JPH08260078A - Sliding contact material, clad composite material, and small DC motor using the same - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] To provide high-quality sliding contact materials and clad composite materials that are non-toxic, have excellent low contact resistance, wear resistance, and electrical characteristics. [Configuration] An AgZn alloy or an AgZnNi alloy, or an AgMg alloy or an AgMgNi alloy, wherein Zn is 0.01 to less than 1 wt% and Mg is 0.0
1 to 1% by weight, and the addition amount of Ni is 0.
01 to less than 0.5% by weight, 0.01 to 0.01 when combined with Mg
0.5% by weight of Zn and Mg in the alloy composition
Is a solid solution in the Agα phase, and Ni particles are sliding contact materials uniformly dispersed in the Agα phase. A commutator formed of a double-layer clad composite material, which forms a surface layer of the clad composite material and is composed of Cu or a Cu alloy as a base layer, is used for a DC small-sized motor for household appliances.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sliding contact material used for electrical and mechanical sliding parts, and more specifically, a small DC power source used for household appliances driven by rechargeable batteries. The present invention relates to a sliding contact material having low contact resistance used for a commutator for motors (others such as an earth ring and a rotary switch).

[0002]

2. Description of the Related Art In the technical field, research and development on new sliding contact materials and wear have been actively conducted at present, and this wear and contact resistance are important for sliding contact materials and clad composite materials. Where the problem is
This wear phenomenon is a difficult problem because it is complicated and there are many points that have not been scientifically elucidated.

Usually, even if the metal surface of the sliding contact material is intended to be finished to be fairly smooth, microscopic observation shows that it is not a perfect flat surface but has fine irregularities. Looking at the contact state of the two metals, it seems that they are in contact with each other over a wide area, but in reality, there are some irregularities and they are in contact only with isolated protrusions.

The wear due to friction is basically proportional to the magnitude of the contacting force and inversely proportional to the hardness. In addition, temperature, humidity, corrosive components, organic vapor, dust, etc. cause wear and change in electrical characteristics (contact resistance).

The manner of wear of the sliding contact material is roughly classified into adhesive wear and scratch wear. Adhesive wear is wear that occurs when metals are welded to each other at a true contact portion, that is, a protruding portion, and a softer metal is torn and converted to a harder metal.

[0006] Scratch wear is wear caused when materials having greatly different hardness are rubbed against each other, or when soft metals or hard metals are contained in one of them.

For example, due to the high speed rotation between the commutator and the brush in a small DC motor, the clad composite material composing the commutator is subjected to long-term contact friction and heat is also applied, so that the micron-order precious metal alloy surface layer of the composite material is generated. It is ground and wear powder is generated, filling the gap of the commutator, and conducting and short-circuiting to cause an electrical trouble or noise.

Moreover, various electrical troubles are caused by the oxide of the base layer, which is easily worn and oxidized even in the intermediate layer of the clad composite material.
Therefore, research into improving alloy materials and alloy compositions forming two or three layers constituting the composite material becomes a very important problem.

Recently, as a commutator material for a small DC motor used in household appliances driven by a rechargeable battery, the surface layer is 1 to 2% by weight of Cd, and the balance Ag is Ag.
Cd alloy, a clad composite material in which the base layer is Cu or a Cu alloy double-layered (for example, AgCd1 / Cu), or Cd whose surface layer is 1 to 2% by weight, 0.01 to 0.7% by weight
Ni, an AgCdNi alloy with the balance Ag, and a clad composite material (for example, AgCd2Ni0.3 / Cu) in which the base layer is a double layer of Cu or a Cu alloy are usually used.

These AgCd alloys and AgCdNi alloys are materials excellent in electrical function, hardness and contact resistance. For example, in Japanese Patent Publication No. 2-60745, at least one of Sn and Cd is 1 in total. ~ 5 wt% balance A of A
There is a disclosure of a sliding contact material for a DC small-sized motor commutator made of g-alloy.

[0011] As an important point, at present, the problem of living environment pollution is being screamed, and in order to avoid pollution of the human body by Cd, large-scale environmental measures are required and implemented at the manufacturing plant, but general consumers From, the electrical components containing Cd of the damaged equipment are discarded as they are,
It is a big social problem.

In addition, AgCu alloys and AgCuCd alloys are also used, but the problem is that the product value of a shaver using a rechargeable battery is poor because the contact resistance changes with time even if the initial contact resistance is low. This is because when the contact resistance becomes high, the starting voltage of the motor increases, the motor does not start with the electromotive force of the battery, and the life of the battery becomes short.
Therefore, the emergence of a commutator material that has a low contact resistance and does not change with time has been required at an early stage.

Further, in JP-A-58-104140, 1 to 10% by weight of Zn and Te, Co, Ni in Ag,
A sliding contact material formed by adding at least one kind of Cu, Ge, Ti and Pb in a total amount of 0.5 to 1% by weight is disclosed, but these Te, Co, Ni, Cu, Ge and T are disclosed.
Since i and Pb are more easily oxidized than Zn, the reason for adding them to the AgZn alloy is to suppress the oxidation to some extent, and the main purpose is to improve the wear resistance while maintaining the sulfidation resistance and lubricity, and to make contact. It is to stabilize the resistance low.

The contact resistance of the material disclosed in the above-mentioned publication is similar to that of AgCu alloy or AgCuCd alloy, and the point intended by the present invention, that is, "the motor has a low electromotive force, Low starting voltage that the
As a result, the problem of "extending continuous use time, in which the time between charging once and charging next time becomes longer", is not satisfactory yet, and further improvement is required.

Further, as a related technique, Japanese Patent Laid-Open No.
No. -130094, in Ag, Mg, Fe, Mg,
At least one of Sn, Si, Cd, and Mn is 0.0
5 to 1 wt% and at least one of Ni Fe Co
A commutator material obtained by internally oxidizing an Ag alloy containing 0.05 to 0.5% by weight of a seed is disclosed, but this one mainly improves the mechanical strength and, as a result, mainly seeks wear resistance characteristics. The contact resistance is the same as that of the AgCu alloy generally used in the past, and does not satisfy the low contact resistance in consideration of the starting voltage and the electromotive force.

The internal oxide material as a sliding contact material has a low electric conductivity as an alloy, but has a drawback that the contact resistance is locally high because it is an oxide already existing on the contact surface. However, it is difficult to use it for sliding parts that require low contact resistance, and there are still many unsolved problems regarding contact resistance.

With the recent trend toward miniaturization of rechargeable battery-operated home appliances, particularly in headphone stereos, cameras, and shavers, a motor with a low starting voltage is used to reduce the size of the rechargeable battery. There is an urgent need to develop a commutator for micromotors that can be made lighter.

[0018]

SUMMARY OF THE INVENTION Therefore, the present invention
Particularly, it has excellent low contact resistance, good electrical function, does not change with time, has abrasion resistance practically comparable to that manufactured by the conventional technique, and can sufficiently replace Cd. The development of the dynamic contact material is a technical subject of this invention,
As a result of repeated research over a long period of time, a technique for reducing the contact resistance by improving the metal composition and composition ratio of the alloy and the metal structure was able to be achieved by the following constitution.

[0019]

The constitution of the present invention is as follows. 1 Ag used as a sliding contact material for electrical and mechanical sliding parts
A sliding contact material comprising a Zn alloy with 0.01 to less than 1.0% by weight of Zn and the balance Ag. 2. The sliding contact material according to the above 1, wherein Zn is a solid solution in the Agα phase of the AgZn alloy. 3 Ag used for sliding contact materials of electrical and mechanical sliding parts
ZnNi alloy, 0.01 to less than 1.0 wt% Zn,
A sliding contact material characterized in that 0.01 to less than 0.5% by weight of Ni and the balance Ag are used. 4 Zn forms a solid solution in the Agα phase of the AgZnNi alloy,
4. The sliding contact material as described in 3 above, wherein Ni particles are dispersed. 5 Ag used for sliding contact materials for electrical and mechanical sliding parts
Mg alloy, 0.01-1.0 wt% Mg, balance Ag
The sliding contact material characterized in that (6) The sliding contact material according to the above (5), wherein Mg is a solid solution in the Agα phase of the AgMg alloy. 7 Ag used for sliding contact material of electrical and mechanical sliding parts
MgNi alloy, 0.01-1.0 wt% Mg, 0.
A sliding contact material, characterized in that 01 to 0.5% by weight of Ni and the balance of Ag are used. 8 Mg dissolved in the Agα phase of the AgMgNi alloy,
8. The sliding contact material as described in 7 above, wherein Ni particles are dispersed. 9 0.01% to less than 1.0 wt% Zn in the surface layer, AgZn alloy with the balance Ag, or 0.01 to 1.
An AgMg alloy with 0% by weight of Mg and the balance Ag,
A clad composite material, wherein the base layer is a double layer of Cu or Cu alloy. 10 Zn whose surface layer is 0.01 to less than 1.0% by weight,
0.01 to less than 0.5% by weight of Ni, and the balance A of A
g-ZnNi alloy, or 0.01-1.0 wt% surface layer
Mg, 0.01-0.5 wt% Ni, balance Ag
The clad composite material, wherein the AgMgNi alloy and the base layer are made of Cu or a Cu alloy. 11 The surface layer is an AgZn alloy or AgZnNi alloy, or an AgMg alloy or an AgMgNi alloy, and the base layer is a double layer of Cu or Cu alloy.
A small DC motor using the clad composite material described in 0 as a commutator.

In the present invention, various experiments were conducted on sliding contact materials, and Zn was contained in 0.01 to less than 1.0% by weight in Ag, and the Zn was uniformly dissolved in the Agα phase. In the case of the structure of No. 1, it has a very low contact resistance that contributes to lubricity, has abrasion resistance practically comparable to that produced by the conventional technique, and has a sufficient Cd.
It was found that a clad composite material that can replace the above can be obtained.

Similarly, in Ag, Mg is 0.01 to 1
When the structure is such that Mg is contained in an amount of wt% and Mg is uniformly dissolved in the Agα phase, a Zn or Mg oxide film (commonly called an oxidation band) is formed on the surface of the sliding contact material like Zn. It was discovered as a material that does not form a metal, and the problem of impeding electrical conductivity and contact stability was solved.

The sliding contact material of the present invention is Zn or Mg.
In addition to that, Ni is dispersed in an amount of 0.01 to less than 0.5% by weight when used in combination with Zn, and 0.01 to 0.5% by weight when used in combination with Mg. Wearability is maintained, and the matrix is a solid solution element Zn, Mg
Since it has an extremely small Agα phase, even if it is left in the air, no oxidation band is formed (against change with time), so that the contact resistance does not increase.

[0023]

As described above, Zn is contained in the Agα phase in an amount of 0.01 to 0.01
Solid solution less than 1.0 wt% or Mg 0.01-1.0
Since it forms a solid solution by weight%, an oxide film (oxidation band) is not unnecessarily formed on the surface of the alloy, and ZnO or M slightly generated during sliding of the commutator and the brush.
The film of gO has the effect of lowering the frictional resistance while maintaining good lubricity. And ZnO and Mg
O has conductivity by itself, and thus has no problem in electrical performance.

What is important in this invention is that the oxide film formed on the metal surface during sliding, that is, a slight oxide band, catches smooth sliding and improves wear resistance, but it is a sliding contact material. Since it can be a factor that hinders the contact function as described above, minimizing the adverse effect on the sliding characteristics of the oxidation band is the deciding factor of quality.

In conventional AgCu and AgCuCd, even if a small amount of solid solution element (Cu) is added, an oxide of the solid solution element is generated as an oxidation band on the contact surface when left in the air (eg CuO), The contact resistance is high.

In comparison with the AgZnNi alloy according to the prior art described above, it has been found that the AgZn alloy containing no elements other than Zn at all is better for achieving the object of the present invention. However, if it is added in an amount of less than 0.01% by weight, the effect is not obtained. If it is added in an amount of 1% by weight or more, Zn is oxidized to form a band when left in the air, resulting in a high contact resistance. The most effective amount of Zn added is 0.5 to less than 1.0% by weight.

On the other hand, Ag in which a small amount of Zn is added to Ag
A Zn alloy, for example, Ag99.1Zn0.9 alloy, has a Vickers hardness of 134 Hv after processing, but sometimes it is left alone at room temperature for a few days to cause aging softening, which may reduce the Vickers hardness to 120 Hv. This phenomenon itself is
It does not deteriorate the sliding characteristics so that it becomes a problem in practical use. However, a dimensional error when punching the clad composite material with a press may cause a problem in assembling the motor. Therefore, in order to prevent such age softening of the material, A
It is preferable to add a small amount of Ni to the gZn alloy.

If the added amount of Ni is less than 0.01% by weight, there is no effect to be observed, and if it is more than 0.5% by weight, Ni is segregated unevenly and, moreover, dispersed on the contact surface during sliding of the commutator. However, there is a drawback that the Ni particles that are formed generate an oxide and locally increase the contact resistance. The AgZnNi alloy in which 0.5 to 1% by weight of Ni is added according to the prior art was intended to improve the wear resistance by the addition of Ni, so the contact resistance is increased, and the problem of the present invention. Cannot be solved. N to prevent this age softening
The most effective amount of i added is 0.2 to 0.4% by weight, and the amount of i added in the prior art hardly improves the wear resistance.

In order to achieve the object of the present invention, it was found that the AgMg alloy without internal oxidation gives better results than the other alloys with internal oxidation of AgMgNi according to the prior art. . However,
If the added amount of Mg is less than 0.01% by weight, there is no effect, and if it exceeds 1.0% by weight, when left in the air, it oxidizes to form a band and the contact resistance increases. This Mg
It is most effective to add 0.3 to 0.6% by weight.

On the other hand, Ag obtained by adding a small amount of Mg to Ag
Similar to the AgZn alloy, the Mg alloy may cause age softening even if it is left alone at room temperature for several days. To prevent the age softening, it is preferable to add Ni to the AgMg alloy. However, if it is less than 0.01% by weight, there is no effect of preventing it, and if it exceeds 0.5% by weight, Ni is segregated unevenly and, moreover, Ni particles dispersed on the contact surface are oxidized during sliding of the commutator. It has a drawback that it produces a substance and locally increases the contact resistance.

The micromotor incorporating the sliding contact material of the present invention has a low contact resistance between the commutator and the brush, is stable, does not change with time, and always rotates the micromotor at a lower starting voltage without any trouble. You can The same effect can be obtained in a clad composite material in which Au or Au alloy is further laminated on the surface of the two-layered structure to form a three-layered structure. Next, the present invention will be described in detail based on examples.

[0032]

Examples 1 to 12, Conventional Examples 1 to 2 and Comparative Examples 1 to 6 The materials having the component compositions shown in Table 1 below are sequentially melt-cast-
Face milling-groove roll processing to 5.5 mm square, then heat treatment (conveyor furnace, 650 ° C, 250 mm / min)
Then, wire drawing was further performed to obtain materials of Examples, Conventional Example and Comparative Example having a diameter of 2 mm. (See Table 1)

However, the test materials of Examples 1 to 12, Conventional Examples 1 and 2 and Comparative Examples 1 to 6 having the above composition have a diameter of 2 m.
Using a round rod of m, crossed with a round rod of 50% by weight of AgPd of the same diameter, and performing a sliding test under the following test conditions, the wear amount (wear volume) and other characteristics were obtained. The results shown in 2 were obtained. (Note) The conventional example and the comparative example refer to the prior art of the commutator of the present applicant.

[0034]

[Table 1]

[0035]

【Test condition】

 Current DC170mA Load 25g Rotation speed 300rpm Amplitude 0.5mm Temperature, humidity 25 ° C, 50% RH Cycle number 100,000 cycles Moving contact material Test material Fixed contact material AgPd 50% by weight

[0036]

[Abrasion Volume] In the test material after the sliding test, the material was transferred from the movable contact material (test material) to the fixed contact material (50% by weight of AgPd).
This wear part was approximated to an ellipsoid and the wear volume was calculated (V
= 4πabc / 3). The result of the wear volume of each material obtained from the SEM (electron microscope) photograph is shown in FIG. Since a 10-point sliding test was performed for each material, the average value of the wear volume was calculated.

During the sliding test, the test material and A
The coefficient of friction of gPd50 usually changes as follows. At the initial stage of the sliding test, the coefficient of friction is low (about 0.3) and the state of so-called mild wear is present. At this time, the adhesive transfer of the material is considered to have hardly occurred. In the middle period of the sliding test, the friction coefficient gradually increases, and in the latter period of the sliding test, the friction coefficient remains high and remains constant (1,
2).

This is the so-called severe wear state. By this time, it is considered that the adhesive transfer of the material has occurred and the wear has advanced. Therefore, it was considered that the number of slides at which the transition from severe wear to mild wear occurs is one of the parameters for evaluating the easiness of adhesion transfer of materials. This value was obtained from the friction coefficient data during the sliding test and plotted on the Weibull probability paper.

Table 2 below summarizes the m value and average life from the above Weibull probability paper.

Table 3 shows the results of evaluation of changes in contact resistance over time. As an accelerated evaluation, a heat treatment was performed at 200 ° C. for 6 hours in the atmosphere to perform an aging treatment for forming an oxide film. Samples before and after aging treatment were measured by Yokogawa Hewlett-Packard Milliohm Meter 4328A, Au probe, contact load 10 g.
The contact resistance at each of 50 points was measured by the AC four-terminal method.

[0041]

[Table 2]

[0042]

[Table 3]

[0043]

EFFECTS OF THE INVENTION In the sliding contact material and the clad composite material having the alloy composition according to the present invention, a specific amount of Zn or Mg is solid-solved in the Agα phase which is the surface layer of the noble metal, and N
Since the i particles are uniformly dispersed, the surface layer shows excellent electrical characteristics without adverse effects of oxidation bands, has low contact resistance, does not change with time, and has abrasion resistance. It has a high commercial value, far beyond the range of prediction.

Moreover, Zn or Mg solid-dissolved in the Agα-phase matrix and dispersed Ni particles have a total surface area that increases the contact resistance even if they are selectively oxidized during sliding. Oxidation has the unexpected effect that it can be avoided. Therefore, the sliding contact material of the present invention effectively maintains a low contact resistance, and has a particularly remarkable function and effect that enables long-term use, particularly in household appliances including a small DC motor using a rechargeable battery, It is a sliding contact material and clad composite material with excellent functions.

Claims (11)

[Claims] 1. A sliding contact material comprising an AgZn alloy used as a sliding contact material for electrical and mechanical sliding parts, wherein Zn is 0.01 to less than 1.0% by weight and the balance is Ag. . 2. The sliding contact material according to claim 1, wherein Zn is a solid solution in the Agα phase of the AgZn alloy. 3. An AgZnNi alloy used for a sliding contact material of an electrical / mechanical sliding part, which comprises 0.01 to less than 1.0% by weight of Zn, and 0.01 to less than 0.5% by weight of Ni. Balance A
A sliding contact material characterized by having g. 4. Zn in the Agα phase of the AgZnNi alloy
5. The sliding contact material according to claim 3, wherein is a solid solution and Ni particles are dispersed. 5. An AgMg alloy used as a sliding contact material for electrical and mechanical sliding parts, containing 0.01 to 1.0% by weight of M.
g, and the balance Ag, a sliding contact material. 6. The sliding contact material according to claim 5, wherein Mg is a solid solution in the Agα phase of the AgMg alloy. 7. An AgMgNi alloy used as a sliding contact material for electrical and mechanical sliding parts, which comprises 0.01 to 1.0% by weight of Mg, 0.01 to 0.5% by weight of Ni, and the balance Ag. The sliding contact material characterized in that 8. An Agα phase of an AgMgNi alloy containing Mg
8. The sliding contact material according to claim 7, wherein is a solid solution and Ni particles are dispersed. 9. The surface layer has a Zn content of 0.01 to less than 1.0% by weight, an AgZn alloy with the balance being Ag, or a surface layer of 0.1% by weight.
A clad composite material, which is an AgMg alloy in which 01 to 1.0% by weight of Mg and the balance Ag are used, and the base layer is a double layer of Cu or Cu alloy. 10. The surface layer comprises 0.01 to less than 1.0% by weight of Zn, 0.01 to less than 0.5% by weight of Ni, and the balance Ag.
The AgZnNi alloy or the surface layer of 0.01-1.
0 wt% Mg, 0.01-0.5 wt% Ni, AgMgNi alloy with the balance Ag, Cu or Cu as the base layer
A clad composite material that is made of two layers of alloy. 11. The surface layer is an AgZn alloy or AgZnN.
A small direct current motor comprising the i-alloy, AgMg alloy or AgMgNi alloy, and the base layer having a double layer of Cu or Cu alloy. The clad composite material according to claim 9 or 10 is used as a commutator. .