JPH06346111A - Sliding material and its production - Google Patents

Abstract

PURPOSE:To produce a sliding member with a bimetal structure excellent in corrosion resistance and small in deteriration in performance by plating the surface of a copper series powder sintered layer formed on a back plate with Zn or Sn and thereafter impregnating resin into the gaps of sintered metal grains. CONSTITUTION:A sintered layer of copper series powder is formed on a back plate 1. After the sintering, the surface of the sintered metal 4 is applied with plating 6 of Zn or Sn, or Zn or Sn series alloy, and, if required, thermal diffusing treatment is furthermore executed to the plating layer 6 and sintered metal 4. After that, resin 9 is impregnated into the gaps of the sintered metal grains 4 of the sintered layer. In this way, the corrosion resistance of the sintered layer to corrosive lubricating oil such as gear oil is improved to obtain the sliding material small in deterioration in bearing performance or the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sliding material and a manufacturing method thereof, and more specifically,
The present invention relates to a sliding material in which a sintered layer of copper-based powder is formed on a back metal, and the sintered layer is impregnated with a resin, and a method for manufacturing the sliding material. Such a sliding material having a bimetal structure in which a resin is impregnated in a sintered layer is mainly used for bearings of automobile manual transmissions and automatic transmissions.

[0002]

2. Description of the Related Art Such sliding materials are disclosed, for example, in Japanese Examined Patent Publication No.
36856, JP-B-63-37445, JP-A-55.
-106230, U.S. Pat. No. 4,208,427, 466.
6787, 5024882, European Patent 044577
The composition of the sliding layer, the manufacturing method, etc.

FIG. 2 is a schematic diagram of a sliding material processed into a bush. In the figure, 1 is a back metal, 2 is a sliding layer which is a composite of resin and lead bronze, 3 is a Sn or Zn plated layer, and 9 is a Is a resin. The plating layer 3 is provided for the purpose of preventing corrosion and improving appearance characteristics. Further, as shown in a partially enlarged view of the sliding layer 2 (FIG. 3), the plating layer 3 does not adhere to the resin 2 but adheres to the lead bronze particles 4.

[0004]

When the bush described above is used in a transmission, the lead bronze is corroded by the gear oil, and a gap is formed at the boundary between the lead bronze particles 4 and the resin layer 2. From this gap, inside the resin layer. Gear oil penetrates to roughen the structure of the sliding layer and swell the surface, resulting in deterioration of bearing performance.

Therefore, an object of the present invention is to provide a sliding material having a bimetal structure in which a resin is impregnated into a sintered layer having an improved corrosion resistance to a corrosive lubricating oil such as gear oil, and a method for producing the same.

[0006]

A sliding material according to the present invention is a sliding material in which a sintered layer of copper-based powder is formed on a backing metal, and a resin is impregnated in the gap between the sintered metal particles of the sintered layer. In the material, the metal particles are characterized in that, at least on the sliding surface side, the surface part thereof is made of Zn or Sn, or is made of a layer containing these metals as a main component and an internal copper-based material. In addition, the method for producing the above sliding material,
In a method for producing a sliding material in which a sintered layer of copper-based powder is formed on a back metal and a resin is impregnated in the sintered layer, Zn metal or Zn-based alloy, Sn metal or Sn-based alloy is plated after sintering. After that, the resin is impregnated with the resin.

The structure of the present invention will be described below. As the copper-based powder, known copper-based materials such as pure copper, bronze, lead bronze and phosphor bronze can be used. Further, as the resin of the resin layer, a fluororesin such as polytetrafluoroethylene,
Known resins used as sliding materials such as phenol resin and polyimide resin can be used.

The Sn or Zn provided on the surface of the sintered metal particles, which is a feature of the present invention, has excellent corrosion resistance to oil and coats copper having a poor corrosion resistance to oil, particularly lead bronze, to prevent the corrosion.

FIG. 1 (a) schematically shows the structure of the sliding layer when the sintered metal particles 4 are one layer. The surface side of the sintered metal particles 4 is Sn / Zn made of Sn, Zn, or an alloy of these.
It is the Zn surface layer 6. FIG. 1B schematically shows the structure of the sliding layer when the sintered metal particles 4 are two layers. The surface side of the upper sintered metal particles 4 is a Sn / Zn surface layer 6. Also, some of the lower layer sintered metal is Sn / Z
n surface layer 6. This surface layer does not slide directly with the mating material, but the material is, for example, (c) -in the bush manufacturing process.
When cut at (c), it appears in the cross section as shown in (c) of FIG. 1 and alleviates the corrosion of the sintered metal, thus contributing to the improvement of corrosion resistance to some extent.

The above-mentioned Sn / Zn layer 6 can be formed by sintering a copper-based powder on a backing metal by a usual method and then performing plating containing Sn, Zn or these components as a main component. After forming the plating layer, impregnate the resin,
Process into product shapes such as bushes. This Sn / Zn layer 6
Is required to be formed so as to leave a gap for resin impregnation, and a preferable plating thickness for this is 5 to 1
It is 0 μm. The Sn / Zn layer 6 contains these elements as main components, and if necessary Cu, Pb, Ni, Bi, Sb
Etc. may be contained.

When the material is cut to form a bush shape, the sintered powder particles are cut, and the core surrounded by the plating layer, that is, the copper-based material is exposed and corrosion due to reaction with oil occurs. Since such a bush has poorer corrosion resistance than the sliding surface side at the cut portion, as a countermeasure against this, a diffusion layer 7 is formed as shown in FIG. 1D by performing a thermal diffusion treatment after plating. Is preferred. If the diffusion is performed at the same time as the baking of the resin, the number of steps can be reduced, so that the temperature is preferably around 400 ° C. When diffusion is performed, the Zn / Sn layer 6 formed on the surface by plating becomes an extremely thin layer, but after diffusion, it is preferable that the Sn / Zn layer 6 be left at least about 0.5 μm in terms of sulfur corrosion resistance. .

[0012]

It is believed that the cause of corrosion of the copper-based powder of the bimetal structure sliding material by the gear oil is the S compound added to the gear oil in order to improve the sliding characteristics. On the other hand, it was examined to change the above-mentioned copper-based powder to another material having excellent corrosion resistance to S, but the present situation is that there is no material having both sinterability, sliding characteristics and corrosion resistance.
Therefore, in the present invention, the surface of the copper-based sintered metal particles is coated with Zn, Sn, or the like, which has high resistance to corrosion by S and excellent adhesion to Cu of the sintered metal.

Further, as a coating method, a plating method excellent in productivity was adopted. However, in the plating method, Zn and Sn can exist only on the surface, and the inside is C
u is the main constituent, and when the material is cut, the Cu-rich surface is exposed and corrosion will occur from the cross section of the bush.
As a countermeasure against this, Zn and Cu are enriched inside the particles by diffusion. Hereinafter, the present invention will be described in detail with reference to examples.

[0014]

[Example] A steel plate (SPC) having a thickness of 1.0 mm as a back metal
C) was used, and 1 to 2 layers of lead bronze (JIS LBC3) powder having a grain size of 80 to 145 mesh were sprinkled on the surface thereof, lightly pressed, and then sintered at 800 ° C. for 13 minutes.

After that, plating was performed in the following Zn plating bath. The composition of the plating bath was 40 g / L of zinc oxide, 73 g / L of soda blue, 12 g / L of caustic soda, and M ratio of 2.2.
7, or zinc cyanide 60 g / L, cyanide soda 23 g /
L, caustic soda 52 g / L, M ratio 2.17. The current density was 2-3 A / dm @ 2 and the bath temperature was 40-50.degree. As a result, a plating layer having a thickness of 5 to 10 μm was formed. Some samples were subjected to diffusion treatment at 400 ° C. for 0.5 hours.

Subsequently, a polytetrafluoroethylene resin was impregnated to a thickness of 20 to 50 μm, baked, and processed into a bush shape to obtain a test piece.

The bimetal material with a back metal prepared as described above was cut into a rectangular sample having a length of 20 × 30 mm,
It was immersed in a commercially available gear oil and the state of CuS formation on the surface was observed. Observed under a microscope of 50 times, those without formation of CuS are good (∘), those with CuS formed up to the bronze layer are bad (×), and the middle of these is shown as pass (Δ) and shown in the following table.

[0018]

[Table 1] Immersion time (hr) 20 40 60 80 No Zn plating (Comparative example) × × × × Zn plating (Example) ○ Δ × × Zn plating + thermal diffusion (Example) ○ ○ ○ ○

From the results shown in Table 1, it is clear that Zn plating and subsequent thermal diffusion are effective in improving corrosion resistance.

Example 2 The Zn-unplated test piece and the Zn-plated + thermal-diffusion test piece prepared in Example 1 were vibrated (30 G, 200 H) while immersed in the gear oil used in Example 1 for up to 200 hours.
After r), it was subjected to the shaft sliding test shown in FIG. In FIG. 4, 10 is a bush, 11 is a shaft that moves in the axial direction, and 12 is a holding ring. Shaft 11
FIG. 5 shows the result of the load when the shaft 11 is moved forward by pushing as a sliding load. From FIG. 5, it can be seen that the sliding load becomes higher as the immersion time becomes longer in the test piece without Zn plating, whereas the sliding load becomes almost constant in the test piece of the present invention.

Further, FIG. 6 shows the result of measuring the inner diameter and the outer diameter of the shaft of the bush-shaped test piece described above and using the difference between them as the oil clearance. From FIG. 6, it can be seen that the oil clearance becomes smaller as the immersion time becomes longer in the test piece without Zn plating, whereas the oil clearance in the test piece of the present invention is almost constant.

[0022]

As described above, according to the present invention, by improving the corrosion resistance of a sintered metal in a bearing having a bimetal structure having a sintered metal impregnated with a resin as a sliding layer,
The sliding characteristics are improved and the oil clearance is kept stable, which contributes to the performance improvement of the transmission and S for improving the sliding characteristics of the gear oil.
The performance of the bearing can be stably maintained even when a large amount of the compound is added. Further, the plating (see 3 in FIG. 2) which has been conventionally performed can be omitted, so that the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic view of a sliding layer of the material of the present invention.

FIG. 2 is a schematic sectional view of a bush.

FIG. 3 is an explanatory diagram of corrosion that occurs in a conventional sliding layer.

FIG. 4 is an explanatory diagram of a shaft load test method.

FIG. 5 is a graph showing the measurement results of sliding load.

FIG. 6 is a graph showing measurement results of oil clearance.

[Explanation of symbols]

 1 Back Metal 2 Sliding Layer 3 Plating Layer 4 Sintered Metal 6 Sn / Zn Layer 9 Resin 10 Bush

Claims (3)

[Claims] 1. A sintered layer of copper-based powder is formed on the back metal,
In a sliding material in which a resin is impregnated in the spaces between the sintered metal particles of the sintered layer, the metal particles are composed of Zn or Sn at the surface portion at least on the sliding surface side, or have these metals as a main component. And a copper-based material inside the sliding material. 2. A method for producing a sliding material, comprising forming a sintered layer of copper-based powder on a backing metal and impregnating a resin into the spaces between the sintered metal particles of the sintered layer, wherein Zn or Sn or Zn is used after sintering. Alternatively, a method for producing a sliding material, which comprises plating an Sn-based alloy and then impregnating the resin. 3. The method for producing a sliding material according to claim 2, wherein the plating layer and the sintered metal are subjected to thermal diffusion treatment after plating.