DE2043492A1 - Palladium-boron alloys - for prodn of torsion bands in electric measuring instruments - Google Patents

Abstract

Alloys contg. 0.8 - 2.0% boron, the balance being Pd, opt. replaced to 50% by other noble metals or to 20% by other metals, have a quality factor higher than other alloys previously used for torsion bands; they also have good electric conductance.

Description

Use of palladium alloys as a material for torsion strips in electrical measuring devices.

The invention relates to the use of palladium-boron alloys as a material for torsion strips in electrical measuring devices.

The sensitivity of electrical measuring devices with strap-mounted, The rotatable measuring mechanism takes along the torsion band (tension band) for a given length decreasing power requirement per AUS steering unit. On the other hand, the devices should but also be insensitive to sudden mechanical loads.

For torsion bands in electrical measuring devices, in general are produced by flat rolling of wires, therefore metallic ones are suitable Materials that achieve high breaking loads with the lowest possible torsional moments.

In order to obtain optimal breaking loads and the risk of plastic Deformation of the torsion bands - which are under tension - can be ruled out with certainty, these are used in a strongly strength-hardened state, with the yield point is relatively high and just below the tensile strength.

The torsional moment M of a wire is given by the relation: G. 2 2 64 * 1 where G = torsion modulus, d = diameter of the wire and 1 = wire length.

If mai introduces the tensile strength 6'B and the breaking load p into this relationship, one obtains This shows that the breaking load for a given torsional moment and a given wire length is proportional to the ratio of tensile strength to the root of the torsional modulus. This ratio is therefore a criterion for the general narrowing of wires for the production of torsion strips. I) there are also a number of other important requirements with regard to certain properties of the material. For example, the lowest possible resistance is desired, since the power is supplied via the tensioning strap, the cross-section of which must be small due to the sensitivity of the device. Furthermore, from the material, among other things

good corrosion resistance and solderability, non-magnetic behavior, low temperature dependence of the torsion module and the thermal voltage Copper as well as low elastic after-effects and hysteresis in the interest of a reproducible Setting accuracy required.

So far there is no alloy that meets all of the above requirements optimally fulfilled. There are therefore always compromises to be made and suitability of an alloy always depends on the respective conditions of use.

Because the tension bands are made by flat rolling thin wires and a high work hardening is required, results as further Requirement that the alloys used for this purpose must be ductile.

Precious metal alloys, such as those described, for example, in patent specifications 1,151,944 and 1,152,826, have proven particularly successful. These are two-component or nutrient alloys, preferably based on AuNi, AuPt, PtNi and ptir. Of the examples given in patents 1,151,944 and 1,152,826, the alloy Au / Ni-65/35 with Z = 2.52 has the highest ratio known as the figure of merit Z. It has now been found that the known alloys for tensioning straps with regard to the figure of merit Z are surpassed by alloys based on palladium-boron with boron contents of from 0 to 2.0%, preferably from 1.0 to 1.7%. These alloys according to the invention also show a high electrical conductivity and their production is not difficult.

Such favorable properties for the manufacture of tensioning straps were used to a previously unknown extent both in the case of the two-component alloy 0.8 to 2.0% boron as well as multi-component alloys with further additions of silver, Gold and platinum are found, with up to 50% of the palladium by eires or several of these precious metals can be replaced. Compared to alloys rich in platinum are the alloys according to the invention because of the lower cost of the starting material much cheaper.

The table below shows some examples of the properties of wires made from the alloys according to the invention.

For comparison, the corresponding properties are in the last row the alloy Au / Ni-65/35 listed.

Alloy Tensile Strength Torsional Z-Wcrt compo- sition module [%] [kp / mm²] [kp / mm²] 1st pd / B-99.2 / 0.8 197 5450 2.66 2. Pd / B-98.9 / 1.1 226 5080 3.17 3. Pd / B-98.4 / 1.6 268 4760 3.88 4. Pd / Ag / B-76.5 / 22.4 / 1.1 230 5060 3.21 5. Pd / Au / B-54.8 / 43.9 / 1.3 223 3400 3.82 6. Pd / Pt / B-90 / 8.5 / l, 5 242 5130 3.38 7. Pd / Ag / Au / B-70.2 / 10.2 / 18.6 / 1 , 0 221 5300 3.03 8. Pd / Ir / B-90.0 / 8.5 / 1.5 235 5650 3.11 9. Pd / Si / B-98.2 / 0.3 / 1.5 242 4740 3.50 10. Pd / Cu / B-80.0 / 19.0 / 1.0 218 5300 3.00 Au / Ni-65/35 + 180 5070 2.52 (+ Quenched and tempered) The alloys according to the invention also correspond to the others The properties required for tensioning straps are the previously known precious metal alloys.

In addition to the additives mentioned above, other additives of precious metals, such as rhodium and iridium, as well as base metals such as aluminum, silicon, Copper, iron, cobalt and nickel, to the extent that such alloys are included are still ductile.

The alloys according to the invention can also be used in other areas Find use where there is a high tensile strength and hardness as well as on easy processability for sal related matters.

Claims (5)

PATENT CLAIMS 1. Use of palladium alloys as a material for torsion strips in electrical measuring devices, characterized in that the alloys O, ff to 2.0 y boron, remainder palladius included. 2. Use of palladium alloys according to claim 1, characterized in that that the alloys contain 1.0 to 1.7% boron, the remainder palladium. 3. Use of palladium alloys according to claims 1 and 2, characterized in that up to 50% of the palladium content is made up of silver, gold and / or platinum can be replaced, provided that such alloys are still ductile. 4. Use of palladium alloys according to claims 1 to 3, characterized in that it contains up to 50% of the palladium content, preferably up to 20, iridium and / or rhodium, if such alloys are still ductile are. 5. Use of palladium alloys according to claims 1 to 4, characterized in that up to 20% (there is precious metal content through base metals, such as aluminum, silicon, magnesium, copper, iron, cobalt and nickel, are replaced, as far as such alloys are still duknil.