JP3339780B2 - Sliding material with excellent wear resistance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sliding material having excellent abrasion resistance, and more particularly to a sliding material and a washer used for automobiles, industrial machines, agricultural machines, and the like. The present invention relates to a sliding material which has excellent wear resistance and is effective in severe boundary lubrication.

[0002]

2. Description of the Related Art Conventionally, among sliding materials used as bushes, washers and the like, a sliding material made of a sintered alloy is mainly made of a sintered alloy such as bronze and lead bronze. These alloys have good sliding characteristics under use conditions in which lubricating oil is present, but cause abnormal wear and seizure under boundary lubricating conditions in which lubricating oil is absent or almost absent.

[0003] That is, in a sintered alloy such as lead bronze, Pb having excellent lubricity and conformability is dispersed throughout, so that when used as a bearing material or a sliding material, good lubricity is maintained. You. However, under severe boundary lubrication conditions, there is a problem in wear resistance, and cases of causing abnormal wear are often reported.

[0004] From such a place, in the lead bronze base,
As a hard material, particles of a hard compound (such as Fe ₃ P)
It has been proposed to improve the seizure resistance and wear resistance by interspersing particles of Mo powder, Co powder, and Ni-based alloy powder. (See Japanese Patent Publication No. 57-50844).

[0005] In order to provide both seizure resistance and wear resistance, sliding materials have been proposed in which graphite particles and Ni-B compound particles are added to a copper bronze base. (JP-A-4-
(See JP-A-198440)

However, the particles interposed as a hard material in such a sliding material are mainly compound-based particles such as Fe ₃ P and NiB and have strong crystallinity.
The shape is such that the crushing surface forms an acute angle like a knife edge. For this reason, even when the sliding material is used as a bearing for an automobile or the like, the amount of wear of the bearing itself can be reduced, but the shaft of the partner is rather worn.

[0007] When finishing the sliding surface by working as a bearing, it is usually finished by cutting. However, even in such a case, if it is too hard, cutting cannot be performed even with a carbide cutting tool. For this reason, a diamond tool must be used for cutting, which is a major problem in machining.

That is, in any of the above sliding materials, the powder of the hard substance to be added is hard. In particular,
Whether the powder of the hard material is a compound or Vickers hardness (H
Since it is made of any one of those which show 1000 or more in v), it means that a hard material powder having too high hardness is added. In addition, the powder of such a hard hard material has a weak sinterability with a lead bronze base, and therefore,
The added hard material powder falls off as wear powder and damages the shaft of the other party.

At the same time, when the lubrication condition reaches a boundary lubrication condition for directly contacting the mating shaft, the load on the mating shaft is received by the powder of the hard material. Also at this time, since the sinterability between the hard material powder and the lead bronze base is weak, frictional heat is generated between the counterpart rotating shaft and the hard material powder,
Since the frictional heat is difficult to dissipate, if heat generation is accelerated, seizure will result.

[0010]

DISCLOSURE OF THE INVENTION The present invention aims at solving the above-mentioned drawbacks, and in particular, sintering by adding a hard material powder to a base powder constituting a base made of a lead-bronze-based sintered alloy. A sliding material having a sintered bearing layer formed thereon,
The hard material powder to be added is configured to give appropriate hardness and appropriate sinterability to the base of the lead-bronze sintered alloy, so that even under boundary lubrication, more appropriate wear resistance is obtained. To provide a sliding material that can be used as a bearing.

With such a sliding material, a hard compound powder having an excessive hardness is not added as a hard material powder, and the compounded hard material powder has an appropriate hardness. , Do not hurt the other party's axis.

Further, since the powder of the hard material to be added is an alloy-based powder called a Co-based alloy, as described later, the sinterability with the lead-bronze matrix is good, and the heat transfer of frictional heat is also high. Good, temperature rise on the bearing surface is small.

[0013]

That is, the sliding material according to the present invention is obtained by spraying and sintering a mixed powder of a base powder and a hard material powder on a back metal of a steel plate and on one surface of the back metal. And a sintered bearing layer provided integrally,
The powder of the hard material in the sintered bearing layer is 10
0.5 to 20% by mass as 0% by mass, and the base powder is a lead-bronze alloy comprising 1 to 30% by mass Pb, 1 to 15% by mass Sn and the balance Cu, and the hard material powder is 1% by mass.
6.5 to 18.5 mass% Cr, 27 to 30 mass% Mo,
C consisting of 3.0 to 4.0 mass% Si and the balance Co
It is an o-based alloy.

More specifically, as described above,
Conventionally proposed hard material powders are mainly of compound type, and all have extremely hard hardness.
00 or more, and powder such as Mo or Co
, The hardness is low at about 200 to 500, and an appropriate performance cannot be achieved under boundary lubrication conditions.

[0015] Even with a hard compound-based powder, the particles themselves are:
Since it is obtained as a result of crushing a compound-based ingot, the shape shows a sharp edge shape.

Therefore, in the present invention, a metal alloy powder is selected as a hard material powder which does not damage the shaft of the counterpart, has an appropriate shape and hardness with respect to the shaft, and has excellent wear resistance.

At the same time, in order to prevent the temperature of the bearing surface from rising and to enhance the heat dissipation as a hard material powder, consideration was given to the sinterability of the lead bronze base.

As a result, the hard material powder to be added is not constituted as a compound-based powder, but is constituted as an alloy-based powder. An alloy of this composition is Co-Mo-C
r-based alloys, in particular, 16.5 to 18.5 mass% Cr,
An alloy consisting of 27 to 30% by mass Mo, 3.0 to 4.0% by mass Si, and the balance Co. Incidentally, 17.5% by mass Cr,
An alloy consisting of 28% by weight Mo, 3.4% by weight Si and the balance Co has been found to be suitable. In the following, mass% is simply shown as%.

Further, the shape of the powder of the alloy-based hard material is a rounded shape, and it is extremely appropriate to manufacture the powder having such a shape by an atomizing method.

By the way, 28% Mo-17.5% Cr-
When it is a Co-based alloy powder of 3.4% Si-balance Co,
The hardness is 800 in Hv (Vickers hardness), and the above conditions such as hardness and sinterability can be satisfied.

Therefore, 23% Pb-2% Sn-balance C
In a base powder composed of a lead-bronze alloy of u, a powder of a hard material having a hardness of up to Hv (Vickers hardness) of 1350 is blended in the same ratio to prepare a sliding material composed of a sintered bearing layer. For the sliding material, the relationship between the hardness Hv of the powder of the hard material and the wear amount (μm) of the mating shaft was determined.
The result shown in FIG.

The conditions of the abrasion test are shown in Table 1. As a hard powder, the hardness of the compound powder of the conventional example is 1000 or more. As the material, a compound-based powder was used. Those with a hardness of Hv 1000 or less are Cr-Mo-S
i-Co based alloy powder, Hv 500 or less is Mo
A simple powder such as Co or Co was used.

In FIG. 5, the abscissa indicates the hardness of the powder of the hard material added, the ordinate indicates the wear amount of the bearing and the shaft, and the line (a) indicates the powder hardness of the hard material in the sintered bearing layer. The line (b) shows the relationship between the powder hardness of the hard material and the amount of wear on the counterpart shaft. Note that the hardness of the shaft of the other party is in a region indicated by (c) in FIG.

In FIG. 5, when an abrasion test is performed under the test conditions shown in Table 1, when 5% of a powder of a compound-based hard material exceeding Hv1000 is added, as is clear from the transition shown by the line (b), A long-term wear test with a test time of 100 hours showed that the mating shaft was considerably worn, and that the amount of wear increased rapidly, especially at a hardness (Hv) of 850.

On the other hand, in the sintered bearing layer of the sliding material, as the hardness of the powder of the hard material increases, the wear amount decreases with the increase in the hardness of the hard material powder, as is apparent from the transition shown by the line (a). are doing.

As a result of the examination, it is found that the bearing is hardly worn, and that the other shaft is not worn.
That is, in order to balance the mutually incompatible conditions, it is effective and appropriate that the hardness of the hard material powder is about 750 to 850 in Hv.

In addition to the above conditions, the powder of the hard material is sintered with the lead bronze base, which contains Pb, with the balance being Cu-Sn. It is necessary to improve the nature.

That is, FIGS. 3 and 4 show that compound-based hard particles are blended as the hard particles, and it can be seen from this that the sinterability is poor and there is a problem in heat dissipation. That is, in FIGS. 3 and 4,
Reference numeral 1 denotes a shaft of the other party, 2 denotes a powder of a hard material, 3 denotes a Pb phase, 4 denotes a matrix, 5 denotes a steel backing, and 6 denotes a heat flow. Hard material powder 2
When the sinterability between the base material 4 and the base material 4 is poor, the hard material powder 2 is surrounded by the low melting point Pb phase 3, and the hard material powder 2 is melted or melted by the Pb phase 3. It becomes like floating in a softened pool.

In this state, the heat flow 6 of the frictional heat generated between the mating shaft 1 and the hard powder 2 must be radiated into the matrix 4 via the Pb phase 3.

In particular, the thermal conductivity of the Pb phase 3 is as poor as 1/10 or less of that of the Cu base. Thus, this poor heat conduction becomes a barrier and heat dissipation is greatly reduced.

Incidentally, the thermal conductivity of Pb phase 3 is 0.08
2 cal / cm · deg · sec, C in base 4
u has a thermal conductivity of 0.94 cal / cm · deg · sec
It is.

On the other hand, as in the present invention, a powder of a Cr—Mo—Si—Co alloy is blended as the hard powder 2 in the matrix 4, and the hard powder 2 is sufficiently mixed with the matrix 4. 1 and FIG. 2. 1 and 2 are the same as those in FIG.
4 and those equivalent to FIG.

In this case, since the hard powder 2 is sufficiently sintered with respect to the matrix 4, the presence of the Pb phase 3 around the particles of each powder 2 is small, and The heat flow 6 is smoothly dissipated to the base 4 and the back metal 5 to suppress a rise in surface temperature.

In particular, under boundary lubrication, this property is extremely important, and when the lubricating oil is poor or the viscosity of the lubricating oil is low, the calorific value between the hard material powder and the counterpart shaft also increases, Dissipation of heat by lubricating oil cannot be expected.
Therefore, heat dissipation to the base is important.

In addition, when the bearing has good heat dissipation, the wear on the surface of the Pb phase is reduced and a stable lubricating state can be maintained.

That is, the matrix, the particles of the hard material powder, and the sinterability have a close relationship from the viewpoint of heat dissipation. Here, the sinterability of the hard particles to the matrix can be confirmed by performing a cavitation test.

As described above, the hard material powder to be added must satisfy the following conditions. (1) that the hardness of the hard material powder is about 750 to 850 in Hv, (2) that the sinterability with the matrix is good,
(3) In addition, it is preferable that the shape of the hard material powder be rounded.

In addition, as a hard material powder satisfying these conditions, a Co-based alloy, in particular, Co-M
o-Cr-Si based alloy, especially 16.5 to 18.5%
A hard powder composed of Cr, 27 to 30% Mo, 3.0 to 4.0% Si, and the balance Co is suitable.

As described above, the hard material powder is preferably adjusted to have a spherical shape, a shape close to a spherical shape, and a partially round shape, but the particle size of the powder is adjusted to 100 μm or less. Is preferred. With this particle size, 1
Compared with those having a particle size of 00 μm or more, the dispersibility is improved, and at least the amount of addition can further improve the abrasion resistance.

Next, the reasons for limiting the content of each component element will be described separately for the base powder constituting the base of the sintered bearing layer and the powder of the hard material mixed with this base powder.
It is as follows.

1. The base powder is a powder of a lead bronze alloy, and the composition of the alloy contains 1 to 30% Pb and 1 to 15% Sn, and the balance is Cu.
Consists of Pb (1 to 30%) Pb is a soft component and contributes to lubricity. In particular, in the case of boundary lubrication where almost no lubricating oil is present, by increasing the Pb phase in the matrix of the sintered bearing layer The amount of wear can be reduced. However, if the content of Pb is less than 1%, there is no effect of the addition. If the content of Pb exceeds 30%, the alloy strength decreases, and if the content of Pb is too large, it melts during sliding,
As described above, there is a possibility that a pool of the Pb phase is generated,
For this reason, 30% or less is preferable. Sn (1 to 15%) Sn alloys with Cu to increase the matrix strength of the sintered bearing layer. If Sn is less than 1%, the effect is small. If Sn exceeds 15%, a Cu—Sn compound is generated and becomes brittle. In addition, this compound shows the same behavior as when a very hard hard material powder is compounded in a matrix. , Sn 15% or less.

[0042] 2. Hard material powder (0.5 to 20% is mixed with 100% of the mixed powder constituting the sintered bearing layer), and the hard material powder is Co-Mn-
Cr-based Co-based alloy powder, which is a Co-based alloy containing Cr, Mo and Si. (See paragraphs [0012] and [0018]) In each particle of this powder, C
o Cr in the base, Mo, Si and some C in the Co base
o is precipitated as a hard phase, that is, a precipitated hard phase, and the hardness (Hv) of the hard phase is about 1100.
Since the hard material powder is an alloy in which a hard phase having a hardness (Hv) of about 1000 is precipitated, the hardness (Hv) of the hard material powder is about 800, as described above, (See paragraph [0020].) Gives appropriate hardness and also good sinterability. Cr (16.5 to 18.5%) Cr has a first solid hardness (Hv) of 1000 in a Co matrix.
It is a component that produces a hard phase of a certain degree. However, when the amount of Cr is too large, when the amount of the hard precipitated hard phase increases, the hardness of the powder of the hard material becomes too hard. From this point, in order to keep the hardness (Hv) of the hard material powder at 750 to 850,
From a balance with other components, 16.5 to 18.5% is appropriate. If the powder of the hardened material is mixed up to 20% with the whole powder of the sintered bearing layer being 100%, it becomes too hard as a sliding material, which is not preferable. Mo (27 to 30%) Mo has a solid hardness (Hv) of 1 together with Cr and Co.
Approximately 000 hard phases are generated, and also contribute to the improvement of the base hardness of the lead-bronze alloy base of the sintered bearing layer, and the sinterability with this lead-bronze alloy base is improved. For this reason, from the viewpoint of balance with other components, appropriate hardness and sinterability, etc.,
7-30% is preferred. Si (3.0-4.0%) Si is used as a flux when melting a Co alloy,
It is absolutely necessary to prevent oxidation of Co during melting at a high temperature (1900 ° C. to 2000 ° C.). Therefore, C
When smelting an o-alloy, Si inevitably penetrates, and in a Co alloy, some infiltration of Si is inevitable. On the other hand, although Si is known as a hardening component, the degree of hardening by a single phase of Si alone is slightly lower than that by the precipitation of a hard phase having a hardness of about 1000 together with the above-mentioned Cr, Mo and Co. However, when Si is introduced, Si contributes to sinterability. In this regard, Si 3.0 to 3.0
In the range of 4.0%, a compound with Co is not formed, and the hardness (Hv) is suitable to be kept in a range of 750 to 850,
If the smelting is such that the mixing of Si is within the range of 3.0 to 4.0%, the smelting of the Co alloy can be performed without any trouble. Co balance Co is extremely expensive compared to other components, and it is desirable that Co be as small as possible. However, as mentioned earlier, C
From the viewpoint that r and Mo form a precipitated hard phase having a hardness (Hv) of about 1000 on the Co base to give wear resistance and also provide good sinterability, it is preferable to use a Co base component.

The powder of the hard material having the composition as described above is 100% of the entire powder constituting the sintered bearing layer.
0.5 to 20%.

That is, the effect of the hard powder is less than 0.5% when the addition is less than 0.5%. If it exceeds 20%, the particles of the hard material will be present in the matrix in a linked manner, impairing the sinterability of the matrix itself. The hardness is too hard.

It is necessary that the particle size of the powder of the hard material be 50 μm or less.

That is, the finish workability and performance of the bearing surface as a sliding material depend on the particle size of the hard material powder.
For example, even if the addition amount of the hard material is the same, the coarse particles (15
0-50 μm), compared with those of fine particles, especially 50 μm
In the following, even if the material is hard, the amount of shaft wear is reduced, and the dispersibility of the powder of the hard material is further improved. As a result, the improvement in the dispersibility leads to the improvement in wear resistance.

To explain this point in more detail, when the particle diameter of the hard material powder is coarse, the surface roughness (Ra) is inevitably 1 in the inner surface finishing of the bearing layer (that is, ordinary machining). 0.0 to 1.2 μm. On the other hand, in the case of fine grains (50 μm or less), the surface roughness (Ra) is 0.5 to 0.3 μm, and the smoothness is greatly improved.

Referring to enlarged photographs of the surface of the bearing layer shown in FIGS. 6 and 7, when the hard material powder is coarse (see FIG. 6), the base material and the added hard material powder particles are mixed. There is a gap between them, and further, there is evidence that the hard material particles have been deformed during cutting of the cutting tool by machining. On the other hand, when fine-grained hardened material powder is added, the hard material powder is densely buried in the matrix, resulting in an effective finished state and an extremely smooth bearing surface.

[0049]

First, as shown in Table 2, sliding material Nos.
1 to No. 12 were prepared. Each sliding material is mixed with 2.5 to 10% of a hard material powder in a base powder forming a base and mixed so as to make a total of 100%, and the mixed powder having a predetermined thickness is formed on a steel plate forming a backing metal. I sprayed it.

It is heated in a hydrogen atmosphere at a temperature of 700-900.
C. for 10 to 30 minutes.

In the powder of the hard material shown in Table 2,
Sliding material No. The hard material powders of 1 to 6 are all C
o-based powder, the composition of which is 28% Mo-17.5%
Each of these components precipitates a hard phase in the Co matrix and has a particle size of 50 μm or less. In addition, the sliding material No. 7 to 12 show comparative examples, and sliding material Nos. 7 and 10 are compounded with Ni-B compound powder as a hard material powder,
o. Nos. 8 and 11 are compounded with a compound powder of Fe ₃ P as a hard material powder. Nos. 9 and 12 do not contain a hard powder.

Each of the sintered bodies obtained by sintering is subjected to rolling, re-sintering and rolling,
Sliding material No. 1-12 were obtained.

In these treatments, rolling is roll rolling, and the density was increased to 100%. Resintering is 700
This was performed at a temperature of 〜900 ° C. to make a stronger base.

The thickness of each sliding member obtained in this manner is 2.20 mm. In order to investigate the friction and wear characteristics using these materials, the sliding member having an inner diameter of 20 mm, a length of 20 mm and a thickness of 2.0 mm was used. A bush was made and tested for wear.

The test conditions for this wear test are as shown in Table 3.

In this wear test, light oil was used as a lubricating oil, and under the test conditions close to boundary lubrication, the amount of wear of the bearing, the amount of wear of the mating shaft, and the back surface temperature of the bearing were measured. Table 2 shows the measurement results.

Each of the sliding materials No. using Co-based alloy powder as the hard material powder was used. 1 to 6 (according to the present invention)
Shows that the wear of the mating shaft is low, the wear of the bearing layer is as low as 1.0 to 3.7 μm, and the back surface temperature is 60 to 75 ° C. regardless of the composition of the matrix. No. As compared with 7 to 12, the heat dissipation was good and excellent results were shown.

Further, although not shown in Table 2, in the Co-based alloy powder, which is a hard material powder, 8% Cr and S
i was reduced to 2.5%, and these powders were added and blended. With this sliding material, the amount of wear on the bearing side is 1.0 to
The back surface temperature was further increased by at most 12 ° C. by 2.0 μm.

Looking at the matrix, the matrix having a larger Pb phase has a smaller amount of wear, and the sliding material No. as a comparative example. In Nos. 7 and 8, although the Pb phase in the matrix was increased, the sliding material No. of the present invention having a small Pb phase was used. As compared with No. 5, the amount of bearing wear was large, and it can be seen that the one according to the present invention was excellent.

As described above, the sliding material according to the present invention has extremely small shaft wear as compared with the comparative example, exhibits excellent wear resistance even under more severe boundary lubrication, and can provide a sliding member. I can do it.

[0061]

[Table 1]

[0062]

[Table 2]

[0063]

[Table 3]

[0064]

As described above, according to the present invention, the sintered bearing layer integrally provided on the steel sheet back metal has a hard powdery material in the matrix.
A sliding material obtained by dispersing and sintering 5 to 20%, and the powder of the hard material is 16.5 to 18.5% Cr, 27 to 3%.
It contains 0% Mo, 3.0 to 4.0% Si, and the balance is made of Cu.

Therefore, even under severe boundary lubrication conditions, excellent wear resistance is exhibited and the amount of wear of the mating shaft can be significantly reduced.

Even if a large amount of frictional heat is generated during boundary lubrication, since the hard material powder is composed of the above-mentioned composition and each component is precipitated in the Co matrix, the hard bearing powder is not formed in the matrix of the sintered bearing layer. The powder of the hard material is uniformly dispersed and the sinterability is extremely good, and the heat dissipation can be promoted by utilizing the fact that the matrix mainly consists of Cu.

Further, when the particle size of the hard material powder is 50 μm or less, the dispersibility of the powder is enhanced, and the wear resistance is further improved.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a structure of a sliding material according to one embodiment of the present invention.

FIG. 2 is an explanatory view showing a heat dissipation mode of the sliding material shown in FIG.

FIG. 3 is an explanatory view showing the structure of one sliding material of a comparative example.

FIG. 4 is an explanatory view showing a heat dissipation mode of the sliding material shown in FIG. 3;

FIG. 5 is a graph showing the relationship between the hardness of the powder of the hard material to be added and the wear amount of the sliding material.

FIG. 6 is a micrograph showing a metal structure of a bearing layer when a hard powder having a diameter of 100 to 150 μm is compounded.

FIG. 7 is a micrograph showing a metal structure of a bearing layer when a hard powder having a diameter of 50 μm or less is compounded.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Counterpart shaft 2 Hard material powder 3 Pb phase 4 Base 5 Back metal 6 Heat flow

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) C22C 1/00-49/14 B22F 7/00 F16C 33/12

Claims (5)

(57) [Claims] 1. A sliding material comprising: a back metal of a steel plate; and a sintered bearing layer provided by integrally spraying and sintering a mixed powder of a base powder and a hard material powder on one surface of the back metal. In the sintered bearing layer, the powder of the hard material contains 0.5 to 20% by mass based on 100% by mass of the whole mixed powder, and the base powder has 1 to 30% by mass Pb and 1 to 15% by mass. % Sn and the balance Cu, which is a lead bronze alloy,
The powder of the hard material is 16.5 to 18.5 mass% Cr, 2
A sliding material having excellent wear resistance, which is a Co-based alloy comprising 7 to 30% by mass Mo, 3.0 to 4.0% by mass Si, and the balance Co. 2. The method according to claim 1, wherein the powder of the hard material has a Vickers hardness (H
2. The method according to claim 1, wherein v) is 750 to 850.
A sliding material with excellent wear resistance as described. 3. The wear-resistant powder according to claim 1, wherein the hard material powder comprises a Co base and a precipitated hard phase of Cr, Mo, Si and Co precipitated in the Co base. Sliding material with excellent properties. 4. The sliding material according to claim 1, wherein the hard material powder has a rounded shape. 5. The sliding material according to claim 1, wherein the hard material powder is adjusted to a particle size of 50 μm or less.