JPH0122340B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electrical contact material with excellent adhesive resistance. Generally, when a Pd electrical contact is used as an encapsulated type, the electrical contact is enclosed in a container with an inert gas atmosphere in order to stabilize the contact resistance. For this reason, although the contact surfaces are always maintained in a very clean state, problems of adhesion may occur due to adhesion between the contact surfaces on the other side. Furthermore, since Pd itself has a high viscosity, there is a drawback that when processing Pd, it may seize on dies or rolls. The present invention has been made in view of these drawbacks, and provides an electrical contact material made of a Pd alloy material with excellent adhesion resistance that prevents adhesion between contacts and seizure on dies or rolls during processing. We aim to provide the following. The present invention is a Pd alloy characterized by comprising 0.01 to 0.5% by weight of at least one of B and Ca, and the balance being Pd. However, by adding at least one of the elements B and Ca to Pd in a range of 0.01 to 0.5% by weight, each of these elements precipitates at the grain boundaries in the crystal structure of Pd. As a result, the viscosity of Pd itself is reduced, preventing adhesion between contacts due to adhesion between metals, and preventing seizure of dies or rolls during processing. The amount of the added element was limited to 0.01 to 0.5% by weight because if it is less than 0.01% by weight, the amount precipitated at the grain boundaries is small and the above-mentioned effect cannot be obtained. This is because the amount precipitated at grain boundaries is too large, and the effect of reducing grain quality is too strong, causing the material to become brittle. Next, in order to further clarify the present invention, specific examples thereof and comparison with conventional examples will be described. Example 1 0.1% by weight of a CaB compound was added to Pd in a molten state, and the mixture was further melted and alloyed at 1650° C. in an Ar gas atmosphere to form an electrical contact material. As a result of chemical analysis of this electrical contact material, it was confirmed that Pd contained 0.03% by weight of Ca and 0.02% by weight of B. Examples 2 to 11 Electric contact materials having the compositions shown in the left column of the table below were obtained in the same manner as in Example 1. Conventional Example 1 Pd of the same type as the Pd used in Example 1 was melted under the same conditions as Example 1 without adding any elements to obtain an electrical contact material. The electrical contact material thus obtained was subjected to wire drawing to obtain electrical contact wires with a diameter of 4 mm and a diameter of 2 mm. Thereafter, the adhesive coefficient of each of these electrical contact wires was investigated. The results are shown in the table below. The adhesion coefficient was determined by dividing the separation force by the contact force, and the higher the adhesion coefficient in the table, the greater the adhesion force. The calculation method is 2mm in diameter.
Electrical contact wire material and a wire material with a diameter of 4 mm of the same type as this electrical contact material were cut sharply using a small object cutting machine without sagging, and the cross sections were butted together with a contact force of 5 kg, and the wire material with a diameter of 2 mm was rotated once. (360°C) and then separated, and the separation force at that time was measured and calculated to determine the adhesive coefficient.

[Table] As is clear from the table, the Pd alloy according to the present invention has a small adhesive coefficient, that is, a small adhesive force, when compared with conventionally used Pd. Therefore, when the Pd alloy according to the present invention is used for an encapsulated contact, even if the contact area is kept highly clean at all times, the adhesion caused by adhesion between the metals of the contact is lower than when the conventional Pd is used for an encapsulated contact. This is extremely rare. Further, when rolling was performed on each of the electrical contact wire rods with a diameter of 4 mm obtained in Examples 1 to 12 and Conventional Example 1, it was found that the electrical contact material of the present invention had a lower resistance during rolling than the conventional electrical contact material. There was no seizure phenomenon on the rolls, and there was little variation in plate thickness, so it was possible to increase the processing rate, and the material could be made to the specified dimensions in a short period of time. As explained in detail above, the electrical contact material of the present invention has a low adhesive coefficient, and when used as an encapsulated contact, even if the contact surface is always kept highly clean, the contact material between the metals of the contact It is less likely to cause adhesion due to adhesion, and therefore high reliability can be obtained. Also, during processing, there is little seizure on rolls or dies, etc., and therefore the processed surface is less rough, the variation in plate thickness is small, and the processing rate can be increased, making it possible to obtain materials with desired dimensions in a short time. It can be said that it is a material with excellent not only contact characteristics but also workability.

Claims (1)

[Claims] 1. An electrical contact material made of a Pd alloy, comprising 0.01 to 0.5% by weight of at least one of B and Ca, and the balance being Pd.