JPS60248847A - Electrical contact material - Google Patents

Abstract

PURPOSE:To obtain an electrical contact material having stable contact resistance and considerably improved welding resistance by adding specified percentages of Bi, Cd, Sn and In to Ag and carrying out internal oxidation. CONSTITUTION:A material consisting of, by weight, 5-20% Bi, 5-10% Cd, 0.5- 8% Sn, 0.5-8% In and the balance Ag or further contg. 0.01-1% Fe group element is internally oxidized to obtain the electrical contact material. Stable electrical contacts which hardly vary are obtd. by using the electrical contact material.

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 gear knobs become narrower, problems with welding resistance have arisen. For this reason, there is a demand for electrical contact materials with even better welding resistance.

(Object of the Invention) The present invention has been made to meet such a demand, and is
It is an object of the present invention to provide an electrical contact material that has the stable contact resistance of an electrical contact material made of bismuth oxide and has greatly improved welding resistance.

(Means for Solving the Problems) One of the electrical contact materials of the present invention contains 5 to 20% by weight of hismuth, more than 5% by weight of cadmium and 10% by weight or less of cadmium, and 0% by weight of tin.
．． It is a material consisting of 5-8% by weight of indium, 0.5-8% by weight of indium, and the balance silver, and is internally oxidized.

Another electrical contact material of the present invention is bismuth 5-20
% by weight, and more than 5% by weight and less than 10% by weight of cadmium,
0.5-8% by weight of tin, 0.5-8% by weight of indium,
It is a material consisting of balance silver and is internally oxidized.

In the electrical contact material of the present invention, bismuth is 5 to 20% by weight, cadmium is more than 5% by weight and 10% by weight or less, and tin is 0%.
．． The reason for setting the values to 5 to 8% by weight and indium to 0.5 to 8% by weight is that bismuth and cadmium improve welding resistance due to their low-temperature sublimation properties, and less than 5% by weight of bismuth and 5% by weight of cadmium reduce this effect. There is no bismuth 20
If it exceeds 10 M% by weight, the melting point of the alloy will drop too much, making internal oxidation at high temperatures difficult, and if it exceeds 10 M% by weight, the welding resistance of silver-bismuth oxide will deteriorate. Tin changes the spherical precipitation of cadmium into a needle shape and improves welding resistance. If it is less than 0.5% by weight, it will not have this effect, and if it exceeds 8% by weight, the welding resistance will improve, but oxides will form when the contacts open and close. condenses on the contact surface, increasing contact resistance and temperature rise. Indium improves welding resistance due to the thermal stability of its oxide, and if it is less than 0.5% by weight, it has no effect, and 8
If it exceeds % by weight, the purpose is to improve the welding resistance like tin, and the contact resistance and temperature rise will increase. From the above, bismuth is 5 to 20% by weight and cadmium is over 5% by weight.
% by weight or less, tin 0.5-8% by weight, indium 0.5-8% by weight
Within the range of 8% by weight, an electrical contact material with sufficiently satisfactory welding resistance can be obtained.

Further, in another electrical contact material of the present invention, bismuth is 5 to 20% by weight, cadmium is more than 5% by weight and 10% by weight or less, tin is 0.5 to 8% by weight, and indium is 0.5 to 8% by weight.
Iron group elements other than weight%: 0. The reason for adding ~1% by weight is that when it is dispersed in electrical contact materials, the resulting uniform and fine dispersion of bismuth oxide and cadmium oxide equalizes consumption due to discharge, making contact resistance more stable. This is because if it is less than 0.01% by weight, hismuth 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.

(Example and Conventional Example) A material having the composition of Example 1.2 shown in the left column of the table below was melted to form an atomized powder, and then internally oxidized at 600°C and 29 atmospheres for 2 days, and the oxidized atomized powder was The powder is compressed and sintered, extruded and drawn, and then cut and processed to have a heso-groove shape.The head diameter is 5 mm, the head height is 1.01, and the leg diameter is 2.5 mm.
Fixed contact with leg length 2.5m + a and head diameter 4 dragons 2 heads height 1.1
4m1. Leg diameter 2.8mm, leg length 1.5-++n.

A movable contact with a spherical head height of 5R was obtained.

In addition, materials having the compositions of Examples 3 and 4 shown in the left column of the table below are melted and formed into chip shapes, which are internally oxidized at 600°C and 9 atm for 2 days, then compressed and sintered, and then extruded. , After drawing, cutting and processing the heel to make a fixed contact with a head diameter of 5 dragons, 5 head height, 1.0 fins, 5 leg diameters of 2.511111°, leg length of 2.51°, a head diameter of 4 mm, and a head height of 1.1 mm. .

A movable contact with a leg diameter of 2.811+n, a leg length of 1.13+*i, and a spherical head of 5R was obtained.

However, the electrical contacts made using the electrical contact materials of Examples 1 to 4 and the conventional materials shown in the left column of the table below were made in the same manner as in Examples 1 and 2. Glue bed-type electrical contacts of the same size were assembled into hinge-type relays and an opening/closing test was conducted under the following test conditions, and the results shown in the right column of the table below were obtained.

Test conditions Voltage: AC 100V 50Hz Current: Input 40A, steady 10A Load: Resistance Switching frequency: 20 times/min Switching/closing frequency: Until welding occurs (blank below) As is clear from the table above, Examples 1 to 4 Head-type electrical contacts made with electrical contact materials have a higher number of openings and closings before welding occurs than conventional electrical contact materials, and have similar contact resistance. It can be seen that it is low and stable with little variation.

(Effects of the Invention) 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, and has significantly improved welding resistance. Therefore, 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) 5 to 20% by weight of bismuth, more than 5% by weight of cadmium and less than or equal to 10% by weight, 0.5 to 8% by weight of tin, 0 indium
．． An electrical contact material comprising 5 to 8% by weight, the balance being silver, and which is internally oxidized. 2) Bismuth 5-20% by weight, cadmium more than 5% by weight and less than 10% by weight, tin 0.5-8% by weight, indium 0
．． An electrical contact material comprising 5 to 8% by weight of an iron group element, 0.01 to 1% by weight of an iron group element, and the balance silver, and which is internally oxidized.