JPS6254043A - Manufacture of silver-tin oxide type electrical contact point material - Google Patents

Abstract

PURPOSE:To obtain an electrical contact point material having superior melt sticking resistance and workability by atomizing a molten alloy contg. tin, a metal forming an intermetallic compound with tin and silver and by using the resulting alloy powder as starting material so as to inhibit the diffusion of tin during internal oxidation. CONSTITUTION:An alloy contg. tin, a metal forming an intermetallic compound with tin and silver is melted. The molten alloy is atomized and the resulting alloy powder is sintered, compressed and plastically worked. The worked body is internally oxidized. The diffusion of tin in the silver alloy is inhibited during the internal oxidation, and an electrical contact point material having superior melt sticking resistance and workability is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for producing a tri-tin oxide-based electrical contact material.

(Prior art) Silver-cadmium oxide or tin oxide electrical contact materials have been widely used as oxide-based electrical contact materials in which a silver alloy is internally oxidized and the oxide is dispersed in the eye. There is.

In particular, electrical contact materials made of tin oxide have superior welding and abrasion resistance than electrical contact materials made of silver and cadmium oxide. - Extremely useful as an alternative to cadmium oxide electrical contact materials.

(Problems to be Solved by the Invention) However, tin diffuses quickly in the eye, and when internal oxidation is performed, an agglomerated layer of tin oxide is likely to be formed on the surface layer. Furthermore, when internal oxidation is performed at low temperature and high pressure to avoid these problems, finely precipitated tin oxide increases the hardness of the material, which tends to reduce workability.

Addition of a third element is effective in preventing deterioration of workability, but in this case, if the third element forms an intermetallic compound with tin, the intermetallic compound will segregate during casting. Therefore, even if this is internally oxidized and processed into a contact shape, it will result in an inhomogeneous structure, resulting in variations in contact properties, especially welding resistance.

Therefore, the present invention aims to provide a manufacturing method that can produce a tin oxide-based electrical contact material with a homogeneous structure even when a metal that forms an intermetallic compound with tin is added to a tin alloy. It is something.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the method for producing a tin oxide-based electrical contact material of the present invention includes tin, a metal forming an intermetallic compound with the tin, and silver. This method is characterized by melting an alloy, then spraying the melted alloy to produce an alloy powder, then sintering, compressing, and plastic working the alloy powder, and then internally oxidizing it.

As the metal forming the intermetallic compound with tin, nickel, iron, cobalt, titanium, zirconium, niobium, etc. are used.

Further, it is desirable that the internally oxidized alloy powder is a fine powder of 32 meshes or less. The reason for this is that if the powder is coarser than 32 mesh, the contact material will become non-uniform due to segregation of intermetallic compounds.

(Function) When the above manufacturing method is used, even if the oxidation temperature is relatively high, the diffusion of tin in the silver alloy can be suppressed, and internal oxidation of the silver-tin alloy becomes possible, and the resulting electrical contact material This eliminates variations in contact characteristics, particularly in welding resistance.

(Example) Examples and conventional examples of the method for manufacturing a tin oxide-based electrical contact material of the present invention will be described below.

To explain the examples, first, 90-t% tin, 8w
t% and nickel at a ratio of 2 wt% in a metal carbon crucible at 1200°C, and then atomized with nitrogen gas at 5 atm to make an alloy powder, and then a fine 0 alloy powder of 32 mesh or less. The material was sintered at 700° C. in a non-oxidizing atmosphere, in vacuum in this example, and compressed.

After repeated sintering and compression, this was extruded into a wire rod with a diameter of 6 fins, and then drawn into a wire rod with a diameter of 2.3 fins.
After forming a crane wire, it was internally oxidized at an oxygen partial pressure of 9 atm and at 700°C.

To explain the conventional example, first of all, 90wt% of granite, 8% of tin
4t% and 2wt% of nickel were melted at 1200℃ in a carbon crucible, and then cast into a copper mold to form a billet, which was then extruded into a wire rod with a diameter of 6 cranes. After that, it was drawn into a wire with a diameter of 2.3 fins.The wire was then heated to an oxygen partial pressure of 9 atm and 700
Internally oxidized at °C.

However, the wire rods made by the methods of the above embodiments and conventional examples were molded into rib-bent electrical contacts with head diameters of 5 and 4, respectively, and then attached to nine relays, AClooV, input current of 40 amperes, and steady current. Opening and closing tests were conducted at 10 amperes. The resulting number of openings and closings until welding occurred was applied to the Weibull distribution, and the Weibull parameters were estimated, and the results shown in the table below were obtained.

As is clear from the above table, the electrical contacts made from the silver-tin oxide based electrical contact material obtained by the manufacturing method of the example are as follows:
Compared to electrical contacts made from silver-tin oxide based electrical contact materials obtained by conventional manufacturing methods, the shape parameter m value is larger, the position parameter γ value is larger, and the number of times until welding occurs is larger. It has excellent welding resistance and has a long average lifespan.

(Effects of the Invention) As can be seen from the above explanation, according to the method for producing a tin oxide-based electrical contact material of the present invention, a metal that forms an intermetallic compound with tin can be added to a silver-tin alloy. The effect is that it is possible to obtain a tin oxide-based electrical contact material that has a homogeneous structure and excellent welding resistance, as well as wear resistance and processability, and is superior to conventional silver-tin oxide electrical contact materials. It can be said to be an epoch-making product that can replace the manufacturing method of

Claims (1)

[Claims] An alloy of tin, a metal that forms an intermetallic compound with tin, and silver is melted, then this melted alloy is sprayed to create an alloy powder, and this alloy powder is then sintered, compressed, and plastically processed. 1. A method for producing a silver-tin oxide-based electrical contact material, which comprises: and then internally oxidizing it.