JPS5831380B2 - three layer bimetal - Google Patents

Description

[Detailed description of the invention] The present invention relates to improvements in three-layer bimetals.

Conventionally, thermostat metals have used nickel-iron-based alloys as constituent elements to obtain high operating temperatures, but in order to give the metal a low resistivity, high-expansion materials and high-expansion materials were used for thermostat metals. It is provided as an intermediate layer between the two sides.

Conventionally, pure copper and copper alloys such as cadmium and zirconium copper have been used for this intermediate layer as they have low resistance and high conductivity.

However, the softening temperature of nickel-iron-based alloys is approximately 600°C.
Although a high temperature usable range can be obtained at a temperature of about 170 to 350°C, the above-mentioned pure copper or copper alloy has a problem in that it becomes soft at temperatures of about 170 to 350°C, and its usable range is limited to low temperatures.

For example, the normal temperature of thermostat metal used in current-carrying circuit breakers is set at approximately 150°C (in the case of pure copper), but in reality it may be instantaneously heated to approximately 350°C; The metal becomes soft and operation becomes difficult.

Therefore, there is a demand for the development of a thermostatic metal having an intermediate layer that has high conductivity, which is the original requirement of the intermediate layer, and has increased heat resistance strength and can be used up to high temperatures, that is, has an intermediate layer that can be used at a high temperature.

The present invention provides a thermostat metal that can satisfy such demands.

The thermostat metal of the present invention has an intermediate layer between the high expansion side and the low expansion side, and the intermediate layer has a weight ratio of 0.5 to 1.5 chromium and 0.15 to zirconium.
0.5%, silicon, magnesium, germanium, and boron alone or in combination of 0.005 to 0.1%, and the remainder substantially copper.

Therefore, the thermostat metal of the present invention is provided with an intermediate layer made of a copper alloy having the above-mentioned composition ratio.

In this copper alloy, copper is used to obtain low resistance and high conductivity.

Chromium and zirconium are useful for improving heat resistance strength and increasing the softening temperature either individually or by interaction, and if the amount exceeds the above range, the conductivity deteriorates, and if it is less than the above range, there is no effect.

In particular, chromium and zirconium individually or in interaction serve to improve mechanical strength.

Silicon, magnesium, germanium, and boron are finely dispersed in the base (matrix) of copper alloys, and when added in small amounts, they contribute to improving mechanical strength, and they also suppress coarsening of crystal grains and prevent rough skin. The above-mentioned range is preferable since it is effective, and if the amount added is too large, the conductivity will be deteriorated.

Among them, silicon is practically preferred because it has particularly stable characteristics, produces uniform effects, and is inexpensive.

In this way, the copper alloy forming the intermediate layer has not only high electrical conductivity and excellent heat resistance strength, but also excellent mechanical strength.

Therefore, the bimetal of the present invention provided with this intermediate layer has high conductivity, can be used at high temperatures, and has particularly high mechanical strength and has excellent performance as a thermostatic metal. ing.

The copper alloy forming the intermediate layer is manufactured, for example, as follows and incorporated into the bimetal.

First, chromium, zirconium, silicon, and the like are melted in a high-frequency melting furnace to form predetermined components, and then poured into a mold to form an ingot.

This ingot is hot-forged and hot-rolled into a plate material.

Thereafter, this plate material is laminated and crimped with another plate material that takes over the bimetal, and hot buttoning, cold working, and annealing are repeated to obtain a bimetal of a predetermined thickness.

The high expansion side of thermostat metals is made of materials such as chromium-nickel-iron alloys and nickel-manganese iron alloys, in order to increase the operating temperature of the metal, while the low expansion side is made of materials such as nickel-iron alloys. It is formed from a material such as an alloy.

〔Example〕

The high expansion side is a nickel-chromium-iron alloy, the low expansion side is a nickel-iron alloy, and an intermediate layer between them is 0.7% chromium-0.35% zirconium-0 silicon.
．． The materials provided with the alloy consisting of 0254-balance copper were laminated at a plate thickness ratio of 3:2:5 (high expansion side: intermediate layer: low expansion side) and hot-pressed.

Thereafter, cold rolling and, if necessary, annealing were repeated, and in the final stage, rolling was performed at a completion rolling rate of 50% to obtain a bimetal, which was heated at a temperature of 100 to 800°C.

Then, the hardness (Brinell hardness) of the alloy of this bimetallic intermediate layer was measured, and the results are shown as line A in the drawings.

In addition, chromium-zirconium-macnesium-copper alloy, chromium-zirconium-germanium-copper alloy, and chromium-zirconium-boron-copper alloy, each containing the same amount of magnesium, germanium, and boron instead of silicon, were used as the intermediate layer alloy. The hardness (Brinell hardness) was measured, and the results are shown as line B in the drawing.

The measurement results for these alloys were approximately the same, so they are shown together as line B.

Furthermore, in the drawing, the measurement results of the hardness (Brinell hardness) of oxygen-free copper, which is a conventional intermediate layer, are shown by the C line, and the hardness (Brinell hardness) of zirconium copper (zirconium 0.33%)
The measurement results are shown by the D line.

In addition, the elastic modulus and volume resistivity of the alloy used for the intermediate layer were determined by oxygen-free copper, zirconium copper (zirconium 0.33
The table shows the results of comparison with those in Section 1).

According to the figure, it can be seen that the alloy of the present invention has high mechanical strength and machining strain remains even when heated at 400 to 450°C.

Further, according to the table, it can be seen that the alloy of the present invention has an excellent elastic modulus, a small volume resistivity, and high electrical conductivity.

Therefore, it can be said that a bimetal using this alloy as an intermediate layer has excellent conductivity, heat resistance, and mechanical strength.

[Brief explanation of the drawing]

The drawing is a diagram showing the relationship between heat treatment temperature and hardness in the alloy of the present invention and other copper alloys.

Claims (1)

[Claims] 1 In a three-layer bimetal in which an intermediate layer is provided between a high expansion side and a low expansion side, the intermediate layer has a weight ratio of 0.5 chromium.
~1.5% and 0.15-0.5% zirconium.
A three-layer bimetal characterized by being formed of an alloy consisting of silicon, magnesium, germanium boron in an amount of 0.005 to 0.1% singly or in combination, and the remainder substantially consisting of copper.