US20220119919A1

US20220119919A1 - Copper alloy material, commutator segment, and electrode material

Info

Publication number: US20220119919A1
Application number: US17/419,008
Authority: US
Inventors: Satoshi Kumagai; Shoichiro Yano; Yoshiyuki Akiyama
Original assignee: Mitsubishi Materials Corp
Current assignee: Mitsubishi Materials Corp
Priority date: 2019-02-20
Filing date: 2020-02-14
Publication date: 2022-04-21
Also published as: WO2020170956A1

Abstract

A composition includes Cr in a range of 0.3% by mass or more and 0.7% by mass or less, Zr in a range of 0.025% by mass or more and 0.15% by mass or less, Sn in a range of 0.005% by mass or more and 0.04% by mass or less, and P in a range of 0.005% by mass or more and 0.03% by mass or less, in which a balance is made of Cu and inevitable impurities, and a Vickers hardness at 20° C. is 149 Hv or higher.

Description

TECHNICAL FIELD

The present invention relates to a copper alloy material that is particularly suitable as a material for components used in applications requiring wear resistance, such as, for example, commutators and electrode materials for DC machines.
Priority is claimed on Japanese Patent Application No. 2019-028048 filed Feb. 20, 2019 in Japan and Japanese Patent Application No. 2020-004203 filed Jan. 15, 2020 in Japan, the content of which is incorporated herein by reference.

BACKGROUND ART

In the related art, since direct current machines such as a direct current electric motor or a direct current generator have a structure in which the commutator described above is in contact with a feeding brush, there is a demand for excellent wear resistance and high electrical conductivity for the commutator segments forming the commutator. In addition, there is also a demand for electrode materials for resistance welding and electrode materials for electrical discharge machining to have wear resistance at high temperatures in addition to wear resistance and electrical conductivity.
In the related art, as materials forming commutator segments and electrode materials, silver-containing copper, oxygen-free copper, tough pitch copper, phosphorous-deoxidized copper, and the like are used and, for example, the various copper alloys disclosed in Patent Documents 1 to 3 were proposed in order to further improve wear resistance.
For example, Patent Document 1 proposes a copper alloy containing Fe: 0.02 to 0.5 wt %, P: 0.02 to 0.15 wt %, and Ag: 0.01 to 0.3 wt %.
In addition, Patent Document 2 proposes a copper alloy containing 0.01 to 0.2 wt % of zirconium (Zr).
Furthermore, Patent Document 3 proposes a copper alloy including Si: 0.1 to 1.0 wt %.

CITATION LIST

Patent Documents

Patent Document 1

Japanese Unexamined Patent Application, First Publication No. H02-025531 (A)

Patent Document 2

Japanese Unexamined Patent Application, First Publication No. H09-071849 (A)

Patent Document 3

Japanese Unexamined Patent Application, First Publication No. H09-263864 (A)

SUMMARY OF INVENTION

Technical Problem

Recently, along with the size reduction, increased output, and the like of the DC motors and DC generators described above as well as resistance welding machines and electrical discharge machining devices, the commutator segments, electrode materials, and the like used in these machines have been used in more severe environments than in the past. For this reason, there is a demand for the above to have better wear resistance and a longer service life than in the past. In components or the like other than commutator segments and electrode materials, there is a demand to improve the wear resistance in order to lengthen the service life thereof. In addition, these components may be used under high temperature conditions and there is a demand for such components to have stable characteristics even at high temperatures.
Here, in the copper alloys disclosed in Patent Documents 1 to 3, the wear resistance was still insufficient and it was not possible to lengthen the service life of components made of these copper alloys.
This invention was created in consideration of the circumstances described above and has an object of providing a copper alloy material, a commutator segment, and an electrode material which are particularly excellent in wear resistance, which have stable characteristics even at high temperatures, and which are able to lengthen the service life of components formed thereof.

Solution to Problem

In order to solve the above problem, a copper alloy material of the present invention has a composition including Cr in a range of 0.3% by mass or more and 0.7% by mass or less, Zr in a range of 0.025% by mass or more and 0.15% by mass or less, Sn in a range of 0.005% by mass or more and 0.04% by mass or less, P in a range of 0.005% by mass or more and 0.03% by mass or less, and a balance consisting of Cu and inevitable impurities, in which a Vickers hardness at 20° C. is 149 Hv or higher.
In the copper alloy material with this configuration, since Cr is contained in a range of 0.3% by mass or more and 0.7% by mass or less and Zr is contained in a range of 0.025% by mass or more and 0.15% by mass or less, respectively, it is possible to precipitate fine precipitates through an aging treatment and to improve the hardness by precipitation hardening.
In addition, since Sn is contained in a range of 0.005% by mass or more and 0.04% by mass or less, it is possible to improve the hardness by solid solution hardening.
Furthermore, since P is contained in a range of 0.005% by mass or more and 0.03% by mass or less, a Zr—P compound or a Cr—Zr—P compound is generated due to the Zr and Cr described above reacting with P. Since the Zr—P compound and the Cr—Zr—P compound are stable even at high temperatures, the hardness does not decrease even in a case of being used under high temperature conditions.
Since the Vickers hardness at 20° C. is 149 Hv or higher, the wear resistance is particularly excellent.
Thus, it is possible to lengthen the service life of components made of this copper alloy material.
Here, in the copper alloy material of the present invention, the Zr content [Zr] of (% by mass) and the P content [P] (% by mass) may have a relationship of [Zr]/[P]>5.
In such a case, since the Zr content [Zr] (% by mass) and the P content [P] (% by mass) have the relationship of [Zr]/[P]>5, even if a Zr—P compound or a Cr—Zr—P compound is generated, the number of Cu—Zr precipitates contributing to an improvement in the hardness is ensured and it is possible to reliably obtain the improvement in the hardness.
In addition, in the copper alloy material of the present invention, the Sn content [Sn] (% by mass) and the P content [P] (% by mass) may have a relationship of [Sn]/[P]≤5.
In such a case, since the Sn content [Sn] (% by mass) and the P content [P] (% by mass) have the relationship of [Sn]/[P]≤5, it is possible to compensate for the decrease in electrical conductivity due to the solid solution of Sn with the increase in electrical conductivity due to the generation of the Zr—P compound or the Cr—Zr—P compound and to ensure excellent conductivity (thermal conductivity). Thus, suitable use is possible in applications where there is a demand for conductivity (thermal conductivity).
In addition, the copper alloy material of the present invention may further include Si of 0.005% by mass or more and 0.03% by mass or less.
In such a case, due to the solid solution dissolution of Si in the copper matrix phase, it is possible to obtain a further improvement in the hardness due to the solid solution hardening.
In addition, in the copper alloy material of the present invention, the total content of the elements of Mg, Al, Fe, Ni, Zn, Mn, Co, and Ti is preferably 0.03% by mass or less.
In this case, since the total content of the elements of Mg, Al, Fe, Ni, Zn, Mn, Co, and Ti, which are impurity elements, is limited to 0.03% by mass or less, it is possible to suppress a decrease in conductivity (thermal conductivity). Thus, suitable use is possible in applications where there is a demand for conductivity (thermal conductivity).
Furthermore, in the copper alloy material of the present invention, the electrical conductivity is preferably 70% IACS or higher.
In such a case, since the electrical conductivity is 70% IACS or higher, Cr-based precipitates and Zr-based precipitates are sufficiently dispersed, a Zr—P compound or a Cr—Zr—P compound is generated, and it is possible to sufficiently improve the hardness. In addition, the invention is particularly suitable for applications where there is a demand for conductivity (thermal conductivity).
In addition, in the copper alloy material of the present invention, the tensile strength is preferably 470 MPa or higher.
In such a case, since the tensile strength is 470 MPa or higher, the strength is sufficient, it is possible to suppress deformation during use, and suitable use is possible as a material for various components.
The commutator segment of the present invention is made of the copper alloy material described above.
According to the commutator segment with this configuration, since the commutator segment is made of the copper alloy material described above, the commutator segment is hard and has excellent wear resistance, the hardness thereof does not decrease even in a case of being used under high temperature conditions, stable use is possible, and it is possible to extend the service life thereof.
The electrode material of the present invention is made of the copper alloy material described above.
According to the electrode material with this configuration, since the electrode material is made of the copper alloy material described above, the electrode material is hard and has excellent wear resistance, the hardness thereof does not decrease even in a case of being used under high temperature conditions, stable use is possible, and it is possible to extend the service life thereof.

Advantageous Effects of Invention

According to the present invention, it is possible to provide a copper alloy material, a commutator segment, and an electrode material which are particularly excellent in wear resistance, which have stable characteristics even at high temperatures, and which are able to lengthen the service life of components formed thereof.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a flow diagram of a method for manufacturing a copper alloy material, which is an embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

A description will be given below of the copper alloy material, which is an embodiment of the present invention.
The copper alloy material of the present embodiment is used, for example, as a material for components requiring particularly excellent wear resistance, such as commutator segments forming the commutator of a direct current machine, and electrode materials for electrical discharge machining or resistance welding.
In addition, the copper alloy material of the present embodiment is shaped according to the processing method when forming the components, for example, to form plate materials, wire rod materials, and tube materials.
The copper alloy material of the present embodiment has a composition including Cr in a range of 0.3% by mass or more and 0.7% by mass or less, Zr in a range of 0.025% by mass or more and 0.15% by mass or less, Sn in a range of 0.005% by mass or more and 0.04% by mass or less, P in a range of 0.005% by mass or more and 0.03% by mass or less, and a balance consisting of Cu and inevitable impurities.
Here, in the copper alloy material of the present embodiment, the Vickers hardness at 20° C. is 149 Hv or higher.
In the copper alloy material of the present embodiment, the Zr content [Zr] (% by mass) and the P content [P] (% by mass) preferably have the relationship of [Zr]/[P]>5.
In addition, in the copper alloy material of the present embodiment, the Sn content [Sn] (% by mass) and the P content [P] (% by mass) preferably have the relationship of [Sn]/[P]≤5.
Furthermore, the copper alloy material of the present embodiment may include Si in a range of 0.005% by mass or more and 0.03% by mass or less.
In addition, in the copper alloy material of the present embodiment, the total content of the elements of Mg, Al, Fe, Ni, Zn, Mn, Co, and Ti may be 0.03% by mass or less.
In the copper alloy material of the present embodiment, the electrical conductivity is preferably 70% IACS or higher.
In addition, in the copper alloy material of the present embodiment, the tensile strength is preferably 470 MPa or higher.
Explanation will be given below of the reasons for specifying the component composition and characteristics in the copper alloy material of the present embodiment as described above.
(Cr: 0.3% by mass or more and 0.7% by mass or less)
Cr is an element that has an effect of improving hardness (strength) and electrical conductivity by causing fine precipitation of Cr-based precipitates in crystal grains of the matrix phase through an aging treatment.
Here, in a case where the Cr content is less than 0.3% by mass, there is a concern that the amount of precipitation may be insufficient during the aging treatment and the effect of improving hardness (strength) and electrical conductivity may not be sufficiently obtained.
In addition, in a case where the Cr content is more than 0.7% by mass, relatively coarse Cr crystallites are generated and there is a concern that this may cause defects.
For the above reasons, in the present embodiment, the Cr content is set in a range of 0.3% by mass or more and 0.7% by mass or less.
To ensure that the effects described above are achieved, the lower limit of the Cr content is preferably set to 0.4% by mass or more and the upper limit of the Cr content is preferably set to 0.6% by mass or less.
(Zr: 0.025% by mass or more and 0.15% by mass or less)
Zr is an element that has an effect of improving hardness (strength) and electrical conductivity by finely precipitating Zr-based precipitates (for example, Cu—Zr) in crystal grain boundaries of the matrix phase through an aging treatment.
Here, in a case where the Zr content is less than 0.025% by mass, there is a concern that the amount of precipitation may be insufficient during the aging treatment and the effects of improving hardness (strength) and electrical conductivity may not be sufficiently obtained.
In addition, in a case where the Zr content is more than 0.15% by mass, there is a concern that the electrical conductivity may decrease and there are concerns that the Zr-based precipitates may become coarse and the effect of improving hardness (strength) may not be obtained.
For the above reasons, in the present embodiment, the Zr content is set in a range of 0.025% by mass or more and 0.15% by mass or less.
To ensure that the effects described above are achieved, the lower limit of the Zr content is preferably set to 0.05% by mass or more and the upper limit of the Zr content is preferably set to 0.13% by mass or less.
(Sn: 0.005% by mass or more and 0.04% by mass or less) Sn is an element that has an effect of improving hardness (strength) by solid solution dissolution in the copper matrix phase. In addition, there is also an effect of increasing the peak temperature of the softening characteristics.
Here, in a case where the Sn content is less than 0.005% by mass, there is a concern that the effect of improving hardness (strength) by a solid solution may not be sufficiently obtained. In addition, in a case where the Sn content is more than 0.04% by mass, there is a concern that the conductivity (thermal conductivity) may decrease.
For the above reasons, in the present embodiment, the Sn content is set in a range of 0.005% by mass or more and 0.04% by mass or less.
To ensure that the effects described above are achieved, the lower limit of the Sn content is preferably set to 0.01% by mass or more and the upper limit of the Sn content is preferably set to 0.03% by mass or less.
(P: 0.005% by mass or more and 0.03% by mass or less)
P is an element that, together with Zr and Cr, generates a stable Zr—P compound or Cr—Zr—P compound at high temperatures and has an effect of suppressing the coarsening of the crystal grain size under high temperature conditions. For this reason, it is possible to suppress a decrease in hardness in a case of being used at high temperatures.
Here, in a case where the P content is less than 0.005% by mass, there are concerns that a Zr—P compound or a Cr—Zr—P compound may not be sufficiently generated and the effect of suppressing the coarsening of the crystal grain size in a high temperature state may not be sufficiently obtained. In addition, in a case where the P content is more than 0.03% by mass, there are concerns that an excessive amount of a Zr—P compound or a Cr—Zr—P compound may be generated, the number of Cu—Zr precipitates contributing to the improvement of hardness (strength) may be insufficient, and it may not be possible to improve the hardness (strength).
For the above reasons, in the present embodiment, the P content is set in a range of 0.005% by mass or more and 0.03% by mass or less.
To ensure that the effects described above are achieved, the lower limit of the P content is preferably set to 0.008% by mass or more and the upper limit of the P content is preferably set to 0.020% by mass or less.
(Vickers hardness at 20° C.: 149 Hv or higher)
The copper alloy material of the present embodiment is used as a material for components used in applications requiring wear resistance. For this reason, it is necessary to improve the Vickers hardness sufficiently.
Here, in a case where the Vickers hardness at 20° C. is less than 149 Hv, there is a concern that it may not be possible to ensure sufficient wear resistance.
For the above reasons, in the copper alloy material of the present embodiment, the Vickers hardness is set to 149 Hv or higher.
The Vickers hardness of the copper alloy material of the present embodiment is preferably set to 155 Hv or higher, and even more preferably set to 160 Hv or higher.
The upper limit value of the Vickers hardness is not particularly limited, but in the copper alloy material of the present embodiment, the Vickers hardness at 20° C. is set to 220 Hv or lower, and more preferably 200 Hv or lower.
([Zr]/[P]: more than 5)
As described above, P reacts with Zr to generate a Zr—P compound or a Cr—Zr—P compound which is stable at high temperatures.
Here, in a case where the ratio [Zr]/[P] of the Zr content [Zr] (% by mass) with respect to the P content [P] (% by mass) is more than 5, the amount of Zr with respect to P is secured, it is possible to secure the number of Cu—Zr precipitates that contribute to the improvement of hardness (strength) by the generation of a Zr—P compound or a Cr—Zr—P compound and to secure the improvement of the hardness (strength).
For the above reasons, in the present embodiment, the ratio [Zr]/[P] of the Zr content with respect to the P content is preferably set to more than 5.
In order to reliably ensure the number of Cu—Zr precipitates contributing to the improvement of hardness (strength), it is even more preferable to set the ratio [Zr]/[P] of the Zr content with respect to the P content to 7 or more.
([Sn]/[P]: 5 or less)
As described above, Sn decreases conductivity (thermal conductivity) by solid solution dissolution in the copper matrix phase. On the other hand, P improves conductivity (thermal conductivity) by generating a Zr—P compound or a Cr—Zr—P compound.
Here, in a case where the ratio [Sn]/[P] of the Sn content [Sn] (% by mass) with respect to the P content [P] (% by mass) is 5 or less, the amount of Sn with respect to P is suppressed and it is possible to compensate for the decrease in conductivity (thermal conductivity) due to the solid solution of Sn with the improvement in conductivity (thermal conductivity) due to the generation of a Zr—P compound or a Cr—Zr—P compound.
For the above reasons, in a case where there is a demand for conductivity (thermal conductivity), the ratio [Sn]/[P] of Sn content with respect to P content is preferably set to be 5 or less.
In addition, in order to reliably improve the conductivity (thermal conductivity), the ratio [Sn]/[P] of Sn content with respect to P content is even more preferably set to 3 or less.
(Si: 0.005% by mass or more and 0.03% by mass or less)
Si is an element that has an effect of improving hardness (strength) due to solid solution dissolution in the copper matrix phase and which may be added as necessary.
Here, in a case where the Si content is less than 0.005% by mass, there is a concern that the effect of hardness (strength) improvement due to the solid solution may not be sufficiently obtained. In addition, in a case where the Si content is more than 0.03% by mass, there is a concern that the conductivity (thermal conductivity) may be decreased.
For the above reasons, in a case where Si is added in the present embodiment, the Si content is preferably set in a range of 0.005% by mass or more and 0.03% by mass or less.
To ensure that the effects described above are achieved, the lower limit of Si content is preferably set to 0.010% by mass or more and the upper limit of Si content is preferably set to 0.025% by mass or less. In addition, in a case where Si is not intentionally added and the effect described above is not expected, less than 0.005% by mass Si may be included.
(Total content of Mg, Al, Fe, Ni, Zn, Mn, Co, Ti: 0.03% by mass or less)
There is a concern that elements such as Mg, Al, Fe, Ni, Zn, Mn, Co, and Ti may significantly decrease conductivity (thermal conductivity). For this reason, in a case where there is a demand for high conductivity (thermal conductivity), the total content of Mg, Al, Fe, Ni, Zn, Mn, Co, and Ti is preferably limited to 0.03% by mass or less. Furthermore, the total content of Mg, Al, Fe, Ni, Zn, Mn, Co, and Ti is preferably limited to 0.01% by mass or less.
(Other Inevitable Impurities)
Examples of other inevitable impurities other than the above Mg, Al, Fe, Ni, Zn, Mn, Co, and Ti include B, Ag, Ca, Te, Sr, Ba, Sc, Y, Ti, Hf, V, Nb, Ta, Mo, W, Re, Ru, Os, Se, Rh, Ir, Pd, Pt, Au, Cd, Ga, In, Li, Ge, As, Sb, Tl, Pb, Be, N, H, Hg, Tc, Na, K, Rb, Cs, Po, Bi, lanthanides, O, S, C, and the like. Since there is a concern that these inevitable impurities may decrease the conductivity (thermal conductivity), the total amount of these impurities is preferably set to 0.05% by mass or less.
(Electrical conductivity: 70% IACS or higher)
In the copper alloy material of the present embodiment, in a case where the electrical conductivity is 70% IACS or higher, the Cr-based precipitates and Zr-based precipitates are sufficiently dispersed and a Zr—P compound or a Cr—Zr—P compound is generated. Thus, the strength and conductivity (thermal conductivity) are excellent and it is possible to suppress the coarsening of the crystal grain size even in a case of being used under high temperature conditions.
For the above reasons, the copper alloy material of the present embodiment preferably has an electrical conductivity of 70% IACS or higher.
The electrical conductivity of the copper alloy material of the present embodiment is even more preferably 75% IACS or higher.
Although the upper limit value of the electrical conductivity is not particularly limited, in the copper alloy material of the present embodiment, the electrical conductivity of the copper alloy material is set to 90% IACS or lower, more preferably 87% IACS or lower, and even more preferably 85% IACS or lower.
(Tensile strength: 470 MPa or higher)
In the copper alloy material of the present embodiment, in a case where the tensile strength is 470 MPa or higher, it is possible to secure sufficient strength and to suppress deformation during use.
For the above reasons, in the copper alloy material of the present embodiment, the tensile strength is preferably set to 470 MPa or higher.
The tensile strength of the copper alloy material of the present embodiment is even more preferably set to 510 MPa or higher.
Although the upper limit value of the tensile strength is not particularly limited, in the copper alloy material of the present embodiment, the tensile strength of the copper alloy material is set to 620 MPa or lower, and more preferably 600 MPa or lower.
Next, a description will be given of a method for manufacturing a copper alloy material according to one embodiment of the present invention with reference to the flow diagram in FIG. 1.
(Melting and Casting Step S01)
First, a copper raw material made of oxygen-free copper with a copper purity of 99.99% by mass or more is charged into a carbon crucible and melted using a vacuum melting furnace to obtain molten copper. Next, the additive elements described above are added to the obtained molten metal to achieve a predetermined concentration and the components are adjusted to obtain a molten copper alloy.
Here, as raw materials for the additive elements Cr, Zr, Sn, and P, for example, it is preferable to use a Cr raw material with a purity of 99.9% by mass or higher, to use a Zr raw material with a purity of 99% by mass or higher, to use a Sn raw material with a purity of 99.9% by mass or higher, and to use a mother alloy with Cu for P. Si may be added as necessary. In a case where Si is added, it is preferable to use a mother alloy with Cu.
Then, the molten copper alloy in which the components are adjusted is poured into a mold to obtain a copper alloy ingot.
(Hot Working Step S02)
Next, the obtained copper alloy ingot is subjected to hot working. Here, the hot working conditions are preferably a temperature: 500° C. or higher and 1000° C. or lower, and a processing rate: 30% or more and 95% or less. In addition, after this hot working, cooling is carried out immediately by water cooling.
The processing method in the hot working step S02 is not particularly limited, but in a case where the final shape is a plate or strip, rolling may be applied thereto. In addition, in a case where the final shape is a wire or bar, extrusion or groove rolling may be applied thereto. In addition, in a case where the final shape is a bulk shape, forging or pressing may be applied thereto.
(Solution Treatment Step S03)
Next, the hot-worked material obtained in the hot working step S02 is subjected to a solution treatment by heating under conditions of a holding temperature: 900° C. or higher and 1050° C. or lower, and a holding time at the holding temperature: 0.5 hours or more and 6 hours or less, followed by water cooling. The heating is preferably performed in air or an inert gas atmosphere, for example.
(First Cold Working Step S04)
Next, cold working is performed on the solution-treated material subjected to the solution treatment step S03. Here, in the first cold working step S04, it is preferable to set the processing rate in a range of 30% or more and 90% or less.
The processing method in the first cold working step S04 is not particularly limited, but in a case where the final shape is a plate or strip, rolling may be applied thereto. In addition, in a case where the final shape is a wire or bar, drawing or groove rolling may be applied thereto. In addition, in a case where the final shape is a bulk shape, forging or pressing may be applied thereto.
(Aging Treatment Step S05)
Next, a cold-worked material obtained in the cold working step S04 is subjected to an aging treatment to finely precipitate precipitates such as Cr-based precipitates and Zr-based precipitates.
Here, the aging treatment is preferably performed under conditions of a holding temperature: 400° C. or higher and 600° C. or lower, and a holding time at the holding temperature: 0.5 hours or more and 6 hours or less.
The heat treatment method during the aging treatment is not particularly limited, but is preferably performed in an inert gas atmosphere. In addition, the cooling method after heating is not particularly limited, but rapid cooling by water cooling is preferable.
(Second Cold Working Step S06)
Next, cold working is carried out on an aging treated material subjected to the aging treatment step S05. Here, in the second cold working step S06, the processing rate is preferably set in a range of 10% or more and 80% or less.
The processing method in the second cold working step S06 is not particularly limited, but in a case where the final shape is a plate or strip, rolling may be applied thereto. In addition, in a case where the final shape is a wire or bar, drawing or groove rolling may be applied thereto. In addition, in a case where the final shape is a bulk shape, forging or pressing may be applied thereto.
This step is used to manufacture the copper alloy material of the present embodiment.
According to the copper alloy material according to the present embodiment with the configuration described above, since Cr is contained in a range of 0.3% by mass or more and 0.7% by mass or less and Zr is contained in a range of 0.025% by mass or more and 0.15% by mass or less, respectively, it is possible to precipitate fine precipitates through an aging treatment and it is possible to improve the hardness by precipitation hardening.
In addition, since Sn is contained in a range of 0.005% by mass or more and 0.04% by mass or less, it is possible to improve the hardness by solid solution hardening.
Furthermore, since P is contained in a range of 0.005% by mass or more and 0.03% by mass or less, a Zr—P compound or a Cr—Zr—P compound is generated due to the Zr and Cr described above reacting with P. Since the Zr—P compound and the Cr—Zr—P compound are stable even at high temperatures, the hardness does not decrease even in a case of being used under high temperature conditions.
In the copper alloy material according to the present embodiment, the Vickers hardness at 20° C. is 149 Hv or higher, thus, the wear resistance is particularly excellent.
In addition, in the copper alloy material of the present embodiment, in a case where the Zr content [Zr] (% by mass) and the P content [P] (% by mass) have the relationship of [Zr]/[P]>5, even if a Zr—P compound or a Cr—Zr—P compound is generated, the number of Cu—Zr precipitates contributing to the improvement in the hardness is ensured and it is possible to reliably obtain the improvement in the hardness.
Furthermore, in the copper alloy material of the present embodiment, in a case where the Sn content [Sn] (% by mass) and the P content [P] (% by mass) have the relationship of [Sn]/[P]≤5, it is possible to compensate for the decrease in electrical conductivity due to the solid solution of Sn with the increase in electrical conductivity due to the generation of a Zr—P compound or a Cr—Zr—P compound and to ensure excellent conductivity (thermal conductivity). Thus, in a case of being used in applications where there is a demand for conductivity (thermal conductivity), it is preferable to have the relationship of [Sn]/[P]≤5.
In addition, in the copper alloy material of the present embodiment, in a case where 0.005% by mass or more and 0.03% by mass or less of Si is included, due to the solid solution dissolution of Si in the copper matrix phase, it is possible to obtain a further improvement in the hardness due to the solid solution hardening.
In addition, in the copper alloy material of the present embodiment, in a case where the total content of the elements of Mg, Al, Fe, Ni, Zn, Mn, Co, and Ti, which are impurity elements, is 0.03% by mass or less, it is possible to suppress the decrease in conductivity (thermal conductivity).
Thus, in a case of being used in applications where there is a demand for conductivity (thermal conductivity), it is preferable to limit the total content of the elements of Mg, Al, Fe, Ni, Zn, Mn, Co, and Ti to 0.03% by mass or less.
Furthermore, in the copper alloy material of the present embodiment, in a case where the electrical conductivity is 70% IACS or higher, the Cr-based precipitates and Zr-based precipitates are sufficiently dispersed, a Zr—P compound or a Cr—Zr—P compound is generated, and it is possible to sufficiently improve the hardness.
In addition, electrical conductivity is ensured, which is thus particularly suitable for applications where there is a demand for conductivity (thermal conductivity).
In addition, in the copper alloy material of the present embodiment, in a case where the tensile strength of the copper alloy material is 470 MPa or higher, a sufficient strength is secured, it is possible to suppress deformation during use, and suitable use is also possible as a material for various components.
The commutator segment and the electrode material made of the copper alloy material of the present embodiment are hard and have excellent wear resistance, the hardness thereof does not decrease even in a case of being used under high temperature conditions, stable use is possible, and it is possible to extend the service life thereof.
Although embodiments of the present invention were described above, the present invention is not limited thereto and appropriate changes are possible in a range not departing from the technical concept of the invention.
For example, the method of manufacturing the copper alloy material is not limited to the present embodiment and the manufacturing may be carried out by other manufacturing methods. For example, a continuous casting apparatus may be used in the melting and casting step.

EXAMPLES

A description will be given below of the results of confirmation experiments conducted to confirm the effectiveness of the present invention.

Example 1

A copper raw material made of oxygen-free copper with a purity of 99.99% by mass or more was prepared, charged into a carbon crucible, and melted in a vacuum melting furnace (vacuum degree of 10⁻²Pa or less) to obtain molten copper. Various additive elements were added into the obtained molten copper to adjust the component compositions shown in Table 1 and, after holding for 5 minutes, the molten copper alloy was poured into a cast iron mold to obtain a copper alloy ingot. The cross-sectional dimensions of the copper alloy ingot were approximately 60 mm in width and 100 mm in thickness.
Regarding the additive elements, a raw material of Cr with a purity of 99.99% by mass or more, a raw material of Zr with a purity of 99.95% by mass or more, and a raw material of Sn with a purity of 99.99% by mass or more, respectively, were used. For P, a Cu—P mother alloy was used.
Next, the obtained copper alloy ingot was subjected to hot rolling under the conditions shown in Table 2 to obtain a hot-rolled material.
The hot-rolled material was heated and held under the conditions shown in Table 2 and then water-cooled and subjected to a solution treatment.
Next, the solution-treated material described above was cut and subjected to cold working (drawing processing) under the conditions shown in Table 2 to obtain a cold-worked material.
This cold-worked material was heated and held in an atmospheric furnace under the conditions shown in Table 2 and then water-cooled and subjected to an aging treatment.
The obtained aging treated material was subjected to cold working (drawing processing) under the conditions shown in Table 2 and various copper alloy materials were obtained.
The obtained copper alloy materials were evaluated for component composition, Vickers hardness, electrical conductivity, tensile strength, and wear resistance.
(Component Composition)
The component compositions of the obtained copper alloy materials were measured by ICP-MS analysis. As a result, it was confirmed that the compositions were as shown in Table 1.
(Vickers Hardness)
In accordance with JIS Z 2244, the Vickers hardness was measured at nine locations on a test piece by a Vickers hardness tester manufactured by Akashi Corporation and the average value of the seven measured values excluding the maximum and minimum values was obtained. The evaluation results are shown in Table 3.
(Electrical Conductivity)
Using SIGMA TEST D2.068 (probe diameter: φ6 mm) manufactured by Foerster Japan Ltd., the center portion of the cross-section of a 10×15 mm sample was measured three times and the average value thereof was obtained. The evaluation results are shown in Table 3.
(Tensile Strength)
Using an AG-X 250 kN manufactured by Shimadzu Corporation, after setting the distance between the test points to 250 mm, a tensile test was conducted two or more times at a crosshead speed of 100 mm/min and the average value thereof was obtained. The evaluation results are shown in Table 3.
(Wear Resistance)
Using an Amsler-type abrasion tester manufactured by Tokyo Koki Co., Ltd., an upper portion copper alloy test piece of φ 32 mm×10 mm and a lower portion test piece of φ 48 mm×10 mm made of SUS were rotated by the rolling sliding abrasion method, with a test load of 50 kgf and a rotation speed of 188 rpm for the upper portion and 209 rpm for the lower portion, and the abrasion weight was measured. The evaluation results are shown in Table 3.

TABLE 1

		Composition

					Total content of
					Mg, Al, Fe, Ni,
Cr	Zr	Sn	P	Si	Zn, Mn, Co, and Ti
(mass %)	(mass %)	(mass %)	(mass %)	(mass %)	(mass %)	Cu	[Zr]/[P]	[Sn]/[P]

Examples	1	0.30	0.050	0.008	0.007	0.007	0.02	Balance	7.1	1.1
	2	0.70	0.110	0.010	0.012	0.012	0.02	Balance	9.2	0.8
	3	0.45	0.025	0.015	0.005	0.015	0.01	Balance	5.0	3.0
	4	0.55	0.150	0.020	0.016	0.019	0.01	Balance	9.4	1.3
	5	0.45	0.120	0.005	0.019	0.016	0.02	Balance	6.3	0.3
	6	0.67	0.070	0.040	0.016	0.028	0.01	Balance	4.4	2.5
	7	0.58	0.080	0.025	0.005	0.021	0.01	Balance	16.0	5.0
	8	0.62	0.150	0.030	0.030	0.013	0.01	Balance	5.0	1.0
	9	0.43	0.110	0.035	0.023	0.025	0.03	Balance	4.8	1.5
	10	0.35	0.090	0.028	0.005	0.020	0.02	Balance	18.0	5.6
	11	0.52	0.100	0.011	0.018	0.003	0.03	Balance	5.6	0.6
	12	0.56	0.110	0.022	0.013	0.030	0.03	Balance	8.5	1.7
	13	0.33	0.140	0.031	0.025	0.040	0.04	Balance	5.6	1.2
Comparative	1	0.20	0.070	0.004	0.004	0.004	0.02	Balance	17.5	1.0
Examples	2	0.90	0.012	0.045	0.042	0.041	0.01	Balance	0.3	1.1
	3	0.45	0.010	0.050	0.035	0.029	0.03	Balance	0.3	1.4
	4	0.82	0.300	0.032	0.022	0.040	0.02	Balance	13.6	1.5
	5	0.55	0.130	0.001	0.013	0.009	0.01	Balance	10.0	0.1
	6	0.63	0.250	0.080	0.009	0.012	0.02	Balance	27.8	8.9
	7	0.22	0.005	0.013	0.001	0.021	0.04	Balance	5.0	13.0
	8	1.38	0.018	0.025	0.050	0.035	0.11	Balance	0.4	0.5
	9	0.49	0.190	0.020	0.015	0.001	0.20	Balance	12.7	1.3

TABLE 2

		Manufacturing Step

First Cold

Second Cold

Hot working

Solution Treatment

Working

Aging Treatment

Working

Temperature	Processing	Temperature	Time	Processing	Temperature	Time	Processing
(° C.)	rate (%)	(° C.)	(h)	rate (%)	(° C.)	(h)	rate (%)

Examples	1	990	60	950	2.5	30	550	1.5	15
	2	950	75	900	3.5	45	575	0.5	35
	3	1000	62	1000	4.5	55	525	2.5	40
	4	890	30	1050	5.5	65	600	6.0	75
	5	870	85	1000	1.5	75	510	3.5	65
	6	850	40	980	2.0	85	480	4.5	10
	7	890	55	960	0.5	80	475	5.5	60
	8	900	65	970	4.0	90	455	5.0	55
	9	950	90	930	5.0	70	600	4.0	60
	10	940	70	910	6.0	60	435	3.0	40
	11	960	30	950	3.0	50	400	2.0	20
	12	980	95	960	1.0	40	425	1.0	55
	13	990	45	1010	2.0	65	410	5.0	80
Comparative	1	1000	60	850	5.0	70	350	5.0	10
Examples	2	850	55	1050	2.0	55	450	0.2	5
	3	900	40	950	8.0	60	360	2.0	60
	4	820	15	900	3.0	20	600	5.0	55
	5	950	20	850	4.0	15	550	3.0	40
	6	970	35	900	0.4	70	400	0.3	65
	7	890	80	870	0.1	60	600	2.0	30
	8	990	60	950	2.0	50	700	3.0	75
	9	910	50	970	7.0	90	500	10.0	45

TABLE 3

		Evaluation

Vickers	Electrical	Tensile	Amount
hardness	conductivity	strength	of wear
(Hv)	(% IACS)	(MPa)	(%)

Examples	1	180	75	560	2.2
	2	175	80	550	3.2
	3	182	73	570	1.8
	4	181	72	560	1.1
	5	170	78	530	0.9
	6	171	79	540	2.3
	7	169	79	520	0.5
	8	173	80	530	1.9
	9	155	82	510	3.9
	10	149	85	480	4.5
	11	151	83	490	3.8
	12	163	80	490	2.1
	13	192	71	590	1.4
Comparative	1	127	75	450	6.2
Examples	2	125	80	380	5.0
	3	115	75	310	7.8
	4	120	78	450	7.0
	5	119	70	400	6.9
	6	126	70	390	4.8
	7	100	85	290	9.1
	8	110	87	260	12.0
	9	Less than 90	91	220	13.0

In Comparative Examples 1 to 9, in which the contents of Cr, Zr, Sn, and P were outside the range of the present invention, the amount of wear increased and the wear resistance was insufficient, in all cases.
On the other hand, in the Examples 1 to 13 of the present invention, in which the contents of Cr, Zr, Sn, and P were within the range of the present invention and the Vickers hardness was 130 Hv or higher, the amount of wear was small and the wear resistance was excellent.

Example 2

A copper alloy material with the composition shown in Table 4 was obtained by the same method as in Example 1 described above.
The manufacturing conditions are shown in Table 5.
The Vickers hardness of the obtained copper alloy materials was evaluated at each temperature. The evaluation results are shown in Table 6.

TABLE 4

		Composition

Examples	21	0.46	0.110	0.021	0.009	<0.001	<0.01	Balance	12.2	2.3
Comparative	21	0.75	0.065	<0.001	0.008	<0.001	<0.01	Balance	8.1	—
Examples	22	0.75	0.065	<0.001	0.008	<0.001	<0.01	Balance	8.1	—

TABLE 5

		Manufacturing Step

Solution

First cold

Second cold

Hot working

treatment

working

Aging treatment

working

		Temperature	Processing	Temperature	Time	Processing	Temperature	Time	Processing
		(° C.)	rate (%)	(° C.)	(h)	rate (%)	(° C.)	(h)	rate (%)

Examples	21	980	99	980	1.5	45	485	1.5	13
Comparative	21	980	99	980	1.5	45	485	1.5	—
Examples	22	980	99	980	1.5	45	485	1.5	13

TABLE 6

		Vickers Hardness (Hv)

		20° C.	100° C.	200° C.	300° C.	400° C.	500° C.	600° C.	700° C.

Examples	21	181	175	175	175	175	164	130	106
Comparative	21	120	118	120	120	120	120	89	65
Examples	22	148	146	146	145	147	144	110	85

In Comparative Example 21, in which no Sn was added and no second cold working was carried out, the Vickers hardness at 20° C. was as low as 120 Hv. In addition, the Vickers hardness at 600° C. was 89 Hv and the Vickers hardness at 700° C. was 65 Hv and the Vickers hardness at high temperature was insufficient.
In Comparative Example 22, in which the second cold working (13% processing rate) was carried out without adding Sn, the Vickers hardness at 20° C. was 148 Hv. In addition, the Vickers hardness at 600° C. was 110 Hv, the Vickers hardness at 700° C. was 85 Hv, and the Vickers hardness at high temperatures was insufficient.
In contrast, in Example 21, which was in the composition range of the present invention and was subjected to the second cold working (13% processing rate), the Vickers hardness at 20° C. was extremely high at 181 Hv. In addition, the Vickers hardness at 600° C. was 130 Hv, the Vickers hardness at 700° C. was 106 Hv, and it was possible to sufficiently maintain the Vickers hardness at high temperatures.
For the above reasons, it was confirmed that, according to the Examples, it is possible to provide a copper alloy material which is particularly excellent in wear resistance, which has stable characteristics even at high temperatures, and which is able to lengthen the service life of components formed thereof.

INDUSTRIAL APPLICABILITY

Claims

1. A copper alloy material having a composition comprising:

Cr in a range of 0.3% by mass or more and 0.7% by mass or less;

Zr in a range of 0.025% by mass or more and 0.15% by mass or less;

Sn in a range of 0.005% by mass or more and 0.04% by mass or less;

P in a range of 0.005% by mass or more and 0.03% by mass or less; and

a balance consisting of Cu and inevitable impurities,

wherein a Vickers hardness at 20° C. is 149 Hv or higher.

2. The copper alloy material according to claim 1,

wherein a Zr content [Zr] (% by mass) and a P content [P] (% by mass) have a relationship of

[Zr]/[P]>5.

3. The copper alloy material according to claim 1,

wherein a Sn content [Sn] (% by mass) and a P content [P] (% by mass) have a relationship of

[Sn]/[P]≤5.

4. The copper alloy material according to claim 1, further comprising:

Si in a range of 0.005% by mass or more and 0.03% by mass or less.

5. The copper alloy material according to claim 1,

wherein a total content of Mg, Al, Fe, Ni, Zn, Mn, Co, and Ti is 0.03% by mass or less.

6. The copper alloy material according to claim 1,

wherein an electrical conductivity is 70% IACS or higher.

7. The copper alloy material according to claim 1,

wherein a tensile strength is 470 MPa or higher.

8. A commutator segment made of the copper alloy material according to claim 1.

9. An electrode material made of the copper alloy material according to claim 1.