JPS6056060A - Sliding contact member and its production - Google Patents

Abstract

PURPOSE:To develop a sliding member having excellent lubricity and wear resistance by providing a nitrogen compd. layer having high hardness on the surface of the sliding member consisting of a ferrous material and plating a metal having excellent lipophilic property to the very small recesses of the nitrogen compd. layer. CONSTITUTION:A mask having many apertures 5a each sized at about 100mu diameter phi is formed on the inside sliding wall surface 2 of a cylindr, etc. manufactured of a steel, cast iron, etc. A plating lever 4 consisting of a metal and alloy having good lipophilic property such as Cu and Cu alloy, Ni and Ni alloy, etc. is plated in the apertures 5a to about 2 mu thickness (t). The mask is then removed and this time with the above-mentioned plated parts 4 as a mask the surface is subjected to a nitroding treatment to form a hard nitride layer 5 on the surface of a base material 3 formed of a steel or cast iron to 4mu height (d) from the surface of the plated player 4. Recesses 6 constituted of such nitride layer 5 and the plating surface 4 are used as the parts for holding lubricating oil, by which the sliding surface 2 having excellent lubricity and wear resistance is formed.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a sliding contact member and a method for manufacturing the same, and is used for sliding contact members such as engine cylinders and bearings that require wear resistance and good lubricity. It is.

(Conventional technology The cylinders, bearings, and other sliding contact members of conventional engine engines are treated with nitrogen to form a sliding surface made of a nitrogen compound layer, increasing the hardness of this sliding surface and improving its wear resistance. This is commonly done, for example, as described in Japanese Patent Application Laid-Open No. 5/737370.However, such a nitrogen compound layer is formed with volume expansion of the surface of the iron-based base material, for example. The flat plate-shaped sliding member is curved in its entirety, and in the case of cylinder lychee, it is deformed into an elliptical shape, causing problems such as its out-of-roundness.

On the other hand, the sliding surfaces of sliding members are usually supplied with lubricating oil to improve their lubricity, but sliding surfaces made only of nitrogen compounds have low oil retention, and the There is a problem that causes seizing between the material and the material.

(Purpose of the invention) The present invention provides a nitrogen compound layer having high hardness.

The present invention aims to provide a sliding contact member that has high wear resistance and good lubricity by combining metal plating with good oil retention properties, and furthermore, it aims to provide a sliding contact member that can be easily and easily processed. The purpose is to provide a manufacturing method that can manufacture objects without causing major deformation.

(Structure of the Invention) A seventh invention relates to a sliding contact member, in which a nitrogen compound layer is formed on the surface of an iron-based base material, four parts are regularly opened on the surface of the nitrogen compound layer, and a copper-based metal is formed in the four parts. , a highly lipophilic plated portion such as nickel-based metal is provided.

The second invention relates to a method for manufacturing a sliding contact member, and includes the following steps.

In the first step, a masking process is performed on the surface of an iron-based base material such as steel or cast iron to form a mask in which openings are regularly arranged.

In the second step, a base material surface is formed by plating with a highly oleophilic metal such as a copper-based metal or a nickel-based metal, and then the mask is removed.

In the third step, a nitriding treatment is performed on the surface of the base material using the plated portion as a mask to form a nitrogen compound layer.

Through the above steps, a sliding contact member in which a plated portion and a nitrided portion are combined is obtained.

(Example y Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an engine cylinder liner 1 as an example of a sliding member. This cylinder liner 1 is made of steel,
The cylinder is made of iron-based material such as cast iron, and the inner wall of the cylinder on which the piston (piston ring) slides, that is, the sliding surface 2, is surface-treated as described below.

That is, the structure of the surface layer of the inner wall of the cylinder is shown in FIG. In the figure, reference numeral 3 denotes an iron-based base material constituting the cylinder liner 1, and the surface side, that is, the sliding contact surface 2, is plated with a highly oleophilic metal such as copper, copper-based alloy, nickel, or nickel-based alloy. and a nitrogen compound layer 5. The nitrogen compound layer 5 partially protrudes from the base material 3 side and forms recesses 5a that are regularly opened in the sliding surface 2, and the plated portions 4 are provided in the recesses 5a.

The nitrogen compound layer 5 has a smooth surface and a surface height higher than the surface of the plated part 4, and an oil holding recess 6 is formed with the plated part 4 as the bottom surface.

To give an example of dimensional settings in the above-mentioned surface layer structure, the thickness t of the plated part 4 is approximately 2μ, and the height of the nitrogen compound layer 5 from the surface of the plated part 4, that is, the depth d of the oil holding recess 6 is based on the When the material 6 is made of steel, it is set to about .mu. Furthermore, the area ratio of the oil holding recess 6 on the sliding surface 2 is 30%.
It is done to a certain degree.

The oil holding recess 6 may be of any type, such as a pinpoint type, a channel type, or a combination type of both types, and in the case of a channel type, the direction of the groove can be made into a desired iR turn by the method described later. I can do it. In the case of the pinpoint type, the diameter φ of the oil holding recess 6 is approximately 100μ.

In addition, when the base material 3 is made of cast iron and the volumetric expansion of the base material surface due to the nitriding treatment cannot be expected to be large, the surface heights of the plated portion 4 and the nitrogen compound layer 5 are made to substantially match each other,
In some cases, no oil retaining recess is formed.

Next, a method of manufacturing the cylinder liner 1, which is the sliding contact member, will be explained.

In the method according to this embodiment, the base material 6 is made of steel and a photoforming method is used to form the plated portion, and as shown in FIG. 3, the method includes the following steps.

-Pre-treatment step So1 This process consists of the following steps.

In the first step 501, steel material (JIS-8TKM/3
) The surface (inner wall surface) of the base material 6 of the cylinder liner molded with
Perform rough processing on.

In the second step 502, the base material 6 is subjected to strain relief annealing treatment. This heat treatment is carried out at 20° C. for about r hours.

In the third step S03, the surface (inner wall surface) of the base material 6 is
Apply finishing processing to. For this finishing process, for example, a JIS-GC'100J grindstone is used.

The first step S is a masking step for partially plating the surface of the base material 3, and consists of the following steps.

In the first step S11, a photosensitive photoresist film is formed on the surface of the base material 3 in close contact. The photoresist film is formed, for example, by applying an ultraviolet-sensitive liquid resin to the surface of the substrate, or by pressing a film-like resin onto the surface of the substrate with a rubber roller or the like.

In the second step S12, a photomask film formed by regularly disposing mask portions of arbitrary 7s11 turns prepared in advance is brought into close contact with the surface of the photoresist film.

The third step S13 is an exposure step, and in the case of an ultraviolet-sensitive photoresist film, a high-pressure mercury lamp is used for this exposure.

The first step S11 is a development step, in which the substrate 3 from which the photomask film has been removed is immersed in a developer such as a trichloroethane solution, the unhardened portion of the photoresist film is dissolved and removed, and a layer is formed on the surface of the substrate 3. As shown in FIG. 7, a mask 7 made of a hardened photoresist film is formed. In other words,
A resist image is formed on the surface of the base material 3, and openings 8 are regularly formed in a mask 7 made of the photoresist film at a predetermined nof turn.

In addition, photoresist film and photomask film are
A positive type and a negative type can be appropriately combined. For example, when a negative star photoresist film and a positive photomask film are combined, the openings 8 of the mask 7 obtained after development are opened at positions corresponding to the mask portions of the photomask film.

The second step s2 is a plating step using an oleophilic metal and consists of the following steps.

In the first step S21, electroplating using a highly lipophilic metal such as copper, copper alloy, nickel, or nickel alloy is performed from the surface side of the mask 7 formed in the first step S1. The lipophilic metal reaches the surface of the base material 3 through the opening 8 of the mask 7 and is deposited, forming a plated portion 4 on the surface of the base material as shown in FIG.

For plating, a method other than electroplating, for example, a chemical plating method may be used.

In the second step S22, the mask 7 is removed, leaving only the plated portion 4 on the surface of the base material 6, as shown in the figure. To remove the mask 7, the base material 3 is immersed in a solvent such as a methylene chloride solution to dissolve the mask 7.

- Third step s3 - This process is a nitriding process.

That is, the partially plated base material is placed in a nitriding furnace,
Perform gas nitrocarburizing treatment. The processing conditions are as follows.

Processing temperature: 67.5°C Processing time: 20 minutes Gas composition RX: NH3=Gj: , 56 (%
) In this step, since the surface of the base material 6 is partially masked by the plated parts 4, nascent nitrogen diffuses into the base material 3 from between the plated parts 4.

In this case, the nitrided portion on the surface of the base material undergoes volumetric expansion (approximately θ% in the case of steel), so a nitrogen compound layer 5 is formed between the plated portions 4 due to the expansion as shown in FIG. The surface of this nitrogen compound layer 5 is higher than the surface of the plated portion 4. The average thickness of the nitrogen compound layer 5 obtained in this step is about 77 μm.

The first step s4 is a finishing step in which the surface of the base material 6 is honed to make the surface height of the nitrogen compound layer 5 uniform, and the oil is retained at a predetermined depth d as shown in FIG. Four parts 6 are formed. For honing, for example, JIS
- Use a GC4100J grindstone for about 76 to 2θ seconds.

In the above embodiment, the base material 3 is made of steel, but it may be made of other iron-based materials such as cast iron. In that case, the oil retaining portions may not be formed because volumetric expansion due to nitriding is not expected to be significant.

Further, in the first step S1, a 7-photoresist film was used for the masking process, but a masking material made of resin or the like having openings in a predetermined pattern may be brought into close contact with the surface of the base material.

Furthermore, in the third step, gas soft nitriding was used as the nitriding process, but other nitriding methods such as gas nitriding, salt bath soft nitriding, and ion nitriding may be used.

Next, the wear resistance of the cylinder inner wall according to the embodiment of the present invention will be explained based on a comparative test with a conventional example.

- Wear Test Apparatus - The test apparatus is shown in FIG. In the same figure, 10
1 is a base, 11 is a support, and the base 10 is provided with an oil tank 12 and an oil pump 13. A cylinder liner specimen 14 is arranged continuously above the oil tank 12, and the cylinder liner specimen 14 is supported by an upper support rod 15 and a lower support rod 16. Cylinder liner sample material 1
A piston 17 is inserted into the oil tank 12, and the piston 17 is connected to a crankshaft 19 in the oil tank 12 via a funnel rod 18.
is connected to. In the figure, arrow A indicates the manner in which the crankshaft 19 rotates. An oil jet 20 extends from the oil pump 13, and this oil jet 20 faces the inside of the cylinder liner specimen 14. A lid 21 is attached to the upper support rod 15 , and the lid 21 closes the upper end opening of the cylinder liner specimen 14 . An air supply pipe 22 is attached to the lid body 21, and the cylinder liner specimen 1
Air is supplied to the space above the piston No. 4. A check valve 23 is interposed in the air supply pipe 22, and a pressure gauge 24 is attached to the lid body 21. 25 is the top ring, 26 is the secondary ring,
27 is an oil ring.

- Test material - The cylinder liner test material 14 is made of steel and has a bore diameter (diameter) of /θθ, a wall thickness of 31TIIn, and a length of /gJ'mm. In the case of the embodiment, the cylinder inner wall (sliding surface) is as shown in FIG. Area ratio is 30%, depth d beam μ
It is. The surface treatment is the treatment step 5Q-54 of the above example.
by. On the other hand, in the case of the conventional example, after the nitriding treatment, J
A single honing process was performed for 75 seconds using a 5-GC, 2jθH grindstone to form cross-hatched oil grooves.

The inclination angle of the cross hafting 2 with respect to the bore circumferential direction is 3
It is θ degrees.

- Wear test conditions - The test conditions are as follows.

Crankshaft rotation speed /jθOrpm Air pressure Top dead center 3. ! Reduction/Changing dead center i6 #7ca Stroke 70rrvn Test time 70 hours Also, engine oil (70W-30) is used for lubricating oil.
%, kerosene jO%, and carbon j% was used to make the viscosity comparable to that of the engine oil used as the backing during actual diesel engine operation. Engine oil (70w-30) has a nooricity value of zero. The tension of the piston rings is 3# for the top ring 25 and 2# for the secondary ring 26. ．． 5jcf, oil ring 2
7 to 2. As Otsukan, the conditions were stricter than for normal engines.

- Comparison details - The roundness (deformation amount) and straightness (ml shape amount 9) of the cylinder liner sample 14 before and after nitriding treatment and the amount of wear of the cylinder liner sample 14 and each oil ring in the wear test were measured. The roundness measurement positions were at three locations whose distances from the upper end of the cylinder liner specimen 14 were as follows.

A...6mm + B...7gmm+C
・・・・・・/G JrNn Straightness is 2 as shown in Figure 2.
Change the position by 0 degrees, or go to E, F, and G.

The amount of wear on the cylinder liner sample 14 was measured at the top dead center position of the piston, and the amount of wear on the piston rings was measured by the amount of weight loss. The test results are shown in the table below.

-Considerations- In the examples, the amount of distortion is minute in both roundness and straightness, and it is recognized that no problems arise. Further, the amount of wear on the cylinder liner sample 14 and the piston ring in the example is much smaller than in the conventional example, and it can be seen that the example has extremely excellent durability. Furthermore, while scuffing was observed in the conventional example, no scuffing occurred in the example. As described above, the reason why the example shows excellent round leather cord and straightness is that the sliding contact surface is partially plated, and deformation during nitriding treatment is suppressed by the plated portion 4. In addition, the sliding characteristics of the examples are excellent because
This is believed to be because the bottom surface of the oil retaining recess 6 is comprised of the plated portion 4 made of highly oleophilic metal, which improves oil retention.

Here, the lipophilicity test results are shown in FIG. In this test, lubricating oil is dropped at θ,/CCM from a height of 10 mm onto the plated surface of each of the metals mentioned above, and the amount of spread (average diameter) of the lubricating oil after being left for 70 minutes is measured. Oil (10W-410) (7)/i was mixed with kerosene in two cases, and the number of measurements was three times.

The test results shown in Figure 1θ show that copper and nickel exhibit higher lipophilicity than chromium, and it is recognized that this is reflected in the results of the above wear test.

(Effects of the Invention) According to the sliding contact member according to the first invention, since the sliding contact surface is provided with a nitrogen compound layer and a plated portion made of a highly oleophilic metal, oil is retained on the sliding contact surface. This results in improved friction properties and improved sliding properties.

According to the second invention, since the nitriding treatment is performed after partially plating the base material surface, the plated portion serves as a mask in the nitriding treatment, and the sliding contact member according to the first invention can be easily obtained. , the plating area narrows the nitriding area,
In addition, since it has the effect of partially suppressing volumetric expansion during nitriding, deformation of the sliding contact member due to nitriding can be reduced.

[Brief explanation of drawings]

Fig. 1 is a perspective view of a cylinder liner shown as an example of a sliding contact member, Fig. 2 is a sectional view of the surface layer structure of the sliding contact member, Fig. 3 is a manufacturing process diagram of the sliding contact member, and Fig. Figure 5 is a cross-sectional view showing the state with this mask installed, Figure 5 is the state after No. 1 treatment, Figure 3 is the state with the mask removed, Figure 7 is a cross-sectional view showing the state after nitriding treatment, and Figure 2 is a cross-sectional view showing the state after nitriding treatment. FIG. 2 is a plan view of the cylinder liner showing the straightness measurement position, and FIG. 1θ is a graph showing the lipophilicity test results. 1...Cylinder liner, 2...Sliding surface, 3...Base material, 4...Plated part, 5...
...Nitrogen compound layer, 5a...Concavity, 6.
...Oil holding recess, 7...Mask, 8
......Aperture Akira 1 Figure J 5a 5a b. 9th part 11 also 10 figure M l

Claims (2)

[Claims] (1) A nitrogen compound layer is formed on the surface of the base material made of iron-based material, and recesses are regularly opened on the surface of this nitrogen compound layer. A sliding contact member characterized by being provided with a metal plated portion. (2) Masking the surface of the base material made of iron-based material to form a mask with regularly arranged openings, and then plating with a highly oleophilic metal such as copper-based metal or nickel-based metal. A plated portion is formed on the surface of the base material at a position corresponding to the opening of the mask, and then the mask is removed, and then a nitriding treatment is performed to form a nitrogen compound layer on the surface of the base material not covered with the plated portion. A method of manufacturing a sliding contact member, characterized in that: