JP6985961B2 - Piston ring and its manufacturing method - Google Patents

Description

The present invention relates to a piston ring and a method for manufacturing the piston ring, and more specifically, a piston ring having an excellent adhesion, scuff resistance, initial familiarity, and a thermal spray coating having low attack resistance to the other party is formed with good adhesion. Regarding the manufacturing method.

In recent years, as the output and performance of internal combustion engines have increased, the usage environment for sliding members such as piston rings has become increasingly severe, and sliding members with good wear resistance and scuff resistance are required. ing. Since the outer peripheral surface of the piston ring slides with the cylinder liner, high wear resistance and scuff resistance are particularly required for the outer peripheral sliding surface. In response to these demands, Patent Documents 1 to 3 propose a technique for providing a thermal spray coating on the outer peripheral sliding surface of a piston ring.

In Patent Document 1, a sprayed base layer formed by spraying a mixed powder containing at least Mo powder, a Ni-based self-soluble alloy powder, and Cu or Cu alloy powder, and a sprayed surface layer containing Cu slide in that order. It is a piston ring formed on the surface, and the thermal spraying base layer contains at least 50 to 80% by mass of Mo, 1 to 12% by mass of Cu or Cu alloy, and the balance: Ni-based self-soluble alloy, etc. The alloyed piston ring has been proposed.

In Patent Document 2, a thermal spray coating for a piston ring obtained by spraying a powder composition onto the outer peripheral sliding surface of a piston ring base material by a plasma spraying method, wherein the powder composition is molybdenum particles or a nickel-chromium alloy. A sprayed coating containing particles and chromium carbide particles and having the median diameter of the chromium carbide particles within a specific range has been proposed.

In Patent Document 3, the thermal spray coating contains a molybdenum phase, a chromium carbide phase and a nickel-chromium alloy phase, and the molybdenum phase, the chromium carbide phase and the nickel-chromium alloy phase are deposited on the sliding surface of the base material, and the base material is rubbed. A thermal spray coating has been proposed in which the ratio between the average value of the thickness of the chromium carbide phase in the direction perpendicular to the moving surface and the average value of the thickness of the molybdenum phase is specified.

In Patent Document 4, a Mo powder, a piston ring having a Cr ₃ C ₂ powder and the sprayed coating formed by thermal spraying a raw material powder containing at least a mixed powder of NiCr powder, the average particle diameter of the mixed powder is more than 50μm Therefore, a piston ring in which the average particle size of the Mo powder is smaller than the average particle size of the mixed powder has been proposed.

Japanese Unexamined Patent Publication No. 2012-46821 WO2014 / 091831 Japanese Unexamined Patent Publication No. 2015-2141719 Japanese Unexamined Patent Publication No. 2016-102233

An object of the present invention is to provide a piston ring and a method for manufacturing the same, wherein a thermal spray coating having excellent wear resistance, scuff resistance, initial compatibility, and low attack resistance to the opponent is formed with good adhesion.

(1) The piston ring according to the present invention is a thermal spray coating having Mo particles, Ni-based self-soluble alloy particles, Co alloy particles and / or Cr ₃ C _{2 particles on at least the sliding surface of the piston ring base material.} Is provided. According to the present invention, since it contains Ni-based self-soluble alloy particles, Co alloy particles and / or Cr ₃ C ₂ particles, it is possible to obtain a thermal spray coating having particularly good adhesion and low attack on the other party.

In the piston ring according to the present invention, when the content ratio of the total of the Mo particles, the Ni-based self-soluble alloy particles, the Co alloy particles, and the Cr ₃ C ₂ particles is 100% by mass, the Ni-based self-soluble alloy is used. It seems that the particles are in the range of 20% by mass or more and 40% by mass or less, _{the total of the Co alloy particles and the Cr 3} C ₂ particles is in the range of 15% by mass or more and 30% by mass or less, and the rest are Mo particles. It is composed of.

In the piston ring according to the present invention, the thermal spray coating may further contain NiCr particles.

In the piston ring according to the present invention, the ratio (A / B) of the content A of the Ni-based self-soluble alloy particles to the content B of the NiCr particles is preferably 1.5 or more in terms of mass ratio.

When the NiCr particles are contained in the piston ring according to the present invention, the piston ring may include a granulated structure of the _{NiCr particles and the Cr 3} C _{2 particles.}

(2) In the method for producing a piston ring according to the present invention, a mixed powder composition of Mo powder, Ni-based self-soluble alloy powder, Co alloy powder and / or Cr ₃ C ₂ powder is sprayed by plasma spraying, and the piston ring is manufactured. It is characterized in that a thermal spray coating is formed on the outer peripheral sliding surface of the base material.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a piston ring and a method for manufacturing the same, in which a thermal spray coating having excellent wear resistance and scuff resistance and low attack resistance to the opponent is formed with good adhesion.

It is sectional drawing which shows an example of the piston ring which concerns on this invention. It is a cross-sectional photograph of the thermal spray coating obtained in Examples 1 and 2 and Comparative Examples 1 and 2. It is a structural principle diagram of the high load type wear tester used for the wear amount measurement.

Hereinafter, the piston ring and the method for manufacturing the piston ring according to the present invention will be described in detail. The present invention is not limited to the following embodiments as long as it is within the scope of the gist thereof.

[piston ring]
As shown in FIG. 1, the piston ring 1 according to the present invention is provided with a characteristic thermal spray coating 3 on at least a sliding surface of the piston ring base material 2. The sprayed coating 3 has Mo particles, Ni-based self-soluble alloy particles, Co alloy particles and / or Cr ₃ C ₂ particles. Such piston rings 1, and Mo powder, and Ni-based self-fluxing alloy powder, plasma sprayed a mixed powder composition of the Co alloy powder and / or Cr ₃ C ₂ powder, the outer peripheral sliding surface of the piston ring substrate 2 It is manufactured by forming a thermal spray coating 3 on the surface. The piston ring 1 on which the thermal spray coating 3 is formed can be a thermal spray coating having particularly good adhesion and lowering the aggression against the opponent.

Each configuration of the piston ring 1 according to the present invention will be described.

<Piston ring base material>
Examples of the piston ring base material 2 on which the thermal spray coating 3 is formed include various types used as the base material of the piston ring 1, and are not particularly limited. For example, various steel materials, stainless steel materials, casting materials, cast steel materials and the like can be applied. Among these, martensitic stainless steel, chromium manganese steel (SUP9 material), chromium vanadium steel (SUP10 material), silicon chromium steel (SWOSC-V material) and the like can be preferably mentioned. Further, as the casting material, boron cast iron, flake graphite cast iron, spheroidal graphite cast iron, CV cast iron and the like can be preferably mentioned. The piston ring base material 2 is manufactured by a general means for manufacturing a piston ring.

The piston ring base material 2 may be pretreated if necessary. Examples of the pretreatment include a treatment of surface polishing to adjust the surface roughness. For the adjustment of the surface roughness, for example, a method of lapping the surface of the piston ring base material 2 with diamond abrasive grains to polish the surface can be exemplified.

<Spray coating>
The thermal spray coating 3 is provided on at least the sliding surface of the piston ring base material 2. The sprayed coating 3 has Mo particles, Ni-based self-soluble alloy particles, Co alloy particles and / or Cr ₃ C ₂ particles, and has Mo powder, Ni-based self-soluble alloy powder, and Co alloy. A raw material powder having powder and / or Cr ₃ C ₂ powder is sprayed to form a film.

The component composition of the spray film 3 is such that the Ni-based self-soluble alloy particles are composed of 100% by mass when the content ratio _{of the Mo particles, the Ni-based self-soluble alloy particles, and the total of the Co alloy particles and the Cr 3} C _{2 particles is 100% by mass.} It is configured such that it is in the range of 20% by mass or more and 40% by mass or less, _{the total of Co alloy particles and Cr 3} C ₂ particles is in the range of 15% by mass or more and 30% by mass or less, and the rest is Mo particles. ing. The content ratio is a mass ratio, and the mass% of each is calculated so that the total content of the Mo particles, the Ni-based self-soluble alloy particles, the Co alloy particles, and the Cr ₃ C _{2 particles is 100% by mass.} If particles other than these are included, the total excluding the particles is calculated as 100% by mass.

The raw material powder may optionally contain, for example, Co, B, Si, Cu, Al, Fe and the like as long as the effect of the present invention is not impaired. Since the content of each particle component constituting the thermal spray coating 3 and the composition ratio in the raw material powder are usually the same, the content of each component of the thermal spray coating 3 can be said to be the component ratio of the raw material powder. .. Therefore, the blending amount of each powder constituting the raw material powder can be adjusted so that the sprayed coating 3 has a desired component ratio. The content of each particle contained in the thermal spray coating 3 can be quantified and obtained by using a backscatter measuring device. Further, since the content of each particle constituting the thermal spray coating 3 is usually the same as the blending amount of each raw material powder contained in the thermal spraying raw material, the raw material powder is measured by measuring the content of each particle of the thermal spray coating 3. It is also possible to specify the blending ratio of each powder constituting the above.

(Mo particles)
Mo particles is a major element constituting the thermal spray coating 3, it is included in the content other than the content of the sum of NiCr self-fluxing alloy particles and Co alloy particles and Cr ₃ C ₂ particles, for example 40 wt% As mentioned above, it is included in the range of 60% by mass or less. When Mo particles, which are refractory metals, are contained in the above range, a thermal spray coating having excellent wear resistance and scuff resistance and excellent adhesion to a piston ring base material can be obtained. If the content is less than 40% by mass, the wear resistance and scuff resistance of the obtained thermal spray coating 3 may be inferior. On the other hand, if the content exceeds 60% by mass, it causes a high cost.

The average particle size of the Mo particles may be about the same as that of general thermal spraying raw material powder, for example, preferably in the range of 10 μm or more and 50 μm or less, and in the range of 20 μm or more and 40 μm or less from the viewpoint of adhesion. More preferred from. In the present application, the average particle size of the Mo particles and other particles is represented by the value of _{D 50} measured by a particle size distribution measuring device (for example, Microtrac HRA manufactured by Nikkiso Co., Ltd.). The shape of the Mo particles is not particularly limited, and may be granulated sintered particles. Granulated sintered particles obtained by granulating Mo particles can be obtained by granulating Mo particles having a small diameter and then heating and sintering them. The average particle size of Mo particles used for granulation is, for example, 1 to 10 μm. The Vickers hardness of Mo particles is in the range of 320 to 420. The Vickers hardness in the present application was measured at 5 points at random with a load of 0.05 kgf using a Micro Vickers hardness tester (manufactured by Akashi Co., Ltd.) and expressed as an average value of the obtained results.

(NiCr self-soluble alloy particles)
The Ni-based self-soluble alloy particles are the main elements constituting the thermal spray coating 3, and are obtained by spraying Ni-based self-soluble alloy powder. The Ni-based self-soluble alloy particles are such that the nickel-based alloy contains a flux component such as boron and silicon, and by performing a fusing treatment after spraying, a sprayed coating having few pores and high adhesion strength can be obtained. It is an alloy particle used as a raw material powder having an action that can be obtained. In the present invention, Ni-based self-soluble alloy particles containing Cr are used as a powder raw material. The Ni-based self-soluble alloy particles contain 14 to 18% by mass of Cr, 2 to 4% by mass of boron, 3 to 4.5% by mass of silicon, and 2 to 5% by mass of iron, and a small amount of unavoidable. Contains impurities. Further, it may contain 1 to 3% by mass of molybdenum and 1 to 4% by mass of copper, or both. Such a Ni-based self-soluble alloy acts as a binder for Mo, which is a base metal. Further, since this Ni-based self-soluble alloy is self-soluble, there is an advantage that good wear resistance can be obtained. NiCr self-soluble alloys and NiCo self-soluble alloys are well known as Ni-based self-soluble alloys, but in the present invention, NiCr self-soluble alloys are used. In particular, according to the present invention, NiCr self-fluxing alloy particles contained in the thermal spray film 3, it is obtained as a new finding that acts to reduce hardness difference between the Mo particles and Co alloy particles or Cr ₃ C ₂ particles, hardness It has the effect of preventing the Co alloy particles and Cr ₃ C ₂ particles from falling off due to the difference, and as a result, has the advantage of suppressing the aggression against the opponent. The Vickers hardness of NiCr self-soluble alloy particles is in the range of 700 to 850.

The NiCr self-soluble alloy particles are 20% by mass or more and 40% by mass or less when the content ratio of the total of Mo particles, Ni-based self-soluble alloy particles, Co alloy particles and Cr ₃ C _{2 particles is 100% by mass.} It is preferably contained within the range. By setting it within this range, the above effect can be more exerted. If the content is less than 20% by mass, the effect of acting as a binder for Mo may be diminished, and the adhesion between Mo particles may be reduced. On the other hand, if the content exceeds 40% by mass, the scuff resistance may decrease. A more preferable content is in the range of 25% by mass or more and 35% by mass or less, and has an advantage of improving adhesion and scuff resistance.

The average particle size of the NiCr self-soluble alloy particles may be about the same as that of general thermal spraying raw material powder, and is preferably in the range of, for example, 15 μm or more and 53 μm or less, and the resistance is in the range of 15 μm or more and 30 μm or less. More preferable from the viewpoint of wear resistance. The average particle size of the NiCr self-soluble alloy particles is also represented by the one measured by a particle size distribution measuring device (for example, Microtrac HRA manufactured by Nikkiso Co., Ltd.). The shape of the NiCr self-soluble alloy particles is not particularly limited, and may be granulated sintered particles. Granulated sintered particles obtained by granulating NiCr self-soluble alloy particles are obtained by granulating small-diameter NiCr self-soluble alloy particles and then heating and sintering them. The average particle size of the NiCr self-soluble alloy particles used for granulation is, for example, 1 to 10 μm.

(Co alloy particles, Cr ₃ C ₂ particles)
Co alloy particles and Cr ₃ C ₂ particles are the main elements constituting the thermal spray coating 3, and are obtained by spraying a raw material powder containing either or both of them. The Co alloy particles are characterized by having good wear resistance, and by being contained in the thermal spray coating 3, a high wear resistance effect can be given. On the other hand, the Cr ₃ C ₂ particles are hard particles, and by being contained in the thermal spray coating 3, good wear resistance and adhesion can be imparted to the thermal spray coating 3. In the present invention, the above effect can be obtained by forming the thermal spray coating 3 containing one or both of the Co alloy particles and the Cr ₃ C _{2 particles.} The Co alloy particles are Co-based alloy particles containing 16 to 20% by mass of Cr.

The Co alloy particles and Cr ₃ C ₂ particles are 15% by mass or more, 30% by mass, where the total content of Mo particles, Ni-based self-soluble alloy particles, Co alloy particles and Cr ₃ C _{2 particles is 100% by mass.} It is preferably contained in the range of mass% or less. By setting it within this range, the above effect can be more exerted. If the content is less than 15% by mass, the wear resistance and adhesion of the obtained thermal spray coating 3 may be inferior. On the other hand, if the content exceeds 30% by mass, for example, Cr ₃ C ₂ particles may fall off on the surface of the sprayed coating, which may increase the aggression against the other party. A more preferable content is in the range of 15% by mass or more and 25% by mass or less, and has advantages of improving wear resistance and suppressing opponent attack.

Whether the mixed powder contains both Co alloy particles and Cr ₃ C ₂ particles is selected in consideration of the characteristics of the thermal spray coating 3 to be obtained. For example, Co alloy particles may be selected when obtaining a thermal spray coating 3 with an emphasis on corrosion resistance, and Cr ₃ C _{2 when obtaining a thermal spray coating 3 with an emphasis on wear resistance and adhesion.} The particles may be selected, and in the case of obtaining the thermal spray coating 3 having both effects, both the Co alloy particles and the Cr ₃ C ₂ particles may be selected. In the thermal spray coating 3 was contained only Co alloy particles is preferably in the range of the content of 17 to 23 wt%, the thermal spray coating 3 was contained only Cr ₃ C ₂ particles, the content The amount is preferably in the range of 18 to 28% by mass, and in the sprayed coating 3 containing both, the total content is in the range of 35 to 55% by mass and the content of Co alloy particles is 20. It is preferably in the range of about 30% by mass, and _{the content of Cr 3} C ₂ particles is preferably in the range of 15 to 25% by mass.

The average particle size of Co alloy particles and Cr ₃ C ₂ particles may be any general spraying material powder as much, for example 10 [mu] m or more, preferably within the range of 45 [mu] m, 10 [mu] m or more, the following 30μm The range is more preferable from the viewpoint of wear resistance. The average particle size of these particles is also represented by the one measured by a particle size distribution measuring device (for example, Microtrac HRA manufactured by Nikkiso Co., Ltd.). The shapes of the Co alloy particles and the Cr ₃ C ₂ particles are not particularly limited, and may be granulated sintered particles. Granulated sintered particles obtained by granulating Co alloy particles and granulated sintered particles obtained by granulating Cr ₃ C ₂ particles are obtained by granulating particles having a small diameter and then heating and sintering them. The average particle size of the particles used for granulation is, for example, 1 to 10 μm. The Vickers hardness of Cr ₃ C ₂ particles is in the range of 1600 to 1800.

(NiCr particles)
The thermal spray coating 3 may contain NiCr particles, if necessary. Generally, NiCr particles which may be contained as to impart good abrasion resistance and adhesion to the thermal sprayed coating 3, in the present invention, for the adhesion and abrasion resistance, Co alloy particles and Cr ₃ C These effects are satisfied by containing a predetermined amount of one or both of the _{two particles.} Further, as described above, by containing NiCr self-soluble alloy particles, it acts to improve the adhesion to the piston ring base material 2, and Mo particles and Co alloy particles or Cr ₃ C ₂ particles can be combined with each other. It works to reduce the difference in hardness. For these reasons, in the present invention, NiCr particles are not an essential composition, but are blended as an optional component. The difference between NiCr self-soluble alloy particles and NiCr particles is that the NiCr self-soluble alloy particles contain boron and silicon in a predetermined ratio, so they can be distinguished or sorted by analysis using fluorescent X-rays. can do.

When the NiCr particles are contained in the thermal spray coating 3, the ratio (A / B) between the content (A) of the Ni-based self-soluble alloy particles and the content (B) of the NiCr particles is 1.5 by mass ratio. The above is preferable. Within this range, the action and effect of NiCr self-soluble alloy particles can be realized. When the ratio (A / B) is less than 1.5, the influence of the NiCr particles becomes relatively large, and the effect of improving the adhesion and the effect of reducing the hardness difference on which the NiCr self-soluble alloy particles act are not sufficient. The NiCr particles may not be included in the thermal spray coating 3. The upper limit of the ratio is not particularly limited, but if it is included, it may be, for example, 20. The content of NiCr particles when contained can be in the range of 0.01% by mass or more and 10% by mass or less.

When the NiCr particles are contained in the thermal spraying raw material, the average particle size of the NiCr particles may be about the same as that of general thermal spraying raw material powder, and is preferably in the range of, for example, 5 μm or more and 45 μm or less. The average particle size of NiCr particles can also be expressed by measuring with a particle size distribution measuring device (for example, Microtrac HRA manufactured by Nikkiso Co., Ltd.). The shape of the NiCr particles is not particularly limited, and the granulated sintered particles may be used. The Vickers hardness of NiCr particles is in the range of 400 to 550. The Vickers hardness of the granulated particles obtained by granulating the NiCr particles and the above-mentioned Cr ₃ C ₂ particles (referred to as “Cr ₃ C ₂ / NiCr granulated particles”) is in the range of 1000 to 1200.

(Other elements)
The mixed powder used as a thermal spraying raw material may contain components other than the above. Examples of the other components include Fe, C, Mn, S and the like. These components may inevitably be contained as impurities. The content of the above impurities may be low enough not to impair the effect of the present invention.

(Means for forming a thermal spray coating)
The thermal spray coating 3 is formed on the sliding surface of the piston ring 1 by plasma spraying. Plasma spraying is thermal spraying in which the above-mentioned raw material powder is used by using a plasma jet generated by a plasma spraying gun, the raw material powder is heated and accelerated, and the raw material powder is melted or brought into a state close to that and sprayed onto a base material. The principle is known, but when a voltage is applied between the cathode and the anode to generate a DC arc, the working gas (argon gas, etc.) supplied from the rear is ionized and plasma is generated. The thermal spray coating 3 is formed on the piston ring base material 2 by feeding the raw material powder into the plasma frame with argon gas or the like and spraying the raw material powder onto the piston ring base material 2. The thermal spray coating 3 according to the present invention is formed by such plasma spraying, and the raw material powder is melted or sprayed at a temperature close to that of the following HVOF thermal spraying, so that the effect peculiar to the present invention can be exhibited. As the sliding surface, an outer peripheral sliding surface on which the piston ring 1 slides in contact with a cylinder liner (not shown) can be mentioned, but it may be provided on another surface.

Although it is not a means for forming the thermal spray coating 3 constituting the present invention, HVOF (abbreviation of High Velocity Oxygen Fuel) thermal spraying is thermal spraying of a high-speed jet frame using oxygen and fuel. Specifically, a mixed gas of high-pressure oxygen and fuel is burned in a combustion chamber, the combustion flame is throttled by a nozzle, and a rapid gas expansion occurs at the moment when it goes out to the atmosphere, resulting in a supersonic jet. The raw material powder accelerated by the high acceleration energy hardly oxidizes or changes in composition, and a high-density sprayed coating 3 is formed on the piston ring base material 2. Although this HVOF spraying has a high film forming speed, it does not raise the temperature, so that the raw material powder is sprayed without being melted so much. Therefore, small fine particles are used as the raw material powder.

The thickness of the thermal spray coating 3 is not particularly limited, but is preferably in the range of, for example, 200 μm or more and 600 μm or less. By having these thickness ranges, the effect peculiar to the present invention can be obtained.

The porosity of the thermal spray coating 3 is also not particularly limited, but is preferably 5% or less in terms of area%. From the viewpoint of the denseness of the sprayed coating 3 and the wear resistance based on the oil retention property, the porosity is more preferably 4% or less. The lower limit of the porosity is not particularly limited, but may be, for example, 0.5%. The porosity can be measured by, for example, image analysis software.

(Application example)
As an application example, a thermal spraying surface layer (not shown) may be arbitrarily provided on the thermal spray coating 3. The sprayed surface layer is not particularly limited, and examples thereof include a layer containing Al, Fe, and Cu. The thermal spraying surface layer may be provided for the purpose of further reducing the aggression against the opponent, improving the initial familiarity, and the like. Such a thermal spraying surface layer can also be formed on the thermal spray coating 3 by plasma spraying, arc spraying, gas spraying, or the like similar to the thermal spray coating 3.

[Production method]
The method for manufacturing the piston ring 1 according to the present invention is a method for manufacturing a piston ring base material 2 having a characteristic sprayed coating 3 on at least a sliding surface, which comprises Mo powder and Ni-based self-soluble alloy powder. , Co alloy powder and / or _{a mixed powder composition with Cr 3} C ₂ powder is sprayed by plasma to form a thermal spray coating 3 on the outer peripheral sliding surface of the piston ring base material 2. Since this manufacturing method has been described in detail in the above-mentioned explanation column for the piston ring, particularly in the explanation column for the formation of the thermal spray coating 3, the description thereof will be omitted here. The above-mentioned granulated sintered powder may be optionally applied to the raw material powder. In the present application, what constitutes the raw material powder is referred to as "powder", and what constitutes the thermal spray coating is referred to as "particle".

The present invention will be described in more detail with reference to Examples and Comparative Examples.

[Example 1]
And Mo powder having an average particle diameter of 31 .mu.m (45 wt%), and NiCr self-fluxing alloy powder having an average particle diameter of 43 .mu.m (25 wt%), Cr ₃ C ₂ powder (22.5 wt%) and NiCr powder (7 The raw material powder was prepared by blending _{Cr 3} C ₂ / NiCr granulated sintered powder having an average particle size of 36 μm obtained by granulating (5.5% by mass). Table 1 shows the blending amount of the raw material powder. At this time, when the content ratio of Mo powder, NiCr self-soluble alloy powder and Cr ₃ C ₂ / NiCr granulated sintered powder is 100% by mass, the NiCr self-soluble alloy powder is 25% by mass, and Cr ₃ C. _{The 2} / NiCr granulated sintered powder is 30% by mass (Cr ₃ C ₂ powder: 22.5% by mass, NiCr powder: 7.5% by mass), and the remaining 45% by mass is Mo powder. The composition of the NiCr self-soluble alloy powder is Ni: 70% by mass, Cr: 17% by mass, B: 3.5% by mass, Si: 4% by mass, Fe: 4% by mass, and the balance: unavoidable impurities. rice field. The composition of the Cr ₃ C ₂ powder was Cr: 86% by mass, C: 13% by mass, and the balance: unavoidable impurities. The composition of the NiCr powder was Ni: 78% by mass, Cr: 20% by mass, and the balance: unavoidable impurities. The composition of the components was analyzed using a backscattering measuring device (manufactured by NHV Corporation), and the average particle size was measured by a particle size distribution measuring device (manufactured by Nikkiso Co., Ltd., Microtrack HRA). It is represented by a value of _50.

Using this raw material powder, plasma spraying was performed under the following conditions to form a thermal spray coating 3 having a thickness of 300 μm on the sliding surface of the piston ring base material 2 made of boron cast iron. Plasma spraying was performed using a 9MB plasma spraying gun manufactured by Sulzer Meteco, and sprayed at a voltage of 60 to 70 V and a current of 500 A.

The component composition of the obtained thermal spray coating 3 was quantified using a backscattering measuring device (manufactured by NHV Corporation) in the same manner as described above, and Mo: 45% by mass and NiCr self-solubilization were the same as the composition of the raw material powder as a raw material. The alloy was 25% by mass, Cr ₃ C ₂ : 22.5% by mass, and NiCr: 7.5% by mass. The ratio (A / B) of the NiCr self-soluble alloy content A and the NiCr content B is 3.3 by mass ratio.

[Example 2]
The thermal spray coating 3 of Example 2 was formed in the same manner as in Example 1 except that the raw material powder was changed. The component composition of the thermal spray coating 3 was also the same as the composition of the following raw material powder, Mo: 50% by mass, NiCr self-soluble alloy: 30% by mass, Co alloy: 20% by mass.

The raw material powders are Mo powder (50% by mass) with an average particle size of 31 μm, NiCr self-soluble alloy powder (30% by mass) with an average particle size of 43 μm, and Co alloy powder (20% by mass) with an average particle size of 31 μm. ) And are shown in Table 1. At this time, when the content ratio of Mo powder, NiCr self-soluble alloy powder and Co alloy powder is 100% by mass, the content ratio of each powder is the same as the above powder composition. The composition of the NiCr self-soluble alloy powder is the same as that of Example 1, and the composition of the Co alloy powder is Co: 49.8% by mass, Mo: 28% by mass, Cr: 18% by mass, Si: 3. .4% by mass, residual: unavoidable impurities.

[Example 3]
The thermal spray coating 3 of Example 3 was formed in the same manner as in Example 1 except that the raw material powder was changed as shown in Table 1. The composition of the component of the sprayed coating 3 was also the same as the composition of the raw material powder in Table 1. In Example 3, NiCr self-soluble alloy powder has an average particle size of 43 μm, Ni: 70% by mass, Cr: 17% by mass, B: 3% by mass, Si: 4% by mass. , Mo: 2% by mass, Cu: 3% by mass, residual: unavoidable impurities are the same except that they are used.

[Examples 4 to 6]
The thermal spray coatings 3 of Examples 4 to 6 were formed in the same manner as in Example 1 except that the raw material powder was changed as shown in Table 1. The composition of the component of the sprayed coating 3 was also the same as the composition of the raw material powder in Table 1. The NiCr self-soluble alloy powders of Examples 4 to 6 are the same as those of Example 1.

[Comparative Example 1]
The thermal spray coating 3 of Comparative Example 1 was formed in the same manner as in Example 1 except that the raw material powder was changed. Component composition of the thermal spray coating 3 also like the composition of the following raw powder, Mo: 33 wt%, NiCr alloy: 17 wt%, Cr ₃ C _2: was 50 wt%.

Raw material powder, a Mo powder having an average particle diameter of 31 .mu.m (33 wt%), and NiCr powder having an average particle size of 21 [mu] m (17 wt%), Cr ₃ C ₂ powder having an average particle size of 21 [mu] m (50 wt%) It is a mixed powder containing and is shown in Table 1. Incidentally, the component composition of the NiCr powder and Cr ₃ C ₂ powder were the same as in Example 1.

[Comparative Example 2]
The thermal spray coating 3 of Comparative Example 2 was formed in the same manner as in Example 1 except that the raw material powder was changed. Component composition of the thermal spray coating 3 also like the composition of the following raw powder, Mo: 50 wt%, NiCr alloy: 15 wt%, Cr ₃ C _2: was 35 wt%.

Raw material powder, a Mo powder having an average particle diameter of 31 .mu.m (50 wt%), and NiCr powder having an average particle diameter of 22 .mu.m (15 wt%), Cr ₃ C ₂ powder having an average particle diameter of 13 .mu.m (35 wt%) It is a mixed powder containing and is shown in Table 1. Incidentally, the component composition of the NiCr powder and Cr ₃ C ₂ powder were the same as in Example 1.

[Comparative Examples 3 and 4]
The thermal spray coatings 3 of Comparative Examples 3 and 4 were formed in the same manner as in Example 1 except that the raw material powder was changed as shown in Table 1. The composition of the component of the sprayed coating 3 was also the same as the composition of the raw material powder in Table 1. The NiCr self-soluble alloy powders of Comparative Examples 3 and 4 are the same as those of Example 1.

[Measurement method and measurement results]
(Abrasion resistance index and mating material wear resistance index)
The wear resistance index and the mating material wear resistance index were measured by a wear test. In the wear test, the high load type wear tester 6 shown in FIG. 3 was used, and the test material 7 was a fixed piece obtained under the same conditions as the piston rings obtained in Examples 1 to 6 and Comparative Examples 1 to 4. The test material 7 (fixed piece) and the mating material 8 which is a rotating piece were brought into contact with each other, and a load P was applied. The test material 7 here is an integrated type of three pins (φ5 mm, 58.9 mm ² ) made of flake graphite cast iron and a disk with an outer diameter of 40 mm. The disk has an outer diameter of 40 mm and the thickness is a pin. 12 mm including. The mating material 8 (rotating piece) is boron cast iron having an outer diameter of 40 mm and a thickness of 12 mm. The wear test conditions were such as lubricating oil: spindle oil equivalent, oil temperature: 125 ° C., peripheral speed: 1.65 m / sec (1050 rpm), contact surface pressure: 76.4 MPa, and test time: 8 hours. ..

For the wear resistance and the wear resistance of the mating material, the wear amount of each test material corresponding to Examples 1 to 6 and Comparative Examples 2 to 4 is compared with the wear amount of the test material corresponding to Comparative Example 1. Compared as a relative ratio, it was used as the wear resistance index. Therefore, the smaller the wear resistance index of each test material is, the smaller the amount of wear as compared with Comparative Example 1. The results are shown in Table 2.

(Adhesion strength)
The adhesion force is measured in accordance with JIS H 8667, and the end face of the cylindrical test piece on which the thermal spray coating 3 is formed and the end face of the cylindrical test piece on which the thermal spray coating 3 is not formed are bonded and integrated with a thermosetting resin. Then, both ends of the cylinder were fixed with the upper and lower chucks of the tensile tester, and the tensile test was performed. In the tensile test, the tensile speed was set to 1 mm / min, and the load when the thermal spray coating 3 was peeled off from the interface of the boron cast iron or when the sprayed coating 3 was delaminated was measured, and the load was divided by the area of the cylindrical end face. The value was calculated. The adhesion of each test sample corresponding to Examples 1 to 6 and Comparative Examples 2 to 4 was relatively evaluated with the value of the sprayed coating 3 of Comparative Example 1 as 100 (reference), and expressed as an adhesion index. The larger the adhesion index, the better the adhesion. Delamination at the interface with the curable resin and delamination within the curable resin layer were excluded from the evaluation. The results are shown in Table 2.

(evaluation)
As shown in Table 2, it was confirmed that the sprayed coatings of Examples 1 to 6 were superior to Comparative Example 1 in the wear resistance index, the wear resistance index of the mating material, and the adhesion.

_{It was found that the difference in hardness between Mo particles and Cr 3} C ₂ particles can be reduced by using a Ni-based self-soluble alloy, which has a higher hardness than the Ni Cr alloy, and in addition to the Ni-based self-soluble alloy, Cr ₃ It is _{considered that by using the C 2} / NiCr granulated sintered powder, it is possible _{to prevent the Cr 3} C ₂ particles from falling off due to the difference in hardness between them and suppress the attack on the cylinder liner.

1 Piston ring 2 Piston ring base material 3 Thermal spray coating 4 Thermal spray surface layer 6 High load type wear tester 7 Test material 8 Rotating piece P load

Claims (5)

At least the sliding surface of the piston ring substrate, and Mo particles, and Ni-based self-fluxing alloy particles, sprayed coating is provided having a Co alloy particles and / or Cr ₃ C ₂ particles,
Wherein when the Mo particles and the Ni-based self-fluxing alloy particles content ratio of the sum of the Co alloy particles and _Cr 3 _{C 2} particles is 100 mass%, the Ni-based self-fluxing alloy particles 20 mass% to 40 mass % Or less, the total of the Co alloy particles and Cr ₃ C ₂ particles is in the range of 15% by mass or more and 30% by mass or less, and the rest is Mo particles . The thermal spray coating further comprises NiCr particles, piston ring according to claim 1. The piston ring according to claim 2 , wherein the ratio (A / B) of the content A of the Ni-based self-soluble alloy particles to the content B of the NiCr particles is 1.5 or more by mass ratio. The piston ring according to claim 2 or 3 , wherein when the NiCr particles are contained, the piston ring includes a granulated structure of the _{NiCr particles and the Cr 3} C _{2 particles.} And Mo powder, and Ni-based self-fluxing alloy powder, plasma sprayed a mixed powder composition of the Co alloy powder and / or Cr ₃ C ₂ powder, to form a sprayed coating on the outer circumferential sliding surface of the piston ring substrate Is a method of manufacturing a piston ring.
When the content ratio of the Mo particles, the Ni-based self-soluble alloy particles, _{the total of the Co alloy particles and the Cr 3} C ₂ particles is 100% by mass, the Ni-based self-soluble alloy particles are 20% by mass or more and 40% by mass. % Or less, the total of the Co alloy particles and Cr ₃ C ₂ particles is in the range of 15% by mass or more and 30% by mass or less, and the rest is Mo particles . Production method.

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