DD218806A3 - ABSORPTIONABLE SWITCH - Google Patents

Abstract

THE INVENTION RELATED TO A SILVERBASIS ABRASION-RESISTANT SWITCH, ESPECIALLY FOR HIGH-VOLTAGE LOW VOLTAGE SWITCHING DEVICES. THE OBJECT OF THE INVENTION IS TO DEVELOP A PRECAST METAL-SAVING SWITCH-PLUG HIGH ABRASPING STRENGTH. IT HAS BEEN FOUND THAT THE ABRASION RATE IS REDUCED IF THE SWITCH HAS A SINGLE-METAL COVER.

Description

Abbrandfestes Schaltstück ''

Field of application of the invention

The invention relates to a erosion resistant contact piece, in particular for use in low-current power switching devices. · (

Characteristic of the known technical solutions

Abbrandfeste switching pieces made of precious metal stoF f eh are known. Such contact pieces consist of a semiconductor matrix in which base metal oxides are embedded. Such base metal oxides are, for example, tin oxide or cadmium oxide. There have been various ways of increasing the erosion resistance of silver metal oxide V contactors

One such way is, for example, that the silver piece consists of 12 to 18% by weight of tin oxide, the tin oxide being in the form of 1 to 15 μm thick fibers extending parallel or perpendicular to the button (FR-OS 2.307 .353). _y V The disadvantages of this solution are that semi-finished

20, for such contact pieces only, by a special procedural ren, the extrusion, produce to achieve the desired fiber formation. To thinner for the training

:: To ensure fibers required formability, the '; Zinnoxidehalt be kept relatively low. Such a.

However, silver-tin oxide material has a lower depreciation.

  .. fire resistance as a silver cadmium oxide vVerkerkstof f.

Another way of increasing the erosion resistance of silver and tin oxide contacts is to make the switch piece at the level of internal oxidation. The disadvantages of this solution are that the metal oxide content must be limited to less than 20 mass% in order to be able to carry out the v / internal oxidation at all. High levels of, for example, tin lead to the formation of barrier layers which hinder the diffusion of oxygen. The erosion resistance of an inner-oxidized silver-tin oxide substance is lower than that of silver-cadmium oxide. '·'. · ':

A more favorable burn-off behavior is shown by contact pieces, which consist of an inner-oxidized silver-cadmium oxide substance.

A further increase in Abbrand'festigkeit should be 'achieve that the material contains other base metal oxides that are excreted at the grain boundaries and embrittle the material (DE-PS 2.0.11.002).' The disadvantages of this solution are that a special procedure of internal oxidation must be adhered to in order to achieve the desired, the combustion-improving microstructure. The time required and the high energy consumption reduce the cost of the process of internal oxidation. The desired microstructure of the material containing several metal oxides is brittle and leaves one. · Reshaping only to a limited extent. Thus, the cadmium content must be limited to about 15%, to allow any production of switching pieces. By this limitation of the cadmium content, a desired further increase in the erosion resistance can not be achieved.

Object of the invention

The aim of the invention is a precious metal-saving contact piece. 'to develop higher erosion resistance.

Invention of the invention:. , '..-.

It has been found that, surprisingly, the burning rate is lowered when the contact piece has a base metal jacket.

The Unedelmetallniantel preferably has a cross-sectional. ¹ 5 area from 10 to 85 % of the total area of the contact piece: ' It preferably consists of one layer, but it can also consist of several layers. The base metal shell can ' _: .'. form .. 'contact piece; AUSER the extent of the contact piece and the joining side the .. · .., "". ,: ' · '..' .. '

The base metal sheath is preferably made of copper or a copper material, nickel or a nickel material or. made of steel or of several of these materials. , :. The core of the contact piece consists of a known per se

Contact material based on silver. It preferably consists of a material, but it can also consist of several materials. , ;, ''

':' The essence of the contact piece is preferably made of silver or of a silver alloy containing up to 20% copper or up to 20% cadmium. He can also be made of an inner-oxidized., Silver:. 20 metal oxide material with up to 20% cadmium oxide, or until> ^v to 10% tin oxide or zinc oxide or up to S%, up to 20 ^; Kad-.:. -....... oxide and tin oxide and / or zinc oxide. The core. , :; ,

of the switching piece can also be made of a pulvsrme.tallurgisch: her-, made silver material with 5 to 40 % nickel and / or:; ;. 25 steel or 5 to 25 % cadmium oxide or tin oxide or zinc oxide

or a mixture of these metal oxides, the remainder silver, or with '. '. .. 5 to 40% nickel and / or steel and up to 25, .. yo Kadmiumaxid _-,: /: '.. ; and / or tin oxide and / or zinc oxide and / or 0.01 to 10 ¹ 5o. : 'Hard materials, such as 3orides, nitrides, suicides, carbides>, balance SiI-30 over. The core of the contact piece can also be made of a silver composite with 5 to 40 % nickel and / or 'steel ' in the form of particles, fibers or the rest of silver or silver with up to .. 25% cadmium oxide and / or oxide and / or zinc oxide; ^·: exist, / - '' ·......

    '' '.4 · .. -....'

Contact pieces, which consist of a noble metal core and a metal Unedelamantel, are known per se (DE-PS 893 498, DE-PS 926 745). These known contact pieces are contact rivets for weak-current systems. Such shunting pieces have a base metal sheath in order to form the sufficient / large cross section required for the joining and holding of the switching piece on the carrier. Since no burn-up occurs with such contact pieces, they do not give any incentive to use the base metal jacket to reduce the burning rate. "

embodiments

The invention is to be explained in more detail by means of 7 exemplary examples. be explained. The numerical data used in the examples refer to the, caused by the burn-off hate loss of a switching piece. inyug / circuit at. a switching current of I = 100 A or 400 A.

Example 1: ·, ~; - / ": ..;

A erfindüngsgemäBes switching piece has a diameter of. 10 mm and consists of a .Silberkern ^: of S mrn / diameter and a copper jacket of 1 mm thickness. At a . Switching current I = 100 A, this contact piece has a burnup of Q.Si-ug / circuit A known contact piece of silver of 10 mm diameter has a higher burnup .. (O, 80 / .mu.g / circuit) when the Scintial current is also I = 100 A. - -

Example 2: './': '? "^;/'. ^: '

An inventive switching piece of 10 mm diameter consists of a core of 8 mm diameter of silver with 10 % cadmium oxide and a copper sheath of. 1 mm thickness. This contact has at I = 100. A a burnup of: O, ISyug / circuit. A known contactor made of AgCdO-IO has a higher burnup (O, 21, ug / circuit) 'at a diameter of 10 mm. ,. ; .: ^.

Example 3:. ^;

A contact piece according to the invention of IO mm in diameter consists of a core of 3 mm diameter made of silver with 25 % nickel in the form of 61 fibers and a copper jacket of 1 mm thickness. This contact has, at I = 100 Λ a burnup of 0.14 and at I = 400 A a burnup of 5.5, ug /,:. Circuit on. The corresponding Abbrandiverie. of an AgNi25

Switching pieces of 10 mm diameter are higher and amount to _ir j 0.77 and 25.4 / jg / circuit. , ·

Be i s ρ i e 1 4:>

A contact piece according to the invention of 10 mm diameter consists of a core of S mm diameter made of silver, with 25 % steel in the form of 61 fibers and 'of a copper jacket, of 1 mm thickness. This switch piece exhibits a burnup of 0.32 .ug / circuit at I = 100 A and a circuit / circuit at I = 400 A of 3.85. The corresponding burnup values of a 10 mm silver ferrule with 25 % steel are higher and are 0.55 and 9.45 μg / circuit. ' _v

Example 5:

An inventive switching piece of 10 mm diameter consists of a. Core of 8 mm diameter. Made of silver with 25 %

' Nickel in the form of 397 fibers and a 1 mm thick man- made of a copper-chromium material, which simultaneously forms the joining side of the contact piece. This contact has at I = 100 A a burnup of 0.07 _/ ug / circuit and at 'I = 400 A a burnup of 1.73. The corresponding burnup values of a 10 mm diameter contact piece consisting of AgGdO-IO are higher, being 0.21 and 3.08 μg / circuit.

, "ν '.'':' ⁶ ''. 'Example 5: * ^Λ

A 10 mm diameter switching element consists of a core of 3 mm diameter, the powder metallurgy of silver with 15 % cadmium oxide, 1 % boron nitride and 19 % Micke! and a 1 mn nickel or steel 34 Cr4 sheath. At I = 100 A, this contact piece exhibits a burnup of O, 22 .ug / switching and at I = 400 A a burnup of 6.4. The corresponding burn-off ratio of a switching plug of ^: 10 n, ~ diameter, which is \. Silver with 25 % Nicksi in the form of 61 · fibers are higher, being 0.77 and 25.4 ug / circuit. , .

Example 7: '' v

A 10 mm diameter gear piece according to the invention consists of a core of 3 mm diameter made of silver with 10 % CdO and of a copper jacket of 2.5 mm thickness. This contact has at I = 100 A a burn of Ö ^ S / Ug / circuit / on. A contact piece of 10 mm diameter made of silver with 10 % CdO shows, despite the significantly higher noble metal content, a ·· Abbrand the same order of magnitude (0.22, ug / 3chaltung) on.

The advantages of the switching pieces according to the invention are that the switching pieces are resistant to burn-off despite the considerably reduced precious metal content. Surprisingly, the erosion resistance does not decrease in the same way with the reduced noble metal content. It is thereby possible to set the required erosion resistance over a wide range and thereby to achieve the desired service life of the contact pieces and the. , Switching device for each application to achieve and. In addition, to save the limited available precious metal considerably. ,

The multiplicity of noble metal materials to be used in the switching pieces according to the invention allows on the one hand adaptation to existing production technologies and thus the selection;

' ' ·· '' , 7-

In addition, the possibility of using untar.schiadlichste precious metals materials, allows: the targeted achievement of other positive properties - such. As the most economical "manufacturing process - and the other the circumvention, such AVerkstoffbestandteile that allow an improvement in the erosion resistance only at the expense of non-deformability of the material

For example, high electrical conductivity - in addition to the Abbnandfestigkeit, so that: 3 the Anpa-Sbarkeit to the respective. ^: '.''. Switchgear type improved · .v / ird The formation of the non-precious i-iantels invention favors ^1, the joining of the contacts according to the invention to the switching tee t, unobtrusive, and thus improves the heat transfer vom'Schaltstück to the contact carrier.

Claims (7)

Invention claim. , , - A burn-off contact piece made of silver, a silver alloy, an inner-oxidized silver-metal oxide material, a powder-metallurgical silver composite of f or a silver composite of f, characterized thereby. net, that it has a base metal sheath. 2. contact piece according to item 1, characterized in that the 'Cross-sectional area of the plain roller shell is 10 to 35 % of the total cross-sectional area of the contact piece .. 3. contact piece according to item 1, characterized in that the base metal sheath consists of layers. 4. Switching piece after. Point 1, characterized in that da3 de, r. Non-precious metal sheath encloses the core also on the joining side of the switching piece. 5. contact piece according to item 1, characterized in that the base metal jacket made of copper or a copper material ', consists. , 6. contact piece according to item 1, characterized in that the base metal jacket consists of nickel or a Nickelvverkstoff. '·.' 7. contact piece according to item I _1, characterized in that the base metal jacket consists of steel.