JPH068473B2 - Sliding member - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sliding member composed of a first member and a second member that abut against each other and slide relative to each other, and more specifically, to the sliding member. The member of No. 2 is made of a fiber-reinforced metal composite material, and the second member is made of steel.

2. Description of the Related Art In order to improve the wear resistance and seizure resistance of a fiber-reinforced metal composite material, the applicant of the present application has disclosed in Japanese Patent Application No. 61-61798 filed by the same applicant as the applicant of the present application. A specific surface of a fiber-reinforced metal composite material having an inorganic fiber as a reinforcing fiber and an aluminum alloy or a magnesium alloy as a matrix is formed by electrolytic etching, and a part of the reinforcing fiber is exposed at the specific surface. , Having concave portions on the surface of the matrix between the reinforcing fibers exposed on the specific surface, the average depth of the concave portions is 1.5 μm or more, and the average ratio of the depth to the opening diameter of the concave portions. A fiber-reinforced metal composite material having a value of 0.01 or more was proposed.

Problems to be Solved by the Invention Although the above-mentioned composite material is excellent in wear resistance and seizure resistance, the above-mentioned one member of the sliding member consisting of two members that abut against each other and slide relative to each other. When the above composite material is applied, the amount of wear of one member or the other member may increase depending on the material of the other member.

The inventors of the present application are a sliding member composed of a first member and a second member that abut against each other and relatively slide, and the first member is made of the composite material as described above, In the case where the second member is made of steel, in order to reduce the amount of wear of these two members and prevent seizure, the composite material and the second member that form the first member are formed. As a result of various experimental studies on what properties of the steel to be used are appropriate, the area ratio of the recesses of the composite material is set within a certain range and the second member is It has been found that it is preferred that the steel making up the has a certain range of hardness.

The present invention is based on the knowledge obtained as a result of various experimental studies conducted by the inventors of the present application, and is a sliding member including a first member and a second member that abut against each other and relatively slide. The first member is composed of a fiber-reinforced metal composite material having reinforcing fibers exposed on the sliding surface and having recesses on the surface of the matrix of the sliding surface, and the second member is composed of steel. It is an object of the present invention to provide a sliding member having excellent wear resistance and seizure resistance of both these members.

Means for Solving the Problems According to the present invention, the object as described above is made into a sliding member by a first member and a second member which are in contact with each other and relatively slide, At least the sliding surface portion of the one member with respect to the second member is composed of a fiber-reinforced metal composite material having an inorganic fiber as a reinforcing fiber and an aluminum alloy or magnesium alloy as a matrix, and the sliding surface is electrolytically etched. A part of the reinforcing fibers is exposed to the sliding, and recesses are formed on the surface of the matox between the reinforcing fibers exposed to the sliding surface, and the average depth of the recesses is 1. 5 μm or more, the average value of the ratio of the depth to the opening diameter of the recess is 0.01 or more, the area ratio of the recess is 5 to 40%, at least the first member of the second member. Sliding against members Surface is achieved by sliding member characterized by hardness Hv (10 kg) is composed of steel is 400 to 900.

According to the present invention, the sliding surface of the composite material is electrolytically etched so that a part of the reinforcing fibers is exposed to the sliding surface, and between the reinforcing fibers exposed to the sliding surface. A recess is formed on the surface of the mattox, the average depth of the recess is 1.5 μm or more, and the average ratio of the depth of the recess to the opening diameter is 0.
The sliding surface portion of the first member is made of a fiber-reinforced metal composite material having a concave area ratio of 5 to 40%, and the matrix is formed by the reinforcing fibers exposed on the sliding surface. Not only the degree of direct contact with the second member is reduced, but also the above-mentioned recesses having the preferable depth, shape, and area ratio work well as oil reservoirs to ensure good oil retention of the composite material. In addition, the state in which the reinforcing fibers are firmly held by the matrix is ensured, and the sliding surface portion of the second member is made of steel excellent in sliding characteristics against the composite material even if the hardness Hv is 400 to 900. Therefore, as is clear from the results of the experimental research conducted by the inventors of the present application, which will be described later, it is possible to obtain a sliding member composed of a combination of two members having excellent wear resistance and seizure resistance. it can

Also, since it is not necessary to plate or spray a material having excellent wear resistance on the sliding surface of the second member,
As compared with the case where the sliding surface portion of the second member is plated or sprayed, it is possible to obtain an inexpensive sliding member.

Further, in order to sufficiently improve the abrasion resistance of the composite material when the concave portion acting as an oil reservoir is not formed on the surface of the matrix, the exposed height of the reinforcing fiber is set to, for example, 10
It must be set to a relatively large value, such as -30 μm, and therefore the aggression of the composite material to the mating material increases and the risk of abnormal wear due to the falling of the reinforcing fibers increases, resulting in While the amount of wear of both composite materials is increased, according to the present invention, since the concave portion that works well as an oil reservoir is formed on the surface of the matrix, the exposed height of the reinforcing fiber is reduced to, for example, 1 μm or less. Therefore, it is possible to reduce the aggressiveness to the mating material and the risk of abnormal wear, which also reduces the wear amount of the two members.

According to the results of the experimental research conducted by the inventors of the present application, when the area ratio of the recesses, that is, the ratio of the total opening area of the recesses to the total area of any region of the sliding surface of the composite material is less than 5%. Cannot retain a sufficient amount of lubricating oil on the surface of the composite material, and when the area ratio of the recesses exceeds 40%, the amount of lubricating oil retained in the recesses becomes rather small, and the surface of the composite material The strength of the matrix that holds the exposed reinforcing fibers is reduced, so that the reinforcing fibers are more likely to fall off and the amount of abrasion of the composite material increases. Therefore, in the sliding member of the present invention, the area ratio of the recess is set to 5 to 40%.

According to the results of the experimental research conducted by the inventors of the present application,
If the average value of the exposed height of the reinforcing fibers on a specific surface of the composite material exceeds 1 μ, the amount of wear increases rather than the opponent material is excessively abraded by the reinforcing fibers exposed from the surface of the composite material. In addition, abnormal wear due to the falling of the reinforcing fibers is likely to occur. Therefore, according to one detailed feature of the present invention, the average value of the exposed height of the reinforcing fibers on the sliding surface of the composite material constituting the first member is set to 1 μm or less.

In one embodiment of the present invention, the sliding member of the present invention is an internal combustion engine, the first member is a cylinder liner,
The second member is the piston ring.

The reinforcing fiber in the fiber-reinforced metal composite material of the present invention is
It may be any inorganic fiber such as ceramic fiber such as alumina fiber and alumina-silica fiber, carbon fiber, various metal fibers, and may be either long fiber or short fiber. Further, the average fiber diameter of the reinforcing fibers is 100 μ or less, particularly 1
The volume ratio of the reinforcing fibers is preferably 30% or less, and particularly preferably 3 to 15%. Furthermore, the orientation of the reinforcing fibers may be any orientation such as unidirectional orientation, two-dimensional random orientation, and three-dimensional random orientation, but in the case of unidirectional orientation and two-dimensional random orientation, the sliding surface is unidirectionally oriented. It is preferable that the direction is set to be perpendicular to or as close to the two-dimensional random orientation plane as possible.

Further, the aluminum alloy and the magnesium alloy may be of any composition as long as they can be electrolytically etched, but in particular, like an aluminum alloy containing silicon,
It is preferably an aluminum alloy or a magnesium alloy which itself has excellent wear resistance.

Further, the electrolytic solution for electrolytic etching in the present invention may be an aqueous nitric acid solution or an aqueous sodium chloride solution, and when an aqueous nitric acid solution is used, its concentration, potential difference and energization amount are 80 to 160 ml / l and 4.5, respectively. ~ 6.0V, 200 ~
It is preferably set to 450 coulomb / dm ^2, and when an aqueous solution of sodium chloride is used, its concentration, potential difference and energization amount are 80 to 160 g / l, 3.0 to 4.0.
V, 100 to 400 clones / dm ² is preferably set.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Example 1 A sliding member composed of two members that abut each other and slide relatively to each other, one member of which is composed of a fiber-reinforced metal composite material that is electrolytically etched, and the other member. A seizure test was carried out to find out what range of hardness of steel is appropriate for the sliding member made of steel.

First, an alumina-silica fiber having an average fiber length of 2.8 μ and an average fiber length of 6 mm (wt% Al ₂ O ₃ , the balance being substantially SiO ₂ ) is formed into a three-dimensional random oriented fiber molding, By high pressure casting performed using the fiber molded body,
A composite material having an aluminum alloy (JIS standard ADT4) in which alumina-silica fibers having a volume ratio of 8% were reinforced as a matrix was manufactured. Next, from this composite material, many cylindrical test pieces having an outer diameter of 25.6 mm, an inner diameter of 20.0 mm and a length of 16 mm and having one end surface as a surface to be tested are prepared,
The surface roughness of the test surface of each test piece is ground to 0.6 μRz
Finished.

Then, a concave portion was formed on the surface of the matrix to be tested by electrolytic etching using an aqueous nitric acid solution. FIG. 1 is a schematic view showing a cross section of a test piece thus formed in the vicinity of a surface to be tested. In the figure, 1 indicates alumina-silica fiber as a reinforcing fiber, and 2 indicates an aluminum alloy as a matrix. And 3 indicates a recess.

In this case, by appropriately setting the electrolytic etching conditions, the average value ▲ ▼ of the depth Di of the concave portion 3 appearing on an arbitrary cross section of the surface under test is 1.8 μ, and the depth of the concave portion 3 with respect to the opening diameter is The average value of the ratios, that is, the depth Di with respect to the opening length Wi of the concave portion 3 appearing in an arbitrary cross section of the surface under test
Average value of the ratio of Is 0.02, and alumina from the surface 4 of the composite material
The average value of exposed height Hi of silica fiber is 0.5μ
, And the area ratio of the recesses, i.e. any percentage of the ratio of the total of the opening length Wi of the recess 3 for a certain reference length L of the cross section is 20% six cylindrical specimens A ₁ ~ composite material A ₆
Was formed.

Then, these cylindrical test pieces and the cylindrical test piece A ₀ which was not subjected to electrolytic etching and thus was made of a composite material in which the depth of the recesses, the exposed height of the alumina-silica fiber and the area ratio of the recesses were ₀ were sequentially subjected to a friction wear test. Set in a machine and made of steel of various hardness, the size is 30 × 30 × 5mm, one surface (30 × 30mm) of which is the surface to be tested and the surface to be tested is brought into contact with the surface to be tested. While supplying the lubricating oil (castle motor oil SAE30) at room temperature to the contact portions of these test pieces and rotating the cylindrical test piece at a rotation speed of 100 rpm,
A seizure test was performed in which the pressing load of the cylindrical test piece against the flat plate test piece was increased from 10 kg to 700 kg, and thereby the seizure limit load was measured. The combinations of the cylindrical test piece and the flat plate test piece in this seizure test are as shown in Table 1 below.

The results of the seizure test described above are shown in FIG. From FIG. 2, the combination A ₀ in which the cylindrical test piece made of the composite material which was not electrolytically etched was used and the hardness H of the flat plate test piece were obtained.
It can be seen that the seizure limit load of the combination A ₁ in which v is 250 is low. Further, the seizure limit load of the combinations A ₅ and A ₆ in which the constituent materials of the flat plate test piece are gas-nitrided stainless steel and Cr-plated bearing steel are relatively low, whereas the hardness of the flat plate test piece is relatively low. Hv is 400 ~ 90
It can be seen that the seizure limit load of the combinations A _{2 to} A ₄ which are 0 is higher than that of any other combination.

From the result of the seizure test, the hardness Hv of the steel as a mating material that relatively abuts against the electrolytically-etched fiber-reinforced metal composite material is 400 in order to increase the seizure limit load. It turns out that it is preferable that it is -900.

Example 2 With respect to the combinations A _{0 to} A ₆ of the test piece 1 shown in Table 1 above, a load was set to 200 kg (constant) and a wear test similar to the above-described seizure test was performed for 1 hour. It was The results of this wear test are shown in FIG. In FIG. 3, the upper half represents the wear amount of the cylindrical test piece (wear loss mg), and the lower half represents the wear amount of the flat plate test piece (wear loss mg).

From FIG. 3, the hardness Hv of the flat plate test piece is 400 to 90.
The wear amount of the cylindrical test piece of the combination A ₂ to A ₄ is zero is smaller than in any other combination, also combined A ₂ to A
The wear amount of the flat plate test piece ₄ is greater than that of the combination A ₅ and A _6, but smaller than in the case of the combination A ₀ and A _1, thus in contact with the fiber-reinforced metal composite material electrolytic etching relative It is understood that the hardness Hv of the steel that slides on is preferably 400 to 900 in order to reduce the amount of wear of both.

Example 3 It was examined what range the area ratio of the recesses is appropriate.

Cylindrical test pieces B _{1 to} B as shown in Table 2 below were obtained by electrolytically etching the test surfaces of the six cylindrical test pieces prepared in Example 1 under various conditions.
No. ₆ was formed, and silicon chromium steel (Hv40) was applied to each test piece under the same conditions and conditions as in Examples 1 and 2.
A seizure test and an abrasion test were performed using 0) as the mating material.
The results of these tests are shown in FIGS. 4 and 5, respectively.

From FIG. 4, it is understood that the seizure limit load becomes high and the seizure hardly occurs when the area ratio of the recesses is about 5 to 40%. Also, from FIG. 5, it can be seen that the wear amount of the cylindrical test piece and the flat plate test piece has a low value when the area ratio of the recesses is about 5 to 40%.

From the results of these seizure test and abrasion test, it is understood that the area ratio of the recesses is preferably 5 to 40%.

The reinforcing fibers were alumina fibers (95 wt% Al ₂ O ₃ balance was substantially SiO ₂ , average fiber diameter 3.2μ, average fiber length 8 m.
m), silicon carbide whiskers (average fiber diameter 0.5 μ, average fiber length 100 μ), silicon nitride whiskers (average fiber diameter 0.5 μ, average fiber length 250 μ) are magnesium alloys (JIS standard MDC1).
When the seizure test and the abrasion test similar to those in Examples 1 to 3 were performed on the composite material of A), the hardness Hv of steel and the area ratio of recesses were 400 in each case.
It has been found that it is preferably 900 to 5% and 5 to 40%.

Example 4 Using the alumina-silica fiber and aluminum alloy used in Example 1 above, reinforced with a substantially three-dimensional randomly oriented alumina-silica fiber with a volume percentage of 12%. A cylinder liner made of an aluminum alloy was manufactured by high pressure casting, and the liner was cast by gravity casting to form seven cylinder blocks for a cylinder bore diameter of 80 mm, 4-cylinder 4-cycle internal combustion engine. Then, the cylinder bore of one cylinder block is finished by honing to have a surface roughness of 0.6 μRz.
μ, and the area ratio of the recesses was 0%). Also, after the cylinder bores of the other remaining cylinder blocks are finished to have a surface roughness of 0.6 μRz by honing, the average depth of the recesses is 1.9 μm by the electrolytic etching using a nitric acid aqueous solution, and the ratio of the depth to the opening diameter of the recesses is A cylinder block having an average value of 0.018, an average value of exposed height of the reinforcing fibers of 0.3 μ, and an area ratio of recesses of 6% was formed.

Then, the internal combustion engine incorporating these cylinder blocks and steel piston rings corresponding to the combinations A _{0 to} A ₅ of Example 1 was subjected to a high-speed durability test at 6000 rpm for 200 hours, and the combination A _{0 was obtained.} , A ₁ , A ₅ , A ₆
While scuffing was found to have occurred in the cylinder bore of the cylinder block, the combination A ₂ ~
It was not observed at all occurrence of scuffing the cylinder bores of the cylinder block of A _4. Also, the combination A ₂ ~
Each average wear amount of the outer peripheral surface of the cylinder block and the cylinder bore and piston rings A ₄ 20 [mu] or less, 20
On the other hand, the average wear amounts of the cylinder bore and the outer peripheral surface of the piston ring of the cylinder blocks of other combinations are 40 to 80 μ and 40 to 70 μ, respectively, and therefore, the cylinder blocks and pistons of the combinations A _{2 to} A ₄ are The ring was found to be much more wear resistant than the other combinations of cylinder block and piston ring.

The above has been described in detail in relation to the results of the experimental research conducted by the inventors of the present invention, but the present invention is not limited to these examples, and the present invention is not limited to these examples. It will be apparent to those skilled in the art that various other embodiments are possible within the scope.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a cross section of a surface portion of a fiber-reinforced metal composite material according to the present invention, and FIGS. 2 and 3 are seizure tests and a seizure test conducted with steel as a mating material and hardness as parameters, respectively. Graphs showing the results of the wear test, FIGS. 4 and 5
The figures are graphs showing the results of a seizure test and an abrasion test, respectively, using the area ratio of the recesses as a parameter. 1 ... Alumina-silica fiber, 2 ... Aluminum alloy, 3
… Recesses, 4… Surface

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display area F02F 1/00 D 8503-3G

Claims (3)

[Claims] 1. A sliding member comprising a first member and a second member which are in contact with each other and slide relatively to each other, wherein at least a sliding surface portion of the first member with respect to the second member is provided. It is composed of a fiber-reinforced metal composite material having an inorganic fiber as a reinforcing fiber and an aluminum alloy or a magnesium alloy as a matrix, and a part of the reinforcing fiber is exposed on the sliding surface by electrolytically etching the sliding surface. Concave portions are formed on the surface of the matrix between the reinforcing fibers exposed on the sliding surface, and the average depth of the concave portions is 1.5 μm or more, and the depth of the concave portion is larger than the opening diameter. The average value of the ratio is 0.01 or more, the area ratio of the recess is 5 to 40%, and the hardness Hv (10 kg) of at least the sliding surface portion of the second member with respect to the first member.
Is made of steel of 400 to 900. 2. The sliding member according to claim 1, wherein an average value of exposed heights of the reinforcing fibers on the sliding surface is 1 μm or less. . 3. The sliding member according to claim 1 or 2, wherein the sliding member is an internal combustion engine, the first member is a cylinder liner, and the sliding member is a cylinder liner. The second member is a piston ring, which is a sliding member.