KR20140043960A

KR20140043960A - Surface treatment method for low friction of internal combustion engine material

Info

Publication number: KR20140043960A
Application number: KR1020120105929A
Authority: KR
Inventors: 이수완; 부펜드라 조쉬; 이현휘
Original assignee: 선문대학교 산학협력단
Priority date: 2012-09-24
Filing date: 2012-09-24
Publication date: 2014-04-14

Abstract

The present invention relates to a surface treatment method for an internal combustion engine material, including a step of forming a dimple pattern on the surface of an internal combustion engine material by irradiating a processing laser beam to the surface of internal combustion engine material. The surface treatment method for an internal combustion engine material using a laser pattern design according to the present invention improves fuel efficiency by reducing friction using a laser surface treatment technology and reduces carbon dioxide emission.

Description

Surface Treatment Method for Low Friction of Internal Combustion Engine Material

The present invention relates to a surface treatment method for an internal combustion engine material, and more particularly, to a surface treatment method for low friction for an internal combustion engine material using a laser pattern design.

The tribological properties of many engine parts in the automotive industry are important for energy savings, maintenance and maintenance, cost savings due to parts replacement and breakdown, investment savings due to extended life, and energy savings due to friction reduction. In particular, wear and friction behavior in tribological properties have a significant effect on the surface morphology in contact with each other. In the case of sliding contact in a lubricated state, tribological properties can be improved by the formation of surface irregularities such as small dimples. These irregularities serve to prevent the lubricant reservoir and lubricant from counting out. In addition, the wear particles can be removed from the contact surface and collected inside the structure, thereby preventing further wear by the wear particles. Therefore, in recent years, researches for improving fuel efficiency and reducing energy loss due to friction in power mechanical parts by reducing energy loss caused by frictional resistance of engine parts have been conducted in various ways. Research is actively underway.

Surface texturing technology involves processing a large number of irregularities, such as dimples or grooves, on at least one of the two surfaces, with the aim of improving the lubrication properties between the two surfaces that are in relative motion through the lubricant. Unevenness of the surface promotes lubricant storage and hydrodynamic pressure generation by trapping abrasive particles.

In particular, laser surface texturing mainly produces patterns in the form of dimples, and the processing time is extremely fast compared to other texturing methods, and the shape or size of the dimples can be adjusted using the parameters of the laser (pulse energy, number of pulses). In the research trend of laser surface texturing, S. Schreck et al., Germany used Nd: YAG laser to study channel and dimple type texturing on Al2O3 and 100Cr6 steels and reduced friction according to their density under lubrication. Israel's Etsion has experimentally confirmed that partial patterning is improved over overall patterning by using laser surface texturing on the cylinder ring, the part of the internal combustion engine that directly contacts the cylinder. In addition, Kovalchenko of Argonne Laboratories in the United States reported that the wear rate of the ball was higher than the initial contact when the dimple was based on dimple density using laser surface texturing (LST), friction coefficient according to the viscosity of the lubricant, and wear scar of the ball. In the case of lubricating state with increased contact area, it is suggested that the transition from boundary lubrication to mixed lubrication area occurs quickly and the friction coefficient is reduced.

However, even with the above studies, there is a limitation in improving fuel efficiency due to friction reduction through laser surface texturing technology, and thus there is a need for improvement.

S. Schreck, K.-H. Zum Gahr, "Laser-assisted structuring of ceramic and steel surfaces for improving tribological properties," Applied Surface Science 247, 616-622 (2005) G. Ryk, I. Etsion, "Testing piston rings with partial laser surface texturing for friction reduction," Wear, 261, 792-796 (2006) Andriy Kovalchenko, Oyelayo Ajayi, Ali Erdemir, Georage Fenske, "Friction and wear behavior of laser textured surface under lubricated initial point contat," Wear, 271, 1719-1725 (2011)

An object of the present invention is to provide a surface treatment method for an internal combustion engine material using a laser pattern design that can improve fuel efficiency of an internal combustion engine due to friction reduction through laser surface treatment technology, thereby contributing to carbon dioxide emission reduction. .

The present invention provides a surface treatment method for an internal combustion engine material, comprising irradiating a surface of the internal combustion engine material with a processing laser beam to form a dimple-shaped pattern on the surface of the internal combustion engine material.

The surface treatment method for an internal combustion engine material of the present invention improves fuel efficiency of an internal combustion engine due to friction reduction through laser surface treatment technology, and thereby surface treatment for an internal combustion engine material using a laser pattern design that can contribute to a reduction in carbon dioxide emission. It may provide a method.

1 is a schematic diagram of an arrangement of dimples in the laser pattern design of the present invention.
2 is a diagram of an engine block used in an embodiment of the present invention.
Figure 3 is a SEM surface photograph of the specimen used in the embodiment of the present invention.
Figure 4 is an EDX analysis graph of the specimen used in the embodiment of the present invention.
5 is a distribution diagram of graphite flakes for an engine block used in an embodiment of the present invention.
Figure 6 is a photograph of the device used in the cylinder-on-plate experiment method of the present invention.
Figure 7 is a schematic diagram and specifications of the device used in the cylinder-on-plate experimental method of the present invention.
8 is a photograph of the surface according to the density and arrangement of the dimples of Examples 1 to 4 of the present invention.
Figure 9 (a) is a photograph of the laser pattern processing the specimen of the present invention, Figure 9 (b) is a photograph in which the residue is removed.
10 is a photograph showing damage to the shape of the dimples generated during laser processing.
11 is a graph of the friction coefficient for each load and sliding speed of Comparative Example 1.
12 is a graph of the friction coefficient for each load and sliding speed of Example 1.
FIG. 13 is a graph of a friction coefficient for each load and sliding speed of Example 2. FIG.
14 is a graph of the friction coefficient for each load and sliding speed of Example 3.
15 is a graph of friction coefficients by load and sliding speed of Example 4. FIG.
Figure 16 (a) is a graph of the friction coefficient change with the increase of the load at the sliding speed 0.1m / s, Figure 16 (b) is a graph of the friction coefficient change with the increase of the sliding speed at the load 20N.
17 is a graph showing the relationship between surface pressure and load capacity.
18 is a graph showing a change in the friction coefficient with an increase in the density-specific load of the dimples.
19 is a graph of change in the coefficient of friction according to the increase in the sliding speed for each density of the dimple.
20 is a graph measuring the width of the worn portion of the SUJ2 cylinder according to the density of the dimple after the friction and wear test.
FIG. 21 is an optical micrograph of the worn part of the SUJ2 cylinder according to the density of the dimple after the friction and abrasion test.
22 is a graph measuring the width of the worn portion according to the sliding speed of Example 3.
23 is an optical micrograph of the worn portion according to the sliding speed of Example 3.

Hereinafter, the present invention will be described in detail.

The surface treatment method for an internal combustion engine material of the present invention includes irradiating a surface of an internal combustion engine material with a processing laser beam to form a dimple pattern on the surface of the internal combustion engine material.

Although the internal combustion engine material of this invention is not specifically limited, Preferably, 1 or more types of material chosen from the group which consists of a cast iron and an aluminum alloy can be used. The materials of these internal combustion engines have three characteristics during operation of the internal combustion engine: friction, wear and lubrication. First, since abrasion is a major cause of material loss and surface damage, a reduction in wear is directly related to longevity and reliability, and friction is a major part of energy consumption. have. And lubrication plays an important role in controlling wear and friction.

First of all, friction refers to the phenomenon of resisting movement in two sides of relative movement and is considered as one of the most important problems in all machines and devices. Friction is an important phenomenon that inevitably occurs in daily life.In addition, friction, such as brakes or clutches for power transmission, can be used as a positive aspect, and automobiles, ships, etc., which have to minimize the waste of power. A great deal of effort has been made to minimize friction in devices that require precise operation, such as engines, gear transmissions and gyroscopes. Because of this important physical meaning of friction, it has been the subject of many physicists' research for a long time and has attracted attention as an important component that directly affects the operation of the machine. The basic laws of friction known by physicists have been

(1) Friction is proportional to the load applied.

(2) Friction is not affected by the external contact area.

(3) Friction is not affected by sliding speed.

(4) Static friction is larger than copper friction.

When a body is subjected to a sliding motion under the load W, the force to resist the friction force F is generated in the direction opposite to the direction of motion of the contact surface. At this time, according to the above (1) can be expressed by the following equation (2).

[Formula 2]

F = μ * W

Where μ is defined as the coefficient of friction.

Paragraph (1) of the law applies to all contact phenomena except that the contact area of the real contact converges to the external contact area due to the large contact pressure applied by a large load, but (2) is fixed unlike general metals. It should be noted that this does not apply to elastic and viscoelastic materials that do not have a specified yield point and that paragraph (3) does not apply consistently to all materials. Paragraph (4) is a common phenomenon in metal and ceramic materials, and the static friction is larger than the friction during operation, that is, the dynamic friction. However, this does not apply to viscoelastic materials having viscosity and elasticity.

Next, wear is the continual separation of materials from the contact surfaces of mutually moving materials, and the wear resistance of the material is not inherent to the material itself, but is determined by the wear conditions and the wear environment at the time of wear. Characteristic. In addition, in most cases, wear is not caused by one cause but is caused by a combination of various causes. The causes of wear include adhesive wear, abrasive wear, fatigue and detachment wear, corrosion and oxidative wear.

Finally, lubrication prevents damage to the surface by separating relative moving objects by a lubricating film with low shear force. Lubrication zones are classified into boundary lubrication, mixed lubrication, elastomeric lubrication, and hydrodynamic lubrication according to lubrication film thickness and surface roughness. The frictional properties are applied during the non-lubricated contact motion where direct physical interaction occurs on the relative moving contact surface. When the lubricant is present at the contact interface to form a lubricating film, the friction coefficient changes with other characteristics.

During each operation of the internal combustion engine, friction characteristics are shown. Among them, friction between the piston and the piston ring, bearing friction, etc. are typical. The frictional characteristics of these internal combustion engines are very important for energy saving, maintenance and repair, cost reduction due to parts replacement and breakdown, investment cost reduction due to life extension, and energy saving due to friction reduction.

To this end, in the present invention, a dimple-shaped pattern on the surface of the internal combustion engine material is formed by irradiating the surface of the internal combustion engine material with a processing laser beam. In tribological characteristics, wear and friction behavior have a significant effect on the surface shapes in contact with each other. In the present invention, in the case of sliding contact in such a lubricated state, small dimple-shaped surface irregularities are formed, thereby providing tribological characteristics. Can improve. The irregularities can serve to prevent the lubricant reservoir and lubricant from counting out, as well as remove wear particles from the contact surface and collect inside the structure, thereby preventing additional wear by the wear particles.

The dimple preferably has a density of 0.05 to 0.5 defined based on Equation 1 below.

[Formula 1]

ρ _A : density of dimples

d: diameter of dimple

p: center distance between dimples

In the above formula, d means the diameter of the dimple, and p means the center distance between the plurality of dimples. In the present invention, when the dimple-shaped laser surface is textured on the surface of the internal combustion engine material to form a pattern, the internal combustion engine material has an advantage of reducing friction as compared to the material of the polished surface.

The material processing method used in the surface treatment method for the internal combustion engine material of the present invention can use a laser beam as a heat source. When using a processing laser beam to form the dimples, the structure, density and arrangement of the dimples can be easily changed due to the usefulness of the laser device, such as the adjustment of laser parameters, to form dimples of various densities. More specifically, the present invention uses a laser marking method. The laser marking method is a non-contact method, which is free from contamination, has high reliability, and can accurately and quickly mark any material without applying mechanical stress. In addition, the laser marking uses a pulsed laser beam, so the pulsed laser beam with a short pulse duration has a great temperature increase, but heat transfer occurs within a short time, so that heat is not transferred to the inner zone, thereby preventing distortion of the component. Therefore, this method is widely used for miniaturizing electronic parts and printed boards, as well as for recording model numbers and manufacturing numbers of machine parts such as tool tips or drill tips, and for displaying barcodes of various products. Laser marking methods usable in the present invention include a laser beam engraving method, a dot matrix method and a mask imaging method.

Hereinafter, although an Example and a test example are given and this invention is demonstrated more concretely, these are for illustrating this invention, and the scope of the present invention is not limited by these.

Manufacture of specimens

As the test specimen used in this study, G's 1600cc gasoline engine can be easily contacted with the relative surface by high-precision flattening in the size of 15mm × 15mm × 4mm closest to the inside of the cylinder as shown in FIG. It was prepared to be. The prepared specimens were subjected to surface photography (FIG. 3) and chemical composition analysis (see Table 1) using an optical microscope, SEM and EDX.

element weight% Standard Deviation C 1.47 0.17 Si 0.46 0.05 P 0.04 0.03 S 0.06 0.03 Cr 0.05 0.08 Mn 1.03 0.12 Fe 96.51 0.42 Ni 0.06 - Cu 0.1 0.09

In particular, the component analysis of Figure 4 was calculated by averaging the value measured more than about 30 times by specifying a wide range rather than a specific area using EDX. In addition, the engine cylinder was cut to a predetermined size using a cutter, and finally manufactured to a size of 15 mm (width) x 15 mm (length) x 4 mm (thickness) with a high speed cutter so as to facilitate the friction wear test. The prepared metal specimen was roughly polished to a surface roughness Ra = 0.1 using a 1 μm Al ₂ O ₃ slurry after rough machining with a planar grinding machine. The polished specimens were used for the wear friction test after ultrasonically drying and washing.

As shown in FIG. 3, the carbon present in the engine block is present in the form of graphite flakes, and each graphite flake has a depth of about 0.162 μm ± 0.03 (Rt-Maximum height of the profile). This is a factor influencing the roughness during the friction test. For this reason, the ratio of the graphite flake area occupying the average distribution of the graphite flakes on the surface was evaluated about 50 times or more, and the results of the distribution of the average values are shown in FIG. 5.

The counterpart material is a SUJ2 bearing steel (Ra-0.35㎛), which is widely used for the friction experiment of cylinder-on-plate type, and was prepared in a cylindrical shape having a diameter of 5 mm and a length of 10 mm.

Laser pattern design and processing

The test pieces were arranged at equal intervals as in FIG. 1 and the working conditions are shown in Table 2. In each condition, the number of laser irradiation is the same as one time, and the density of the dimples was theoretically calculated using the following Equation 1.

[Formula 1]

Output (W) Frequency (kHz) Scanning speed (mm / s) Pulse width (ns) Theoretical density of dimple (%) Comparative Example 1 10 20 300 200 0 Example 1 10 20 300 200 5 Example 2 10 20 300 200 10 Example 3 10 20 300 200 20 Example 4 10 20 300 200 30

Under the same conditions as above, the pattern was processed using a Yb fiber laser (INYA, Inlaser Co., Korea). The surface phase of the processed specimens was measured in 2D using an OLYMPUS OLS1100 Laser Scanning Microscope equipped with a confocal laser scan measurement analysis system, and the width and depth of the removed part were measured.

Preparation for experiment

In this study, PLINT TE77 (Plint & Partners Co., Ltd., UK) was used as a cylinder-on-plate test method at room temperature, atmospheric pressure, and lubricated state to evaluate friction characteristics. Is shown in FIG. 7. The movement of the upper specimen was a linear reciprocating motion using the cam's rotating force, and the repetition speed was adjustable to about 0.025 ～ 0.5 m / s. Vertical loads were used up to 200 N using a maximum 200 N load cell. The friction force was detected by the Piezo-Electiric sensor detecting the movement of the table on which the specimen was fixed during operation. The experimental conditions are shown in detail in Table 3 below, and all friction experiments were performed after removing the lubricant after one use to prevent impurity incorporation and obtaining reliable data. Measured.

Tribometer time Cylinder on plate Substrate Material and Size GM. Engine block (15mm × 15mm × 4mm) Cylinder material and size SUJ2 bearing steel
Diameter: 5mm, length: 10mm Normal load 10N-30N stroke 5mm Frequency 5 Hz-30 Hz Average sliding speed 0.05 m / s-0.3 m / s lubricant Distilled water Temperature Room temperature Humidity 20% less than

First, the experimental calculation of the dimples formed on the surface of the specimen by laser surface texturing is shown in Table 4 below.

Theoretical calculation Experimental calculation Diameter (um) density(%) Diameter (um) density(%) Comparative Example 1 - Example 1 50 5 64 6 Example 2 50 10 63 14 Example 3 50 20 63 31 Example 4 50 30 53 50

Since the diameter of the laser beam was about 50 to 52㎛, the diameter of the dimple was estimated to be about 50㎛ and theoretically calculated, the ratio of the density on the surface was 5 to 30%. Variables due to ancillary surface finishes, such as polishing, were used to remove debis, which is different from the theoretical results. The experimental dimple density ranged from 6 to 50%. 8 shows the surface according to the density and arrangement of the dimples of Examples 1 to 4. FIG.

Figure 9 (a) is a photograph immediately after the laser pattern processing and Figure 9 (b) is a photograph in which the residue is removed by a simple polishing operation. Here, it can be seen that the residue affects about 70 to 80 μm due to the heat effect when the diameter of the laser pattern is processed to about 50 to 60 μm dimples. Therefore, when the interval between the dimples is 80 μm or less, the range of influence of the pulse beams forming the dimples overlaps, and thus the shape of the dimples cannot be produced in laser pattern processing. FIG. 10 shows that the shape of the dimples is damaged due to overlap of heat affected parts generated during laser processing with a gap between the dimples of 50 μm. In particular, when the density of the pattern is more than 50%, that is, the interval between the dimples is 80 μm or less, the dimples do not have the shape due to the thermal orientation between the dimples and the dimples generated during the laser pattern processing. This is the reason why the minimum dimple spacing is 80 μm.

Friction Coefficient by Load and Velocity According to Dimple Density

Laser surface texturing was used to measure the load at 10, 15, 20, 25, and 30 N for the specimens of Examples 1 to 4 and Comparative Examples, each of which had a different surface depending on the presence of dimples on the surface and the density of the dimples. During the measurement, the sliding speed was fixed at 0.1 m / s, and the measurement was performed while changing the sliding speed to 0.05, 0.1, 0.15, 0.20, 0.25, 0.30 m / s, and the load was fixed at 20 N for 20 minutes.

Figure 11 shows the friction coefficient change for each load and sliding speed of Comparative Example 1. The coefficient of friction decreased with the change of the load, and the coefficient of friction decreased from 0.1 to 0.15 m / s until about 10 minutes at the speed of 0.05 m / s, and then gradually increased. Overall, the coefficient of friction decreased with increasing load and sliding speed.

Figure 12 shows the change in friction coefficient for each load and sliding speed of Example 1. As the load increased, the friction coefficient decreased, and the friction coefficient was measured to be about 0.05 lower than that of the polished specimen. In Example 1, the effect was greater than that of Comparative Example 1 at 0.2 to 0.3 m / s when the sliding speed was changed.

Figure 13 shows the change in friction coefficient for each load and sliding speed of Example 2. As the load increased, the friction coefficient decreased, and in Example 2, the friction coefficient suddenly decreased at a speed of 0.2 m / s or more.

14 shows the change in friction coefficient for each load and sliding speed of Example 3. As the load increased, the friction coefficient decreased, and in Example 3, the friction coefficient decreased rapidly at a speed of 0.2 m / s or more.

Figure 15 shows the change in friction coefficient for each load and sliding speed of Example 4. Compared with other dimple density specimens, the friction coefficient decreased with increasing load and the friction coefficient was higher than that of the polished specimen. In Example 4, a sharp friction coefficient was also decreased at 0.2 to 0.3 m / s. The difference in Example 4 is that the lines in the graph are relatively curved, which is considered to be the reason for the sharp increase in the roughness of the surface in Example 4.

Overall, the results of loading and sliding speed change experiments with and without laser surface texturing showed that the friction coefficient decreased with increasing load, and also the friction coefficient decreased with increasing sliding speed.

According to dimple density Kinetic Coefficient of friction

FIG. 16 illustrates the values of FIGS. 11 to 15 by removing the coefficient of friction coefficient from the starting point where the change of the value is large, to 5 minutes (static friction), and calculating the average value of the interval where the value is stabilized. The effect of density on friction characteristics was compared. In the case of Figure 16 (a) shows a change in friction coefficient with increasing load at a common sliding speed 0.1m / s. The friction coefficient decreased with increasing load, with or without dimples. In particular, the lowest coefficient of friction was observed at a dimple density of 6% (Example 1). The friction coefficient tends to decrease with increasing load due to plate-like graphite. Except for some areas, most of the comparative examples showed a lower coefficient of friction, which is considered to increase the load capacity by generating a surface pressure as shown in FIG. 17, unlike the surface dimpled on the surface under lubrication.

At low loads, the difference in reduction width was low, but as the load increased, the width increased. In addition, as the dimple density increased, the coefficient of friction increased, which may be because the average roughness of the surface also increased.

Figure 16 (b) shows that the friction coefficient decreases as the sliding speed increases at 20N load. In particular, at a speed of 0.15 m / s or less, some examples showed a higher friction coefficient than the comparative example, but at a speed of 0.20 m / s or more, the low friction coefficient was measured as compared to the comparative example. Based on both results, the effect of dimples on the surface of this material shows that the friction reduction is more affected by the sliding speed than the load.

Friction due to dimple density Abatement ratio

18 and 19 are the increase and decrease ratios of the friction coefficient obtained by using Equation 3 based on the friction coefficient for each load and sliding speed according to the presence or absence of dimple and density.

[Formula 3]

COF _p : Friction coefficient of Comparative Example 1

COF _t : Friction Coefficient of Example

In the graphs of FIGS. 18 and 19, the + value on the right side represents the reduction ratio of the friction coefficient, and the − value represents the increase of the friction coefficient, based on the zero value of the x axis.

18 shows the coefficient of friction as the density of dimples increases. Compared with the comparative example, the coefficient of friction tended to decrease, with a maximum reduction of 20% or more. However, in Example 4 (dimple density of 50%), the average roughness of the surface was increased by more than about, resulting in an increase in the coefficient of friction.

Figure 19 shows the friction coefficient according to the increase in the sliding speed for each density of the dimple. At a relatively low speed of 0.05 m / s, the friction coefficient tended to increase a little, but at 0.1 m / s it tended to decrease. In particular, at the sliding speed of 0.2m / s or more, the width was sharply increased, Example 3 (a maximum reduction of 45% or more at the dimple density of 31%).

As shown in the results shown in Figs. 18 and 19, it was observed that the friction coefficient at the sliding speed was sharply reduced in this material rather than the effect of the load.

From this point of view, it can be expected that a significant energy saving effect can be expected by applying the experimental results of the present invention to an actual automobile engine.

Wear Characteristics According to Dimple Density

20 shows the results of measuring the width of the worn portion of the SUJ2 cylinder according to the cylinder-on-plate friction and the dimple density after the abrasion test. According to this result, it can be seen that the wear width increases as the dimple density increases. In Examples 1 to 3 with dimple densities of 6%, 14%, and 31%, the wear width was wider than that of the comparative example, but as shown in FIGS. 18 and 19, the coefficient of friction decreased. The initial contact state between the cylinder and the plate will be in contact with numerous illuminances in enlargement, and the apparent contact will be a line contact. Line contact will be converted to surface contact as the time of the friction wear test progresses. In other words, although the wear width of the cylinder increased due to the increase in the surface roughness, the area in contact with the surface became wider. Therefore, the transition from the boundary lubrication zone to the mixed lubrication zone is consequently increased because the thickness of the oil film is larger than that of the boundary lubrication zone.

FIG. 21 is an optical micrograph of the worn part of the SUJ2 cylinder according to the density of the dimple after the friction and abrasion test. After the test, the SUJ2 cylinder specimens exhibited a phenomenon in which hard particles, which were generated due to abrasion during relative movement, were removed by ploughing the soft surface, leaving grooves or scratches. This shows that abrasive wear predominates in the wear mechanism for engine materials and SUJ2 specimens under lubrication (distilled water).

Wear Characteristics According to Sliding Speed

FIG. 22 shows the width of the worn portion according to the sliding speed of Example 3 having a dimple density of 31%. The wear width increased at a sliding speed of 0.05 to 0.20 m / s. The wear width decreased in the 0.25 to 0.30 m / s speed range. Since the friction wear test operation time is the same for each sliding speed for 20 minutes, it is shown in Table 5 when converted to the travel distance.

Sliding speed (m / s) 0.05 0.1 0.15 0.2 0.25 0.3 Sliding distance (m) 60 120 180 240 300 360

In the 0.25 ~ 0.3m / s speed range, the travel distance was relatively longer than other speeds, but the wear width was narrow. Also, from 0.20m / s, the coefficient of friction decreased rapidly. However, the wear rate was 0.20 m / s. The friction coefficient was similar from 0.20m / s, but it is thought that 0.25 or 0.30m / s has a narrow wear width because the lubricating film increases due to the speed increase.

FIG. 23 is an optical micrograph of the worn portion at sliding speed of Example 3 having a dimple density of 31%. FIG. As shown in FIG. 21, the same abrasive wear as that of the wear mechanism according to the change of the density of the dimple predominated.

Claims

Irradiating a surface of the internal combustion engine material to the surface of the internal combustion engine material to form a dimple-shaped pattern on the surface of the internal combustion engine material.

The method according to claim 1,
The dimple has a density of 0.05 to 0.5 based on the following formula 1, the surface treatment method for an internal combustion engine material.
[Formula 1]

ρ _A : density of dimples
d: diameter of dimple
p: center distance between dimples

The method according to claim 1,
The processing laser uses any one or more of a laser beam engraving method, a dot matrix method and a mask imaging method.

The method according to claim 1,
The internal combustion engine material is a surface treatment method for an internal combustion engine material, characterized in that at least one member selected from the group consisting of cast steel, cast iron and aluminum alloy.

The internal combustion engine material surface-treated by the surface treatment method for internal combustion engine materials of Claim 1.