JPS62255667A - Piston ring - Google Patents

Abstract

PURPOSE:To promote the improvement of wearing resistance, by forming a sliding surface by a compound film layer constituted such that hard quality particles are dispersed in a plated base layer of iron, cobalt and phosphor alloy. CONSTITUTION:A piston ring 1 forms its sliding surface by a compound film layer 2 in which hard quality particles of 0.5-10mum mean grain size are dispersed by a 5-30% range by volume ratio in a plated base layer of iron, cobalt and phosphor alloy consisting of 0.2-10wt% phosphor, 10-40wt% cobalt and the rest of iron. The phosphor contained in the alloy base layer increases hardness if thermo-setting treatment is applied, displaying an excellent effect in wearing resistance. Metal nitride, metal carbide and metal oxide of silicon nitride, silicon carbide, titanium carbide, zirconia, alumina, cobalt oxide, etc. are suitable for the hard quality particle.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a piston ring for an internal combustion engine that has a composite plating layer with excellent wear resistance on its sliding surface.

(Prior art and problems) Problems that occur in the function of piston rings include oil consumption and blow pie from the perspective of the engine as a whole, and issues such as wear resistance, heat resistance, oil retention, and cylinder material from the perspective of the piston ring itself. Problems include wear and tear. For this reason, current piston rings are coated with hard chrome plating,
Surface treatments such as molybdenum spraying or nitriding treatment such as tuftride are carried out on steel.

However, hard chrome plating has problems with wear resistance and seizure resistance when leaded gasoline is used, while molybdenum thermal spraying has good heat resistance and seizure resistance, but has poor wear resistance, and the mating cylinder material also wears out. let Tuftride treatment has excellent wear resistance, but when nitriding cast iron or common steel, the treatment temperature is raised, which is undesirable as the ring deforms, and the seizure resistance is also poor.

The present invention aims to eliminate the drawbacks of conventional hard chromium plating, MO spraying, nitriding, etc., and to provide a piston ring having a hard coating layer that itself has excellent wear resistance and a small coefficient of friction.

(Structure of the Invention) In order to achieve the above object, the present invention provides, as a first invention, an iron-cobalt-phosphorus containing 0.2 to 10% by weight of phosphorus, 10 to 40% by weight of cobalt, and the remainder iron. A piston ring characterized by having a composite coating layer on a sliding surface in which hard particles with an average particle size of 0.5 to 10 μm are dispersed in a volume ratio of 5 to 30% in a base layer of alloy plating. provide,
As a second invention, iron-cobalt-containing 0.2 to 10% by weight of phosphorus, 10 to 40% by weight of cobalt, and the remainder iron.
In the base layer of phosphorus alloy plating, the average grain size is 0.5 to 10 μm.
hard particles in a volume ratio of 5 to 30% and an average particle size of 0.5 to 30%.
The lubricant particles of 20 μm are in the range of 5 to 20% by volume, and the total of hard particles and lubricant particles is 10 to 45% by volume.
The above-mentioned point of flexure is solved by providing a piston ring characterized in that the sliding surface has a composite film layer dispersed in a range of .

When the phosphorus contained in the alloy base is subjected to thermosetting treatment, its hardness increases and it exhibits an excellent effect on 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 wear resistance will be small.

If it exceeds 10%, the hardness increases, but the film becomes brittle, the impact strength becomes weak, and the adhesion deteriorates. Therefore, the amount of phosphorus is preferably 0.2 to 10%.

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 effect will not be obtained significantly, and if it exceeds 40% by weight, there will be no significant change in the effect. Therefore, the amount of cobalt should be 10 to 40% by weight. % is good.

Hard particles, together with phosphorus, have an excellent effect on improving the abrasion resistance of the coating. Hard particles include silicon nitride, silicon carbide,
Metal nitrides, metal carbides, and fully curved oxides such as titanium carbide, zirconia, alumina, and cobalt oxide are suitable.

It is preferable that the capacity of the hard particles is 0.5 to 30% and the average particle size is 0.5 to 10 μm. If the capacity is 0.5% or less or the average particle size is 0.5 μm or less, the hard particles occupy a large proportion of the base surface. If the area is small and the abrasion resistance effect is low, and if the capacity exceeds 30% or the average particle size exceeds 10 μm, the abrasion of the mating material will increase and the strength of the film will also decrease.

In the present invention, as a second invention, lubricating particles are also dispersed in addition to hard particles. Lubricant particles have an excellent effect on improving the wear of the mating material. As the lubricant particles, 1 For example, solid lubricants with low coefficient of friction that have cleavability are suitable. 1 Typical examples include particles of molybdenum disulfide, graphite fluoride, boron nitride, graphite, mica, Teflon, etc. .

The capacity of the lubricant particles is preferably 0.5 to 20% and the average particle size is 0.5 to 20 μm. If the capacity is 0.5% or the average particle size is less than 0.5 μm, the lubricant is less effective. Moreover, if the capacity exceeds 20% or the average particle size exceeds 20 μm, not only will the wear resistance of the plating layer itself decrease;
The strength of the film also decreases.

The total amount of hard particles and lubricant particles is suitably 10 to 45% by volume from the viewpoint of wear resistance and effectiveness as a lubricant.

(Example 1) First, as a first step, for tlIII first pressure culling with a nominal diameter x width x thickness of 78 mm x 1.5 m x 3.2 am.
Nickel plating with a thickness of 10 μm was formed on the sliding surface by a common nickel strike plating method. Next, as a second step, an iron-cobalt-phosphorus composite plating having a thickness of 120 μm in which silicon nitride was dispersed was formed on the sliding surface of the ring using the bath composition and plating conditions shown in Table 1.

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 silicon nitride was 25% by volume.

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 micropicchus hardness of 800 to 900.

(Example 2) As a second embodiment of the invention, the same as in the first embodiment.

Nominal diameter x width x thickness 78nyn x 1.5nn+
After forming nickel strike plating on the 3.2 m steel first pressure ring, in the second step, silicon nitride was applied as hard particles to the sliding surface of the ring using the bath composition and plating conditions shown in Table 2 for lubrication. An iron-cobalt-phosphorus composite plating having a thickness of 110 μm was formed in which molybdenum disulfide was dispersed as agent particles.

The amount of phosphorus in the composite plating layer was 5% by weight, the amount of cobalt was 35% by weight, the amount of silicon nitride was 15% by volume, and the amount of molybdenum disulfide was 10% 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 micropicchus hardness of 800 to 900.

(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 78Iff and 11.4 cycles, and 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 78Iff and a 6-cylinder engine using high lead gasoline as fuel.
A bench test was conducted at 800 rpm, full load, and for 100 hours.
e12)) The amount of wear on the inner circumferential surface was measured.

For comparison, piston rings with hard chrome plating, molybdenum spraying, and Tuftride treatment were also tested in the same way.

The test results are shown in Figure 2.

(Effects) As is clear from FIG. 2, both the piston rings of the first invention and the second invention have less wear than the comparative piston ring and less wear of the mating cylinder.

Furthermore, since the piston ring of the second invention has lubricant particles dispersed therein, the wear of the mating member is less than that of the first invention.

Therefore, it can be understood that it is particularly excellent for engines using high lead gasoline as fuel, which requires high wear resistance.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the piston ring of the present invention.
Piston ring 2: Composite plating layer FIG. 2 is a graph showing the wear of the piston ring and the mating cylinder in an actual machine test.

Claims (2)

[Claims] (1) Phosphorus: 0.2-10% by weight, cobalt: 10-40%
A composite coating layer in which hard particles with an average particle size of 0.5 to 10 μm are dispersed in a volume ratio of 5 to 30% in a base layer of iron-cobalt-phosphorus alloy plating, the balance of which is iron. A piston ring characterized by having on its sliding surface (2) Phosphorus: 0.2-10% by weight, cobalt: 10-40%
Hard particles with an average particle size of 0.5 to 10 μm account for 5 to 30% by volume in the base layer of iron-cobalt-phosphorus alloy plating, the remainder of which is iron, and the remainder is iron. The sliding surface has a composite film layer in which lubricant particles are dispersed in a volume ratio of 5 to 20%, and the total of hard particles and lubricant particles are dispersed in a volume ratio of 10 to 45%. A piston ring featuring