JPH01225749A - Sintered material for oilless bearing and production thereof - Google Patents

Abstract

PURPOSE:To stably produce a sintered material for oilless bearing having excellent strength, corrosion resistance and wear resistance and small coefficient of friction and good thermal conductivity by compacting and sintering powdery body coating the specific quantity of non-ferrous metal to iron powder and executing sizing to the above. CONSTITUTION:The powdery body coating 18-50wt.% the non-ferrous metal to the iron powder is compacted. The above non-ferrous metal is used with, for example, silver, copper, tin, etc., and it is desirable to coat substantially on the whole circumferential surface of the iron powder with electroplating, etc. Further, in the above green compact, to 100wt. parts of the coated powdery body, 11-240wt. parts of the non-ferrous metal and further, 0.3-4.5% solid lubricating material powder can be added. Successively, the above green compact is sintered and the bearing material composing of 45-82% Fe and the balance the non-ferrous metal and if necessary, containing the solid lubricating material and having good compactibility with 15-28vol.% porocity and bearing to high load without segregation and excellent various characteristic, is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] The present invention relates to a sintered metal bearing and a method for manufacturing the same. It is an object of the present invention to provide a bearing material that has excellent corrosion resistance and wear resistance, accurately prevents segregation, has a small coefficient of friction, and has excellent thermal conductivity, and a method for manufacturing the same.

(Industrial Application Field) Sintered metal bearings and their manufacturing technology suitable for various bearing purposes.

(Prior art) Sintered alloy materials are widely used in oil-impregnated bearings and other products, and the JIS standards for bearings also specify various types of bearings for household electrical equipment, audio equipment, office equipment, agricultural machinery, transportation equipment, etc. regulated, and its composition is pure iron,
Various materials and types are specified, including iron-copper, iron-carbon, iron-copper-carbon, iron-copper-lead, bronze, copper, and lead-bronze.

For example, JP-A No. 56-51554 discloses sintering a green compact using iron powder and brass powder, and the present inventors also published JP-A No. 60-2009.
In Publication No. 27, using iron powder, brass powder and nickel silver powder,
It is proposed to sinter a compacted body made of these mixed powders in a reducing atmosphere.

(Problems to be Solved by the Invention) In the conventional products as described above, although each characteristic can be obtained depending on the component composition, iron powder is used when strength is important for boat fishing. It is essential that However, those using this iron powder have disadvantages such as poor corrosion resistance, high coefficient of friction, and wear on the mating member.

A sintered material using copper powder compensates for the disadvantages of using iron powder, but this copper-based material has disadvantages such as not having sufficient strength and being expensive. There is.

Therefore, in order to harmonize these relationships, the above-mentioned bearing materials use both iron powder and copper powder, or bronze, brass, lead, and nickel silver.
Conventional bearings that use a combination of these types of metal or alloy powders tend to cause segregation during the preparation and handling of raw material powders, and those that use relatively large amounts of iron-based powders tend to suffer from the above-mentioned problems as iron-based bearings. On the other hand, bearings in which a relatively large amount of copper or copper-based alloys are used are expensive and the disadvantages described above in copper-based bearings are unavoidable.

A specific example of such a conventional product is shown in Figure 4, which shows the surface of a powder compact mixed with 30 wt% copper powder, which was observed under a microscope and enlarged. The iron particle (1) and the copper particle (
2) are distributed in a mixed state roughly according to their weight blending ratio, and even though macroscopic observation gives a certain feeling of blended copper powder, microscopically it is clearly iron powder. It is clear that the exposure of That is, even if the copper powder provides a certain degree of corrosion resistance, conformability, or friction coefficient reduction effect, the iron powder portion remains disadvantageous as a conventional sintered material for iron powder bearings.

In addition, in the conventional products as described above, especially those made mainly of iron powder, the compactability to obtain a predetermined shape before sintering is not necessarily favorable, and therefore the compacting pressure must be adjusted to a certain degree. It is necessary to increase the size or add a solid lubricant to ensure smooth compression molding.

If this compression molding pressure is increased, the wear and tear of the compression molding mold will increase at an accelerated rate, making it impossible to obtain sufficient durability.On the other hand, products containing solid lubricants will be inferior in strength. I have no choice but to.

"Structure of the Invention" (Means for Solving the Problems) 1. Iron is made of 45 to 82 wt% of non-ferrous metal, the iron is in the form of granules, and substantially the entire circumferential surface of the granular iron is as described above. A sintered material for an oil-impregnated bearing, characterized in that the sintered material is sintered and bonded to each other while being coated with a non-ferrous metal, and has a porosity of 15 to 28% by volume.

2. 45 to 82 wt% of iron, 0.0% of one or more solid lubricant powders such as graphite or molybdenum disulfide.
The sintered material for oil-impregnated bearings according to the above item, which is formed into a ring shape with a porosity of 15 to 28% by volume, with the remainder being non-ferrous metal at 3 to 4.5 wt%.

3. The sintered material for oil-impregnated bearings according to any one of the preceding item or the item before the previous item, wherein the nonferrous metal is copper or a copper-based alloy.

4. W4 is 18-49.5wt%, tin is 0.5-6wt
% and 45 to 82 wt% of iron, and the iron is in the form of powder and granules, and is sintered with substantially the entire circumferential surface of the granular iron coated with the copper and tin, and the porosity is A sintered material for oil-impregnated bearings, characterized in that the amount of oil is 15 to 28% by volume.

5. Copper is 6-40wt%, zinc is 0.8-14.8w
t% and 50 to 82 ivt% of iron, and the iron is in the form of powder and granules, and is sintered with substantially the entire circumferential surface of the granular iron coated with the copper and zinc. A sintered material for oil-impregnated bearings, characterized in that the ratio is 15 to 28% by volume.

6. Copper: 6-37.5 wt%, zinc: 0.8-14.8
wt%, nickel is 0.8 to 9.0 wt% and 45 to 82
wt% of iron, and the iron is in the form of powder particles, and is sintered with substantially the entire circumferential surface of the powder iron coated with the copper, zinc, and nickel, and the porosity is 15. A sintered material for oil-impregnated bearings, characterized in that the oil content is 25% by volume.

7. A method for producing a sintered material for oil-impregnated bearings, which comprises compacting a powder obtained by coating iron powder with 18 to 50 wt % of a non-ferrous metal, followed by sintering and sizing.

8. Raw material powder made by adding 11 to 240 parts by weight of non-ferrous metal powder to 100 parts by weight of granules in which iron powder is coated with 18 to 50-1% by weight of non-ferrous metal is compacted and then sintered. , a method for producing a sintered material for oil-impregnated bearings, characterized by sizing.

9. In any one of the two preceding paragraphs or the preceding paragraph using raw material powder to which 0.5 to 5% by weight of one or more solid lubricant powders such as graphite, molybdenum disulfide, and lead are added. The method for producing the described sintered material for oil-impregnated bearings.

10. The non-ferrous metal coated on the iron powder is silver, copper, tin, lead, zinc, nickel, aluminum, cobalt, chromium, molybdenum, titanium, manganese, tungsten, and alloys consisting of two or more of these. Sintering for oil-impregnated bearings according to any one of items 7 to 9 above, which is performed by electroplating, hot-dip plating, electroless plating, thermal spraying, or dry plating using an alloy containing phosphorus, sulfur, etc. Manufacturing method of wood.

11. The method for producing a sintered material for oil-impregnated bearings according to the preceding item, wherein the non-ferrous metal coated on the iron powder is brass as an alloy mainly composed of copper and zinc.

12. The method for producing a sintered material for oil-impregnated bearings according to item 10 above, wherein the nonferrous metal coated on the iron powder is bronze as an alloy mainly composed of copper and tin.

13. The method for producing a sintered material for oil-impregnated bearings according to item 10 above, wherein the non-ferrous metal coated on the iron powder is nickel silver as an alloy mainly composed of copper and zinc-nickel.

14. The non-ferrous metal powder that is further added to the iron powder that coats the non-ferrous metal is Agz C11% Sns pb, Zns
Ni, A2, Crs MO% Tts Mns
W, Sb, 8SX 88% 81%
B s In, or alloys thereof, or oxides thereof or P.S. The method for producing a sintered material for oil-impregnated bearings according to any one of items 7 to 13 above, which is a powder that also contains S.

15. The method for producing a sintered material for oil-impregnated bearings according to the above item, wherein the non-ferrous metal powder further added to the iron powder coating the non-ferrous metal is brass powder as an alloy mainly composed of copper and zinc.

16. The method for producing a sintered material for oil-impregnated bearings according to item 14, wherein the non-ferrous metal powder further added to the iron powder coating the non-ferrous metal is bronze powder as an alloy mainly composed of copper and tin.

17. The method for producing a sintered material for oil-impregnated bearings according to item 14 above, wherein the non-ferrous metal powder further added to the iron powder coating the non-ferrous metal is nickel silver powder as an alloy mainly composed of copper and zinc-nickel.

1B, the method for producing a sintered material for oil-impregnated bearings as described in the preceding paragraph using nickel silver powder with Ni content reduced to 3.5 to 8.0%.

19. The sintered material for oil-impregnated bearings according to item 7, wherein a non-ferrous metal oxide powder is further added to the iron powder coated with a non-ferrous metal, and the non-ferrous metal oxide powder is reduced and sintered in a reducing atmosphere. Manufacturing method.

20. The method for producing a sintered material for oil-impregnated bearings according to the above item, wherein the nonferrous metal oxide is lead oxide.

(Function) By using a powder in which iron powder is coated with a non-ferrous metal, the properties such as corrosion resistance and friction coefficient can be obtained in the coating layer of the non-ferrous metal while ensuring the strength and load-bearing properties of the iron powder itself. .

If the amount of non-ferrous metal to be coated is less than 18 wt%, it will be difficult to effectively obtain the above-mentioned properties by the coated non-ferrous metal layer, while on the other hand, if the amount of non-ferrous metal to be coated exceeds 50 wt%, the strength or strength that can be obtained using iron powder as a skeleton will be reduced. It becomes difficult to obtain sufficient load resistance and it becomes expensive.

As mentioned above, iron powder coated with a non-ferrous metal generally has good compactability.

Nonferrous metals that coat iron powder particles include silver, zinc, tin, copper,
May be any of lead, nickel, aluminum, chromium, manganese, molybdenum, tungsten, titanium, etc.
Also, an alloy consisting of two or more of these, or even one containing phosphorus, silicon, etc., can be used.

As mentioned above, copper powder itself has traditionally been used as a sintered metal, and iron powder particles coated with copper or other non-ferrous metals (including their alloys) are used. This results in a material that generally has almost all of the advantages of iron-based sintered metal materials and copper-based sintered metal materials.

Moreover, by employing an alloy of this copper and other metals as an alloy body for coating iron powder grains, it is possible to bring out the respective characteristics more than in the case of the above-mentioned copper itself.

Furthermore, properties can be improved by adding other non-ferrous metals or alloy powders to the above-mentioned iron powder coated with non-ferrous metals such as copper. For example, by adding Sn powder or other nonferrous metal powder to the nonferrous metal-coated iron powder, the coefficient of friction and other properties can be further reduced or improved. In this case, if the amount of non-ferrous metal powder such as Sn powder added is less than 0.5 parts by weight per 100 parts by weight of the above-mentioned non-ferrous metal coated iron powder, the reduction in the coefficient of friction and other improvements in properties due to its addition will be insufficient; Even if it exceeds 67 parts by weight, the effect will be saturated and it will become expensive, which is disadvantageous in terms of cost.

In particular, in the case of Sn powder, it is less than 0.5 parts by weight based on the copper content, and in the case of bronze powder, it varies depending on the Sn content, but if it is less than 10 parts by weight for boat fishing, the friction coefficient decreases due to its addition. It is difficult to obtain effectively, Sn powder is 7 parts by weight, bronze powder is 67 parts by weight.
If the amount exceeds 1 part by weight, the effect will be saturated and the price will increase. Brass powder can increase the strength by using 11 parts by weight or more based on 100 parts by weight of nonferrous metal-coated iron powder, but if it exceeds 67 parts by weight, the effect is saturated and the cost increases. At 11 parts by weight or more, nickel silver powder also increases the strength and has the effect of improving corrosion resistance. On the other hand, at 67 parts by weight or more, the effect is saturated and the low cost properties of iron powder as the main ingredient are lost.

Bearing performance can be significantly improved by using a partially alloyed copper-tin-lead powder as another non-ferrous metal powder added to the iron powder coated with a non-ferrous metal such as copper. In other words, it is known that adding lead to such bearings improves their bearing performance, but if sufficient lead is added using conventional methods, lead oozes out during sintering, making it difficult to produce desirable products. I can't get it. In the present invention, by using the above-mentioned copper-tin-lead partially alloyed powder, the above-mentioned leaching of lead can be eliminated and reduced,
Moreover, since the skeleton is mainly made of iron powder, a bearing body with improved strength and bearing performance can be obtained.

In the present invention, in which copper is used as a coating for iron powder, in order to obtain the above-mentioned lead-containing bearing, an alloy powder of tin and lead is used, and during sintering, the copper coating the iron powder is mixed with the copper that coats the iron powder. Alloying with the alloy powder can be performed. Further, by employing the added lead as lead oxide and sintering it in a reducing atmosphere, the lead oxide can be reduced and contained as lead or its alloy with copper and tin. In any case, it is possible to fully obtain the strength provided by the iron powder and the bearing performance improvement provided by the copper-tin-lead alloy. In addition, the sintering temperature in these cases is 500 to 780°C, and if it is less than 500°C, favorable sintering cannot be obtained, while if it is higher than 780°C, the strength may decrease and dimensional changes in the molded product may increase. Disadvantage is recognized.

Of course, in these cases, the product of the present invention, in which 45% or more is iron powder, can achieve sufficient effects even though the content of lead etc. in the entire product is small, and such an outstanding product can be produced at a low cost. Acquire.

By adding one or more solid lubricant powders such as graphite and molybdenum disulfide, powder compaction can be made easier, and the lubrication performance can be improved and the coefficient of friction can be reduced. In this case, the amount added is 0.5 of the copper-coated iron powder or the raw material powder obtained by adding other metal or alloy powder to it.
If it is 4% or more and less than 0.5%, the effect of addition cannot be obtained appropriately, while if it is added in excess of 5wt%, it is difficult to ensure strength.

In the case of raw material powder containing alloying components such as Zn that vaporize at a temperature lower than the sintering temperature, the compacted powder is placed in a heat-resistant container, covered and sintered in a reducing atmosphere. By doing so, a sintered product can be obtained by appropriately suppressing the diffusion of the above-mentioned components.

By sizing the sintered body, it is made into a product with a predetermined size. That is, it is clear that sintering causes a certain amount of distortion, and this is sized to produce a product with the desired dimensions, and distortions and deformations are corrected. The amount of compression for straightening during this sizing is about 15 to 35% of the volume of the sintered body, and if it is less than 15%, it is difficult to obtain the above straightening effect, and if it is more than 35%, it will be difficult to obtain the straightening effect due to sintering. The painstakingly formed sintered structure will be damaged, and especially when the product is made into an oil-impregnated product such as a bearing body, the oil content will be so small that it will be difficult to obtain the desired lubricity and durability.

(Example) To explain the specific embodiment of the present invention as described above, the present invention uses iron powder coated with non-ferrous metals (including alloys) as described above. The iron powder can be coated with copper to an appropriate degree by appropriately selecting the amount and time of energization using a plating method or the like.

As mentioned above, the coating amount of such non-ferrous metal is 18 to 55% by weight, but a more preferable range is about 25 to 45%, and as described later, non-ferrous metal powder may be added. In this case, even 20% is sufficient. Due to such non-ferrous metal coating, the peripheral surface of the iron powder particles is completely covered with the non-ferrous metal, and a soft layer of non-ferrous metal is formed on the surface of the iron powder particles in an uneven manner. Powder compaction is facilitated.

There are no particular restrictions on the size of the iron powder particles used as the raw material, but the size is about +80 to -320 meso (including less than 320 meso), which is conventionally used for manufacturing pure iron sintered bodies. A further expanded particle range can be employed.

In other words, even relatively fine grains can be increased in diameter by copper coating and can be processed in the same way as those in the conventional - boat fishing range, and as mentioned above, compaction is easier. Even if the particle size is larger than the conventional conventional particle size range, it can be molded equally or more easily by the same powder molding process as the conventional method.

The cross section of a typical non-ferrous metal coating on the surface of a specific iron powder particle is shown in Section 1.2.
As shown in the figure, the surface of the iron powder particles is effectively encapsulated by the copper film, which is at least 85 wt% or more, generally 90 wt%.
% or more are encapsulated, and as shown in FIG. 1, the particle 1 with a nearly spherical cross section becomes a coating 2a with slight irregularities on its circumferential surface, but this coating 2a is made of a non-ferrous metal. Also, due to its fineness, it is advantageous for powder compaction.

It is clear from this photomicrograph that even in the case of iron powder particles 1 as shown in Fig. 2, which are long and have irregularities, the coating 2a with non-ferrous metal such as copper is effective and complete. The iron powder particles are obtained in such a manner that substantially no exposed portions of the iron powder particles remain. In addition, although the amount of copper coating in these Fig. 1.2 is about 30 wt% of the iron powder particles, even if the amount of copper coating is smaller than this, it is encapsulated in the same way, and generally more than 18 wt%. The coating amount can nearly completely cover the surface of the iron powder particles and provide a stable coating, and is preferably 20 wt% or more, more preferably 25 wt% or more.

It goes without saying that the iron powder particles encapsulated with nonferrous metal as described above may be compacted as they are, but in the present invention, the properties of the obtained sintered metal body can be further improved. The addition of non-ferrous metal powder for this purpose is as described above, and in this way even a sintered metal material mainly composed of iron powder particles can be modified by the composite non-ferrous metal.

It goes without saying that the non-ferrous metal powder to be further added may be the same or similar metal or alloy as the non-ferrous metal that encapsulates the iron powder particles as described above, but it may also be a different non-ferrous metal or its alloy. Can be used. In the case of metals or alloys that are the same or similar to the encapsulated nonferrous metal, there is a strong tendency to stabilize the sintered structure, while in the case of different nonferrous metals or alloys, different properties may be imparted. can. For example, copper-based metals are generally lipophilic, while aluminum-based metals are hydrophilic, and they each have different chemical, electrical, mechanical strength, and other physical properties. can be obtained by combining the characteristics of

The powder further added to the non-ferrous metal-coated iron powder in this way may be an oxide of a non-ferrous metal. That is, since sintering is generally performed in a reducing atmosphere, the oxide can be reduced during sintering, and furthermore, it can be alloyed. For example, by adding lead oxide and reducing it during sintering, it can be contained as lead or an alloy thereof, thereby improving bearing performance. Furthermore, by using iron powder as the main component and adding lead in such a manner, it is possible to obtain preferable improvement in bearing performance with a relatively small lead content, or to control lead content leaching during sintering.

In addition, nonferrous metal-coated iron powder tends to shrink during sintering after compaction, whereas a bulking phenomenon is observed when powder compaction and sintering is performed using a mixed powder method. By doing so, it becomes possible to control and moderate expansion and contraction during sintering. In particular, iron powder coated with a non-ferrous metal of 18% or more has a large shrinkage during sintering and can be well balanced with the expansion and expansion of the mixed powder. The iron powder used may be produced by any of the spraying method, reduction method, electrolytic method, carbonyl method, pulverization method, etc. In other words, the specific shape of the iron powder varies depending on the method of producing the iron powder, but in the case of the present invention, in which the iron powder is completely coated with a non-ferrous metal or alloy, the shape of the iron powder is different. Differences and similarities have very little influence on its effects.

The operation of coating the above-mentioned iron powder with a non-ferrous metal or its alloy can be appropriately carried out by methods such as electroplating, hot-dip plating, electroless plating, thermal spraying, and dry plating. In the case of electroplating, the amount of coating or the state of the coating can be appropriately selected depending on the amount of current applied and the time of energization, and in the case of hot-dip plating, it can be selected appropriately by controlling the melting temperature or the preheating temperature of the iron powder. The range can be covered. It is obvious that in other cases as well, any coating state can be formed depending on the processing conditions.

Powder compacting for sintering generally has a porosity of 23 to 38v.
o1%, especially about 26 to 32 o1%, 26v
If it is less than oβ%, especially less than 23vo1%, it is necessary to ensure an appropriate compression allowance for the sizing performed after sintering, and after this sizing, to obtain the desired oil content when used as an oil-impregnated bearing. difficult to obtain.

On the other hand, this porosity exceeds 32vo1%, especially 38vo1%.
A material having a large porosity exceeding voffi% is not preferred because it increases the possibility of partial loss or destruction during handling or sintering after compaction.

In addition, as mentioned above, iron powder encapsulated with non-ferrous metal according to the present invention generally employs iron powder with a coverage ratio of 100 to 300 ml, but in some cases, iron powders with different coverage ratios may be mixed. and can be adopted.

For example, a raw material powder with a copper coverage of 10% and one with a copper coverage of 20% or 30% can be used, and the same applies to other non-ferrous metal coatings.

As mentioned above, the compacted material is generally sintered in a reducing or inert atmosphere. This sintering temperature is generally 700 to 1050°C, but bronze powder, brass powder,
When nickel silver powder, manganese bronze powder, phosphor bronze powder, or the like is also used, it is preferable to set the sintering temperature to be different. For example, if bronze powder is also used, 75
0℃~900℃, 800~9 if brass powder is also used
50℃, 800-950℃ if nickel flour is also used
, 800-950℃ when manganese bronze powder is also used.
When phosphor bronze powder is also used, sintering is performed at 750 to 950°C. When tin powder is also mixed, it is sintered at 700 to 850°C, and when powder containing lead as well as tin is used, it is sintered at 500 to 780°C to form a copper coating on the surface of the iron powder. The Sn or Sn and Pb components are suitably alloyed for the layer.

A sintering temperature below the lower limit of the sintering temperature mentioned above will result in the inability to obtain the desired sintered structure or alloying, while a sintering process at a high temperature exceeding the upper limit is energetically and equipment-efficient. This is disadvantageous and causes fluidization or loss of the thin coating of copper or other non-ferrous metals formed on the surface of the iron powder particles. Note that the sintering time can be suitably carried out within a range of about 30 minutes to 60 minutes.

After sintering as described above, sizing is performed to produce a product with desired dimensions and porosity, and the compression allowance for such sizing is generally 2 times the porosity before sintering.
The porosity of the product obtained after sizing is approximately 0 to 35%, and is 15 to 28%. 15%
If it is less than 28%, it will not be possible to obtain a desirable oil content for use as bearings, while if it is more than 28%, the product will be inferior in strength. A more preferable product porosity is 18 to 24%, which provides appropriate strength, oil content, etc.

The above-mentioned bronze generally contains 5 to 15% Sn and 85% Cu.
-95%, and further contains Zn appropriately, and brass contains Cu: 60-80%, Zn: 20-4
0% and Sn: about 1 to 3%, but depending on the case, the Zn content may be adjusted to about 10% and the Cu content may be adjusted to about 90%. Nickel silver is Z
n: 5.5-32.5% and Ni: 8.5-19.5
% and the balance is Cu, and such nickel white flour may be used as is, but as a preferred nickel white powder, the Ni content is adjusted to be further lower than the above range, and Ni: 35 , ~8.0%. For example, 75% Cu-21% Zn-4% Ni is preferable, and nickel silver powder with Zn and Ni adjusted according to the purpose can also be prepared as appropriate.

In addition to these copper-based alloys, those containing lead, zinc, aluminum, chromium, manganese molybdenum, other non-ferrous metals, or their alloys, as well as P, S, etc. As mentioned above, it is used as a metal or alloy powder to be added to the mechanical, physical, chemical, etc. of the resulting sintered metal material.
It is possible to obtain variously modified and adjusted electrical and other characteristics.

In addition, when using an alloy powder containing a considerable amount of Zn, such as brass powder or nickel silver powder, the Z at the time of sintering is
It is necessary to prevent vaporization and dissipation of n minutes, and for this purpose, sintering by embedding it in the returned powder can be considered, but a more preferable method is to charge the compacted compact into a heat-resistant container and perform the process. Cover and carry out. That is, by doing so, the vapor pressure of vaporized Zn during sintering is increased in the container, and diffusion and penetration into copper and iron are improved, resulting in a product with a small range of physical fluctuation.

By adding tin powder to the copper-coated iron particles and sintering them, the copper-coated layer becomes bronze, and even bearings containing more than 50% iron particles can achieve the same bearing performance as bearings made entirely of bronze powder. obtained, and also has excellent strength. Ni contained in nickel silver has excellent oxidation resistance and alkali resistance, and forms a passive oxide film against external corrosion, which greatly contributes to improving corrosion resistance. As mentioned above, the Zn content also vaporizes and diffuses into the iron particles, thereby providing excellent corrosion resistance. In addition, for example, bronze containing 10% Sn exhibits a liquid phase at a sintering temperature of 850°C, so Cu-Zn-Ni particles and F
e It diffuses into the particles and at the same time exists between the particles to improve the sliding characteristics.

It is natural that solid lubricants such as graphite and molybdenum disulfide are added in the form of powder, but solid lubricants such as graphite have a low specific gravity compared to iron powder, nickel silver powder, and bronze powder. Therefore, even if such graphite is simply mixed, it is difficult to uniformly disperse it in other raw material powders, and furthermore, graphite may be mixed during transportation, transfer to the press hopper, compaction, etc. Segregation occurs due to floating of powder, unevenness, etc. Therefore, it has been confirmed through experiments that it is effective to use a solid lubricant such as graphite that is a relatively coarse powder, and to use one in which the fine powder has been classified and removed. That is, the graphite powder that is generally commercially available has a diameter of 1 to 30 μm, or 1 to 30 μm.
50 μm, whereas graphite as a solid lubricant preferred by the present inventors has a diameter of 10 to 150 μm, particularly 20 to 150 μm.
100μm, coarse powder and 10μm or 2
The fine particles of 0 μm or less are cut, which facilitates uniform dispersion and prevents segregation as much as possible during cargo handling and other handling. 10 as above
Fine particles less than .mu.m or less than 20 .mu.m can be classified appropriately without generating dust by classification treatment in liquid.

A specific manufacturing example of the product according to the present invention, in which a copper coating and a copper-based powder are typically used, is as follows.

Production example 1 Copper plating is applied to iron powder with a particle size of 100 mesh or less, and the energization conditions including the processing time are selected so that the amount of copper coating is 20%.
, three copper coating layers of 30% and 40%, powder Y
# Prepared.

However, these compacted compacts as ring-shaped bearing bodies using only copper-coated iron powder were mixed with 1.8% and 2%.
．． Powder compacts ■~■ made by adding 7% and 3.6% Sn powder, similarly powder compacts ■~■ made by adding 25% bronze powder to these copper-coated iron powders, brass. Powder compacts made by adding 25% of powder @ 1 to 0, compacts made by adding 25% of nickel silver powder ◎～[
phase] was produced.

Three types of these green compacts were prepared, each with a density ratio within the range of 70 to 75%, and the sintering temperature was also varied in steps of 50 °C within the range of 150 to 250 °C. Furthermore, the porosity of the sintered body thus obtained was varied in 2% increments within the range of 18 to 24 von%.

Among the obtained products of the present invention and comparative materials, FIG. 3 shows an enlarged view of the sizing surface of the sintered metal body of the present invention described in (1) above, and shows that some parts of the sintered metal body were enlarged due to the sizing treatment. It is confirmed that even if there are parts of the iron powder particles where the copper coating layer is worn away, at least 90% or more (approximately 98%) of the copper coating layer forms an effective coating state. On the other hand, Fig. 4 is an enlarged view similar to Fig. 3 when 30i% of Cu powder is mixed with iron powder using conventional technology, compacted and sized in the same way. The iron powder is exposed as it is, with copper powder scattered between the iron powder. In other words, the exposed area of the iron powder particles is proportional to the proportion of iron added, and in particular, in the case of the fine uneven particle-like surface texture due to the copper coating as shown in Fig. 3, it is clearly seen in Fig. 1.2. While this is generally recognized as such, such a state cannot be found in the case shown in FIG. As shown in Figure 3, almost all of the surface is coated with copper, and the surface texture, which has a fine uneven structure as shown in Figure 1.2, is estimated to contribute to the accumulation of oil when used as an oil-impregnated bearing. It is clear that it will be done.

However, Table 1 summarizes the manufacturing conditions and characteristic values of the obtained products for these compacted compacts ■ to ■. condition, PV value I Q Q Q kg/c
This figure shows the measurement results obtained when rotation was continued for 40 minutes at nI-m/min.

Some of the details of the results in Table 1 above are shown in Table 2 below for samples 1 to 2.

In addition, the specific data for the items from ■ to ■ in Table 1 are typically as shown in Table 3 below, but the items from ■ to [phase] in Table 1 are also based on the same specific data. This is a summary.

Production Example 2 40 parts by weight of bronze powder containing 9% Sn was blended with 60 parts by weight of iron powder coated with 40 wt% Cu, the same as in Production Example 1 (theoretical component values, Fe: 36 wt%, Cu
: 60.4wt%, Sn: 3.6wt%) with molding density ratios of 65%, 70% and 75%, and the sintering temperature was 80%.
The measurement results for products sintered at 0°C and 850°C are summarized in Table 4 below.

Although the above description is a typical example of copper-coated iron powder, the essence of the present invention is to completely coat iron powder with a non-ferrous metal.
The characteristic of this is that it completely eliminates the corrosion resistance of iron powder and allows the entire amount to achieve corrosion resistance equivalent to that of copper and other non-ferrous metals. It has been confirmed that similar results can be obtained even when coated with a non-ferrous metal. Also A6. Products coated with a material such as Sn can lower the sintering temperature more than Cu, and are also effective in preventing moldability and cracking or chipping during handling, as well as in terms of conformability to the shaft material. Results similar to those obtained using coated iron powder can be obtained.

"Effects of the Invention" As explained above, the present invention is made mainly of iron powder and has appropriate strength, has excellent corrosion resistance and wear resistance, has good conformability to the shaft material, and has a low friction coefficient. Bearing materials with low dimensional stability and favorable characteristics such as thermal conductivity, as well as their formability and low sintering temperature (relatively simple and stable manufacturing method that does not show defects etc.) can be provided. This is an invention with great industrial effects.

[Brief explanation of the drawing]

The drawings show the technical contents of the present invention, and FIGS. 1 and 2 are cross-sectional views of enlarged micrographs of cut surfaces of each example of nonferrous metal-coated iron powder used in the present invention, FIG. 3 is an enlarged plan view of the sintered alloy bearing according to the present invention, and FIG. It is an enlarged sectional view similar to the figure. In these drawings, 1 indicates iron powder particles, 2 indicates copper powder particles, 2a indicates non-ferrous metal coating, and 3 indicates non-ferrous metal fine powder. May 29, 1989 Director General of the Japan Patent Office Yoshi 1) Takeshi Moon 1, Indication of the case 1986 Patent Application No. 48633 2, Name of the invention Oil-impregnated bearing Sintered material for use and its manufacturing method 3. Relationship with the case of the person making the amendment. Patent applicant 4. Contents of the amendment by the agent. , Cu: 85-95%'' is corrected to 'Sn: 5-50%, Cu: 50-95%''. 2. ``Table 1'' on page 34 is corrected as shown in the attached sheet.

Claims (1)

[Scope of Claims] 1. Iron is composed of 45 to 82 wt% of non-ferrous metal, the iron is in the form of powder and granules, and substantially the entire circumferential surface of the granular iron is coated with the above-mentioned non-ferrous metal. A sintered material for an oil-impregnated bearing, characterized in that the sintered material is sintered and bonded to each other and has a porosity of 15 to 28% by volume. 2. 45 to 82 wt% of iron, 0.0% of one or more solid lubricant powders such as graphite or molybdenum disulfide.
2. The sintered material for oil-impregnated bearings according to claim 1, wherein the sintered material is formed into a ring shape with a porosity of 15 to 28% by volume, with the remainder being non-ferrous metal. 3. The sintered material for oil-impregnated bearings according to claim 1 or 2, wherein the nonferrous metal covering the iron powder is copper or a copper-based alloy. 4. Copper 18-49.5wt%, tin 0.5-6wt%
and 45 to 82 wt% of iron, and the iron is in the form of powder and granules, and the granular iron is sintered with substantially the entire circumferential surface covered with the copper and tin, and the porosity is reduced. A sintered material for oil-impregnated bearings, characterized in that the oil content is 15 to 28% by volume. 5. Copper is 6-40wt%, zinc is 0.8-14.8w
t% and 50 to 82 wt% iron, and the iron is in the form of powder and granules, and is sintered with substantially the entire circumferential surface of the granular iron coated with the copper and zinc,
A sintered material for oil-impregnated bearings, characterized in that the porosity is 15 to 28% by volume. 6. Copper: 6-37.5 wt%, zinc: 0.8-14.8
wt%, nickel is 0.8 to 9.0 wt% and 45 to 82
wt% of iron, and the iron is in the form of powder particles, and is sintered with substantially the entire circumferential surface of the powder iron coated with the copper, zinc, and nickel, and the porosity is 15. A sintered material for oil-impregnated bearings, characterized in that the oil-impregnated sintered material has a content of ~28% by volume. 7. A method for producing a sintered material for oil-impregnated bearings, which comprises compacting a powder obtained by coating iron powder with 18 to 50 wt % of a non-ferrous metal, followed by sintering and sizing. 8. Raw material powder made by adding 11 to 240 parts by weight of non-ferrous metal powder to 100 parts by weight of granules in which iron powder is coated with 18 to 50 wt% of non-ferrous metal by weight is compacted, then sintered, and sized. A method for producing a sintered material for oil-impregnated bearings, characterized by: 9. Either one of claims 7 or 8, wherein raw material powder is used, to which 0.3 to 4.5% by weight of one or more solid lubricant powders such as graphite, molybdenum disulfide, and lead are added. A method for producing a sintered material for oil-impregnated bearings as described in . 10. The non-ferrous metal coated on the iron powder is silver, copper, tin, lead, zinc, nickel, aluminum, cobalt, chromium, molybdenum, titanium, manganese, tungsten, and alloys consisting of two or more of these. The sintered material for oil-impregnated bearings according to any one of claims 7 to 9, which is any one of electroplating, hot-dip plating, electroless plating, thermal spraying, and dry plating using an alloy containing phosphorus or sulfur. manufacturing method. 11. The method for producing a sintered material for oil-impregnated bearings according to claim 10, wherein the non-ferrous metal coated on the iron powder is brass as an alloy mainly composed of copper and zinc. 12. The method for producing a sintered material for oil-impregnated bearings according to claim 10, wherein the non-ferrous metal coated on the iron powder is bronze as an alloy mainly composed of copper and tin. 13. The method for producing a sintered material for oil-impregnated bearings according to claim 10, wherein the non-ferrous metal coated on the iron powder is nickel silver as an alloy mainly composed of copper and nickel-zinc. 14. The non-ferrous metal powder added to the iron powder coated with the non-ferrous metal is Ag, Cu, Sn, Pb, Zn, Ni, Al.
, Cr, Mo, Ti, Mn, W, Sb, As, Be, B
i, B, In, their alloys, their oxides, or P. The method for producing a sintered material for oil-impregnated bearings according to any one of claims 7 to 13, wherein the powder also contains S. 15. The method for producing a sintered material for oil-impregnated bearings according to claim 14, wherein the non-ferrous metal powder further added to the iron powder coating the non-ferrous metal is brass powder as an alloy mainly composed of copper and zinc. 16. The method for producing a sintered material for oil-impregnated bearings according to claim 14, wherein the non-ferrous metal powder further added to the iron powder coating the non-ferrous metal is bronze powder as an alloy mainly composed of copper and tin. 17. The method for producing a sintered material for oil-impregnated bearings according to claim 14, wherein the non-ferrous metal powder further added to the iron powder coating the non-ferrous metal is nickel silver powder as an alloy mainly composed of copper and nickel-zinc. 18. The method for producing a sintered material for oil-impregnated bearings according to claim 17, wherein nickel silver powder with Ni content reduced to 3.5 to 8.0% is used. 19. The sintered material for oil-impregnated bearings according to claim 7, wherein a non-ferrous metal oxide powder is further added to the iron powder coated with the non-ferrous metal, and the non-ferrous metal oxide powder is reduced and sintered in a reducing atmosphere. Manufacturing method. 20. The method for producing a sintered material for oil-impregnated bearings according to claim 19, wherein the nonferrous metal oxide is lead oxide.