JPS60245745A - Electrical contact material - Google Patents

Abstract

PURPOSE:To obtain an electrical contact material having stable contact resistance and superior welding resistance by compressing and sintering internally oxidized alloy powder having a specified composition consisting of Ag, Bi, Cd and Zn or further contg. an Fe group metal and by extruding and drawing the sintered body. CONSTITUTION:A molten alloy consisting of, by weight, 7-20% Bi, 0.1-5% Cd, 0.5-5% Zn and the balance Ag or further contg. 0.01-1% Fe group metal such as Ni is atomized, and the resulting powder is internally oxidized. The powder is then compressed and sintered, and the sintered body is extruded, drawn, and cut to obtain an electrical contact material. This electrical contact material has stable contact resistance and superior welding resistance.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to electrical contact materials.

(Prior Art and its Problems) Silver-bismuth oxide has conventionally been used as one of the electrical contact materials manufactured by internal oxidation method. Silver-bismuth oxide has contact performance such as excellent arc resistance and welding resistance, and stable contact resistance. As gears become narrower, problems have arisen in welding resistance. For this reason, there is a demand for electrical contact materials with even better welding resistance.

The present invention was developed as a result of intensive research to meet such demands.
An electrical contact material has been discovered that retains the stable contact resistance of an electrical contact material made of bismuth oxide, but has greatly improved welding resistance.

(Means for Solving the Problems) One of the electrical contact materials of the present invention contains 7 to 20% by weight of bismuth, 0.1 to 5% by weight of cadmium, 0.5 to 5% by weight of zinc, and the balance being silver. and is internally oxidized.

Another electrical contact material of the present invention is bismuth 7-20
wt%, cadmium 0.1-5 wt%, zinc 0.5
-5% by weight, 0.01-1% by weight of iron group elements, and the balance is internally oxidized.

(Function) The reason why the electrical contact material of the present invention contains 7 to 20% by weight of bismuth, 0.1 to 5% by weight of cadmium, and 0.5 to 5% by weight of zinc is less than 7% by weight of bismuth.

Good welding resistance cannot be obtained with less than 0.1% by weight of cadmium and less than 0.5% by weight of zinc, and 20% by weight of bismuth.
If the temperature exceeds 1, the melting point of the alloy will drop too much, making internal oxidation difficult at high temperatures. Both cadmium and zinc are useful for improving the welding resistance, but in the case of cadmium, if it exceeds 5% by weight, it will conversely deteriorate the welding resistance of silver-hismuth oxide. On the other hand, in the case of zinc, if it exceeds 5% by weight, layered precipitation will occur and the contact resistance will increase. From the above, an electrical contact material with sufficiently satisfactory welding resistance properties can be obtained within the ranges of 7 to 20% by weight of bismuth, 0.1 to 5% by weight of cadmium, and 0.5 to 5% by weight of zinc.

Furthermore, in another electrical contact material of the present invention, in addition to 7 to 20% by weight of bismuth, 0.1 to 5% by weight of cadmium, and 0.5 to 5% by weight of zinc, 0.01 to 1% of iron group elements weight%
The reason for adding it is that when it is dispersed in an electrical contact material, the resulting uniform and fine dispersion of bismuth oxide and cadmium oxide equalizes consumption due to discharge, making the contact resistance more stable. , 0.01
If it is less than 1% by weight, bismuth oxide and cadmium oxide will not be uniformly and finely dispersed, and if it exceeds 1% by weight, their segregation will increase and the contact resistance will become unstable.

Next, specific examples and conventional examples will be described in order to clarify the 9) J advantages of the electrical contact material according to the present invention.

(Example) After melting the materials having the compositions of Examples 1 and 2 shown in the left column of the table below to form atomized powder, the mixture was heated at 600°C, 9 atm,
After internal oxidation for 2 days, this oxidized atomized powder is compressed and sintered, extruded and drawn, and then cut and processed into belly and belly parts. Waist diameter: 5, fins: 2 heads, height: 1.0 sins, 1 leg diameter: 2.5 dragons. 9 leg length 2.
5 Tuna fixed contact and head note 1: Diameter 4■i, head height L1i+i,
Leg diameter 2.8 female, 1 leg length 1.6 crane.

A movable contact point for Udaka's spherical elbow R was obtained.

In addition, materials having the compositions of Examples 3 and 4 shown in the left column of the table below were melted and formed into a chip shape, and then internally oxidized at 600'C + 9 atm for 2 days, then compressed and sintered, and then extruded. After being pulled out, the pieces were cut and processed to have two tuna with a head diameter of 5 mm, a height of 1.0 mm, and a leg diameter of 2.5 mm.

A fixed contact of a tuna with a leg length of 2.5 mm and a tuna with a head diameter of 4 mm and a head height of 1.1 mm.

A movable contact with a leg diameter of 2.8 mm, a leg length of 1.6 mm, and a spherical head shape of 5R was obtained.

However, head-type electrical contacts made using the electrical contact materials of Examples 1 to 4, and identical contacts made using the same method as in Example 1.2 using materials having the component compositions of the conventional examples shown in the left column of the table below. When a rivet-type electrical contact with the same dimensions was assembled into a hinge-type relay and an opening/closing test was conducted under the test conditions below, the results shown in the right column of the table below were obtained.

Test conditions Voltage: AC100V 50Hz Current: Input 40A, steady 10A Load: Resistance Switching frequency: 20 times/min Number of switching: Until welding occurs (Effects of the invention) As is clear from the table above, Examples 1 to 4 Compared to rivet-type electrical contacts made with conventional electrical contact materials, rivet-type electrical contacts made with electrical contact materials have a higher number of openings and closings before welding (welding resistance and contact resistance are the same). It can be seen that the contact resistance is low and stable with little variation.As detailed above, the electrical contact material of the present invention has a stable contact resistance equivalent to that of the conventional electrical contact material made of silver-bismuth.
Furthermore, the welding resistance has been significantly improved, and it can be said to be an epoch-making product that can replace conventional electrical contact materials.

Applicant Tanaka Kikinzoku Kogyo Co., Ltd.

Claims (1)

[Claims] 1) 7 to 20% by weight of bismuth and 0.1 to 5% of cadmium
An electrical contact material consisting of 0.5-5% by weight of zinc and the balance silver, and which is internally oxidized. 2) 7-20% by weight of bismuth and 0.1-5% of cadmium
Weight%,! IIi 0.5-5% lead and 0 iron group elements
．． An electrical contact material comprising 0+ to 1% by weight and the balance silver, and which is internally oxidized.