JPS62159864A - Piston ring - Google Patents

Abstract

PURPOSE:To improve wear resistance and seizing resistance by dispersing a nickel-phosphorus composite metallic deposit and a short fiber and forming a nickel-cobalt-phosphorus composite metallic deposit. CONSTITUTION:5-30vol% of wear resistant particles 4 with a particle diameter of 10mum or less and 5-30vol% of short fibers 5 of metallic nitride, metallic carbide, metallic oxide, etc. with a fiber diameter of 0.05-1mum and a length of 10-200mum, are dispersed in an alloy base 3 with an ingredient composition of 2-15wt% of phosphorus and 85-98wt% of nickel, to form a composite metallic deposit for the sliding surface of a piston ring 1. Accordingly, the short fibers are dispersed, improving the brittleness of a film as well as wear resistance and seizing resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a piston ring having a dispersed plating layer.

(Prior Art) Various improvements have been made to piston rings to improve their wear resistance, seizure resistance, and corrosion resistance.

Conventionally, metal piston rings with chromium plating or nickel plating on the sliding surface have been proposed, but the wear resistance of these rings has not been satisfactory. To improve this, composite plating, in which wear-resistant particles are dispersed in a metal base such as nickel, is beginning to attract attention.

(Problems to be Solved by the Invention) Dispersing wear-resistant particles in the plating base improves the wear resistance of the coating, but if the amount of dispersion is too large, it may actually weaken the coating. On the other hand, adding shikophosphorus to the base of the composite plating layer and applying heat treatment increases the hardness of the film and improves wear resistance.
Although it shows an excellent effect in improving corrosion resistance, if the phosphorus content is too high, the base becomes brittle and the WI impact strength of the film decreases. If the strength of the coating is reduced in this way, problems such as peeling of the coating during operation will occur.

The present invention improves the brittleness of the film, which is a problem with conventional composite plating, and provides a piston ring having a film layer on its sliding surface that has excellent wear resistance, seizure resistance, and corrosion resistance.

(Means for solving problems) The present invention will be explained with reference to FIG.

The first invention includes wear-resistant particles 4 having a particle size of 10 μm or less in an alloy matrix 3 containing 2 to 15% by weight of phosphorus and 85 to 98% by weight of nickel on the sliding surface of a piston ring 1.
30% by volume, wire diameter 0°05~1μm, length 10~2
This piston ring has a composite plating layer in which short fibers 5 of 00 μm such as metal nitride, metal carbide, metal oxide, etc. are dispersed at 5 to 30% by volume.

The second invention uses cobalt 10 on the sliding surface of the piston ring 1.
~40% by weight, 2-15% by weight phosphorus, 50-88% nickel
In the alloy matrix 3 whose component composition is weight %, grain size 10 μm
5 to 30% by volume of the following wear-resistant particles 4 and wire diameter 0
．． 05-1 μm.

This piston ring has a composite plating layer in which 5 to 30% by volume of short fibers 5 of metal nitride, metal carbide, metal oxide, etc. having a length of 10 to 200 μm are dispersed.

(Function) Phosphorus contained in the alloy base increases the hardness of the film by heat treatment as described above. If the phosphorus content is low, the hardness of the film will not increase and the effect of improving wear resistance will be small.

If it exceeds 15% by weight, the base becomes brittle and the impact strength and adhesion of the film deteriorate. For this reason, the phosphorus content is preferably 2 to 15% by weight.

Wear-resistant particles dispersed in the composite plating film include:
Metal nitrides, metal carbides, metal oxides, etc., such as alumina, silicon nitride, silicon carbide, zirconia, and titanium carbide, are used. By dispersing such wear-resistant particles, the wear resistance and seizure resistance of the piston ring can be improved. If the amount dispersed in the base is less than 5% by volume, the effect of improving wear resistance will be small, and if the amount dispersed exceeds 30% by volume, the strength of the coating will decrease. Furthermore, if the particle size of the dispersed wear-resistant particles is too large, the effect of improving wear resistance will be small.

Therefore, the average particle size of the wear-resistant particles is preferably 10 μm or less, and the dispersion amount is preferably 5 to 30% by volume, preferably 0.5 to 5% by volume.
μm, and the dispersion amount is preferably 15 to 25% by volume.

As the short fibers dispersed in the composite plating film, alumina, silicon nitride, silicon carbide, zirconia, etc. are used as in the above wear-resistant particles. By dispersing such short fibers, the brittleness of the film can be improved. The wire diameter of the short fibers dispersed in the base is 0.05μm to 1.0μm.
m, L/D (length/diameter ratio) is preferably about 50 to 200; if the LZD ratio is less than 10, it resembles particles rather than fibers, and is less effective in improving the brittleness of the film.

Figure 2 shows measurements of the tensile strength of the plating film when the amount of short fibers dispersed was varied. This figure shows that if the amount of dispersion is less than 5%, the strength of the film is insufficient, and even if it exceeds 20%, there is no significant change in the effect. minttl
Increasing the amount of Bc will instead create pores in the base and cause the surface of the film to become rough.

In the present invention, as a second invention, cobal 1- is added to the alloy base in addition to the above-mentioned nickel and phosphorus.

Addition of Kobal 1- improves the seizure resistance and corrosion resistance of the alloy base, and also improves the crush fatigue strength of the coating. If the amount of nickel contained 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 preferably 10 to 40% by weight.

In the present invention, lubricating particles are not dispersed, but by dispersing them together with wear-resistant particles, the wear of the mating material can be further reduced. As the lubricant particles, for example, a solid lubricant having a low coefficient of friction and cleavability is used. Typical examples include particles of molybdenum disulfide, graphite fluoride, boron nitride, graphite, mica, and Teflon. The particle size of the lubricant particles dispersed in the base is 0.5 μn1 or less, depending on the lubricant used, and the amount of dispersion is 5 μm.
If it is less than % by volume, it will have little effect as a lubricant.

In addition, if the particle size exceeds 20 μm and the dispersion amount exceeds 35% by volume,
Base strength decreases.

(Example) As the first invention, silicon nitride particles and silicon nitride fibers were dispersed in a test piece of piston ring steel material (SKD-61) with a tip end face of 5 n+m x 5 nun according to the conditions shown in Table 1. A nickel-phosphorus composite plating layer with a thickness of 120 μm was formed.

As a second invention, silicon nitride particles and silicon nitride fibers are dispersed in a test piece made of the same material as in the above invention, and the thickness is 120 μm.
A nickel-cobalt-phosphorus composite plating layer of m was formed.

Next, each test piece obtained by each of the above methods was heated at 370'C for 1 hour to undergo a thermosetting treatment. Regarding the obtained test piece,
Table 2 shows the composition of the plating layer of the test piece and the results measured with a micro Vickers hardness meter.

Next, a wear resistance test and a seizure test of sliding surfaces according to the present invention will be explained. The test was conducted using a lidar one-type abrasion tester shown in FIGS. 3 and 4. The outline is Fe1 used as cylinder material etc. in stator holder l.
A disk 3 made of aluminum alloy and having a honed sliding surface 2 is removably attached, and in the center thereof, lubricating oil is supplied from the back side through an oil fill hole 4, and a hydraulic device (not shown) A suppressing force is applied to the stator holder l toward the right in the figure at a predetermined pressure. A test piece 7 is attached to each of four attachment holes carved at equal intervals on a circumference concentric with the rotation axis of a test piece holder 6 attached to the rotor 5 facing the disk 3, The 5×5 mm square tip end face of each test piece, which had been subjected to a predetermined surface treatment, came into contact with the sliding surface 2 of the disk 3 and was rotated at a predetermined speed by a drive device (not shown). The test is conducted while lubricating oil at a constant temperature is supplied to the sliding surface from the oiling hole 4 on the stator side.

) The wear test rotates the rotor 5 under a constant pressing force,
Wear resistance is evaluated based on the amount of wear between the test piece 7 and the stator disk 3 when the test piece 7 slides on the disk 3 by a predetermined sliding distance.

Furthermore, when the rotor 5 is rotated, a torque F is generated in the stator holder l due to the friction between the test piece 7 and the disk 3 as shown in the figure, so this torque F is applied to the load cell 9 via the spindle 8, and the pressing force is The change in torque F caused by the change in is read by the dynamic strain meter 10, and seizure resistance is evaluated based on the suppressing force at that time, assuming that seizure has occurred when torque F suddenly increases.

In addition to the test piece obtained in the above example, test piece 7 includes, for comparison, hard chromium plating generally used for wear-resistant surface treatment, silicon nitride dispersed nickel-phosphorus composite plating that does not contain short fibers, and nitrided Similar tests were conducted on silicon-dispersed nickel-cobalt-phosphorus composite plating. In addition, all composite plating test pieces had 10% silicon nitride particles dispersed in them. 6 a) As a wear test lubricant, dust (JI32 Using oil at a temperature of 80°C to which 0.2 g/l of (seed) was added, it was supplied from the oil hole 4, and while applying a pressing force of hydraulic pressure of 100 kg/a 112 toward the rotor side to the stator holder l, the test piece 7 was heated. The rotor 5 was rotated at a friction speed of 3 to 5 m/see until the sliding distance reached 100 KOI.

The test results are shown in Table 3 below.

b) Seizure test The same lubricant as that used in the wear test was used, and a pressing force of 40 Kg/mouth 2 was first applied to the stator holder l toward the rotor, and the rotor 5 was moved at a friction speed of 8 m/see.
Rotate for 3 minutes, then increase the pressing force to 50 kg/(2)2 for 3 minutes, and then increase the pressing force to 10 kg.
/an'' stepwise and held for 3 minutes each time, the change in torque F was recorded with the dynamic strain meter 10 via the load cell 9, and the contact surface pressure was determined from the pressing force when the torque suddenly increased. This was taken as the surface pressure at which seizure occurred.

The test results are shown in Table 4 below.

C) Strength test of composite plating layer Next, a strength test of the composite plating layer according to the present invention will be explained. The test was conducted using the testing machine shown in Figure 5. For the test piece 2, a piston ring whose outer peripheral surface had been subjected to a specified surface treatment was used, with the abutment section facing sideways and the upper end attached to the fixed head L.
The lower end is attached to the upper end of the load cell 4 of the movable head 5. When the movable head 5 is raised, a crack occurs on the surface of the test piece 2 opposite to the abutment. A strain gauge 3 is attached to the outer peripheral surface of the test piece 2 on the opposite side of the abutment.

Read the change in strain with a strain meter. When a crack occurs, the strain changes rapidly. The change in the pressing force at this time is read with a strain meter via the load cell 4 to evaluate the strength of the composite plating layer.

The test piece was a nickel-phosphorus composite in which 20% by volume of silicon nitride particles, 10% by volume of silicon nitride short fibers, and 5.5% by weight of phosphorus according to the first invention were dispersed on the outer peripheral surface of a cast iron piston ring. The one on which the plating layer was formed, the second invention, 208% by weight of silicon nitride particles, and 10% of silicon nitride short fibers.
% by volume, 32% by weight cobalt and 5.5% by weight phosphorus
For comparison with the one in which a dispersed nickel-cobalt-phosphorus composite plating layer was formed, a layer containing 20% by volume of silicon nitride particles and 30% by weight of cobalt without containing short silicon nitride fibers was used.
and nickel-cobal 1 with 5.5% by weight of phosphorus dispersed in it.
--The one on which a phosphorus composite plating layer was formed was used. The test results are shown in FIG.

(Effects) From Table 31 and Table 4, the nickel-phosphorus composite plating layer of the present invention in which short fibers are dispersed, and the nickel-cobalt-phosphorus composite plating layer of the present invention in which short fibers are dispersed, compared to the conventional plating layer. It can be seen from FIG. 6 that the composite plating layer of the present invention has high film strength and is suitable as a surface treatment layer for piston rings and the like.

[Brief explanation of drawings]

Figure 1 is a plan view of the plating area of a test piece showing an example of the present invention. Figure 2: Nickel strike plating layer 4: Wear-resistant particles 5: Short fibers Figure 2 shows the amount of dispersed short fibers varied. A diagram showing the tensile strength when From the top, the phosphorus content is 3% by weight. Changes at 5% by weight and 8% by weight are shown. Figures 3 and 4 are diagrams of the rider wear tester. In the figure l: Stator holder 2: Sliding surface 3: Disc 4: Lubricating hole 5: Rotor 6: Test piece holder 7: Test piece
8 Nispindle 9: Load cell lo: Dynamic strain meter Figure 5 shows the tensile testing machine used for the strength test of the composite plating layer. In the figure, 1: Fixed head 2: Test piece 3: Strain gauge 4: Load cell 5 : Movable head FIG. 6 is a diagram showing the results of a strength test of the composite plating layer.

Claims (2)

[Claims] (1) A piston ring with a composite plating layer formed on the sliding surface, where the composite plating layer has a wear-resistant particle size of 10 μm or less in an alloy base of 2 to 15% by weight of phosphorus and 85 to 98% by weight of nickel. 5 to 30% by volume of particles and a wire diameter of 0.05
A piston ring containing 5 to 30% by volume of short fibers such as metal nitride, metal carbide, metal oxide, etc., with a length of ~1 μm and a length of 10 to 200 μm dispersed. (2) A piston ring with a composite plating layer formed on the sliding surface, the composite plating layer being in an alloy matrix of 10 to 40% by weight of cobalt, 2 to 15% by weight of phosphorus, and 50 to 88% by weight of nickel. , 5 to 3 wear-resistant particles with a particle size of 10 μm or less
0 volume% and wire diameter 0.05-1μm, length 10-20
Piston ring in which 5 to 30% by volume of 0 μm short fibers such as metal nitride, metal carbide, metal oxide, etc. are dispersed.