JP2010274386A - SLIDING MATERIAL OF Si-PARTICLE-CONTAINING Al-Si ALLOY AND METHOD FOR FORMING SLIDING SURFACE - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sliding material of Si-particle-containing Al-Si alloy, preventing generation of scuffing (in particular, at low temperature) on a sliding surface. <P>SOLUTION: The sliding surface contains at least 17-35 mass% of Si, and includes groove parts formed by grinding processing and retaining lubricating oil therein and flat parts to which plastic forming is applied, wherein a part of Si particles is protruded from at least surfaces of the flat parts. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a Si particle-containing Al—Si alloy sliding material and a method for forming a sliding surface.

  For example, in a cylinder liner or a cylinder bore of a cylinder block that forms part of a combustion chamber of an internal combustion engine such as an engine, from the viewpoint of life, durability, etc., improved scuffing resistance, improved wear resistance, and lubricating oil Conventionally, reduction of consumption has been demanded.

  In particular, aluminum cylinder bores are known to have lower seizure resistance than cast iron. Specifically, when the engine is stopped, left to cool, and then restarted, scuffing during a short period of time until the viscosity of the lubricating oil is lowered and is supplied from the pump after being warmed up ( In particular, scuffing that occurs at a low temperature after cooling may be referred to as “low temperature scuffing”). Scuffing refers to scratches and seizures on the piston surface and the like caused by local welding with the piston or cylinder due to friction in the cylinder or the like. This occurs because the oil runs out temporarily, and prevention of scuffing (especially low temperature scuffing) due to this running out of oil is essential for stabilizing the performance of the cylinder bore made of aluminum.

  The piston used in combination with the cylinder bore is often used as a ring material having a piston ring that has been subjected to dry plating of steel or its nitriding material, CrN, TiN or the like, or wet plating of Cr or the like. . However, these piston ring ring materials tend to adhere to aluminum, and therefore, seizure and wear tend to occur when the oil film breaks. On the other hand, diamond-like carbon (DLC) is known as a material having low adhesion to aluminum. By using this DLC piston ring, scuffing resistance can be maintained, but DLC is a hard and wear-resistant material, but it is a thin film of 5 μm or less, so it has a long life as an engine piston ring. However, since the adhesion to the base material is not high, peeling easily occurs. Also, the limited ring material is undesirable in design. In addition, even in DLC, it is difficult to completely avoid seizure early in an unlubricated state under sliding conditions such as between the bore / ring of the engine. It is indispensable to form on the bore surface.

  As a technique related to prevention of seizure or the like as described above, there is a method for reducing the chance of contact between an aluminum material and a piston ring. For example, when machining the surface of an aluminum bore with hard particles dispersed in the sliding part with a honing device with a grindstone on the spindle that reciprocates and rotates, the direction of rotation that processes the bore surface in the previous process is reversed. A surface processing method for an aluminum bore that is rotationally moved in a direction to finish is disclosed (for example, see Patent Document 1).

  Further, a cylinder bore including a groove for retaining an oil film formed by grinding a hole in a cylinder block and a plateau portion plastically deformed by roll burnishing is disclosed (for example, see Patent Document 2). .

JP-A-5-57597 JP-A-5-65849

  However, the above-mentioned surface processing method of the aluminum bore, which is finished in the direction opposite to the rotation direction of the previous process for processing the bore surface, aims to reduce the contact opportunity with the piston ring by removing burrs from the honing marks. However, since the Si particles and aluminum are at the same level, contact between the aluminum and the ring is inevitable, so that scuffing resistance cannot be ensured.

  Also, cylinder bores with grooves and plateaus described above work harden in plastic processing such as roller burnishing, so that seizure resistance is improved, especially in the case of cast iron, which has high seizure resistance and is plastically processed. However, in the case of an aluminum material softer than cast iron, seizure cannot always be prevented by plastic working alone.

  The present invention has been made in view of the above, and an Si-particle-containing Al—Si alloy sliding material in which the occurrence of scuffing (especially scuffing at a low temperature) on the sliding surface is prevented, and scuffing during sliding ( It is an object of the present invention to provide a method for forming a sliding surface that can form a sliding surface in which the occurrence of scuffing in particular at a low temperature is prevented, and to achieve the object.

  The present invention employs an aluminum-Si based alloy for improving the seizure resistance and wear resistance of a sliding surface using an aluminum material (for example, a sliding surface of a cylinder bore on which a piston ring slides). The inventors have obtained the knowledge that it is effective to make Si included in a granular form so as to contribute to surface properties, and have been achieved based on such knowledge.

  In order to achieve the above object, the Si particle-containing Al—Si alloy sliding material according to the first aspect of the present invention contains at least 17 to 35% by mass of Si and is a lubricating oil formed by grinding. It has a configuration in which a groove portion that can be held and a flat portion that has been subjected to plastic working are provided, and at least a sliding surface from which a part of Si particles protrudes from the surface of the flat portion.

  In the first invention, the ratio of Si in the Al—Si based alloy is 17 to 35% by mass, and is formed by plastic working together with a concave groove portion capable of retaining lubricating oil on the surface serving as the sliding surface. By providing a flat portion and allowing a part of the Si particles to protrude from the surface of the flat portion, for example, the lubricating oil retained in the groove portion and remaining before warming up when restarting an internal combustion engine such as an engine. As the sliding surface is lubricated, the protruding portion of the Si particles that protrudes from the surface of the flat portion on the sliding surface slides with the sliding portion disposed opposite thereto. It becomes difficult for aluminum to come into contact with the opposing sliding portion, and the occurrence of scuffing (particularly low-temperature scuffing) can be prevented. Also, during normal operation after restart, the sliding surface has a groove portion adjacent to the flat portion (preferably surrounded by the groove portion), so that an oil film is easily formed on the flat portion, and the Al-Si alloy slides. Since solid contact with the Si particles protruding on the sliding surface of the material is suppressed, the friction loss can be reduced.

  Thus, the Al-Si alloy sliding material according to the first invention reduces the friction on the sliding surface, prevents the occurrence of scuffing, and has a long life and high durability. have.

  In the first invention, the groove portion can be formed into a linear shape (line shape) by inclining with respect to the sliding direction. Specifically, for example, honing or boring is performed as a grinding process, thereby forming a line-shaped groove that intersects the sliding direction, for example, inclined in one direction or inclined in two or more directions. It is preferable. By providing the line-shaped grooves so as to be inclined or crossed in one direction, it is easy to hold the lubricating oil on the sliding surface, and the oil film forming property during normal operation is enhanced. As a result, it is possible to effectively prevent the occurrence of low-temperature scuffing while suppressing the generation of friction loss due to the provision of Si particles protruding from the surface of the sliding surface.

  According to the first aspect of the present invention, a cylinder bore made of an Al—Si alloy, for example, casting or liner body casting can be formed. That is, the first invention includes a Si particle-containing Al-Si alloy including a hole in which a piston having a piston ring is reciprocally accommodated, and an oil film is formed between the outer periphery of the piston and the surface of the hole. It is a cylinder bore, and at least the surface of the hole includes at least 17 to 35% by mass of Si, and has a groove portion formed by grinding and capable of holding a lubricating oil, and a flat portion subjected to plastic working. A part of the Si particles protrudes from the surface of at least the flat part.

  As a result, the bore surface is lubricated with the lubricating oil held in the groove portion before warming up when the engine is restarted, and the protruding portion of the Si particles that protrude from the surface of the flat portion on the bore surface is the piston ring. Therefore, the aluminum of the Al—Si alloy becomes difficult to come into contact with the piston ring, and the occurrence of scuffing (especially low temperature scuffing) can be prevented. In addition, during normal operation after restart, an oil film is likely to be formed on the flat portion of the bore surface as described above, so that solid contact with Si particles protruding on the bore surface which is a sliding surface is suppressed, and friction loss is reduced. It can be kept small.

  A method for forming a sliding surface according to a second aspect of the present invention is an Si particle-containing Al-Si alloy containing 17 to 35 mass% of Si and having a rough geometric shape having a sliding surface. A groove forming process for forming a groove capable of holding the lubricating oil by grinding the surface, a flattening process for performing a plastic processing on the surface on which the groove is formed, and a flattening process. The surface is polished using an elastic substrate, and a particle projecting step for projecting Si particles from the surface is provided.

  In the second invention, the surface of the groove formed by grinding and planarized by plastic working is polished using an elastic base material (buff, rubber, etc.), so that the Si particles in the alloy are polished. By projecting a part from the surface, Si particles can be present on the sliding surface so that a part of the Si particle projects. As a result, at the time of sliding, for example, when the internal combustion engine such as an engine is restarted and still warmed before being warmed, it is lubricated with the remaining lubricating oil held in the groove portion, and the flat portion protrudes and protrudes. Since the Si particles can form a sliding surface that slides against the opposing sliding portion disposed opposite thereto, the aluminum on the sliding surface is difficult to contact the opposing sliding portion, and scuffing (particularly low temperature scuffing) occurs. Is prevented. Further, during normal operation after restarting, the sliding surface has a groove portion adjacent to the flat portion (preferably surrounded by the groove portion), so that an oil film is easily formed on the flat portion. Thereby, since a solid contact with Si particle | grains is suppressed, a friction loss is suppressed small.

  The particle projecting step of the second invention can be suitably performed by buffing using a buff and an abrasive. Buffing is performed by, for example, rotating an elastic base material such as a disk-shaped, cylindrical or conical buff at high speed, and polishing by applying an abrasive to this. The planarized surface alloy can be removed while the Si particles remain on the sliding surface. As a result, the Si particles can be projected and the Si height can be leveled to form a flat portion in which the Si particles protrude to a desired height.

  As an abrasive | polishing agent, it is preferable to use the abrasive grain whose volume average diameter is below the volume average diameter of Si particle | grains. Since the abrasive grains having a volume average diameter smaller than that of the Si particles are used, it is possible to efficiently polish while suppressing the removal of the Si particles.

  In the second aspect of the invention, the Si particle-containing Al-Si alloy having a rough geometric shape is provided with a hole in which a piston having a piston ring is accommodated so as to be able to reciprocate. A cylinder bore in which an oil film is formed between the surface and the surface can be used. In this case, the surface of the hole (bore surface) of the Si-particle-containing Al-Si alloy cylinder bore is ground, and the groove that can hold the lubricant is in the sliding direction in the cylinder bore (ie, the reciprocating direction of the piston). A groove part forming step for forming a linear shape having an inclination angle, a flattening process step for performing a plasticizing process on the bore surface on which the groove part is formed, and a flattening process. And a particle projecting step for projecting Si particles from the surface.

  Thus, by polishing the bore surface sliding with the piston ring using an elastic base material, Si particles in the alloy can be present so that a part thereof protrudes from the surface of the bore surface. . In this case, as described above, the bore surface is lubricated with the lubricating oil held in the groove portion at the low temperature before warming up when the engine is restarted during sliding, and the bore surface protrudes from the surface of the flat portion. Since the protruding part of the raised Si particles slides on the piston ring, the aluminum of the Al—Si alloy is difficult to come into contact with the piston ring, and the occurrence of scuffing (particularly low temperature scuffing) is prevented. In addition, during normal operation after restart, an oil film is likely to be formed on the flat portion of the bore surface as described above, so that solid contact with Si particles protruding on the bore surface which is a sliding surface is suppressed, and friction loss is reduced. It can be kept small.

  In the present invention, it is possible to construct a long-life, high-durability sliding mechanism. For example, in an internal combustion engine such as an engine, when the engine is restarted after being cooled down after being stopped or left standing, Thereafter, it is possible to construct an internal combustion system in which scuffing of the bore surface of the cylinder bore, which is caused by running out of oil in a short time until the viscosity of the oil is lowered and the lubricating oil is supplied by the pump, is suppressed.

ADVANTAGE OF THE INVENTION According to this invention, the Si particle containing Al-Si type alloy sliding material (for example, cylinder bore) in which generation | occurrence | production of the scuffing (especially scuffing at low temperature) in a sliding surface was prevented can be provided. Also,
ADVANTAGE OF THE INVENTION According to this invention, the formation method of the sliding surface which can form the sliding surface by which generation | occurrence | production of the scuffing at the time of sliding (especially scuffing at low temperature) was prevented can be provided.

It is a fragmentary sectional view showing the state where the piston was stored in the cylinder bore concerning an embodiment. (A) is a schematic diagram showing a groove pattern for retaining lubricating oil inclined at an inclination angle θ in one direction with respect to the sliding direction, and (b) is inclined in two directions with respect to the sliding direction. It is a schematic diagram showing a groove pattern for retaining lubricating oil that has an angle θ and is inclined and intersected. It is a figure which shows typically the cross section of the processing surface after passing through a groove part formation process. It is sectional drawing which shows typically the state in which the flat part and groove part which Si particle protrudes from the surface are formed in the sliding surface formed by performing a particle | grain protrusion process. It is process drawing which shows the processing flow which concerns on embodiment of the formation method of the sliding surface of this invention. It is sectional drawing which shows typically a mode that the surface after a groove part formation process is plastically deformed by rollering. It is explanatory drawing for demonstrating the scuffing-proof evaluation method by a scuffing test method. It is a graph which shows the result of scuffing resistance.

  Hereinafter, the Si particle-containing Al—Si alloy sliding material and the method of forming the sliding surface according to the embodiment of the present invention will be described in detail with reference to FIGS. The Si particle-containing Al—Si alloy sliding material according to the present embodiment is a cylinder bore, a cylinder bore using an Si particle-containing Al—Si alloy (hereinafter also referred to as “Al—Si alloy cylinder bore”) and its sliding. The method for forming the moving surface will be mainly described.

  An Al—Si alloy cylinder bore 1 according to an embodiment of the present invention is provided in a cylinder block 100 made of an Al—Si alloy containing Si particles in an engine which is an internal combustion engine as shown in FIG. It is. The Al—Si alloy cylinder bore 1 has a hole having a circular cross section, and a piston 3 having a piston ring 4 is accommodated in the hole so as to be capable of reciprocating in an axial direction perpendicular to the circular cross section of the hole.

The Al—Si alloy is an alloy containing at least aluminum (Al) and Si (silicon), and may contain other components as necessary or as an unavoidable component as long as the effects of the present invention are not impaired. it can.
Among the components in the alloy, the content ratio of Si in the alloy is in the range of 17 to 35 mass% with respect to the total mass of the Al-Si alloy. When the Si content is less than 17% by mass, the frequency of protrusion of Si particles decreases, and the occurrence of scuffing cannot be sufficiently suppressed, and when it exceeds 35% by mass, the wear of the mating member is suppressed. I can't. Especially, the range of 20-30 mass% is preferable from a viewpoint of improving the scuffing resistance in low temperature more.

  A plurality of piston rings 4 are mounted on the outer periphery of the piston 3. When the piston 3 reciprocates in the cylinder bore in the axial direction (vertical direction in FIG. 1), the piston ring 4 slides on the inner wall (bore surface) of the cylinder bore 1. At this time, an oil film made of lubricating oil is formed between the outer periphery of the piston 3 and the inner wall of the cylinder bore 1.

  On the inner wall (bore surface) of the Al—Si alloy cylinder bore 1, as shown in FIG. 1, a mesh-like groove 5 for retaining lubricating oil is formed. The groove 5 intersects the sliding direction of the piston 3 sliding in the cylinder bore 1 (vertical direction in FIG. 1) in two directions, that is, inclined at an inclination angle θ as shown in FIG. It is formed in a mesh shape. By forming the groove in a mesh shape, it is easy to hold the lubricating oil, and since the region other than the groove is surrounded by the groove, lubrication is facilitated according to the reciprocating motion of the piston.

The shape of the groove 5 is not limited to a mesh shape, and is inclined at an inclination angle θ in one direction with respect to the sliding direction of the piston of the cylinder bore 1 (vertical direction in FIG. 1) as shown in FIG. It may be formed linearly. In the case of having an inclination angle, the range of the inclination angle θ is not particularly limited, and can be arbitrarily selected within a range of 0 <θ <180 ° with respect to the sliding direction. Further, the inclination angle θ may be 0 ° with respect to the sliding direction as long as there is no hindrance in holding the lubricating oil. Further, in the present embodiment, the shape of the cross section of the linear groove (cross section orthogonal to the length direction of the groove) is formed in a triangular shape as shown in FIG. The cross-sectional shape of the groove may be formed in any shape such as a rectangle, a trapezoid, a semicircle, and a semi-elliptical shape in addition to a triangle.
The shape of the groove is not limited to a linear shape, and may be formed by providing a depression with a shape such as a point or a rectangle.

  The groove 5 is formed in a concave shape to the extent that the lubricating oil can be held. By holding the lubricating oil in this groove, scuffing will not occur due to running out of oil during the period from when the engine is warmed up and restarted after the engine stops until the viscosity of the lubricating oil decreases and is supplied from the pump Lubricate the sliding surface. The size of the groove can be selected as desired.

  The groove 5 is formed by performing a honing process as a grinding process on a hole formed in the cylinder block 100 when the cylinder bore 1 is finished. This groove can be formed not only by honing but also by other machining such as boring.

  As shown in FIGS. 2B and 4, a portion surrounded by the groove 5 is a flat portion 7 that receives pressure from the piston ring 4. The flat portion 7 is formed by forming a groove by honing or the like and then performing plastic processing by, for example, applying pressure and applying a roller as shown in FIG. 6, and the surface thereof is deformed by plastic processing. It is hardened with an obtuse angled and smooth surface.

  As shown in FIG. 4, Si particles 8 are arranged on the flat portion 7 so that a part of the particles protrudes from the surface. At the time of sliding, the flat portion 7 slides with the piston ring 4, but when oil runs out and no oil film is formed between the flat portion 7 and the piston 3, the Si particles 8 of the flat portion 7 slide with the piston ring 4. This prevents aluminum (Al) in the cylinder bore from coming into contact with the piston ring 4 and causing scuffing (particularly low temperature scuffing).

  As the Si particles in the Al—Si alloy, those in which Si contained for the purpose of alloying is crystallized and exist in the alloy are preferable in that the particles exist uniformly. In this case, an Si concentration in which primary crystal Si having a large particle size precipitates is necessary for wear resistance, and for example, an A390 alloy containing 17% Si and obtained by casting can be used. Moreover, you may use a commercial item and A390 alloy by Showa Denko Co., Ltd. is mentioned as an example of a commercial item.

  The distance from which the Si particles 8 protrude from the surface of the flat portion 7 (projection distance d) is preferably in the range of 0.1 to 2 μm from the viewpoint of suppressing contact between the aluminum matrix and the counterpart material, A range of 0.2 to 1 μm is more preferable. When the protrusion distance d is within the above range, the effect of preventing scuffing at a low temperature is high when restarting after the engine is stopped, and solid contact due to oil film formation is suppressed during normal operation, and the effect of reducing friction loss is high.

As the Si particles, hard particles such as Si, SiO ₂ , SiC, ZrSiO ₄ can be used. The average particle size of the Si particles contained in the alloy is preferably in the range of 10 to 150 μm and more preferably in the range of 30 to 150 μm in terms of volume average particle size. When the volume average particle diameter of the Si particles is within the above range, the Si particles can be easily present in the flat portion 7 in a state in which a part thereof protrudes, and the influence of friction loss during normal operation can be suppressed to a small level. Further, the wear of the mating member can be kept small.

  The cylinder bore of the present embodiment is manufactured using an Al-Si alloy containing Si particles, but other particles other than Si particles are included in the alloy as long as the effects of the present invention are not impaired. May be.

  Next, a method for forming the sliding surface of the Al—Si alloy cylinder bore will be specifically described with reference to FIGS.

The Al—Si alloy cylinder bore according to the present embodiment has a rough geometry having a hole (hereinafter referred to as a bore hole) having a sliding surface on which the piston ring slides, as shown in the work procedure of FIG. The groove that can hold the lubricating oil is tilted with respect to the sliding direction of the cylinder bore by honing the inner wall surface of the bore hole of the Si-particle-containing Al-Si alloy that has been processed into a shape. A step of forming a linear shape having a corner (groove portion forming step), a step of flattening the inner wall surface of the bore hole in which the groove is formed by performing a roll burnishing process as a plastic processing (a flattening process step), and a flattening process The processed inner wall surface is buffed, and a process of projecting Si particles from the inner wall surface of the bore hole (particle projecting process) is provided.
Hereinafter, each step will be described.

-Groove formation process-
In the groove forming process, a piston having a piston ring is accommodated so as to be able to reciprocate, and a coarse geometrically shaped Al having a bore hole having a surface that forms a sliding surface on which the piston ring slides is provided. -By performing honing on the inner wall surface of the bore hole of the Si-based alloy, the linear groove 5 having an inclination angle inclined with respect to the sliding direction of the cylinder bore is formed so as to be able to hold the lubricating oil. .

Before grinding in this process, the rough geometric shape of the Si particle-containing Al-Si alloy is processed in advance to obtain the desired cylinder bore shape, and then the piston ring slides when the cylinder bore reciprocates. The wall surface (sliding surface) to be machined is machined. The machining here can be performed by boring or the like in addition to honing. For example, honing is a processing method in which a honing head in which rod-shaped grindstones are arranged on the same circumference is rotated at a high speed and the wall surface of the hole is ground by reciprocating within the bore hole.
As shown in FIG. 3, when the honing process or the like is performed as described above, the protrusions 7a having sharp tips are formed on the wall surfaces of the holes together with the grooves 5a for retaining the lubricant, and the grooves 5a can be formed in a mesh shape.

-Flattening process-
In the flattening process, the surface of the bore hole is flattened by performing roll burnishing on the wall surface of the hole in which the groove 5a and the protrusion 7a are formed in the groove forming process.

  By performing plastic working as shown in FIG. 6, the protrusion 7a on the wall surface of the bore hole is mainly plastically deformed, and the groove 5a (see FIG. 3) is formed in the groove 5 to the extent that the lubricating oil can be retained, and the flat portion. 7 is formed. The plastic working can be performed by, for example, roll burnishing. Roll burnishing is a method in which a burnish roller is pressed against a work having an arcuate peripheral surface to transfer the surface shape of the burnish roller. In this step, the burnish roller is pressed against the inner wall of the bore hole, and in this state, the vanish roller is spirally moved by rotating and raising and lowering, thereby forming the groove 5a and the protrusion 7a formed by the honing process. The groove 5 and the flat portion 7 are formed as shown in FIG. 4 by plastically deforming the tip portion of the protrusion 7a with the groove remaining. As shown in FIG. 4, the surface of the flat portion 7 is a smooth surface, and the surface layer portion is hardened.

  In the cylinder bore subjected to the honing process and the roll burnishing process as described above, the groove 5 exhibits a function of forming and holding an oil film between the piston 3 and the outer periphery of the piston 3, and the flat part 7 is the piston ring 4. Demonstrates the function of receiving pressure. In this embodiment, in order to further improve the scuffing resistance on the inner wall surface of the cylinder bore on which the piston ring 4 slides, the following particle protrusion process is further provided.

-Particle protrusion process-
In the particle protruding step, the inner wall surface flattened in the flattening step is buffed to cause Si particles to protrude from the surface of the bore (bore hole) of the cylinder bore. Thereby, when it is easy to run out of oil when the engine is restarted after the engine is stopped, the piston ring slides with the Si particles on the inner wall of the bore hole, thereby preventing the occurrence of scuffing.

  Buffing is one method of polishing using an elastic base material. For example, an elastic base material such as a cylindrical buff is rotated at high speed, and polishing is performed by applying an abrasive thereto. For example, it can be carried out by polishing with an abrasive nonwoven wheel, further with a sisal buff or cotton buff.

Examples of buffs include cotton buffs and sisal buffs. Examples of abrasives include fats and oils (eg, animal, vegetable, mineral, etc.) and abrasives (alumina, chromium oxide, silica, etc.) Mixture. Abrasive nonwoven fabric is obtained by fixing abrasive grains to a nonwoven fabric such as nylon. The abrasive grains are in the form of particles, granules or powders among abrasives, and are abrasive grains having a volume average diameter equal to or less than the volume average diameter of the Si particles (polishing) in that they are efficiently polished while leaving Si particles. The form using the abrasive | polishing agent containing (material) is preferable. Among these, the abrasive is preferably alumina particles smaller than the volume average particle diameter of Si particles.
The volume average particle size of the abrasive grains is preferably 1/2 or less, more preferably 1/20 to 1/2 of the volume average particle size of the Si particles. When the volume average particle diameter of the Si particles is 1/2 or less, the destruction of the Si particles can be further suppressed. The volume average particle diameter is a value measured by a laser diffraction / scattering method or the like.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist thereof.

(Examples 1-4, Comparative Examples 1-6)
(Production of evaluation sample 1)
A flat plate of A390 alloy (Al-17Si, volume average particle size of Si particles 80 μm; manufactured by Showa Denko KK) was prepared as a test piece, and evaluation sample 1 (TP1) shown in Table 1 below was prepared under the following conditions. .
<Condition>
・ Rough geometric shape processing: The surface of the test piece is polished with # 2000 polishing paper (manufactured by Noritake Coated Abrasive Co., Ltd.) and groove forming step (1) Tool: # 80, # 120, # 400 polishing paper [ (Made by Noritake Coated Abrasive)
(2) Grinding direction angle: 30 °
(3) Manual machining and flattening process (rolling)
(1) Equipment: Rolling mill, manufactured by YOSHIDA Co., Ltd. (2) Use additive-free mineral oil (3) Processing pressure: 1% reduction
・ Particle protrusion process: Flattening by buffing and Si leveling (1) Buff type: Cotton (2) Abrasive: Alumina particles (volume average particle size = 0.3 μm) + tap water (3) Protrusion distance of Si particles d: 0.2 μm

(Preparation of reference sample)
A flat plate of A390 alloy (Al-17Si, volume average particle size of Si particles 80 μm; manufactured by Showa Denko KK) is subjected to buffing and ECM treatment (electropolishing method) as shown in Table 1 below, and scuffing resistance A reference sample serving as a reference material for evaluating the properties was used.
The ECM treatment was performed using a platinum plate as a counter electrode under the conditions of electrolyte solution: 120 g / l sodium nitrate aqueous solution, current density: 15 A / dm ² , and liquid temperature: 60 ° C.

(Production of evaluation sample 2)
Alumina crucible containing molten aluminum is placed in a SiO ₂ particle that has been sieved, stirred uniformly, poured into a mold and solidified, and then cut to prepare a flat plate as a test piece. And the evaluation sample 2 (TP2) shown in following Table 1 was produced on the said process conditions.

The surface roughness (Ra, Rz _JIS , Rvk, Rk, Rpk) in Table 1 is measured using SEF3400 (manufactured by Kosaka Laboratory Ltd.). The surface roughness is based on JIS B 0601: 2001, Ra: arithmetic average height of the roughness curve, Rz _JIS : ten-point average height of the roughness curve, and Rvk: oil pool depth of the load curve. , Rk: effective load height of the load curve, Rpk: initial wear height of the load curve.

(Evaluation)
Scuffing resistance was evaluated with respect to the evaluation sample and the reference sample obtained above, using a nitriding stainless steel piston top ring cutting material as a counterpart material. Specifically, as shown in FIG. 7, an evaluation sample or a reference sample is used as a sample, and a piston top ring is reciprocated in the direction of the arrow under the following evaluation conditions. The time to increase (scuff resistance time) was measured, and the length of the measured value was evaluated as an index. At this time, only a certain amount of oil was applied to the surface of the sample, and oil supply during the test was not performed. The evaluation results are shown in FIG.

<Evaluation conditions>
・ Load: 19.6N
-Surface pressure: 530 MPa (iron equivalent)
・ Number of round trips: 500 cpm
・ Reciprocal amplitude: 40mm
・ Temperature 70 ℃
・ Coating oil amount: 0.13 mg / cm ²
-Oil type: 5W-30 oil (manufactured by TonenGeneral Sekiyu KK)

As shown in FIG. 8, in Examples 1 to 4, a superior scuffing resistance was obtained compared to a reference sample having a practical track record in an engine, and only a groove formation by polishing could be performed. In comparison with Example 4, Comparative Example 3 in which flattening is performed, and Comparative Example 5 in which Si particles are raised but not formed by buffing, the scuffing resistance can be remarkably improved. It was.
Further, in Comparative Example 1 having a low Si concentration, the scuffing resistance was low, and in Comparative Example 2 in which the Si concentration was 39% by mass, the wear of the mating ring was extremely large.

DESCRIPTION OF SYMBOLS 1 ... Cylinder bore 3 ... Piston 4 ... Piston ring 5 ... Groove 7 ... Flat part 8 ... Si particle

Claims (7)

Containing at least 17 to 35% by mass of Si,
Si particles having a groove formed by grinding and capable of retaining lubricating oil and a flat portion subjected to plastic working, and having a sliding surface in which at least a part of the Si particles protrudes from the surface of the flat portion Containing Al-Si alloy sliding material.   The said groove part is formed in the linear which has an inclination | tilt angle with respect to a sliding direction, The Si particle containing Al-Si type alloy sliding material of Claim 1 characterized by the above-mentioned.   The sliding surface is a surface of the hole of the cylinder bore having a hole in which a piston having a piston ring is reciprocally accommodated, and an oil film is formed between the outer periphery of the piston and the surface of the hole. The Si-particle-containing Al—Si alloy sliding material according to claim 1, wherein the groove portion and the flat portion are provided on a surface of the hole. In order to retain lubricating oil by grinding the surface of the Si-particle-containing Al-Si alloy containing 17 to 35% by mass of Si and having a rough geometric shape having a sliding surface. A groove forming step of forming a groove of
A flattening process step of performing plastic processing on the surface on which the groove is formed;
Polishing the planarized surface using an elastic base material, a particle protruding step of protruding Si particles from the surface,
A method for forming a sliding surface.   The method for forming a sliding surface according to claim 4, wherein the particle protruding step is performed by buffing using a buff and an abrasive.   The sliding surface forming method according to claim 5, wherein the abrasive includes abrasive grains having a volume average diameter equal to or less than a volume average diameter of the Si particles. The Si particle-containing Al-Si alloy is a cylinder bore having a hole in which a piston having a piston ring is reciprocally accommodated, and an oil film is formed between an outer periphery of the piston and a surface of the hole. ,
The said groove part formation process forms the said groove part in the surface which has the inclination | tilt angle with respect to the sliding direction of the said piston in the surface of the said hole, The said any one of Claims 4-6 characterized by the above-mentioned. A method for forming a sliding surface as described.

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