JP3066798B2 - Surface treatment method for sliding members - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a material made of an aluminum alloy used for a part used under a high load such as a vane or a differential for a rotary type compressor, a washer for a transmission, or a partial load to which a local load is applied. The present invention relates to a method for performing a surface treatment for the purpose of improving sliding characteristics.

[0002]

2. Description of the Related Art In the above-mentioned compressors and the like, the counterpart material is often aluminum for weight reduction, and the following surface treatment is applied to the vanes to cause sliding between aluminum. One of them is to apply, for example, electroless Ni-P plating or electroless Ni-B plating having excellent wear resistance to the vane surface. Next, the sliding characteristics are also improved by dispersing a hard material and a solid lubricant in the electroless Ni-P plating film. In addition, electroless Ni-
Heating the P plating to 300 ° C. or lower to improve the wear resistance is also performed.

[0003] In general, electroless Ni-P plating used for surface treatment of sliding members has a P content of 6 to 10%.
It is a high P type, and the hardness of Hv450-500 after plating increases to an extremely high hardness of Hv700-800 by heat treatment. For example, according to Japanese Patent Application Laid-Open No. 64-32087, an electroless Ni having a Ni content of 8 to 10%
-P plating film is formed and Hv700-8 by heat treatment
The hardness is increased to about 00. However, in the case of an aluminum alloy, since the material strength is reduced at a high heat treatment temperature, there is a limit to the heat treatment temperature, and substantially Hv 500
Only a film having a hardness of about 600 can be obtained.

[0004]

Conventionally, the Ni-P plating film applied to the surface of the sliding member has been of a medium / high P type which can obtain high hardness by heat treatment. Did not reach the expected level. In particular, if the primary crystal Si in the Al-Si alloy of the rotor and the housing, which is the partner material of the vane, becomes coarse to 50 μm or more and / or the number of Si particles becomes 300 particles / mm ² or more, the high P
Abnormal wear occurred on the electroless plating film. Further, when the load was increased, the surface pressure of the vane was increased, and abnormal wear was also caused.

[0005]

The present inventor has proposed an electroless Ni.
After extensive research to improve the sliding characteristics of the aluminum alloy material coated with the -P plating film, surprisingly, a low P-type electroless plating film with a high hardness when the heat treatment temperature is low is specially hardened. It has been found that it is effective to perform the treatment. The first method of the present invention, which has been completed based on this finding, is based on electroless Ni-containing alloy having a P content of 0.1 to 5% by weight formed on a sliding surface of a material made of an aluminum alloy.
The second method of the present invention is a method of subjecting a P plating film to a barrel polishing treatment. The second method of the present invention is a method of electroless Ni having a P content of 0.1 to 5% by weight formed on a sliding surface of a material made of an aluminum alloy. The third method of the present invention is a method of subjecting a P plating film to a shot blast treatment, wherein a P content of 0.1 to 5% by weight is formed on a sliding surface of a material made of an aluminum alloy. This is a method of irradiating the Ni-P plating film with a laser beam. The fourth method of the present invention is a method of subjecting an electroless Ni-P plating film having a P content of 0.1 to 5% by weight formed on a sliding surface of a material made of an aluminum alloy to a high-frequency induction heat treatment. . Hereinafter, the present invention will be described in detail.

In the present invention, the low P type having a P content of 0.1 to 5% by weight is selected as the electroless Ni-P plating film because the P content is small and the strain of the Ni crystal lattice is low. It is almost crystalline, and even if it is subjected to barrel polishing, shot blasting, laser beam treatment, and high-frequency induction heat treatment, the crystal will not be significantly distorted and deformation and melting will proceed uniformly. This is because a preferable crystal structure and a surface state such as high film hardness can be obtained. For example,
Grain boundaries are observed on the surface after plating. However, as the surface is crushed by, for example, barrel polishing or shot blasting, the crystal grain boundaries disappear near the surface, and a smoother and harder state is obtained. P of electroless Ni-P plating film
If the content is less than 0.1%, electroless plating itself is difficult, and sliding characteristics are not excellent in terms of seizure resistance. On the other hand, if the P content exceeds 5% by weight, the structure tends to be a composite structure of Ni ₃ P and an amorphous structure. In this structure, since there are many easily deformable places such as a Ni ₃ P precipitation interface and a crystal grain boundary, non-uniform deformation is likely to occur when an external force is applied. When high-density energy is applied by a laser beam, segregation after solidification increases due to a large difference between the liquidus line and solidus line of the melt, and the melt flows violently and crystal distortion increases.
The preferred P content is 1 to 3% by weight. The thickness of the electroless Ni—P plating film is generally 5 to 40 μm, and more preferably 10 to 20 μm.

The barrel polishing employed in the first embodiment of the present invention is as follows.
This is a process in which a vane, a barrel material such as a polyester-based media material as a polishing medium, and water are put into a rotating container and rotated or vibrated to smoothen and harden the plating film surface. As the polishing conditions, a rotation speed of 240 rpm and a time of 5 min can be preferably adopted. The structure of the low-P electroless plating film after barrel polishing was observed by a scanning electron microscope. As a result, there was essentially a difference in uniformity from the high-P electroless plating film.

[0008] The shot blasting process employed in the second aspect of the present invention is a process in which particles such as steel collide with the electroless plating surface at high speed to generate a compressive stress on the surface. More preferably, the conditions for raising the temperature of the electroless Ni-P film by the shot to a temperature equal to or higher than the recrystallization temperature and causing a certain degree of plastic deformation on the plating surface to generate a microstructure having a crystal form different from that immediately after plating are set. I do. The shot particles Specifically, hardness using Hv600 or more steel or hard beads such as Al ₂ O _3, or carbon, etc., the particle size in the range of 0.03～0.4Mm, projection speed 80 m / sec or more. Photograph of the structure of the low-P electroless plating film observed with an optical microscope (1000 magnification).
1) and FIG. 4 shows a photograph (1000 times magnification) of the high-P electroless plating film. From this comparison, it can be seen that the structure of the low P electroless plating film is fine and dense. Further, a photograph after the shot blasting treatment (magnification 1000 times) and a photograph after the barrel polishing (magnification 10 times)
2 and 3 are shown in FIGS. By performing these treatments, the structure is further refined and dense.

The laser irradiation treatment employed in the third aspect of the present invention is a treatment for instantaneously and locally melting the electroless Ni-P plating film.
The heat is deprived by the P and the base material to solidify. In this case, melting
Since the heat treatment is performed locally, the amount of heat removed from the melt becomes extremely large, causing rapid solidification, and P is forcibly dissolved in the Ni crystal to cause hardening and the crystal grains become fine. The type of laser is not particularly limited, but is 100 to 400 W / cm.
A YAG pulse laser having an output of about ² (beam area) can be preferably used. The laser irradiation operation is performed by appropriately moving the laser gun and the sliding member, and using an appropriate jig so that the former spot is sequentially irradiated on the entire surface of the latter.

Next, an example of curing by laser irradiation will be described. Laser irradiation conditions are as follows. Table 1
It can be seen that extremely large curing occurs in the range of P = 1.0 to 4.5%. Laser type: YAG pulse Laser output: 100-400 W / cm ² Laser beam diameter: 2 cm Laser scanning speed: 10 cm / sec Electroless Ni-P coating: thickness 0.02 mm

[0011]

TABLE 1 Plating film hardness (Hv) P content (wt%) Before laser irradiation After laser irradiation 0.2 480 490 1.0 640 860 2.0 650 910 3.0 620 870 4.5 580 840 650 550 830

The high frequency heat treatment employed in the fourth aspect of the present invention is to perform the above-mentioned forced solid solution of P by high frequency induction heating. In the high-frequency heating, the temperature of the plating film does not exceed the Curie point of Ni (631 K) so that the temperature of the aluminum alloy as the base material is preferably maintained at 220 ° C. or less, and eddy current concentrates on the plating film and the base material Should be as low as possible. The high frequency is preferably 70 kHz or more.

Next, an example of hardening by high frequency heat treatment will be described. The induction heat treatment conditions are as follows. Table 2 shows that extremely large curing occurs in the range of P = 1.0 to 4.5%. Frequency: 100kHz High frequency output: 80KW Electroless Ni-P coating: thickness 0.02mm

[0014]

[Table 2] Plating film hardness (Hv) P content (wt%) Before induction heat treatment After induction heat treatment 0.2 480 490 1.0 640 880 2.0 650 920 3.0 620 860 4.5 4.5 580 850 6 550 830

In order to enhance the adhesion of the low-P electroless Ni-P plating film subjected to the first to fourth treatments of the present invention to a material, a medium-high P electroless Ni-P plating film is used as a base. Is preferably applied. The latter medium / high P film is used as a base to utilize excellent adhesion,
In addition, it is used as a base for a low-P electroless Ni-P plating film so that the above-mentioned defects caused by the hardening treatment do not appear. High P
The P content of the electroless Ni-P plating film is 5 to 15% by weight.
Is preferred. A more preferred P content is 5 to 8% by weight.

The low P electroless Ni-P plating film subjected to the first to fourth treatments of the present invention can be hardened by heat treatment to improve the wear resistance. FIG. 5 is a graph showing the relationship between the heat treatment temperature (maintained for 1 hour) and the surface hardness of the electroless Ni-P plating film containing 1.9 wt% P, and FIG. 6 shows the hardness of the aluminum alloy substrate and the heat treatment temperature. 6 is a graph showing the relationship of. Here, the surface hardness was determined by using a Vickers hardness meter (load: 0.1 kg), and the hardness was determined by measuring the surface hardness of each sample using a Rockwell B hardness meter. That is, the measurement site is changed using the fact that the depth of the indentation differs depending on the magnitude of the measurement load. Reference numerals in the drawing indicate three samples. 5 and 6, it can be seen that the heat treatment slightly increases the surface hardness but hardly changes the hardness of the aluminum alloy base material at a heat treatment temperature of 220 ° C. or less.

FIG. 7 is a graph showing the relationship between the P content of the electroless Ni-P plating film, the surface hardness, and the heat treatment time at 200 ° C. From this graph, it can be seen that the surface hardness of the electroless Ni-P plating film having a low P content of 2.8% increases to about Hv1000 when held for 20 hours or more. On the other hand, most aluminum alloys are 2
If the heat treatment is performed at 20 ° C. for 20 hours or more, overaging occurs, so it is necessary to select the 2218 alloy as a material even in the 2000 series having a long appropriate aging time. If the heat treatment time is less than 10 hours, most heat treatment type aluminum alloys do not overage. Among them is 2214
And other high-strength alloys. In order to increase the adhesion of the electroless Ni-P plating film to the aluminum alloy as a raw material, it is preferable to perform a pretreatment exemplified below.

Alkaline degreasing (50 ° C. × 5 minutes, use of alkaline degreasing agent) Alkaline etching (50 ° C. × 40 seconds, NaOH bath) Smut removal (27 ° C. × 40 seconds, cleaning bath mainly composed of nitric acid) Zinc displacement plating Treatment (1) (27 ° C x 25 seconds, zincate bath) Zinc peeling (27 ° C x 60 seconds, 50% nitric acid) Zinc displacement plating treatment (2) (27 ° C x 25 seconds, zincate bath)

After surface treatment such as shot blasting, barrel treatment, and laser beam irradiation, the treated surface is used as it is as a sliding surface. In the case of high-frequency heat treatment, polishing treatment may be performed. The material treated as described above can be used as a vane, a radial plain bearing, a thrust plain bearing, etc. of a rotary compressor. Next, a description will be given of the results of a test for reproducing a high load condition under which the aluminum alloy material treated by the method of the present invention causes one-side contact.

[0020]

【Example】

Example 1 FIG. 8 is a conceptual diagram illustrating a test method in the present example, in which 10 is an aluminum alloy material (AHS-3-T ₇ ) treated by the method of the present invention or the comparative method, 11
Is a block (A390 aluminum alloy, primary crystal Si average particle diameter 30 μm). The dimensions of the material are 35 × 14 × 3m
m. 8, the angle θ is 1 °, the load P is 150 kgf (15.3 N), the test time is 5 hours,
The reciprocating sliding frequency was 10 Hz, the stroke was 6 mm, and the oil supply was 30 mL / h. After performing the above-mentioned preliminary surface treatment, the material is subjected to electroless plating having a P content of 1.9% by weight by using a plating solution (trade name: Top Nicolon Y) manufactured by Okuno Pharmaceutical Co., Ltd.
M), and a plating having a thickness of 15 μm was formed on the entire surface of the material. The surface hardness after plating was Hv645.

The surface treatments used for the test were as follows. 1. Barrel polishing treatment Polishing medium type: polyester resin + zircon Polishing medium amount: 1.5 kg Liquid amount: 1.0 kg (water) Material number: 20 Rotating container volume: 0.01 m ³ rotating container rotation speed: 200 rpm Processing time: 5 min 2. 2. Shot blast treatment Shot grain material: Al ₂ O ₃ , hardness Hv1000 Shot grain size: 200 μm average Shot projection speed: 150 m / sec Projection amount: 50 kg / m ² / sec Laser irradiation treatment Laser type: YAG pulse (manufactured by Toshiba Corporation) Laser output: 10 kW Output per beam diameter: 100 to 400 W / m ² 4. Heat treatment A heat treatment was performed at 200 ° C. for 60 minutes, and then the first treatment was performed. 5. Heat treatment A heat treatment was performed at 200 ° C. for 60 minutes, and then the second process was performed. 6. Heat treatment A heat treatment was performed at 200 ° C. for 60 minutes, and then the treatment 3 was performed.

The electroless plating having a content of 6% by weight formed on the sliding surface before the above-described electroless Ni-P plating was plated with a plating solution (trade name: Top Nicolon TO, manufactured by Okuno Pharmaceutical Co., Ltd.).
M), and formed over the entire surface of the intermediate plating material having a thickness of 2 μm. Thereafter, the following surface treatment was performed. 7: 1 processing 8: 2 processing 9: 3 processing 10: 4 processing 11: 5 processing 12: 6 processing

The following processing was also performed as a comparative example. (A) Low P electroless plating described above (b) High P electroless plating (P content = 10% by weight) (c) Low P electroless plating after high P electroless plating of (b) above (d) Table 1 shows the results of the heat treatment test in the fourth step after (c).

[0024]

[Table 1] Treatment method After treatment Test material Block Remark surface Specific wear amount Specific wear amount Hardness (Hv) (10 ^-9 mm ² kg ^-1 ) (10 ^-9 mm ² kg ^-1 ) 1 680 6.0 1.0 The present invention 2 690 5.0 1.0 The present invention 3 910 2.2 0.7 The present invention 4 810 3.2 0.7 The present invention 5 820 2.4 0.6 The present invention 6 990 1.9 0.6 The present invention 7 680 4.1 0.9 The present invention 8 690 3.9 0.8 The present invention 9 910 1.7 0.6 The present invention 10 750 2.4 0.7 The present invention 11 760 3.8 0.9 The present invention 12 770 2.9 0.8 The present invention a 650 8.0 1.2 Comparative example b 560 12.0 3.0 Comparative example c 660 7.6 1.0 Comparative example d 740 6.5 0.8 Comparative example

As shown in Table 1, the specimens obtained by the treatment method of the present invention have less wear of the specimens and blocks than those of the comparative examples.

[Brief description of the drawings]

FIG. 1 is a photograph (1000-fold magnification) of the structure of a low-P electroless plating film observed with an optical microscope.

FIG. 2 is a photograph (magnification: 1000 times) of a structure obtained by subjecting a low P electroless plating film to a shot blast treatment and observed by an optical microscope.

FIG. 3 is a photograph obtained by observing the structure of a low-P, electroless plating film after barrel polishing by an optical microscope (magnification: 1000).
Times).

FIG. 4 is a photograph of a high-P electroless plating film (magnification: 1000).
Times).

FIG. 5 is a graph showing the relationship between the surface hardness of an electroless plating film having a P content of 10% by weight and the heat treatment temperature.

FIG. 6 is a graph showing the relationship between aluminum alloy substrate hardness and heat treatment temperature.

FIG. 7 is a graph showing the relationship between the surface hardness of an electroless plating film having a P content of 2.4, 6.5, 7.1, and 12% by weight and a heat treatment time.

FIG. 8 is an explanatory diagram of a wear test.

Continuation of the front page (72) Inventor Kenichi Kondo 3-65 Midorigaoka, Toyota City, Aichi Prefecture Inside Taitoyo Kogyo Co., Ltd. (56) References JP-A-7-285032 (JP, A) JP-A 5-306650 (JP, A) JP-A-8-1558058 (JP, A) JP-A-5-71525 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C23C 18/00-18/54

Claims (7)

(57) [Claims] An electroless Ni-P having a P content of 1 to 3% by weight formed on a sliding surface of a material made of an aluminum alloy.
A surface treatment method for a sliding member, comprising subjecting a plating film to barrel polishing. 2. An electroless Ni having a P content of 0.1 to 5% by weight formed on a sliding surface of a material made of an aluminum alloy.
-A surface treatment method for a sliding member, wherein the P plating film is subjected to a shot blast treatment. 3. The slide according to claim 2, wherein the shot blasting is performed by projecting particles having a hardness substantially equal to or higher than the hardness of the electroless Ni—P plating film at a speed of 80 m / sec or higher. Surface treatment method for members. 4. Prior to the formation of the electroless Ni—P plating film having a P content of 0.1 to 5% by weight, the P content was 5%.
4. The method according to claim 1, wherein an electroless Ni-P plating film of more than 15% by weight is applied.
A surface treatment method for a sliding member according to claim 1. 5. An electroless Ni-P plating film having a thickness of 100
The surface treatment method for a sliding member according to any one of claims 1 to 4, wherein a heat treatment is performed at a temperature of up to 220C. 6. The method according to claim 5, wherein the heat treatment time is 0.3 to 5 hours. 7. The method for surface treating a sliding member according to claim 1, wherein the aluminum alloy is of a heat treatment type.