JPH06146017A - Cylinder - Google Patents

Abstract

PURPOSE:To provide the cylinder which has its slide surface coated with a film having superior wear resistance, burning resistance, and corrosion resistance. CONSTITUTION:This cylinder 1 has a compound plating layer 3, having 5-30vol.% chromium oxide particles of 0.5-10mum in mean particle size dispersed in the base of nickel-tungsten alloy consisting of 2-40wt.% tungsten and the remainder substantially of nickel, in the inner peripheral slide surface of the cylinder base material 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder having a composite plating layer having excellent wear resistance.

[0002]

2. Description of the Related Art Instead of a conventional cast iron engine cylinder, an aluminum alloy cylinder has been put into practical use for the purpose of reducing the weight of an internal combustion engine. However, since the aluminum alloy cylinder is slightly inferior in wear resistance to the cast iron cylinder, it is generally used to combine a cast iron cylinder liner on the sliding surface. However, when a cast iron liner is combined, the cost of the engine cylinder increases and the weight also increases, so the fuel consumption increases correspondingly, which is not economically preferable.

For this reason, it has been proposed that the inner peripheral surface of an aluminum alloy cylinder is subjected to surface treatment such as hard chrome plating or nickel-silicon carbide composite plating (hereinafter referred to as Nikasil plating).

However, although hard chrome plating is excellent in wear resistance, it requires a long time for plating treatment and has problems in seizure resistance, corrosion resistance and the like. On the other hand, Nikasil plating has excellent corrosion resistance in an internal combustion engine that uses gasoline as a fuel, but it has the drawbacks of poor seizure resistance and great attack on the mating material. Further, in an internal combustion engine that uses alcohol as a fuel, there is a problem that formic acid is generated, corrosion occurs, and wear resistance decreases.

Further, with the recent increase in engine speed, the load on the cylinder is increasing. Therefore, a coating having excellent wear resistance and seizure resistance is desired.

Therefore, an object of the present invention is to provide a cylinder whose sliding surface is coated with a film having excellent wear resistance, seizure resistance and corrosion resistance.

[0007]

As a result of earnest research in view of the above problems, the present inventor has found that by providing a composite plating layer in which chromium oxide particles are dispersed in a matrix of nickel-tungsten alloy, wear resistance and wear resistance are improved. We have found that a cylinder with excellent seizure can be obtained, and completed the present invention.

That is, the cylinder of the present invention has a mean particle size of 0.5 in a matrix of nickel-tungsten alloy containing 2 to 40% by weight of tungsten and the balance of nickel.
It is characterized in that it has a composite plating layer in which 5 to 30% by volume of chromium oxide particles having a size of 10 μm are dispersed on the sliding surface.

[0009]

The present invention will be described in detail below.

As shown in FIG. 1, the cylinder 1 of the present invention.
Has a chromium oxide particle-dispersed nickel-tungsten alloy composite plating film 3 on the sliding surface of the cylinder base material 2.

Tungsten contained in the nickel-base alloy matrix enhances the hardness of the plating film at high temperature, wear resistance,
It has excellent heat resistance and corrosion resistance to strong acids such as formic acid. Total of nickel + tungsten 1
If the amount of tungsten is less than 2% by weight as 00% by weight, the above effect cannot be remarkably obtained, and if it exceeds 40% by weight, the effect is not significantly changed, which is economically unfavorable.
Therefore, the amount of tungsten is 2 to 40% by weight.
The preferred amount of tungsten is 5 to 30% by weight. On the other hand, nickel that serves as a matrix enhances the heat resistance and corrosion resistance of the coating and also enhances the toughness of the coating. The amount of nickel is 60 to 98% by weight, preferably 70 to 95% by weight, based on 100% by weight of the total of nickel and tungsten.

Chromium oxide (Cr ₂ O ₃ ) dispersed in the alloy matrix
The particles have an excellent effect in improving the wear resistance of the coating. Further, since the coefficient of friction is small, it is effective in reducing friction.
Among the ceramics, chromium oxide has low wettability with metals and is unlikely to be in a molten state, and therefore contributes to improvement in seizure resistance. The content of the dispersed chromium oxide particles is 5 to 30% by volume based on the entire composite plating layer, and the average particle size thereof is 0.5 to 10 μm. If the content is less than 5% or the average particle size is less than 0.5 μm, the area of the chromium oxide particles on the surface of the matrix is small and the effect of improving wear resistance is not sufficient. On the other hand, if the content exceeds 30% by volume or the average particle size exceeds 10 μm, the wear of the mating material increases, and the strength of the coating also decreases. The preferable average particle size of the chromium oxide particles is 0.8 to 1.2 μm, and the preferable content is 10 to 25% by volume.

In the present invention, the chromium oxide particles and the lubricating particles may be mixed and dispersed in the alloy matrix.
By adding the lubricating particles, a synergistic effect with the chromium oxide particles can be exhibited, and wear resistance and seizure resistance can be further improved.

As the lubricant particles, solid lubricant particles having a cleavage property and a low friction coefficient are suitable. Solid lubricant particles include molybdenum disulfide, graphite fluoride, boron nitride, and the like. The volume of the lubricating particles is 5 to 20% by volume based on the entire composite plating layer, and the average particle size is
0.5 to 10 μm is preferable. If the capacity is less than 5% or the average particle size is less than 0.5 μm, the effect of improving wear resistance and seizure resistance is small. The volume is 20% by volume, or the average particle size is
If it exceeds 10 μm, the strength of the film is reduced and the film becomes brittle and easily comes off.

To form the composite plating layer, chromium oxide particles are dispersed in a plating bath in which a tungsten compound and a nickel compound are dissolved so as to have the desired composition. As the tungsten and nickel compounds, sulfate, sulfamate and the like are used.

The thickness of the chromium oxide particle-dispersed nickel-tungsten alloy composite plating film is preferably 30 to 100 μm. If the thickness of the film is less than 30μ, it is easy to wear,
On the other hand, if it exceeds 100 μm, not only the treatment cost rises, but also the plating layer tends to peel off, which is not preferable. A particularly preferable thickness of the plated layer is 50 to 80 μm.

The composite plating film obtained is washed with water and dried,
Baking treatment is performed if necessary. The baking temperature is about 200 to 400 ° C and the time is about 30 to 100 minutes. By this baking treatment, hydrogen occluded in the composite plating film and the base material is released, and a good composite plating film is obtained.

The present invention will be described in more detail with reference to the following specific examples. Example 1 On a disc-shaped aluminum alloy test piece having a diameter of 80 mm and a thickness of 10 mm, a chromium oxide particle-dispersed nickel-tungsten alloy composite plating film was formed under the plating conditions shown in Table 1. Next, the test piece was heated at 200 ° C. for 1 hour to perform baking treatment of the film. The composition, hardness and thickness of the obtained composite plating film were measured. The results are shown in Table 2.

[0019]

[0020]

Comparative Examples 1 and 2 For comparison, the same test piece as in Example 1 was plated with hard chrome to 100 μm and baked at 200 ° C. for 1 hour (Comparative Example 1), and 80 Nikasil plating
A film having a thickness of 100 μm and baked at 200 ° C. for 1 hour was prepared (Comparative Example 2).

Then, the test pieces obtained in Example 1 and Comparative Examples 1 and 2 were subjected to a wear resistance test and a seizure resistance test as follows.

(1) Abrasion resistance test The abrasion resistance test was carried out by a rider type abrasion tester shown in FIGS. 2 is a partial cross-sectional view showing the main part of the test apparatus, and FIG. 3 is a view taken along the line XX in FIG. A test piece 6 is detachably attached to the stator holder 4, and lubricating oil is injected into the center of the test piece 6 from the back side through an oil injection hole 7. Here, a pressing force (P) is applied to the stator holder 4 by a predetermined pressure by a hydraulic device (not shown) toward the right in FIG.

The mating member holder 9 mounted on the rotor 8 facing the test piece 6 is provided with four mounting holes at equal intervals on a circle concentric with the rotating shaft. The mating material 10 is attached to the hole. 5mm x 5mm of mating material 10
The leading end surface of the test piece contacts the sliding surface 5 of the test piece 6, and is rotated at a predetermined speed by a driving device (not shown).

The test is conducted while supplying lubricating oil having a constant oil temperature to the sliding surface from the oil injection hole 7 on the stator side. Test piece 6 when the mating material 10 slides on the test piece 6 for a predetermined sliding distance
And the wear resistance of the mating material 10 is evaluated.

Specifically, engine oil SAE after being used in an actual machine test using leaded gasoline as a lubricating oil as a fuel.
No.30 dust (JIS type 2) 0.2 g / l was added to the oil at a temperature of 80 ° C, and the stator holder 4 supplied from the oiling hole 7 was pressed with a hydraulic pressure of 100 kg / cm ² toward the rotor side. In addition, the friction speed of the mating material 10 made of gas-nitrided SUS440B was set to 3 to 5 m / sec, and the rotor 8 was rotated until the sliding distance became 100 km. The test results are shown in Table 3.

[0027]

(2) Seizure resistance test A seizure resistance test was conducted using the same tester as the above wear resistance test. When the rotor 8 is rotated, the test piece 6 and the mating material 10
Due to friction between the stator holder 4 and the torque F
(F in Fig. 2) occurs, but the torque F is
The change was detected by the load cell 12 via 11, and the change of the torque F due to the change of the pressing force was read by the dynamic strain gauge 13. When seizure occurs, the torque F rises sharply, so the pressing force at that time was taken as the seizure resistance of the test piece.

The test conditions were as follows: . Mating member: SUS440B friction velocity was subjected to gas nitriding treatment: 8m / sec Lubricating oil: same oil oil temperature as in Example 1: 80 ° C. oil absorption: 400 cc / min contact pressure; 40 kg / cm ² than to baking occurs 10kg /cm
Table 4 shows the test results of increasing the pressure by ^{2 and} holding each surface pressure for 3 minutes.

[0030]

As is clear from Tables 3 and 4, the cylinders according to the present invention are superior in wear resistance and seizure resistance as compared with hard chrome-plated cylinders and Nikasil-plated cylinders. I understand. Moreover, the amount of wear of the counterpart material made of the alloy steel subjected to the gas nitriding treatment is small.

[0032]

As described in detail above, the cylinder of the present invention having the chromium oxide particle-dispersed nickel-tungsten alloy composite plating film is excellent in wear resistance, seizure resistance and corrosion resistance. Further, the wear amount of the piston ring combined with the cylinder of the present invention can be suppressed to a small amount.

[Brief description of drawings]

FIG. 1 is a sectional view of a cylinder according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view showing a rider wear tester.

FIG. 3 is a view on arrow XX in FIG.

[Explanation of symbols]

1 ... Cylinder 2 ... Cylinder base material 3 ... Chromium oxide particle dispersed nickel-tungsten alloy composite plating film 4 ... Stator holder 5 ... Sliding surface 6 ... Test piece 7 ... Oiling hole 8 ・ ・ ・ Rotor 9 ・ ・ ・ Mating material holder 10 ・ ・ ・ Mating material 11 ・ ・ ・ Spindle 12 ・ ・ ・ Load cell 13 ・ ・ ・ Dynamic strain gauge

Claims (1)

[Claims] 1. Chromium oxide particles having an average particle size of 0.5 to 10 μm dispersed in a nickel-tungsten alloy matrix consisting of 2 to 40% by weight of tungsten and the balance substantially of nickel in a volume ratio of 5 to 30%. A cylinder having a composite plating layer on the sliding surface.