JPS5844140B2 - Composite sliding material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an Al-8n alloy bearing, and particularly to an Al-8n alloy bearing in which an overlay is applied to the bearing surface layer.

Sliding bearings are required to have surface properties such as foreign matter embedding, conformability to the shaft, and seizure resistance, as well as mechanical properties such as load resistance and fatigue resistance. It is necessary to be present.

Conventional AI-8n alloy bearings, such as A1 alloy bearings with high Sn content (15% or more), have excellent surface performance but poor mechanical properties because a large amount of soft Sn is dispersed.

On the contrary, alloy bearings containing low Sn content, particularly containing 10% or less Sn, have excellent mechanical properties but have the disadvantage of poor surface performance.

In general, high Sn-containing AI alloy bearings have excellent surface performance, but are inferior in mechanical properties, and as the amount of Sn decreases, mechanical properties tend to improve, but conversely, surface performance tends to deteriorate. There is.

As described above, surface performance and mechanical properties have contradictory properties, and it is extremely difficult to solve them all at once.

Therefore, in order to improve the surface performance of low Sn-containing AI alloy bearings, it is common to use an overlay on the bearing surface.

This overlay is typically formed by electroplating an alloy based on a low melting point metal such as PB or Pb-8n alloy.

This type of plain bearing takes advantage of the inherent mechanical properties of the low Sn-containing AI alloy layer, and also utilizes pb or Pb-
8n alloy etc. is overlay plated to improve surface performance.

That is, the surface performance is affected by the overlay, and the low Sn-containing AI
The alloy layer takes on mechanical properties and compensates for the mutually contradictory surface properties and mechanical properties to obtain good bearing performance.

However, forming this overlay by plating can have a remarkable effect if only the surface performance is improved, but the manufacturing process and manufacturing cost are 1. There are many disadvantages from various aspects such as pollution problems and quality control.

In other words, it is disadvantageous in terms of manufacturing process and cost because it requires various electroplating steps, and an expensive plating waste liquid treatment facility is required to prevent pollution.

Furthermore, it is extremely difficult to control the thickness of the plating layer, especially when plating is performed after processing into a semicircular shape, and it is impossible to obtain a uniform plating thickness. Since the balance of thickness was also large, it was extremely difficult to maintain quality within a certain range.

Further, since this overlay is mainly composed of pb or pbSn, it is soft and has poor mechanical properties, and cracks may occur in the overlay during use, and furthermore, there is a risk that it may cause peel-off seizure.

In addition, as another conventional example, Al or AI is applied on the backing steel plate.
There is a multilayer sliding bearing material made by press-welding and/or sintering several layers of alloy powder or mixed powder containing -Pb as a main ingredient and adding various elements in different proportions of the various elements.

However, in this multilayer sliding bearing, since the intermediate layer is formed by pressing and/or sintering alloy powder or mixed powder, its mechanical properties are inferior to that of a cast material, and there are problems in fatigue resistance.

In view of the above-mentioned circumstances, the present invention has been developed without overlay plating with an alloy mainly composed of PB or PB-8N.
In addition, an A1 alloy composite sliding material having a well-balanced surface performance and mechanical properties can be obtained without press-welding and/or sintering multiple layers of powder on a backing steel plate. A cast material of an AI-low Sn alloy having a certain degree of surface performance and mainly mechanical properties is pressed on top as an intermediate layer, and a further surface layer has a certain degree of mechanical properties and mainly has surface properties. Alpb alloy powder and/or mixed powder are bonded together, and the final thickness is set to 5 to 70 μm like a conventional overlay.

The intermediate layer and overlay of the present invention will be explained in detail below.

The intermediate layer of the present invention contains Sn 3.5 to 10% by weight.
%, 0.1 to 9% Cr, a total of 3% or less of one or both of Cu and Mg (excluding O), and the balance essentially consisting of Al-8n alloy. , and P
3% or less in total of one or more of b, Bi, In, Si, Mn, Sb, Ti, Ni, Fe, Zr, Mo,
One or more types of Co0 are added in a total amount of 10% or less as required.

In addition, this intermediate layer requires a certain level of surface performance because, as mentioned above, the overlay is extremely thin at 5 to 70 μm, so if the overlay is worn out, there is a possibility of seizure. To this end, it is desirable to have a certain level of surface performance, that is, to contain 10% or less of Sn.

The intermediate layer of the composite sliding material of the present invention is characterized by the addition of Cr, which reduces the decrease in high-temperature hardness and has excellent mechanical properties such as fatigue resistance, and prevents the coarsening of Sn particles. It can be effective.

Particularly when used in sliding bearings for automobile internal regulation engines, these days, internal combustion engines are required to be smaller and have higher output, and devices for exhaust gas purification are being installed. Since it is used under high temperature conditions, fatigue resistance under high temperatures is particularly required, and in this sense, the addition of Cr has been found to have a significant effect.

The reason for limiting the Sn content to 3.5 to 10% by weight is that Sn is an element added primarily for lubrication, but adding 10% or more improves compatibility and lubricity. However, the hardness decreases and problems arise in mechanical properties such as fatigue resistance, which does not meet the purpose of the present invention.

If it is less than 3.5%, the bearing alloy will have poor surface performance such as conformability, which is necessary when the overlay wears out as described above.

The amount of Sn added within the range of 3.5 to 10% should be determined as appropriate depending on the application, but in general, when the load on the bearing is significant, Sn
It is preferable to reduce the amount of Sn, and increase the amount of Sn when the load is small.

From another point of view, it is preferable to increase the amount of Sn when used in a state where seizure is a concern.

However, recently, bearings have become hot due to high oil temperatures, and this has caused problems such as deformation, seizure, and fatigue of the bearings, so it is also necessary to determine the amount of Sn from the viewpoint of minimizing deformation at high temperatures.

Cr has a particularly high addition effect in that it prevents increase in hardness and softening at high temperatures, and does not cause coarsening of Sn particles even during annealing.

First, let's talk about increasing hardness and preventing softening at high temperatures.
If the amount of Cr added is less than 0.1% by weight, no improvement in high-temperature hardness can be expected, and if it is added more than 7%, Al-Cr intermetallic compounds such as CrAl7 will precipitate too much, making the bearing base metal too hard. If it becomes too thick, the conformability will be extremely reduced, so the amount added is limited to 0.1 to 7%.

To explain this improvement in high-temperature hardness in more detail, Cr increases the recrystallization temperature of Al by solid solution in Al, and the solid solution itself increases the hardness of the AI base. Even by rolling several times, the hardness increases compared to when it is cast.

Increasing the recrystallization temperature is effective in maintaining stable mechanical properties even in the high temperature range to which internal combustion engine bearings are exposed. This can prevent the bearing from softening in this region, which in turn improves fatigue strength.

In addition, the Al-Cr intermetallic compound that precipitates beyond the solid solubility limit has a Vickers hardness of about 370, so the dispersed precipitation of this compound helps maintain high-temperature hardness.
Dispersing this in an appropriate amount produces good effects.

Next, the effect of adding Cr to prevent coarsening of Sn particles will be described.

The coarsening of Sn particles is a phenomenon that occurs when the AI-Sn alloy is exposed to high temperatures, as the A1 grain boundary and Sn particles move, but as mentioned above, Cr
This precipitate is finely dispersed in the A1 metal, so this intermetallic compound directly prevents the movement of the A1 grain boundary and at the same time prevents the growth of the AI crystal grain. This is thought to be because it prevents the movement of Sn particles, that is, the coarsening of Sn particles.

This leads to keeping the Sn particles that have been refined by rolling, annealing, etc. as they are, and has the various effects mentioned above.

Furthermore, the fact that the Sn particles remain fine and exist in the Al base metal is also effective in preventing the elution phenomenon of Sn particles, which have a low melting point of 232°C, at high temperatures. From this point of view, the effect of preventing a decrease in hardness is confirmed.

The above is a description of the effect of inhibiting the coarsening of Sn particles with respect to annealing, but the above effect is also valid even when the use environment of this composite sliding material is at a high temperature comparable to that of annealing. By preventing softening, fatigue strength can be improved.

The purpose of adding one or both of Cu and Mg to an alloy of AI, Sn, and Cr is to strengthen the AI base by solid solution and to reduce the decrease in hardness at high temperatures. If it is added in excess, the increase in hardness due to rolling becomes too large, making it impossible to perform sufficient rolling, making it impossible to obtain a fine Sn structure.

Furthermore, the above-mentioned effects of Cu and Mg occur when they are added simultaneously with Cr, and Cu and Mg alone cannot be expected to have the effect of inhibiting hardness reduction at high temperatures.

That is, if Cr, Cu, and Mg are added at the same time, C
The hardness, which increased during rolling due to the effect of addition of u and Mg, does not decrease much even after annealing due to the effect of addition of Cr, that is, the increase in recrystallization temperature.

This hardness is maintained even at high temperatures, resulting in an alloy with higher high-temperature strength than conventional alloys, which in turn leads to improved fatigue strength.

The purpose of adding one or more of Pb, Bi, and In is to improve the properties of Sn as a lubricating metal, and if it is added in excess of 3%, the melting point becomes too low.

In addition, it is preferable to add Pb, Bi, and In at the same time as Cr, as they can improve the lubricity of Sn and cause less decrease in high-temperature hardness, so they can also be used in sliding bearings that require high fatigue strength. It would be possible to improve not only fatigue resistance but also conformability.

Si, Mn, Sb, Ti, Ni, Fe, Zr, Mo, C
The purpose of adding one or more types of o is to strengthen the AI ingot; if the total addition is less than 1%, the addition effect will not be exhibited, and if it exceeds 10%, the AI ingot will be strengthened. becomes too hard and brittle.

In this way, Al-Sn thread alloys containing one or more of Cr, Ca, and Li in a total of 0.1 to 9% are hard, and their hardness does not decrease particularly at high temperatures, so they have good fatigue resistance and other properties. It is suitable for use as an intermediate layer where mechanical properties are required.

Furthermore, if an Al-Sn alloy containing Cr, Ca, and Li, whose lubricity has been improved by adding Pb, Bi, and In, is applied, it is more suitable as an intermediate layer that requires surface performance such as a certain level of conformability. It is.

Next, the bearing surface layer of the present invention, that is, the overlay will be described in detail.

The overlay of the present invention has a weight percentage of 5 to 40% Pb, Si,
A total of 0.1 to 3% of one or more of Mn, Sb, Cr, Ti, Ni, and Fe; a total of 3% or less of one or two of Cu and Mg (not including 0); and an alloy powder and/or a mixed powder in which the remainder essentially consists of Al, and if necessary, one or two types of Sn.
A total of 0.5-8% seed addition is applied.

The reason why the content of PB was limited to 5 to 40% by weight is as follows.
Pb is added to improve the surface performance, and if it is less than 5%, the effect of Pb will not be exhibited and the surface properties such as conformability will be poor, which is undesirable. If it is added in excess of 40%, it will cause softness. Mechanical properties such as load carrying capacity deteriorate due to the strong influence of PB.

Si, Mn, Sb, Cr, Ti, and Fe are used for the purpose of strengthening the overlay, and one or more of them are used in a total of 0.
Add 1-3%.

If the total amount of one or more types is less than 0.1%, the effect of the addition will not be sufficiently exhibited, and if it is added in excess of 3%, the overlay will become brittle, making it unsuitable.

Cu and Mg are added for the purpose of strengthening the overlay, but if one or both of them are added in a total amount exceeding 3%, the steel becomes too hard (too much) and impairs rollability.

Sn and In are added to improve the corrosion resistance and conformability of PB, and if the total amount of one or both of them is less than 0.5%, the effect of their addition will not be fully exhibited. If it is added in excess of 8%, the melting point of PB will be greatly lowered, and mechanical properties such as load carrying capacity will be lowered.

In addition, in order to improve the surface performance, the amount of Pb in AI is preferably the largest among the additive elements, and in order to bond the overlay and the intermediate layer well, the content of AI should be 55% or more. It is preferable.

Overlay is made by scattering alloy powder and/or mixed powder of the above composition onto a cast material (intermediate layer) of Al-Sn alloy containing one or more of Cr, Ca, and Li, which is pressure-welded to a backing steel plate. , adhere and form using a roll or the like.

Note that during the bonding process, in order to improve the adhesion between the intermediate layer and overlay, pure Al (excluding unavoidable impurities) is placed between the two.
It is effective to interpose a layer because the adhesion is further increased.

Further, when adhering with a roll, the degree of processing of the powder layer is preferably 90% or more, preferably 95% or more, as this ensures adhesion and provides a dense structure.

The overlay thickness is between 5 and 70 μm in final thickness.

The reason for limiting the thickness is that if it is less than 5 μm, foreign matter will not be easily buried, and the hard intermediate layer will have a strong influence, resulting in poor conformability and causing seizure, which is not preferable.

If it is 701 tm or more, the load resistance will decrease, which is not preferable.

The overlay according to the present invention is composed of elements mainly composed of Al-Pb, and the constituent element is pb, which is said to be the most effective for surface performance.The surface performance is comparable to that of conventional overlays. , in terms of mechanical properties, Al is the main constituent element, and Si, M
The powder contains n, Sb, Cr, Ti, Ni, Fe, Cu, and Mg, and the degree of processing of the powder is quite high at over 90%, resulting in a dense structure and less cracking compared to conventional overlays. It is also excellent in that peeling does not easily occur.

As described above, the overlay according to the present invention has surface performance due to the effect of pb and AI, Si, Mn, Sb, Cr, Ti, N
The synergistic effect of improving mechanical properties by adding i, Fe, Cu, and Mg provides a well-balanced surface performance and mechanical properties.

Figure 1 schematically shows the structure of the composite sliding material according to the present invention, in which 1 is a backing steel plate, 2 is an intermediate layer of Al-Sn alloy containing Cr, and 3 is an overlay mainly composed of Al-Pb. It is.

The thicknesses of the backing steel plate 1 and the intermediate layer 2 are set within a wide range depending on the application, and the range of components of the intermediate layer 2 and the overlay 3 is also applied within the above range depending on the application.

The overlay of the composite sliding material according to the present invention has excellent surface performance because it contains PB, which has particularly good lubricity, and has a high degree of processing of 90% or more, resulting in a dense structure that prevents cracking and peeling. is difficult to wake up.

And this overlay is pb or pb, Sn, I
The higher the proportion of n added, the better the surface properties such as conformability, but the worse the mechanical properties such as load carrying capacity.
The thickness of this overlay is thin, and there is an intermediate layer made of an AI-low Sn alloy containing Cr, which has excellent mechanical properties, which affects the fatigue resistance of the material as a whole. The load resistance or seizure resistance is AI-
This is much better than when only a high Sn alloy is laminated and pressure welded to a steel plate.

Furthermore, when comparing a material made of PB plating on an Al-low Sn alloy and the sliding material of the present invention, the PB plating material is slightly better in terms of conformability and low friction, but the material is more durable. The material of the present invention has excellent abrasion resistance, and in particular, when only the surface layer is observed, cracking and peeling are much less likely to occur than the PB plating layer.

That is, the material of the present invention has better fatigue resistance and load resistance, and these properties are maintained even at high temperatures because the intermediate layer contains Cr, Ca, and Li.

Next, a specific method for manufacturing the composite sliding material of the present invention will be explained using materials having the composition shown in FIG. 4. Examples 1 to 9
The Al-8n alloy that will form the middle layer is cast into a slab with a thickness of 15 mm, and the surface of the slab is machined to remove casting defects on the surface.

Next, this slab is rolled with rolls, and the thickness at this time is set so as to satisfy the thickness required when it becomes a sliding material and the following rolling conditions.

In this case, annealing is performed during rolling to improve rolling properties.

Thereafter, the surface of this Al-8n alloy was cleaned by brushing, etc., while the alloy powder and/or mixed powder that was to become the overlay of Examples 1 to 9 was removed from the Al-8n alloy.
Sprayed on 8n alloy and fed to a roll to form Al-8n
The above powder is pressure-welded onto the alloy at room temperature.

At this time, the temperature rises to about 80°C.

It should be noted that as the temperature rises during pressure welding, an oxide film is more likely to form on the AI, making pressure welding more difficult, so when pressure welding is performed in the atmosphere, it is preferable to carry out the temperature below 180''C.

Furthermore, when pressure welding is carried out in a reducing atmosphere, it is recognized that the higher the temperature, the lower the adhesion strength up to a maximum of about 350°C.

Next, the AlSn alloy plate to which the powder has been bonded and a separately prepared steel strip are fed to rolls and pressed together to obtain a trimetal strip, which is then annealed and subjected to the necessary forming processing to achieve the desired purpose. This results in a composite sliding material with the following properties.

The rolling reduction ratio of the overlay is 90% or more, preferably 95% or more.

Then, the overlay is finally formed to a thickness of about 5 to 70 μm in a subsequent molding process of the material obtained by the above-mentioned rolling.

In addition, when cutting is not performed in the forming process, the thickness of the alloy powder and/or mixed powder to be sprinkled is 0.1 to 1.4
It is desirable to set it to m□ in relation to the rolling reduction rate.

That is, in the present invention, powder of 0.1 mm or more is spread and rolled down.

Then, if necessary, cutting is performed leaving a predetermined overlay thickness.

In addition to cold rolled steel plate JIS 5PCC,
Stainless steel or other materials may be used depending on the purpose.

Pretreatment includes degreasing and surface polishing, and nickel plating is applied if necessary.

Note that Comparative Materials 10 to 12 were also produced using the same manufacturing method.

FIG. 2 shows Example 1.3.4 of the present invention by the above manufacturing method.
．． 6.8.9 and comparative material Example 11.12 were representatively subjected to a seizure test.

In this experiment, the shaft rotation speed was 30 Or, p, m, 855C hardened material was used as the shaft material, and the oil temperature was constant (140℃).
Seizure occurs under forced lubrication.

The load measured up to this point is Example 1 of the present invention.
3.4.6 shows a much better seizure load than the comparative material Example 8.9.

Next, FIG. 3 shows the results of a dynamic load bearing fatigue test using representative examples 1.3.4.6.8 of the present invention and example 7.9 of comparative materials.

In this test, the shaft rotation speed was 300 Or, p6m, 855C hardened material was used as the shaft material, and the oil temperature was varied under forced lubrication at a constant oil temperature under the condition of 107 stress repetitions to determine the fatigue state of steel materials. This is a measurement of fatigue resistance surface pressure.

As is clear from this graph, Examples 1.3.4.6.
8 is Example 10.1 of comparative material with a degree of decrease in fatigue resistance surface pressure.
It is recognized that it is not as large as 2 and has excellent fatigue resistance.

As described above, the composite sliding material according to the present invention has A
Since the intermediate layer made of l-8n alloy is bonded with alloy powder and/or mixed powder mainly composed of Alpb, it is easier to manufacture than a material in which pb plating is applied after bonding Al-8n alloy. In terms of its properties, it has excellent effects such as easy manufacturing and quality control, and there is no possibility of causing pollution problems due to plating waste liquid. It is recognized that it has excellent load resistance and fatigue resistance because it is difficult to use.

In addition, compared to multilayer sliding materials in which powder is formed directly on steel plates, the present invention uses a cast Al-Sn alloy as the intermediate layer, which has excellent mechanical properties, resulting in better conformability and lower friction. Not only is there no inferiority, but the fatigue resistance and load resistance are further improved.

Therefore, the material of the present invention has various properties required as a sliding material in a well-balanced manner, and the cost is lower than or equal to the above conventional materials, so it can be used in various sliding applications such as bearings for vehicle engines. It is extremely useful for materials.

The symbols for each element used in the text are as follows.

AI (aluminum), Sn (tin), Cr (chromium), Cu (copper), Mg (magnesium), Pb (lead), Bi (bismuth), I
n (indium), Si (silicon), Mn (manganese), Sb (antimony), Ti (titanium)
, Ni), Fe (iron), Zr (zirconium), Mo (molybdenum), Co (cobalt).

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view schematically showing the structure of a composite sliding material according to the present invention, and FIG. 2 is a graph similarly showing changes in seizure load. FIG. 3 is a graph similarly plotting the change in fatigue resistance surface pressure, and FIG. 4 is a diagram showing the composition of the overlay and intermediate layer of the example.

Claims (1)

[Scope of Claims] 1. A backing steel plate, an intermediate layer made of a cast material of composition A laminated on this backing steel plate, and a surface consisting of an alloy powder and/or mixed powder of composition laminated on this intermediate layer. A composite sliding material comprising: a metal layer, the three metal layers being pressure-welded, and the surface layer having a thickness of 5 to 70 μm. Composition A: Sn 3.5-10%, Cr 0.1-9
%, Cu, and Mg in a total of 3% or less (O
), one or more of P b , B I N I n in a total of 3% or less, Si, Mn, Sb, T
A cast material (wt%) consisting of a total of 10% or less of one or more of Ni, Fe, Zr, Mo, and Co, and the balance essentially consisting of AI. Composition: Pb5-40, Si, Mn, Sb, Cr, Ti
, Ni, and Fe in total of 0.1 to 3
%, Cu, and Mg in a total of 3% or less (O
) and the balance essentially consisting of Al and/or mixed powder (wt%). It is characterized by comprising a surface layer consisting of an alloy powder and/or a mixed powder having a composition laminated on an intermediate layer, these three metal layers are pressure-welded, and the thickness of the surface layer is 5 to 70 μm. Composite sliding material. Composition A: Sn 3.5-10%, Cr 0.1-9
%, Cu, and Mg in a total of 3% or less (0
3% or less in total of one or more of Pb, Bi, In, Si, Mn, Sb, Ti, Ni
, Fe, Zr, Mo, and Co in a total of 10% or less, and the balance essentially consists of Al (weight %). Composition B: Pb5-40, Si, Mn, Sb, C
0 in total of one or more of r, Ti, Ni, and Fe
．． 1 to 3%, a total of 3% or less of one or two of Cu and Mg (not including 0), a total of 0.5 to 8% of one or two of Sn and In, and the remainder being essential. alloy powder and/or mixed powder (wt%) consisting of AI.