JPH0379865A - Combination of piston ring and cylinder - Google Patents

Abstract

PURPOSE:To obtain high abrasion resistance by forming this combination of a piston ring provided with a composite plating layer composed of chromium oxide particles of the specific average particle diameter dispersed, at the specific volume ratio, in the nickel-phosphorous alloy base at its sliding surface, and a cylinder made of a hyper-eutectic Al-Si alloy. CONSTITUTION:In the combination of a piston ring and a cylinder for an inter nal combustion engine, the piston ring is provided with a composite plating membrane containing chromium oxide particles on its sliding surface. The composite plating membrane is composed of chromium oxide particles of 0.5-10mum in the average particle diameter dispersed, within the volume ratio range of 5-30%, in the nickel-phosphorous alloy base composed of 0.2-10 wt.% of phosphorous and the rest substantially of nickel. The cylinder is provided with the hyper-eutectic Al-si alloy membrane at its sliding surface. As a result, this combination is excellent in abrasion resistance in the case of being used for a high-lead gasoline fueled engine and the like.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a technology for combining a piston ring for an internal combustion engine having a composite plating layer with excellent wear resistance on its sliding surface and a cylinder made of an Al-Si alloy.

[Problems to be solved by conventional techniques and inventions] In recent years,
As internal combustion engines become lighter, cylinders made of hypereutectic Aj2-Si alloys or hypoeutectic Aj2-Si alloys are being put into practical use in some cases. Although this ^1-3i alloy cylinder exhibits good wear resistance, it is somewhat inferior to cast iron cylinders. Conventionally, piston rings used in combination with this type of cylinder have been proposed in which the sliding surfaces are coated with nickel composite plating with silicon carbide dispersed therein or iron composite plating with silicon carbide dispersed therein. By dispersing hard particles such as silicon carbide, the wear resistance is improved due to the oil retaining effect between the first sliding surface due to the hard particles and the second sliding surface due to the base portion.

However, in the case of nickel or iron composite plating in which silicon carbide is dispersed, the silicon carbide particles of the dispersed material are hard and the edges of the crystals are sharp, so that the mating cylinder material is likely to wear out. Furthermore, if the base of the composite plating layer is only nickel or iron, the hardness is insufficient, and conversely, the primary crystal silicon of the cylinder material is susceptible to wear.

Furthermore, hard chrome plating, which is commonly used for surface treatment of piston rings, has poor wettability with lubricating oil, so it has little oil retention effect and is prone to seizure. In this way, the piston ring with conventional plating and Aj2
- In combination with a Si alloy cylinder, the piston ring or cylinder may suffer abnormal wear, especially when leaded gasoline is used or under severe operating conditions.

Therefore, an object of the present invention is to eliminate the drawbacks of conventional hard chrome plating and composite plating when a cylinder made of Aj2-3i alloy is used as a mating material, and to provide a combination of a piston ring and cylinder with excellent wear resistance. It is to be.

[Means to solve the problem]

As a result of intensive research in view of the above problems, the present inventors have discovered that Aj? -3
The present invention was completed by discovering that the wear resistance can be improved together with the i-alloy cylinder.

That is, in order to achieve the above object, the present invention provides, as a first invention, a nickel-phosphorus alloy base containing 0.2 to 10% by weight of phosphorus and the remainder substantially nickel, with an average grain size of 0.2% by weight. To provide a combination of a piston ring having a composite plating layer on its sliding surface in which chromium oxide of 5 to 10 μm is dispersed in a volume ratio of 5 to 30%, and a cylinder made of a hypereutectic Al-3i alloy.

Further, as a second invention, in a base of a nickel-cobalt-phosphorus alloy consisting of 0.2 to 10% by weight of phosphorus, 10 to 40% by weight of cobalt, and the remainder substantially nickel, an average particle size of 0.5% is obtained. ~1.0μm chromium oxide accounts for 5~30% by volume
The present invention provides a combination of a piston ring having a sliding surface with a composite plating layer dispersed in a range of 1 and a cylinder made of a hypereutectic Aj2-3i alloy.

The present invention will be explained in detail below.

Phosphorus contained in the alloy base of composite plating increases its hardness when subjected to thermosetting treatment, exhibiting an excellent effect on improving wear resistance, and is also effective in improving the corrosion resistance of the base. If the amount of phosphorus is less than 0.2%, the hardness will not increase even if heat curing treatment is performed, and the effect of improving wear resistance will be small. If it exceeds 10%, the hardness increases, but the plating film becomes brittle, the impact strength becomes weaker, and the adhesion to the piston ring base material deteriorates.

The amount of phosphorus is therefore between 0.2 and 10% by weight.

Chromium oxide particles dispersed in the alloy base, together with phosphorus, have an excellent effect on improving the wear resistance of the coating.

In addition, since the crystals are less sharp than silicon carbide particles, they are less likely to wear out the mating cylinder material. Furthermore, chromium oxide particles have poor wettability with metals among ceramics and are difficult to melt with metals, so they have better scuff resistance than silicon carbide particles.6 The capacity of chromium oxide is 0.5 to 30. % and its average particle size is preferably 0.5 to 10 μm. If the capacity is less than 0.5% or the particle size is less than 0.5 μm, the area of chromium oxide occupying the base surface is small, and the effect of improving wear resistance is small.

Furthermore, if the capacity exceeds 30% or the particle size exceeds 10 μm, the wear of the mating material will increase, and the strength of the coating will also decrease.

In the present invention, as a second invention, cobalt is further added to the alloy matrix. Cobalt improves the heat resistance and corrosion resistance of the alloy base, as well as the crush fatigue strength of the coating.

If the amount of cobalt in the alloy matrix is less than 10% by weight, the above effects cannot be obtained significantly, and even if it exceeds 40% by weight, there is no significant change in the effect. Therefore, the amount of cobalt is between 10 and 40% by weight.

〔Example〕

The present invention will be explained in more detail by the following specific examples.

Example 1 Nominal diameter x width x thickness 78mm x 1.5mm
As a first step, the sliding surface of the 3.2 mm steel first pressure ring is coated with the usual nickel strike plating method.
Nickel plating with a thickness of 10 μm was formed. Next, as a second step, the sliding surface of the ring is coated with chromium oxide to a thickness of 12 mm using the bath components shown in Table 1 and the plating conditions below.
A 0 μm nickel-phosphorus composite plating was formed.

The amount of phosphorus in the composite plating layer was 5% by weight, and the amount of chromium oxide was 25% by volume.

(Plating conditions) Liquid temperature: 50 to 53°C pH: 3.5 Current density: 8/dm2 Plating time: As a third step, the piston ring was heated at 400°C for 1 hour to perform a thermosetting treatment to harden the base. This treatment resulted in a micro Vickers hardness of 800 to 900.

Example 2 Similar to Example 1, the nominal diameter x width x thickness was 78 mm x 1.
After forming nickel strike plating on the 5mm x 3.2mm steel first pressure ring, as a second step,
The sliding surface of the ring was coated with the bath components shown in Table 1 and the same plating conditions as Example 1 to a thickness of 110 chromium oxide dispersed.
A nickel-cobalt-phosphorus composite plating with a thickness of μm was formed.

The amount of phosphorus in the composite plating layer was 5% by weight, the amount of cobalt was 35% by weight, and the amount of chromium oxide was 15% by volume.

As a third step, the piston ring was heated at 400° C. for 1 hour to harden the base. This treatment resulted in a micro Vickers hardness of 800 to 900.

Table 1 (Actual Machine Test) The piston rings obtained in Example 1 and Example 2 were installed in a water-cooled 4-cylinder engine with a cylinder bore diameter of 781111114 cycles, and high-lead gasoline was used as fuel for 6
A bench test was conducted at 800 rpm, 1 full load, for 100 hours, and the amount of wear on the outer circumferential sliding surface of the piston ring and the inner circumferential surface of the AA-Si alloy cylinder (made of A390 alloy) was measured.

For comparison, piston rings with hard chromium plating, nickel composite plating with silicon carbide dispersed therein, and iron composite plating with silicon carbide dispersed therein were similarly tested.

The test results are shown in Figure 2.

〔Effect of the invention〕

In the test results, the combinations of the piston rings of Example 1 and Example 2 and the AI-Si alloy cylinder were as follows:
Compared to the combination with conventional hard chrome plating, the amount of piston ring wear is approximately 1/10, and the amount of cylinder wear is approximately 1/1
It has decreased to 75. Furthermore, it can be seen that the wear resistance is excellent when compared with the combination with a comparative piston ring that has been subjected to conventional dispersion plating.

From the above, it can be seen that the combination of the piston ring and cylinder according to the present invention has excellent wear resistance, especially when used in an engine using high lead gasoline as fuel.

[Brief explanation of drawings]

FIG. 1 is a graph showing the amount of wear of piston rings and cylinders in actual machine tests.

Claims (2)

[Claims] (1) In a base of a nickel-phosphorus alloy consisting of 0.2 to 10% by weight of phosphorus and the remainder substantially nickel, an average grain size of 0.
A combination of a piston ring having a composite plating layer on its sliding surface in which chromium oxide with a diameter of 5 to 10 μm is dispersed in a volume ratio of 5 to 30%, and a cylinder made of a hypereutectic Al-Si alloy. (2) Phosphorus: 0.2-10% by weight, cobalt: 10-40%
% by weight, in a matrix of nickel-cobalt-phosphorus alloy consisting essentially of nickel, with an average grain size of 0.5 to 10 μm.
A combination of a piston ring having a composite plating layer on its sliding surface in which chromium oxide is dispersed in a volume ratio of 5 to 30%, and a cylinder made of a hypereutectic Al-Si alloy.