JPS63297870A - Piston ring - Google Patents

Abstract

PURPOSE:To enhance the wear-resistant and anti-seizure abilities of a piston ring by forming a composite dispersion plated layer having a specified thickness on a nitride layer formed at least on the outer peripheral slide surface of the piston ring. CONSTITUTION:A steel material used as the base body of a piston ring is a material which is suitable for obtaining a nitride processed layer exhibiting a satisfactory wear-resistant characteristic, and a steel material containing about 0.16-1.3% of C and about 12-19% of Cr, or a chrome steel material containing the same components together with a slight amount Mo or V are generally used. After a nitride process is applied to at least on the slide surface of the base body, a thin layer consisting of a composite dispersion plated layer having a thickness of about 0.5-20mum is formed on the slide surface. This composite dispersion plated layer is obtained by dispersing hard particles of silicone nitride into a metal plate base consisting of a nickel group material containing phosphorus and a cobalt.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to improved piston rings, and more particularly to copper piston rings for internal combustion engines that have improved sliding characteristics during initial operation.

Prior art and its problems In recent years, as internal combustion engines have become lighter and more powerful, the quality required of piston rings has become higher. Conventionally,
Piston rings for internal combustion engines have their sliding surfaces subjected to wear-resistant surface treatments such as hard chromium plating, thermal spraying, or nitriding as a means of improving their durability. Among these surface treatments, nitriding treatment in particular has attracted attention and is widely used as a surface treatment for piston rings used under severe operating conditions because it exhibits excellent wear resistance properties.

However, while the nitrided layer has excellent wear resistance, it cannot necessarily be said to have sufficient seizure resistance compared to hard chrome plating layers or thermal sprayed layers, and may cause abnormal wear when used under harsh operating conditions. However, further improvements have been desired.

In view of the above, an object of the present invention is to provide a piston ring for an internal combustion engine that has excellent wear resistance and seizure resistance, and exhibits good sliding characteristics even under severe usage conditions. It has been done.

Means for solving the problems and their effects In this invention,
A piston ring that achieves the above purpose has a nitrided layer formed on at least the outer peripheral sliding surface, and a thin layer of a composite dispersion plating layer with a thickness of 0.5 to 20 μm is further formed on the nitrided layer. The Company provides steel piston rings for internal combustion engines.

The piston ring of the present invention has a base made of steel, and at least its sliding surface is nitrided to form a nitrided layer, and the good wear resistance of this nitrided layer increases its durability. Therefore, in the present invention, it is preferable that the steel material used as the base of the piston ring be a steel material suitable for obtaining a nitrided layer exhibiting good wear resistance properties. Steel containing 19% Cr or chromium steel containing a small amount of MO and/or V is generally used.

These chromium steel materials are suitable for forming a good wear-resistant nitrided layer. Therefore, piston rings made of these steel materials and whose sliding surfaces are nitrided have excellent wear resistance properties.

However, as described above, although the nitrided ring exhibits good wear resistance, it has a problem with seizure resistance, and abnormal wear may occur particularly during initial operation. Also, recently, nickel-phosphorus composite plating has been used, but under severe conditions such as high speed and high load in internal combustion engines with superchargers, peeling of the film may occur.

In the present invention, as a means to eliminate the above-mentioned disadvantages of the nitrided ring, a composite dispersion plating with a thickness of 0.5 to 20 μm is further applied on the wear-resistant nitrided layer formed on the outer peripheral sliding surface of the piston ring. A thin layer (initial najimi layer) is formed.

Here, the composite dispersion plating layer refers to silicon nitride (SiJa) in a nickel-based metal plating base containing phosphorus and cobalt.
) This is a plating layer in which hard fine particles are dispersed, and this plating layer has excellent wear resistance, and particularly in terms of seizure resistance, it is much better than a nitrided layer or a hard chromium plating layer.

In the piston ring of the present invention, an extremely thin composite dispersion plating layer is formed on the nitriding layer that has good wear resistance properties, and this composite dispersion plating layer prevents seizures that are likely to occur during initial smooth operation. The occurrence of abnormal wear is effectively prevented.

If the thickness of the composite dispersion plating layer is too thin, the composite dispersion plating layer will disappear before a sufficient initial smooth state is achieved, and the expected effect will not be sufficiently obtained. In the present invention, it is necessary that the thickness of the composite dispersed plating layer be 0.5 μm or more.

On the other hand, increasing the thickness of the composite dispersion plating layer not only increases processing costs, but also makes it easier for the plating layer to peel off, or makes it difficult to utilize the good wear resistance properties of the nitrided layer. There is more wear on the outer periphery,
There are disadvantages such as the ring abutment gap rapidly increasing and the airtightness of the piston ring deteriorating rapidly.

Therefore, in the present invention, the thickness of the composite dispersion plating layer is 20 μm.
m or less, preferably 10 μm or less.

In addition, in the present invention, as a composite dispersion plating layer, a grain size of silicon nitride in a base of a nickel alloy containing 10 to 50% by weight of cobalt and 2 to 10% by weight of phosphorus:
When adopting a composite dispersed nickel plating layer in which hard particles of 10 μm or less are dispersed in a volume ratio of 5 to 30%, the wear resistance properties of the composite dispersed plating layer are close to those of the nitrided layer, and therefore initial wear is also reduced. This is particularly suitable.

Here, the inclusion of phosphorus increases the hardness of the plating base and effectively acts to improve wear resistance properties. For this effect, the content is preferably 0.2% by weight or more. However, if it is contained in a large amount exceeding 10%, the plating base becomes brittle, so the content is preferably 10% or less. Furthermore, the inclusion of cobalt has the characteristic of increasing the seizure resistance and abrasion resistance of the plating base and increasing the film strength. For this effect, the amount is preferably 10% by weight or more, and 5% by weight or more.
Even if it exceeds 0% by weight, there is no significant change in the effect and it is not economical. In addition, the amount and particle size of silicon nitride (SiJ4) hard particles dispersed are also related to the thickness of the plating layer to be formed, but if they are excessively large or large, the plating layer becomes brittle and the sliding Since this increases the wear of the mating material, in the present invention, the amount of dispersion is 5 to 30% by volume.
It is desirable that the range and particle size be 10 μm or less.

In addition, the hardness of the film is 600 to 800 with Micropinkers.
Good. If it exceeds 800, the film becomes brittle and tends to peel off under severe usage conditions. Also, if the hardness is less than 800,
Seizure resistance and abrasion resistance are poor, and the effect is not fully demonstrated.

Example 1) Seizure resistance test Alloy steel 5US440B (C: 0.75-0.95%,
Si: 1.0% or less, Mn: 1.0% or less, P: 0.0
4% or less, Ni: o, 60% or less, Cr: 16.0-1
8.0%, Mo: 0.75% or less) with a hard chromium plating layer formed (A), a sample with a nitrided layer formed (
B) Silicon nitride with a particle size of 5 μm or less is about 10% by volume in a nickel matrix containing 30% cobalt and about 5% phosphorus.
Sample with a dispersed composite dispersed nickel plating layer (C
), and a sample (D) containing approximately 90% phosphorus and a composite dispersed nickel plating layer in which approximately 10% by volume of silicon nitride with a particle size of 5 μm or less is dispersed in a nickel matrix was prepared. A sex test was conducted.

The main parts of the test equipment are schematically shown in Figures 1 and 2. Lubricating oil is supplied from the back side to the center of a disc 3 with a diameter of 80 mm that is removably attached to the stator holder l through an oil filling hole 4. Lubricated. A predetermined pushing pressure is applied to the stator boulder 1 toward the right in the figure by a hydraulic device (not shown). A rotor 5 is provided opposite to the disk 3, and is rotated at a predetermined speed by a drive device (not shown). A test piece holder 6 removably attached to the rotor 5 has four test pieces 7 of 51 squares and a height of 10 mm spaced concentrically at equal intervals. In such a device, a predetermined pressing force is applied to the stator holder 1 so that the disc (mate material) 3 and the test piece 7 come into contact with each other at a predetermined pressure. rotor 5 while refueling at a predetermined refueling speed.
Rotate. Using this testing device, a seizure resistance test was conducted in the following manner. That is, while sliding the test piece 7 on the disk 3 and increasing the pressure acting on the stator holder 1 step by step at regular intervals, the pressure generated on the stator holder 1 due to the friction between the test piece 7 and the disk 3 is increased. Torque (frictional force) T is applied to the load cell 9 via the spindle 8 shown in FIG. 2, which is a side view taken along line nn in FIG. When the torque T suddenly increases, it is assumed that seizure has occurred, and the contact surface pressure at that time is used as the surface pressure for seizure, and the quality of the seizure resistance is determined based on the magnitude.

The test conditions are as follows.

Friction speed: 3m/sec Lubricating oil: Motor oil #30 Contact surface pressure: 10kg/cs every 3 minutes from 40kg/cs
Increase by cm.

The test results are shown in Figure 3. As can be seen from the figure, the sample (C) on which the composite dispersion plating layer of the present invention was formed, the sample (D) on which the nickel-phosphorus-silicon nitride composite dispersion plating layer was formed, and the sample (A) on which the hard chromium plating layer was formed.
) and sample (B) in which a nitrided layer was formed, the seizure resistance was significantly improved.

2) Wear resistance test The same steel material (
A sample (B-1) in which a 100 μm thick nitrided layer was formed by nitriding SUS440B), the sample (B-
Sample (A-1) in which a hard chromium plating layer with a thickness of 10 μm was formed on the nitrided layer of 1), Sample (B-1)
), a composite dispersed nickel plating layer with a thickness of 10 μm is formed by dispersing approximately 10% by volume of silicon nitride with a particle size of 3 μm or less in a nickel matrix containing 30% cobalt and 5% phosphorus. The formed sample (C-1), the sample (B-
A sample in which a composite dispersed nickel plating layer with a thickness of 10 μm was formed on the nitrided layer of 1), in which silicon nitride with a particle size of 3 μm was dispersed at a volume ratio of 5% in a nickel base containing about 9% phosphorus ( Regarding D-1), a wear resistance test was conducted using the test equipment used in the seizure resistance test. The test conditions are as follows.

Friction speed: 5 m/sec Mating material: FC25 for cylinder liner Contact surface pressure: 100 kg/c11 Lubricating oil: Motor oil #30 + oil temperature with dust:
80℃ Supply fl: 400 cc/min
As shown in the figure.

As is clear from Fig. 4, the sample (A-1) on which a hard chromium plating layer was formed wore out the fastest, followed by the sample (D) on which a nickel-phosphorus-silicon nitride composite dispersion plating layer was formed.
-1), the sample on which the composite dispersion plating layer of the present invention was formed (
The wear rate of C-1) is close to that of the nitrided layer (B-1), indicating good wear resistance properties. In addition, in the above test, 5US440B material was used as the steel material, but
The steel material is not limited to this, but other chromium steels containing high chromium, such as 1.0 to 1.4%C213 to 16%C
r, and a total of 0.2 to 1 of one or two of Mo and ■
．． Of course, chromium steel containing 0% can also be used.

3) Actual machine test Next, the nominal diameter x width x thickness is 81 x 1.5 x 3.3 tar.
The composite dispersion plating of the present invention was applied to the steel first pressure ring of No. Sliding surfaces and cast iron (F
The amount of wear on the inner circumferential surface of the e12) cylinder liner and defects such as film peeling and scuffing were investigated.

The composite dispersion plated piston ring of the present invention is made of the same steel material (SUS440B) used in the seizure resistance test described above.
A nitrided layer with a thickness of 100 μm was formed by nitriding the piston ring. On top of the nitrided layer, a nickel base containing 30% cobalt and 5% phosphorus with a particle size of 3 μm was added.
Thickness 15μ with the following silicon nitride dispersed at 10% by volume
A composite dispersed nickel plating layer of m was applied. In addition, as comparative materials, we used a steel material of the same quality (SUS440 B) with a nitrided layer of 100 μm as is, a hard chromium plating layer of 15 μm formed thereon, and a steel material with grains in a nickel base containing approximately 9% phosphorus. Silicon nitride with a diameter of 3 μm is 10% by volume.
The tests were also carried out on a composite dispersion plating layer with a thickness of 15 μm and a composite dispersion plating layer of the present invention containing about 9% of phosphorus, which had a micropinkers hardness of 950. The test results are shown in Table 1.

As can be seen from Table 1, the steel piston ring for internal combustion engines of the present invention has a thin composite dispersion plating layer that has good wear resistance, especially good seizure resistance tests, on a nitrided layer that has good wear resistance. layer (initial nudging layer), it effectively prevents the occurrence of seizure that tends to occur during the initial nudging period of operation, prevents peeling of the film (and increases the durable life, making it suitable for industrial use). The utility value of the above is great.

[Brief explanation of drawings]

Figures 1 and 2 are diagrams showing the main parts of the test equipment used for the seizure resistance test and the wear resistance test. FIG. 3 is a graph showing the results of the seizure resistance test, and FIG. 4 is a graph showing the results of the wear resistance test. In the figure: 1... Stator holder, 3... Disc (mating material), 4... Lubrication hole, 5... Rotor, 6... Test piece holder, 7... Test piece, 9...Load cell, 10...Dynamic strain meter. Agent Patent Attorney Hideaki Kuwahara BCD Figure 4 Examination Q (Intermediate)

Claims (1)

[Claims] (1) An internal combustion engine characterized in that a nitrided layer is formed on at least the outer peripheral sliding surface, and a thin layer of a composite dispersion plating layer with a thickness of 0.5 to 20 μm is further formed on the nitrided layer. Piston ring for engines (2) The composite dispersion plating layer is made of a nickel alloy base containing 10 to 50% by weight of cobalt and 2 to 10% by weight of phosphorus, and a hard material made of silicon nitride with a particle size of 10 μm or less. A composite dispersed nickel plating layer in which particles are dispersed in a volume ratio of 5 to 30%, and the plating layer is heat-treated to have a hardness of 600 to 800 micro Vickers.
A steel piston ring for an internal combustion engine according to claim 1, which is a plating layer tempered to