after being cast into a bar.

One example of a continuous casting and rolling operation capable of producing continuous rod as specified in this application is as follows:

A continuous casting machine serves as a means for solidifying the molten aluminum alloy metal to provide a cast bar that is conveyed in substantially the condition in which it solidified from the'continuous casting machine to the rolling mill, which serves as a means for hot-forming the cast bar into rod or another hotformed product in a manner which impartssubstantial movement to the cast bar along a plurality of angularly disposed axes.

The continuous casting machine is of conventional casting wheel type having a casting wheel with a casting groove partially closed by an endless belt supported by the casting wheel and an idler pulley. The casting wheel and the endless belt cooperate to provide a mold into one end of which molten metal is poured to solidify and from the other end of which the cast bar is emitted in substantially that condition in which it solidified.

The rolling mill is of conventional type having a plurality of roll stands arranged to hot-form the cast bar by a series of deformations. The continuous casting machine and the rolling mill are positioned relative to each other so that the cast bar enters the rolling mill substantially immediately after solidification and in substantially that condition in which it solidified. In this condition, the cast bar is at a hot-forming temperature within the range of temperatures, for hot-forming the cast bar at the initiation of hot-forming without heating between the casting machine and the rolling mill. In the event that it is desired to closely control the hotforming temperature of the cast bar within the conventional range of hot-forming temperatures, means for adjusting the temperature of the cast bar may be placed between the continuous casting machine and the rolling mill without departing from the inventive concept disclosed herein.

The roll stands each include a plurality of'rolls which engage the cast bar. The rolls of each roll stand may be two or more in number and arrange diametrically opposite from one another or arranged at equally spaced.

positions about the axis of movement of the cast bar through the rolling mill. The rolls of each roll stand of the rolling mill are rotated at a predetermined speed by a power means such as one or more electric motors and the casting wheel is rotated at a speed generally determined by its operating characteristics. The rolling mill serves to hot-form the cast bar into a rod of a crosssectional area substantially less than that of the cast bar as it enters the rolling mill.

The peripheral surfaces of the rolls of adjacent roll stands in the rolling mill change in configuration; that is, the cast bar is engaged by the rolls of successive roll stands with surfaces of varying configuration and from different directions. This varying surface engagement of the cast bar in the roll stands functions to knead or shape the metal in the cast bar in such a manner that it is worked at each roll stand and also to simultar neously reduce and change the cross-sectional area of the cast bar into that of the rod.

As each roll stand engages the cast bar, it is desirable that the cast bar be received with sufficient volume per unit of time at the roll stand for the cast bar to generally fill the space defined by the rolls of the roll stand so. I

that the rolls will be effective to work the metal in the cast bar. However, it is also desirable that the space defined by the rolls of each roll stand not be overfilled so that the cast bar will not be forced into the gaps be-- tween the rolls. Thus, it is desirable that the rod be fed toward each roll stand at a volume per unit of time 1 which is sufficient to fill, but not overfill, the space defined by the rolls of the roll stand.

As the cast bar is received from the continuous casting machine, it usually has one large flat surface corresponding to the surface of the endless band and inwardly tapered side surfaces corresponding to. 'the shape of the groove in the casting wheel. As the cast bar is compressed by the rolls of the roll stands, the cast bar is deformed so that it generally takes the crosssectional shape defined by the adjacent peripheries. of the rolls of each roll stand.

Thus, it will be understood that with this apparatus, cast aluminum alloy rod of an infinite number of different lengths is prepared by simultaneous casting of the molten aluminum alloy and hot-forming or rolling the. cast aluminum bar. t

The continuous rod produced by continuous casting and rolling can be hot forged into an electrical contact device of required size and shape, or can be cold forged into the required size and shape and, if desired, an-

nealed. It also can be impact extruded, extruded through dies into tube form, cold drawn or coldforged into the required size and shape and, if desired, annealed.

The conventionally cast bar, billet, or shape can be impact extruded, extruded through dies into tube form,

cold drawn or cold forged into the required size and shape, and if desired, annealed. It can also be pierced and the pierced portion either cold forged into the required size and shape, or extruded through dies into tube form, cold drawn or cold forged intothe required size and shape and, if desired, annealed.

The continuously cast and continuously rolled rod and the conventionally cast baror billet can be cold or I hot rolled into a sheet. The sheet then can be stamped,

punched, or cut and formed into the required shape about 1/l0,000 of a minute. Generally, howevencontinuous annealing temperatures and times may be adjusted to meet the requirements of the particular overall processing operation so long as the desired connec. tor properties are achieved. In a batch annealing operation, a temperature of approximately 400F to about 750F is employed with residence times of about 30 minutes to about 24 hours. As mentioned with respect to continous annealing, in batch annealing the time and temperatures may be varied to suit the overall process so long as the desired connector properties are obtained.

During the casting of this alloy, a substantial portion of the iron present in the alloy precipitates out of solution as iron aluminate intermetallic compound (FeAl Thus, after casting, the bar contains a dispersion of FeAl in a supersaturated solid solution matrix. As the bar or billet is rolled the FeAl particles are broken up and dispersed throughout the matrix, inhibihiting large cell formation. When the contact device is then formed to its final shape and size without intermediate anneals and aged in a final annealing operation, the thermal stability, tensile strength, elongation and bendability are increased due to the small cell size and the additional pinning of dislocations by preferential precipitation of FeAl on the dislocation sites.

The properties of the present electrical contact device are significantly affected by the size of the FeAl particles in the matrix. Coarse precipitates reduce the thermal stability, percent elongation and bendability of the contact device by enhancing nucleation and thus, formation of large cells which, in turn, lowers the recrystallization temperature of the connector. Fine precipitates improve the thermal stability, percent elongation, and bendability by reducing nucleation and increasing the recrystallization temperature. Grossly coarse precipitates of FeAl cause the contact device to become brittle and generally unusable. For purposes of this invention it is understood that coarse precipitates have a particle size of below 10,000 angstrom units. The majority of FeAl particles in the present aluminum alloy have a particle size of below 10,000 angstrom units.

Upon examination of a cold drawn contact device, it is found that the precipitates are oriented in the direction of drawing. In addition, it is found that the precipitates can be rod-like, plate-like, or spherical in configuration.

Other intermetallic compounds which may be formed, depending upon the constituents of the melt and the relative concentrations of elements present in the alloy includethe following: Al,Cu Fe, Mg Si, FeSi), CuAl Al Fe Si FeAl 3Fe Si- Al Mn, FeAl AI Mg Cu, Al Mg Al Cu Mg- AlCuMg.

The following specific examples are intended to be illustrative of the invention, but not limiting of the scope thereof, parts and percentages being by weight unless otherwise specified.

EXAMPLE 1 A comparison between prior EC aluminum alloy contact devices and the present aluminum alloy contact devices was provided by preparing aprior EC alloy with aluminum content of 99.73 weight percent, iron content of 0.18 weight percent, silicon content of 0.059 weight percent, and trace amounts of typical impurities. The present alloy was prepared with aluminum content of 99.45 weight percent, magnesium content of 0.15 weight percent, iron content of 0.45 weight percent, silicon content of 0.056 weight percent, copper content of 0.05 weight percent, and trace amounts of typical impurities. Both alloys were continuously cast into continuous bars and hot-rolled into continuous rod in similar fashion. The alloys were then formed into size 12-10 AWG ferrule connectors and tongue type connectors. The connectors were then batch furnaceannealed at similar temperatures and for similar lengths of time. The annealed connectors were attached to copper wires and subjected to a heat cycling test in which current was passed through a circuit containing four samples; a prior EC Alloy ferrule connector, a prior EC alloy tongue connector, a present alloy ferrule connector, and a present alloy tongue connector. The test consisted of controlled current cycling on-off periods. Failure was considered when the connection temperature reaches C. A minimum testing time of 10,000 hours on" period (or energized) was used. Current cycle was five hours on controlled currenton hour off. The controlled current used was 30 amperes. After 10,000 hours on period, in excess of 50 percent failures were experienced in the prior EC alloy ferrule and tongue connectors. No failures were experienced for the present alloy ferrule and tongue connectors. A test time of 10,000 hours on" period was considered to be equal to a minimum 7 year life actual service.

EXAMPLES 2 THROUGH 8 The procedure of Example I was repeated using seven aluminum alloys prepared with the varying amounts of major constituents listed below.

No failures were experienced for ferrule and tongue connectors prepared from the seven alloys listed.

EXAMPLES 9 THROUGH 16 The procedures of Examples 1 through 8 were repeated except the alloys were conventionally cast into a bar, rolledinto sheet and the ferrule and tonque connectors stamped from the sheet and cold-formed into the desired shape. In excess of 50 percent failures were experienced in the prior EC alloy connectors after a test time of 10,000 hours on period. No failures were experienced for the present alloy ferrule and tongue connectors.

While this invention has been described in detail with particular reference to preferred embodiments thereof, it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinbefore and as defined in the appended claims.

What is claimed is:

1. An electrical contact device having a minimum conductivity of 57% IACS consisting essentially of more than about 0.02 weight percent iron, from about 0.07 to about 0.35 weight percent magnesium, from about 0.01 to about 0.25 weight percent silicon, from about 0.0003 to about 0.02 weight percent copper, less than about 0.05 weight percent each of trace elements selected from the group consisting of vanadium, manganese and zinc, and from about 97.25 to about 99.78

weight percent aluminum, said alloy containing no more than about 0.15 total weight percent of said trace elements, said contact device having improved thermal stability when compared against conventional EC aluminum devices which renders said contact device capable of withstanding repeated current cycling over an extended period of time, without failure.

2. The electrical contact device of claim 1 consisting essentially of from about 0.20 to about 2.00 weight percent iron, from about 0.07 to about 0.25 weight percent magnesium, from about 0.02 to about 0.15 weight percent silicon, from about 0.005 to about 0.15 weight percent copper, and from about 97.25 to about 99.72 weight percent aluminum.

3.The electrical contact device of claim 2 consisting essentially of from about 0.05 to about 1.50 weight percent iron, from about 0.10 to about 0.20 weight percent magnesium, from about 0.04 to about 0.10 weight percent silicon, from about 0.01 to about 0.10 weight percent copper, and from about 97.90 to abot 99.35 weight percent aluminum.

4. The electrical contact device of claim 1 wherein the silicon content is from about 0.02 to about 0.15 weight percent, the individual trace element content is from about 0.0004 to about 0.04 weight percent, and the total trace element content is from about 0.002 to about, 0.10 weight percent.

5. The electrical contact device of claim 1 wherein the individual trace element content is less than about 0.0004 percent and the total trace element content is less than about 0.002 weight percent.

6. An electrical contact device having a minimum conductivity of 57% IACS containing substantially evenly distributed iron aluminate inclusions in a concentration produced by the presence of more than about 0.02 weightpercent iron in an alloy mass consisting essentially of from about 97.25 to about 99.78 weight percent aluminum, from about 0.01 to about 0.25 weight percent silicon, from about 0.07 to about 0.35 weight percent magnesium, from about 0.0003 to about 0.20 weight percent copper, less than about 0.05 weight percent each of trace elements selected from the group consisting of vanadium, manganese, and zinc, said alloy containing no more than about 0.15 total weight percent of said trace elements, said iron aluminate inclusions having a particles size of less than 10,000 angstrom units, said contact device having im-. proved thermal stability when compared against conventional EC aluminum devices which renders said contact device capable of withstanding repeated current cycling over an extended period of time, without failure.

7. The electrical contact device of claim 6 wherein the individual trace element content is less than about 0.0004 weight percent, and the total trace element content is less than about 0.002 weight percent.

8. The electrical contact device of claim 6 wherein iron is present in a concentration of from about 0.20 to about 2.00 weight percent, magnesium is present in a concentration from about 0.07 to about 0.25 weight percent, silicon is present in a concentration of from about 0.02 to about 0.15 weight percent, copper is present in a concentration of from about 0.005 to about 0.15 weight percent, and aluminum is present in a concentration of from about 97.25 to about 99.72 weight percent.

9. The electrical contact device of claim 8 wherein iron is present in a concentration of from about 0.50 to about, 1.50 weight percent, magnesium is present in a concentration of from about.0.l0 to about 0.20 weight percent, silicon is present in a concentration of from about 0.04 to about 0.10 weight percent, copper is present in a concentration of from about 0.01 to about 0.10 weight percent, and aluminum is present in a concentration of from about 97.90 to about 99.35 weight percent. 7

10. The electrical contact device of claim 6 wherein the silicon content is from about 0.02.to about 0.15

weight percent, the individual trace element content is I from about 0.0004 to about 0.04 weight percent, and

the total trace element content is from about 0.002 to about 0.10 weight percent.

11. A process for preparing an electrical contact device having a minimum conductivity of at least 57% IACS comprising the steps of: a. Alloying from about 97.25 to about 99.78 weigh percent aluminum with more than 0.20 weight percent iron, from about 0.07 to about 0.35 weight percent magnesium, from about 0.01 to about 0.25

of withstanding repeated current cycling over an extended period of time, without failure.

12. The process of claim 11 including the step of an-:

nealing or partially annealing the contact device.

13. A process for preparing an electrical contact device having a minimum conductivity of at least 57% IACS comprising the steps of:

a. Alloying from about 97.25 to about 99.78 weight percent aluminum with more than about 0.20

weight percent iron, from about 0.07 to about 0.35

weight percent magnesium, from about 0.01 to about 0.25 weight percent silicon, from about 0.0003 to about 0.20 weight percent copper, and

less than about 0.05 weight percent each of trace elements selected from the group consisting of vanadium, manganese and zinc, the total trace element content being no more than about 0.15 weight percent of said trace elements:

b. Continuously casting the alloy into a continuous:

bar;

0. Continuously rolling the bar in substantially that condition in which it was cast to form a continuous.

rod; and d. Forming the rod with no preliminary or intermediate anneals into a contact device, said contact device having improved thermal stability when compared against conventional EC aluminum devices which renders said contact device capable of withstanding repeated current cycling over an extended period of time, without failure.

14. The process of caim 13 wherein the individual trace element content is less than about 0.0004 weight percent, and the total trace element content is less than about 0.002 weight percent.

15. The process of claim 13 wherein step (a) comprises alloying from about 97.25 to about 99.72 weight percent aluminum, from about 0.20 to about 2.00 weight percent iron, from about 0.07 to about 0.25 weight percent magnesium, from about 0.02 to about 0.15 weight percent silicon, and from about 0.005 to about 0.15 weight percent copper.

16. The process of claim 15 wherein step (a) comprises alloying from about 97.90 to about 99.35 weight percent aluminum, from about 0.50 to about 1.50 weight percent iron, from about 0.10 to about 0.20 weight percent magnesium, from about 0.04 to about 0.10 weight percent silicon, and from about 0.01 to about 0.10 weight percent copper.

17. The process of claim 13 wherein the silicon content is from about 0.02 to about 0.15 weight percent, the individual trace element content is from about 0.0004 to about 0.04 weight percent, and the total trace element content is from about 0.002 to about 0.10 weight percent.

18. The process of claim 13 including the step of annealing or partially annealing the contact device.

19. A process for preparing an electrical contact device having a minimum conductivity of at least 57% IACS and containing substantially evenly distributed iron aluminate inclusions having a particle size of less than 10,000 angstrom units, comprising the steps of:

a. Alloying from about 97.25 to about 97.78 weight percent aluminum with more than about 0.20 weight percent iron, from about 0.07 to about 0.35 weight percent magnesium, from about 0.01 to about 0.25 weight percent silicon, from about 00003 to about 0.20 weight percent copper, and less than about 0.05 weight percent each of trace elements selected from the group consisting of vanadium, manganese and zinc, the total trace element content being no more than about 0.15 weight percent of said trace elements,

b. Continuously casting the alloy into a continuous bar;

c. Continuously rolling the bar in substantially that condition in which it was cast to form a continuous rod; and

d. Forming the rod with no preliminary or intermediate anneals into a contact device, said contact device having improved thermal stability when compared against conventional EC aluminum de vices which renders said contact device capable of withstanding repeated current cycling over an extended period of time, without failure.

20. The process of claim 19 wherein the individual trace element content is less than about 0.0004 weight percent, and the total trace element content is less than about 0.002 weight percent.

21. The process of claim 19 wherein step (a) comprises alloying from about 97.25 to about 99.72 weight percent aluminum, from about 0.20 to about 2.00 weight percent iron, from about 0.07 to about 0.25 weight percent magnesium, from about 0.02 to about 0.15 weight percent silicon, and from about 0.005 to about 0.15 weight percent copper.

22. The process of claim 21, wherein step (a) comprises alloying from about 97.90 to about 99.35 weight percent aluminum, from about 0.50 to about 1.50 weight percent iron, from about 0.10 to about 0.20 weight percent magnesium, from about 0.04 to about 0.10 weight percent silicon, and from about 0.01 to about 0.10 weight percent copper.

23. The process of claim 19 wherein the silicon content is from about 0.02 to about 0.15 weight percent, the individual trace element content is from about 0.0004 to about 0.04 weight percent, and the total trace element is from about 0.002 to about 0.10 weight percent.

24. The process of claim 19 including the step of anealing or partially annealing the contact device.

25. A process for preparing an electrical contact device having a minimum conductivity of at least 57% IACS and containing substantially evenly distributed iron aluminate inclusions having a particle size of less than 10,000 angstrom units comprising the steps of:

a. Alloying from about 97.25 to about 99.78 weight percent aluminum with more than about 0.20 weight percent iron, from about 0.07 to about 0.35

weight percent magnesium, from about 0.01 to about 0.25 weight percent silicon, from about 0.0003 to about 0.20 weight percent copper, and less than from about 0.0003 to about 0.20 weight percent copper, and less than about 0.05 weight percent each of trace elements selected from the group consisting of vanadium, manganese and zinc, the total trace element content being no more than about 0.015 weight percent of said trace elements: Casting the alloy to form a cast bar; and

Forming the bar with no preliminary or intermediate anneals into a contact device, said contact devicehaving improved thermal stability when compared against conventional EC aluminum devices which renders said contact device capable of withstanding repeated current cycling over an extended period of time, without failure.

26. The process of claim 25 including the step of annealing or partially annealing the contact device.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 1 3,914,009

DATED 3 October 21, 1975 |NVENTOR(S) I Enrique hi et a1.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 50; "percent elongations" should be -tensile strengths-- Column 2, line 67; "conponent" should be --component-.

Column 3, line 53; "arrange" should be --arranged--.

Column 5, line 33; "below" should be --above-- Column 6, line 15; "on" should be -one-- Column 7, line 20; "abot" should be --about--.

Column 10, line 26; "anealing" should be --annealing-.

Signed and Scaled this Twenty-ninth Day Of March 1977 [SEAL] Arrest:

RUTH C. MASON C. MARSHALL DANN Altesn'ng Officer Commissioner ofParents and Trademarks

Claims

1. AN ELECTRICAL CONTACT DEVICEHAVING A MINIMUM CONDUCTIVITY OF 57% IACS CONSISTING ESENTIALLY OF MOETHAN ABOUT 0.02 WEIGHT PERCENT IRON, FROM ABOUT 0.07 TO ABOUT 0.35 WEIGHT PERCENT AGNESIUM, FROM ABOUT 0.01 TO ABOUT 0.25 WEIGHT PER SILION, FROM ABOUT 0.0003 TO ABOUT 0.02 WEIGHT PERCENT COPPER, LESS THAN ABOUT 0.05 WEIGHT PERCENT EACH OF TRACE ELEMENTS SELECTED FROM THE GROUP CONSISTING OF VANDIUM, MANGANESE AND ZINC, AND FROM ABOUT 97.25 TO ABOUT 99.78% WEIGHT PERCENT ALUMINIUM, SAID ALLOY ONTAINING NO MORE THAN ABOUT 0.15 TOTAL WEIGHT PERCENT OF SAID TRACE ELEMENTS, SAID CONTACT DEVICE HAVING IMPROVED THERMAL STABILITY - WHEN COMPARED AGAINST CONVENTIONAL EC ALUMINUM DIVECES - WHICH RENDERS SAID CONTACT DEVICE CAPABLE OF WITHSTANDING EPEATED CURRENT CYCLING OVER AN EXTENDED PERIOD OF TIME, WITHOUT FAILURE.

3. The electrical contact device of claim 2 consisting essentially of from about 0.05 to about 1.50 weight percent iron, from about 0.10 to about 0.20 weight percent magnesium, from about 0.04 to about 0.10 weight percent silicon, from about 0.01 to about 0.10 weight percent copper, and from about 97.90 to abot 99.35 weight percent aluminum.

4. The electrical contact device of claim 1 wherein the silicon content is from about 0.02 to about 0.15 weight percent, the individual trace element content is from about 0.0004 to about 0.04 weight percent, and the total trace element content is from about 0.002 to about 0.10 weight percent.

6. An electrical contact device having a minimum conductivity of 57% IACS containing substantially evenly distributed iron aluminate inclusions in a concentration produced by the presence of more than about 0.02 weight percent iron in an alloy mass consisting essentially of from about 97.25 to about 99.78 weight percent aluminum, from about 0.01 to about 0.25 weight percent silicon, from about 0.07 to about 0.35 weight percent magnesium, from about 0.0003 to about 0.20 weight percent copper, less than about 0.05 weight percent each of trace elements selected from the group consisting of vanadium, manganese, and zinc, said alloy containing no more than about 0.15 total weight percent of said trace elements, said iron aluminate inclusions having a particles size of less than 10,000 angstrom units, said contact device having improved thermal stability - when compared against conventional EC aluminum devices - which renders said contact device capable of withstanding repeated current cycling over an extended period of time, without failure.

9. The electrical contact device of claim 8 wherein iron is present in a concentration of from about 0.50 to about 1.50 weight percent, magnesium is present in a concentration of from about 0.10 to about 0.20 weight percent, silicon is present in a concentration of from about 0.04 to about 0.10 weight percent, copper is present in a concentration of from about 0.01 to about 0.10 weight percent, and aluminum is present in a concentration of from about 97.90 to about 99.35 weight percent.

10. The electrical contact device of claim 6 whErein the silicon content is from about 0.02 to about 0.15 weight percent, the individual trace element content is from about 0.0004 to about 0.04 weight percent, and the total trace element content is from about 0.002 to about 0.10 weight percent.

11. A PROCESS FOR PREPARING AN ELECTRICAL CONTACT DEVICE HAVING A MINIMUM CONDUCTIVITY OF AT LEAST 57% IACS COMPRISING THE STEPS OF: A. ALLOYING FROM ABOUT 97.25 TO ABOUT 99.78 WEIGHT PERCENT ALIMINUM WITH MORE THAN 020 WEIGHT PERCENT IRON, FROM ABOUT 0.07 TO ABOUT 0.35 WEIGHT PERCENT MAGNESIUM, FROM ABOUT 0.01 TO ABOUT 0.25 WEIGHT PERCENT SILICON, FROM ABOUT 0.0003 TO ABOUT 0.20 WEIGHT PERCENT COPPER, AND LESS THAN ABOUT 0.05 WEIGHT PERCENT EACH OF TRACE ELEMENTS SELECTED FROM THE GROUP CONSISTING OF VANADIUM, MANGANESIUM AND ZINC, THE TOTAL TRACE ELEMENT CONTENT BEING NO MORE THAN ABOUT 0.15 WEIGHT PERCENT OF SAID TRACE ELEMENTS, B. CASTING THE ALLOY TO FORM A CAST BAR, AND C. FORMING THE BAR WITH NO PRELIMINARY OR INTERMEDIATE ANNEALS INTO THE CONTACT DEVICE, SAID CONTACT DEVICE HAVING IMPROVED THERMAL STABILITY - WHEN COMPARED AGAINST CONVENTIONAL EC ALUMINIUM DEVICES - WHICH ENDERS SAID CONTACT DEVICE CAPABLE OF WITHSTANDING REPEATED CURRENT CYCLING OVER AN EXTENDED PERIOD OF TIME, WITHOUT FAILURE.

12. The process of claim 11 including the step of annealing or partially annealing the contact device.

13. A process for preparing an electrical contact device having a minimum conductivity of at least 57% IACS comprising the steps of: a. Alloying from about 97.25 to about 99.78 weight percent aluminum with more than about 0.20 weight percent iron, from about 0.07 to about 0.35 weight percent magnesium, from about 0.01 to about 0.25 weight percent silicon, from about 0.0003 to about 0.20 weight percent copper, and less than about 0.05 weight percent each of trace elements selected from the group consisting of vanadium, manganese and zinc, the total trace element content being no more than about 0.15 weight percent of said trace elements: b. Continuously casting the alloy into a continuous bar; c. Continuously rolling the bar in substantially that condition in which it was cast to form a continuous rod; and d. Forming the rod with no preliminary or intermediate anneals into a contact device, said contact device having improved thermal stability - when compared against conventional EC aluminum devices - which renders said contact device capable of withstanding repeated current cycling over an extended period of time, without failure.

19. A process for preparing an electrical contact device having a minimum conductivity of at least 57% IACS and containing substantially evenly distributed iron aluminate inclusions having a particle size of less than 10,000 angstrom units, comprising the steps of: a. Alloying from about 97.25 to about 97.78 weight percent aluminum with more than about 0.20 weight percent iron, from about 0.07 to about 0.35 weight percent magnesium, from about 0.01 to about 0.25 weight percent silicon, from about 0.0003 to about 0.20 weight percent copper, and less than about 0.05 weight percent each of trace elements selected from the group consisting of vanadium, manganese and zinc, the total trace element content being no more than about 0.15 weight percent of said trace elements; b. Continuously casting the alloy into a continuous bar; c. Continuously rolling the bar in substantially that condition in which it was cast to form a continuous rod; and d. Forming the rod with no preliminary or intermediate anneals into a contact device, said contact device having improved thermal stability - when compared against conventional EC aluminum devices - which renders said contact device capable of withstanding repeated current cycling over an extended period of time, without failure.

25. A process for preparing an electrical contact device having a minimum conductivity of at least 57% IACS and containing substantially evenly distributed iron aluminate inclusions having a particle size of less than 10,000 angstrom units comprising the steps of: a. Alloying from about 97.25 to about 99.78 weight percent aluminum with more than about 0.20 weight percent iron, from about 0.07 to about 0.35 weight percent magnesium, from about 0.0l to about 0.25 weight percent silicon, from about 0.0003 to about 0.20 weight percent copper, and less than from about 0.0003 to about 0.20 weight percent copper, and less than about 0.05 weight percent each of trace elements selected from the group consisting of vanadium, manganese and zinc, the total trace element content being no more than about 0.015 weight percent of said trace elements: b. Casting the alloy to form a cast bar; and c. Forming the bar with no preliminary or intermediate anneals into a contact device, said contact device having improved thermal stability - when compared against conventional EC aluminum devices - which renders said contact device capable of withstanding repeated current cycling over an extended period of time, without failure.