JPH03260475A - Piston ring - Google Patents

Abstract

PURPOSE:To enhance the anti-abrasiveness and resistance against seizure, provide excellent anti-corrosiveness when laid in a high pressure, high temperature, and sulfuric acid attacking atmosphere, and increase the anti-exfoliation strength by using a Ni- based amorphous alloy in specific wt.% and certain grain sizes together with Mo to form a metallizing material for the base metallization film, wherein amorphous shall remain over a certain percentage after plasma metallization. CONSTITUTION:The base metallization film 3 consists of 60-80wt.% Mo having grain sizes between 44 and 125mum and 20-40wt.% Ni-based amorphous alloy having grain sizes between 10 and 64mum, wherein the Ni-based alloy shall cause remaining of amorphous over 50% after plasma metallization. A piston ring is made of spherical graphite cast iron, and the mother material surface 1 on its periphery is subjected to a blasting process into a courseness of approx. 20mum RZ, and the base metallizing material undergoes plasma metallization in a single layer. After metallization amorphous of 55% remains, which is followed by finish processing by conventional method. Containing of Ni-based amorphous alloy as a result will provide excellent anti- abrasiveness and resistance against seizure and also a high tensile strength, so that cracks will hardly be initiated.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to thermal spray piston rings.

[Conventional technology]

Piston rings with a thermally sprayed coating formed on the outer circumferential surface are known, and when using a thermally sprayed material other than Mo salt,
In order to improve adhesion to the base material, a base sprayed coating is provided below the surface sprayed coating. In this case, usually a shallow groove is formed on the outer circumferential surface of the piston ring,
A base thermal spray coating is provided on the entire surface within the groove, and the thermal spray material for the surface layer is welded into the groove.

Conventionally, for example, a Ni-Al base thermal spray material has been used and achieved a certain degree of effectiveness in internal combustion engines, but it is insufficient under high loads, and the Ni-Al base thermal spray coating may peel off within the layer. be.

In high-load diesel engines, high temperatures and
High price eI! Corrosion resistance in a corrosive atmosphere is required,
When the Ni-A42 base thermal spray coating is plasma sprayed, the components are NiA 145%, Ni is A 1245%, N
10 +A 1. It has a three-component structure with 10% gos, and pure Ni and pure AJ are locally observed, but a problem occurs between the fused and laminated particles. That is, NiO has poor corrosion resistance and may cause lamination corrosion, which may destroy the sprayed layer and cause peeling in combination with twist stress.

In addition, the Ni-Al base thermal spray material contains 5 to 10% Al and Ni.
Therefore, it has the disadvantage of low hardness and poor wear resistance.
The Ni-Al base thermal spray coating exposed on the outer circumferential surface is easily abraded by the hard powder produced by combustion, causing stepped wear between the base material and the surface spray coating on the outer circumferential surface, and the concave portion acts as a notch. As a result, the peeling resistance deteriorates, and the edges of the recessed portions may cause abnormally accelerated wear on the cylinder wall surface.

The present invention has been made in view of the above circumstances, and is a thermal spraying base that has excellent wear resistance, seizure resistance, corrosion resistance in high pressure, high temperature, and corrosive sulfur atmosphere, and has high peeling resistance. An object of the present invention is to provide a thermal sprayed piston ring with a coating.

[Means to solve the problem]

The structure of the present invention is that in a piston ring in which a surface sprayed coating is formed on a base sprayed coating formed on the outer peripheral surface, the base thermal sprayed coating contains 60 to 80% by weight of Mo and 20 to 40% by weight of a Ni-based amorphous alloy. It is characterized by being made of a thermal sprayed material and having a coating thickness of 20 to 1100p.

The grain size of Mo is preferably 44 μm or more and less than 125 μm, and the grain size of the Ni-based amorphous alloy is preferably 10 μm or more and less than 64 μm.

The Ni-based amorphous alloy is 50%
% or more of amorphous remains.

[Effect]

Since it contains 60 to 80% by weight of Mo, it has good adhesion to the piston ring base material.

An evaluation test for adhesion to the piston ring base material will be described below.

The base material surface of the outer peripheral surface of a piston ring made of spheroidal graphite cast iron and having a ring diameter of 9Q mmφ was blasted to a roughness of 20 μm RZ, and then a single layer of base thermal spray material was plasma sprayed and finished using a conventional method. Then, a pair of bottles arranged at symmetrical positions on the inner periphery of the piston ring were moved in opposite directions to spread the piston ring, and adhesion was examined based on the amount of spread until peeling or cracking occurred and the amount of residual thermal spray coating.

Thermal spraying materials used: Mo and Ni-based amorphous alloy Mo has a purity of 99.7%, and the Ni-based amorphous alloy contains Cr in addition to Ni.
, W, Mo, and some BSC, 55% after thermal spraying
Amorphous remains.

In addition, the particle size of Mo is 44 μm or more and less than 125 μm, and the particle size of Ni is
The grain size of the base amorphous alloy is 10 μm or more and less than 64 μm
It is full.

Table 1 shows the results when the amount of Mo was changed.

(Margins below) Table 1 From the above results, it can be seen that when Mo is 60 to 80% by weight, the sprayed residual amount is 100% and the amount of expansion is large (see Figure 3).
.

Also, since it contains an Nt-based amorphous alloy in addition to Mo,
It has excellent wear resistance and seizure resistance, and has high tensile strength, making it difficult to develop cranks. The Ni-based amorphous alloy has a high tensile strength of 72 K g/mm'' and hardness of HeC45.

In addition, when the Mo particle size is 44 μm or more and less than 125 μm, the roughness of the base sprayed coating becomes large and the bonding force with the surface sprayed coating is large.The bond between the base sprayed coating and the surface sprayed coating is an interlock bond. Yes (see Figure 2, 1 is the piston ring base material, 3 is the base sprayed coating, and 4 is the sprayed coating on the surface layer).Therefore, in order to increase the bonding strength, it is necessary to roughen the surface roughness of the base sprayed coating. For this purpose, it is better to increase the particle size of the base thermal spray material. In addition, if it is 125 μm or more, the Mo powder becomes undissolved and the bonding strength deteriorates.

On the other hand, if the particle size of the Ni-based amorphous alloy is large, the uniformity within the sprayed coating will be poor, the intralayer strength will decrease, and intralayer peeling will occur. This is a characteristic of the thermal spray coating in which particles are melted and each particle is layered, and N acts as a reinforcing material for the Mo layer.
The i-based amorphous alloy needs to be uniform, and the smaller the particle size, the more uniformly distributed it will be and the stronger the bonding force will be. Therefore, the grain size of the Ni-based amorphous alloy is 10 μm.
The above value is less than 64 μm.

Below, piston rings in which a surface sprayed coating was formed on a base thermal sprayed coating were subjected to a torsion test in which the particle sizes of Mo and Ni-based amorphous alloys were varied, and the presence or absence of peeling was investigated.

A shallow groove was formed on the outer circumferential surface of a piston ring with a ring diameter of 90 mmφ made of spheroidal graphite cast iron, and after blasting the base material surface of the groove to a roughness of 20 μm RZ, the entire surface inside the groove was The base sprayed material was plasma sprayed to form a base sprayed coating with a thickness of 60 ttm, and the surface sprayed material was plasma sprayed into the grooves to form a 140μm thick sprayed coating, which was then finished using a conventional method. Then, the piston ring was twisted 60 degrees (shifting the abutment up and down), and the presence or absence of peeling in a 20 mm section on the opposite side of the abutment was examined.

The results are shown in Table 2. The test was performed on 10 piston rings, and those with no 11111 were rated O, those with peeling were 1 to 5, △, and those with peeling were 6 to 5.
In the case of 10 pieces, it is indicated by ×.

Base thermal spraying material used: Mo 70% by weight Ni-based Amol 30! Amount % Fas alloy (same as that used in the adhesion test above) Thermal spraying material used for the surface layer: High Cr casting 1! [-50% by weight M0 30% by weight Ni self-fusing alloy 20% by weight (JIS gate 5FNi-2 equivalent material) Table 2 It can be seen that the upper diameter of less than 64 μm is good.

Next, a spread adhesion test was conducted.

Piston rings were made in the same manner as described in the sagging test above. In addition, as a comparative example, one without a base thermal spray coating (Comparison 1) and one with a base thermal spray coating of Ni
-5%Af (Comparison 2) was also produced.

Then, by moving a pair of bottles arranged at symmetrical positions on the inner circumference of the piston ring in opposite directions, the piston ring is expanded.
The amount of expansion until peeling or cranking occurred and the amount of remaining thermal spray coating were investigated.

The base sprayed material and the surface sprayed material were the same as those used in the above-mentioned sagging test. The grain size of Mo is 44 μm or more and less than 125 μm, and the grain size of Ni-based amorphous alloy is 1
Those with a diameter of 0 μm or more and less than 64 μm were used.

The results are shown in Table 3.

(Left below) From the above, the particle size of Mo is 44 μm or more and less than 125 μm, N
Particle size of i-base amorphous alloy 10 μm or less Table 3 As mentioned above, those without a base sprayed coating will peel off on the base metal surface, and those with a base sprayed coating of Ni-5%A1 will peel off within the base sprayed coating, but this The invention only causes cranking and does not peel off.

Next, Ni self-fusing alloy (JIS A5FNi-5 equivalent material)
Corrosion resistance tests were conducted on the Ni-based amorphous alloy (same as that used in the adhesion test) with hydrochloric acid (leaded gasoline) and sulfuric acid (diesel engine) generated in internal combustion engines.

As a result, neither was affected by 10% hydrochloric acid.

In addition, the results of comparing the corrosion rates after immersion in a 25% sulfuric acid solution at 100°C are as follows: Ni self-fluxing alloy 0.418mm/24HrN
i-based amorphous alloy 0.001+u+/24Hr, Ni-based amorphous alloy has approximately 400% of Ni self-fusing alloy
It can be seen that it has twice the corrosion resistance.

If the thickness of the base thermal sprayed coating is less than 20 μm, the roughness of the base sprayed coating will be insufficient, and if it exceeds 100 μm, the ratio of the base thermal sprayed coating to the entire thermal sprayed coating will increase, resulting in poor durability. become.

〔Example〕

Fig. 1 shows a piston ring with a thermally sprayed coating formed on its outer circumferential surface. In other words, a piston ring base material 1 is made of spheroidal graphite cast iron, and shallow grooves 2 are formed over the entire circumference of the piston ring. After the material surface is blast-processed to a roughness of 20 μm RZ, a base thermal spraying material shown below is plasma sprayed into the groove 2 to provide a base thermal spray coating 3 with a thickness of 60 μm on the entire surface within the groove 2, and then as shown below. The surface sprayed material is plasma sprayed into the grooves 2, and a surface sprayed coating 4 with a thickness of 150 μm is provided on the base sprayed coating 3, followed by a predetermined finishing process.

Base sprayed material: Mo 70% by weight Ni-based amol 30% Fas alloy (same as that used in the adhesion test) Surface sprayed material: High Cr cast iron 50 fE amount% Mo 30% Ni self-fluxing alloy 20 Overlapping % (JIS gate 5FNi-2 equivalent material) Although spheroidal graphite cast iron is used as the piston ring base material in the above, it is of course not limited to this, and other cast iron or steel may be used as appropriate.

Further, the thermal spraying material for the surface layer portion is not limited to those mentioned above, but it is also preferable to use, for example, those shown below.

High Cr cast iron 50% by weight Mo 30% by weight Nil amorphous alloy 20% by weight or high C ferrochrome alloy 70% by weight Mo 9% by weight Ni self-fusing alloy 21% by weight (JIS MSFNi-2 equivalent material) Mo particle size is 44 μm or more and 125 μm The grain size of the Ni-based amorphous alloy was 10 μm or more and less than 64 μm.

Note that the Ni-based amorphous alloy has a 55% strength after plasma spraying.
% amorphous remained.

In addition, the thickness of the base thermal spray coating is particularly preferably 30 to 80 μm.

〔Effect of the invention〕

As explained above, according to the present invention, the base thermal sprayed coating has excellent wear resistance and seizure resistance, has excellent corrosion resistance in high pressure, high temperature, and corrosive sulfuric acid atmosphere, and has high peeling resistance. It becomes a thermally sprayed piston ring.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional view of a portion of a piston ring showing an embodiment of the present invention, FIG. 2 is an enlarged view of the main part thereof, and FIG. 3 is a view showing the results of an adhesion test with a base material. 1 is the piston ring base material, 2 is the groove, 3 is the base sprayed coating, and 4 is the surface sprayed coating.

Claims (3)

[Claims] (1) In a piston ring having a surface sprayed coating on a base sprayed coating formed on the outer peripheral surface, the base sprayed coating is made of a thermal sprayed material containing 60 to 80% by weight of Mo and 20 to 40% by weight of a Ni-based amorphous alloy. A piston ring having a coating thickness of 20 to 100 μm. (2) Mo particle size is 44 μm or more and less than 125 μm, N
The grain size of the i-based amorphous alloy is 10 μm or more and 64 μm
The piston ring according to claim 1, characterized in that the piston ring is less than or equal to (3) 50% Ni-based amorphous alloy after plasma spraying
Claim 1 characterized in that the above amorphous remains.
Or the piston ring described in 2.