JPH0686871B2 - Combination of sliding members - Google Patents

Description

Detailed Description of the Invention a. TECHNICAL FIELD The present invention relates to a combination of sliding members.

B. 2. Description of the Related Art For example, in a sliding member such as a vane and a housing of a rotary compressor, or a vane and a rotor that is required to have wear resistance and seizure resistance, a specific gravity is required for the material of the vane where inertia is important. A combination of a hypereutectic aluminum-silicon alloy, which is small in size and excellent in wear resistance, and a cast iron or iron-based sintered alloy is used as a material for the housing and rotor in which inertia does not matter.

In Bosch type and yoke type rotary compressors,
The plurality of vanes fitted in the plurality of bevel grooves of the rotor slide on the housing while receiving a centrifugal force due to the rotation of the rotor.

In the rotasco type rotary compressor, one vane fitted into a vane groove of the housing and pressed against the rotor by a spring from behind is in sliding contact with the rotor which is eccentrically positioned with respect to the housing and rotates.

In the former type rotary compressor, the sliding area of the housing is relatively large between the housing and the vane, and the sliding area of the vane is relatively small. In the latter type rotary compressor, the sliding area of the rotor is relatively large and the sliding area of the vane is relatively small between the rotor and the housing.

Recently, due to a demand for weight reduction, there is an increasing demand for using a lightweight aluminum alloy for sliding members (housing and rotor) which have conventionally used cast iron or iron-based sintered alloy. However, in the combination of aluminum alloys,
Both the wear resistance and seizure resistance are poor, and even among aluminum alloys, even if a combination of hypereutectic aluminum-silicon alloys with excellent wear resistance and seizure resistance is used, the sliding characteristics are not sufficient, and the above requirements are met. A combination of aluminum alloy sliding members has not been realized.

C. OBJECT OF THE INVENTION The present invention has been made in view of the above circumstances,
An object of the present invention is to provide a combination of both sliding members that slide with each other, which are made of a lightweight aluminum-based material, and have excellent wear resistance and seizure resistance.

D. Configuration of the Invention That is, the present invention is a combination of a sliding member in which a first sliding member having a relatively large contact area and a second sliding member having a relatively small sliding area slide on each other. And the first sliding member is an aluminum alloy in which silicon is 12 to 30% by weight, copper is 2 to 8% by weight, magnesium is 0.2 to 2.0% by weight, lead is 0.5 to 5% by weight, and the balance is substantially aluminum. In the second sliding member, 10 to 30% by weight of silicon, 3 to 10% by weight of one or two kinds of transition metals in total, 2 to 8% by weight of copper, and 0.2 to 3.0% of magnesium are included. %, The balance consisting essentially of aluminum, and 3 to 10% by volume of hard particles having an average particle size of 3 to 60 μm in an aluminum alloy substrate in which extremely fine primary crystal silicon and / or extremely fine eutectic silicon are dispersed. The present invention relates to a combination of sliding members, which is a composite material having a dispersed structure.

E. Effects of the Invention In the first sliding member having a relatively large contact area, the primary eutectic silicon of the hypereutectic aluminum-silicon alloy has a hardness H _M V700 to 1000.
Is harder than the eutectic portion, and the primary crystal silicon becomes a convex portion relative to the eutectic portion during sliding, and the eutectic portion relatively forms a concave portion. Since the convex part is hard, it contributes to wear resistance, the eutectic part that becomes the concave part has less chance of contacting the second sliding member, and it becomes an oil reservoir of lubricating oil and it is easy to hold the oil film , Make it hard to run out of oil.

In the second sliding member having a relatively small contact area, by dispersing the hard particles that are harder than the primary silicon of the first sliding member, the hard particles are relatively slid against other parts during sliding. The aluminum-silicon alloy base material relatively forms a concave portion to form an oil reservoir, which facilitates holding of the oil film and prevents seizure.

The second sliding member, which has a relatively small contact area, slides constantly during movement, so that wear easily progresses, and the deformation resistance decreases as the surface temperature rises, and the second sliding member becomes Easy to adhere. In order to prevent these, hard particles having a hardness of H _M V1000 to 3500 are dispersed on the side of the second sliding member.

Next, each component that constitutes the first sliding member will be described.

The first sliding member is a hypereutectic aluminum-silicon alloy. The hypereutectic aluminum-silicon alloy is a casting alloy and has excellent wear resistance and seizure resistance as described above. The Al-Si-based eutectic composition is 11.3% by weight of silicon (hereinafter, "%" represents "% by weight" unless otherwise specified). If the content exceeds 30%, the effect is not significantly increased, and the solid-liquid coexisting temperature range is widened, the castability is greatly deteriorated, and the toughness and machinability are also deteriorated.

Copper and magnesium have the function of strengthening the matrix by age hardening. In addition, as the copper content increases, the coefficient of thermal expansion decreases, which is advantageous. However, if the copper content exceeds 8%, the coarse intermetallic compound of Cu ₂ Al will crystallize and embrittle the matrix, and the corrosion resistance will also decrease. Therefore, the lower limit is 8%, and the lower limit is aging. 2% of which hardening appears
Is desirable. A particularly preferable range is 3 to 6%.

Magnesium strengthens the matrix by the action of age hardening like copper, but it is not preferable because the higher the content, the higher the coefficient of thermal expansion and the brittleness action, which is not preferable. In consideration of the fact that magnesium is used, the range of magnesium is 0.2 to 2.0%. A particularly preferred range is 0.3 to 1.5%.

Lead supplements the lubricity of the sliding surface under severe sliding conditions that tend to cause oil shortage. It is effective to contain lead on the side of the first sliding member having a large contact area because the amount of lead is large. Further, by containing lead, the machinability of the hypereutectic aluminum-silicon alloy, which has a poor machinability, is improved. If the lead content is less than 0.5%, the above effect is not remarkable, and if it exceeds 5%, the mechanical strength is lowered, so the range of 0.5 to 5% is preferable.

The second sliding member is made of a composite material in which hard particles are uniformly dispersed in a substantially eutectic or hypereutectic aluminum-silicon alloy matrix in which extremely fine primary crystals and / or eutectic silicon are crystallized. . In the second sliding member, the hard particles form hard spots to improve wear resistance and seizure resistance.

The aluminum-silicon alloy in which the fine primary crystals and / or eutectic silicon are uniformly crystallized as described above can be obtained by extruding alloy powder rapidly solidified by the atomizing method. According to the atomization method, solidification is much faster than in the case of casting, so that the primary crystal and / or eutectic silicon becomes extremely fine, and the second sliding member made of such alloy powder as a raw material. The fine silicon particles improve the mechanical strength and wear resistance of the base material. That is, in the second sliding member, the fine particles of silicon contribute to the strengthening of the base material, and the hard particles to be described later rather act as hard spots.

The extrusion process is preferably performed by hot extrusion with an extrusion ratio of 10 or more, and particularly preferably by an indirect extrusion method in which the flow of particles is substantially uniform and the resistance is low. For this extrusion processing, a mixed powder obtained by mixing the above-mentioned aluminum-silicon atomized alloy powder with hard particles, a green compact formed by molding this mixed powder, or a sintered body obtained by sintering the green compact by a conventional powder metallurgy method is used. Is used as the work material. When the sintered body is the work material,
The work piece is easy to handle.

The thin alumina (Al ₂ O ₃ ) film inevitably formed on the surface of the aluminum-silicon atomized alloy powder by the hot extrusion process is superfinely divided by the plastic flow due to the extrusion process, and the Al ₂ O ₃ film intervenes. Thus, the problem that the diffusion between the powder particles is prevented and, as a result, the formability is impaired is solved. For that purpose, the extrusion ratio needs to be 10 or more, and the processing temperature is suitably 400 to 500 ° C. Further, the hard particles dispersed in the extruded body obtained by doing so receive a strong compressive force from the surrounding aluminum-silicon alloy, so that these particles are prevented from falling off during sliding.

Since the extruded product thus obtained can be easily made to have a size close to the size of the target part, the yield in the subsequent finishing process can be made extremely high.

Hereinafter, each component that constitutes the second sliding member will be described.

If the content of silicon is less than 10%, the effect of improving the wear resistance of the base material is not sufficient. The higher the silicon content, the higher the hardness and wear resistance, and the lower the coefficient of thermal expansion. However, if it exceeds 30%, the above effect is not significantly increased, the base material becomes brittle, and it is extremely difficult to extrude. It is not preferable because it requires a large load. Therefore, the silicon content in the substrate is 10-30%
And A particularly preferred range is 16 to 25%.

A transition metal (a metal of Group IIIB to VII and VIII of the periodic table, particularly iron, nickel, manganese, chromium, etc. can be preferably used) is an intermetallic compound which is stable at high temperature and is finely molded to form a base metal. It contributes to the improvement of mechanical strength. These 1 type (s) or 2 or more types may be used, but if the total amount is less than 3%, the above effect is not remarkable, and if the total amount exceeds 10%, the mechanical strength is rather lowered, and extrudability and machinability are reduced. It comes to harm.

Copper and magnesium are the same as those in the above-mentioned first sliding member. However, as for the magnesium, since the base material is made from rapidly solidified atomized alloy powder, it can be dissolved in a supersaturated amount in a larger amount than the first sliding member, and its upper limit is 3.0%.

The hard particles to be dispersed in the alloy base are those having a hardness higher than that of the primary crystal silicon (hardness H _MV 700 to 1000 or more). The hard particles include metallic silicon and silicon nitride (Si
₃ N ₄ ), silicon carbide (SiC), titanium nitride (TiN), titanium nitride (TiC), tungsten carbide (WC), alumina (Al ₂
O ₃ ), chromium oxide (Cr ₂ O ₃ ), titanium boride (TiB), chromium boride (CrB ₂ ), ceramics such as molybdenum boride (MoB), intermetallic compounds such as TiSi ₂ , WSi, MoSi ₂ Alternatively, powders of hard alloys such as ferro-molybdenum and ferro-tungsten can be used. In particular, metallic silicon, Si ₃ N ₄ , SiC, TiC, Al
_{Since 2} O ₃ and TiN have a specific gravity of about 6 g / cc and are close to those of aluminum-silicon alloy, they are easy to uniformly mix without being unevenly distributed in the aluminum-silicon alloy powder, which is advantageous. Among them, metallic silicon, Si ₃ N ₄ and SiC are advantageous because they have good adhesion to an aluminum-silicon alloy and are inexpensive.

The particle size of the hard particles needs to be larger than the particle size of the aluminum-silicon atomized alloy powder forming the matrix in order to improve wear resistance under low-speed sliding conditions, and the average particle size is at least 3 μm. However, if it exceeds 60 μm, extrusion processing becomes difficult, so the thickness is set to 3 to 60 μm. However, the maximum particle size should be limited to 80 μm or less. A particularly preferable range of the average particle size is 10 to 40 μm.

The dispersion amount of the hard particles needs to be at least 3% by volume in order to exert the above-mentioned effects. If it exceeds 10% by volume, extrusion processing becomes difficult and the first sliding member becomes worn.

F. EXAMPLES The present invention will be described below with reference to examples.

As the first sliding member, a mold casting material consisting of silicon 16%, copper 3%, magnesium 1%, lead 1.5%, and the balance substantially aluminum is made, and T6 is applied to this, and a test piece is prepared from this. It was collected.

As the second sliding member, hypereutectic aluminum-silicon atomized alloy powder (under 100 mesh sieve) as shown in the table below
Hard particles were mixed and mixed in, and this mixed powder was filled in a molding rubber mold and molded using a cold isostatic press at a pressing force of 4 ton / cm ² to obtain a pellet. The resulting pellet is the outline
It has a length of 49.5 mm and a length of 90 mm, and its true density ratio is 70%.
Next, the above-mentioned pyret previously heated and held at 450 ° C was inserted into a container having an inner diameter of 50 mm which was heated and held at 450 ° C, and an extruded rod having a diameter of 12 mm was obtained by an indirect extrusion method. The extrusion ratio at this time is 17.4. The extruded rod was subjected to T6 treatment, and then a test piece was collected. The particle size of the hard particles is
Metallic silicon is 5 to 50 μm, average particle size is 30 μm, Si ₃ N ₄ is 1 to 5
When the average particle size is 0 μm, the average particle size is 30 μm.
It is 10 μm.

For comparison, the second sliding member (Comparative Examples 1 and 2) produced in the same manner as above except that it does not contain hard particles and the transition metal are not contained, and the others are produced in the same manner as above. Test pieces of the second sliding member (Comparative Examples 3 and 4) were prepared.

FIG. 1 is a micrograph showing the structure of the first sliding member at a magnification of 100 times, and FIG. 2 is a micrograph showing the structure of the second sliding member (symbol C) at a magnification of 400 times.

In the structure of the first sliding member shown in FIG. 1, rod-shaped lump-shaped primary crystal silicon is crystallized in the matrix made of aluminum that appears white and elongated eutectic silicon that appears rodent. A black lead-like lead phase can be observed in the primary crystal silicon.

In the structure of the second sliding member shown in FIG. 2, rodent-colored angular silicon carbide (SiC) particles are dispersed in the base crystallized in the aluminum-silicon eutectic structure in which light gray-colored primary silicon appears white. It is observed that it is doing. Since the second sliding member uses atomized alloy powder, the base structure is much finer than that of FIG. 1, and therefore primary silicon cannot be observed.

A wear test and a seizure test were conducted by combining the test piece of the first sliding member and the test piece of the second sliding member shown in the table.

As another comparative example, a first sliding member test piece and a second sliding member test piece were sampled from the first sliding member test piece test material, and the same materials were combined. Was tested (Comparative Example 5). In addition, cast iron FC25 that has been conventionally used for rotors and housings of rotary compressors
As a test piece of a hypereutectic aluminum-silicon casting alloy which is also used for a vane as a test piece for the first sliding member and a second sliding member from the test material for the first sliding member test piece. A test piece of the member was sampled and the same test was performed (Comparative Example 6).

(1) Seizure test The test apparatus is schematically shown in FIG. 3 and FIG. 4 which is a side view taken along the line IV-IV in FIG. 3 and is detachable to the stator holder 1. Mounted diameter 80mm,
Lubricating oil is injected into the center of the circular plate 2 having a thickness of 10 mm from the back side through an oil injection hole 3. A hydraulic device (not shown) applies a pressing force P to the stator holder 1 toward the right in the figure at a predetermined pressure.
A rotor 4 is provided opposite to the disc 2 and is rotated at a predetermined speed by a driving device (not shown). Test piece holder 4a attached to the end surface of the rotor 4 with respect to the disc 2
In this case, four test pieces 5 of the second sliding member can be removed concentrically at regular intervals with the square end surface as a sliding surface, and the disk 2
It is slidably attached to.

In such a device, a predetermined pressing force P is applied to the stator 1.
Then, the disc (counterpart material) 2 and the test piece 5 are brought into contact with each other at a predetermined surface pressure, and the rotor 4 is rotated while the sliding surface is lubricated at a predetermined lubrication speed. The pressure acting on the stator 1 is increased stepwise at regular time intervals, and the torque generated by the stator 1 by the friction between the test piece 5 and the disc 2 of the other party due to the rotation of the rotor 4 (torque generated by the frictional force) T Is applied to the load cell 7 via the spindle 6, and the change is read by the dynamic strain gauge 8 and stored in the recorder 9. It is assumed that seizure occurs when the torque T rapidly rises, and whether the seizure resistance is good or not is judged based on the magnitude thereof.

The test conditions are as shown below.

Friction speed: 5m / sec Lubricating oil: Compressor oil with an oil temperature of 90 ℃ (SUNISO 5GS)
350 ml / min Lubrication Contact pressure: 20 kg / cm ² at the start of the test, then every 3 minutes
Increase by 10 kg / cm ² Counter disk: Test piece of the first sliding member The test results are shown in FIG. The test was performed 5 times for each test of the second sliding member made of the same material.

The test results are shown in FIG. The figure shows the range of the test results performed on the test pieces of the same material.

The figure can be seen from FIG.

In the combination of the examples, the seizure resistance is improved to the same level as or higher than that of the comparative example 6 which is the conventional combination.

In the combinations of Comparative Examples 3 and 4 containing no transition metal, the scup resistance was almost the same as that of the combination of A, and the effect of the transition metal on seizure resistance was not clearly recognized.

In Comparative Examples 1 and 2 which do not contain hard particles, the seizure resistance is clearly inferior to the examples, and the effect of improving the seizure resistance of the hard particles is remarkable.

The combination of Comparative Example 5 is also not good in durability.

(2) Abrasion test The test was conducted by the method shown in FIG. The test piece (15) is held by a test piece holder (16), brought into pressure contact with the outer peripheral surface of the counter rotating disk (17) at a constant pressure, and is slid while supplying lubricating oil from a lubricating oil supply pipe (18). The test piece has a 5 × 5 × 20 mm prismatic shape, and the tip sliding surface is rounded with a radius of 6 mm and polished. The mating disc 17 has an outer diameter of 44.2 mm, and the outer peripheral surface of the sliding surface is polished to a surface roughness of 0.6 to 1.5 μm.

With such a test apparatus, the disk 17 is used as the test piece of the first sliding member, the test piece 15 is used as the test piece of the second sliding member, and the disk 17 is set to 1, 3, 5, 10 m. While rotating at a peripheral speed of / sec, the compressor oil (SUNISO 5GS) heated to 80 ± 1 ℃ is supplied from the supply pipe 18 at a rate of 300 ml / min, while the test piece 15 is 3 kg on the outer peripheral surface of the mating disc 17. The test piece 15 and the mating disk 17 were slid with a pressing force of / mm ² and a friction distance of 150 km.

The surface roughness of the outer peripheral surface of the mating disk 17 before the test was measured by scanning the stylus of a surface roughness meter in the axial direction.

After the test, the wear width of the sliding surface of the test piece 15 was measured with a tool microscope.

In this test, representative combinations are selected and tested from the results of Examples and Comparative Examples in the above-mentioned seizure test.

The test results are shown in FIG.

The following can be seen from FIG.

In each of the combinations of the examples, the wear resistance is improved to about the same level or more as compared with the comparative example 6 which is the conventional combination for each sliding speed.

The combination of Examples has less wear than the combination of Comparative Example 1 containing no hard particles, and the effect of improving wear resistance of the hard particles is clearly recognized. In particular, the wear resistance tends to be improved when SiC is used for the hard particles.

In the combination of Comparative Example 3 containing no transition metal, there was much wear at each sliding speed, and the transition metal did not show a clear effect in improving the seizure resistance as described above, but contributed to the improvement in wear resistance. It is clear that

In the combination of the hypereutectic aluminum-silicon alloys of Comparative Example 5, the amount of wear is much larger than that of the other combinations.

From the results of the above-mentioned tests, the combination of the sliding members according to the present invention is a conventional combination in which the first sliding member is cast iron because both the first and second sliding members are aluminum-based materials. It can be understood that the weight is lighter than that of the above, and the seizure resistance and the wear resistance are improved to the same level or higher than the conventional combination.

[Brief description of drawings]

 Each of the drawings shows an embodiment of the present invention, wherein FIG. 1 is a micrograph showing the metal structure of the first sliding member, and FIG. 2 is a microscope showing the metal structure of the second sliding member. Photograph, FIG. 3 is a partial crushing front view showing the outline of the seizure test apparatus, FIG. 4 is a side view taken along the line IV-IV of FIG. 3, FIG. 5 is a graph showing the result of the seizure test, and FIG. Is a schematic front view of the wear test apparatus, and FIG. 7 is a graph showing the results of the wear test. In the drawings, reference numerals 1 ... Stator 2, 17 ... Test piece of first sliding member 3, 18 ... Lubrication hole 4 ... Rotor 4a, 16 ... Test piece holder 5, 15 ... A test piece of the second sliding member.

Claims (1)

[Claims] 1. A combination of a sliding member in which a first sliding member having a relatively large contact area and a second sliding member having a relatively small contact area slide with each other, wherein: One sliding member is an aluminum alloy having 12 to 30 wt% silicon, 2 to 8 wt% copper, 0.2 to 2.0 wt% magnesium, 0.5 to 5 wt% lead, and the balance substantially aluminum. The second sliding member contains 10 to 30% by weight of silicon, 3 to 10% by weight of one or more kinds of transition metals in total, 2 to 8% by weight of copper, 0.2 to 3.0% by weight of magnesium, and the balance substantially. Has a structure in which hard particles having an average particle size of 3 to 60 μm are dispersed in an amount of 3 to 10% by volume in an aluminum alloy base in which extremely fine primary crystal silicon and / or extremely fine eutectic silicon are dispersed A combination of sliding members that is a composite material.