JPH08332562A - Production of sliding member - Google Patents

Abstract

PURPOSE: To easily produce a sliding member excellent in machinability and aluminum adhesion resistance by compacting/sintering the mixed powder consisting of iron base metal powder and solid lubricant having covered layer and impregnating Al base metal in pores of sintered body. CONSTITUTION: A mixed powder consisting of iron base metal powder and solid lubricant having covered layer covered with metal or ceramic is compacted to a green compact. Successively, the green compact is sintered to sintered compact having pores in the inside. By this method, adhesion strength with matrix is improved, even in heating to 1000-1200 deg.C at sintering process and 800-850 deg.C at impregnating aluminum base metal, decomposition of solid lubricant is prevented due to existence of covered layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a sliding member used in a piston ring groove of an internal combustion engine.

[0002]

2. Description of the Related Art With the recent increase in engine combustion temperature and increase in hardness of piston rings, various measures have been taken against wear of piston ring grooves. For example, an Al-based MMC material in which an alumina-silica fiber is compounded with an aluminum-based metal is known, and an example in which it is used for a piston top ring groove is known (Japanese Patent Laid-Open No. 58-93835, etc.).

Japanese Patent Laid-Open No. 6-264079 discloses that
A sliding material is disclosed which comprises a carbonaceous powder, a solid lubricant whose surface is coated with a metal such as Au, Pt, or Ag, and an aluminum-based metal. According to this sliding material, since the solid lubricant coated with a specific metal is used, the reaction between the solid lubricant and the aluminum-based metal is prevented and the life can be extended.

However, in the piston top ring groove for a diesel engine using the above Al-based MMC material, due to the recent increase in the output of the diesel engine and the temperature rise in the piston ring groove portion, the adhesion between the piston ring and the piston ring (hereinafter , Aluminum adhesion) is a concern.
Also, the sliding material disclosed in Japanese Patent Laid-Open No. 6-264079 does not have sufficient heat resistance and sufficient strength for a piston ring groove because it is an aluminum matrix.

Therefore, it has been conceived to replace the aluminum-based metal with the iron-based metal, and conventionally, the piston ring groove is formed by Ni-resist cast iron. In this way, aluminum adhesion can be effectively prevented.

[0006]

However, as the amount of iron-based metal increases, the hardness increases remarkably and the machinability deteriorates remarkably. Therefore, it is conceivable to add a solid lubricant to reduce the cutting resistance between the cutting tool and the material during machining.
However, since a temperature of 1000 to 1200 ° C. is required to sinter the mixed powder containing a large amount of iron-based metal powder, there is a problem that the solid lubricant decomposes during sintering. JP-A-6-
Even the solid lubricant powder coated with a metal as disclosed in Japanese Patent No. 264079 can be protected up to 800 ° C., but is not protected at a sintering temperature of 1000 ° C. or higher and decomposes.

The present invention has been made in view of the above circumstances, and an object thereof is to manufacture a sliding member containing an iron-based metal as a matrix and containing a solid lubricant while preventing the solid lubricant from being decomposed. To do.

[0008]

Means for Solving the Problems A first method for solving the above problems is described below.
The method for manufacturing a sliding member of the invention comprises a molding step of molding a mixed powder of an iron-based metal powder and a solid lubricant having a coating layer coated with metal or ceramics to form a molded body, and sintering the molded body. And a sintering process for forming a sintered body having pores inside,
And a step of impregnating the pores of the sintered body with an aluminum-based metal.

The method of manufacturing the sliding member of the third invention is
It is characterized in that a mixed powder, in which an iron-based metal powder, a solid lubricant having a coating layer coated with a metal or ceramics, and aluminum or aluminum alloy powder are mixed, is sprayed on a material. The composition of the obtained sliding member is preferably 40 to 70% iron-based metal, 1 to 20% solid lubricant and 10 to 50% aluminum based metal in terms of volume ratio.

[0010]

In the manufacturing method of the first aspect of the invention, the solid lubricant contained in the molded body has a coating layer made of metal or ceramics. Therefore, the adhesion strength with the matrix is improved, and 1000 to 1200 ° C. in the sintering process.
Even when heated to 8 ° C when impregnated with aluminum-based metal
The presence of the coating layer prevents the solid lubricant from being decomposed even when heated to about 00 to 850 ° C.

Then, for example, when the aluminum base metal base material is manufactured, the base material is formed by using the sintered body as an insert. At this time, the pores formed in the sintered body are impregnated with the aluminum-based metal that constitutes the base material, and the anchoring effect causes the base material and the sintered body to be integrally bonded and slide on the surface of the base material. Is formed. Therefore, in the obtained sliding member, since the iron-based metal constitutes the matrix and the volume ratio of the aluminum-based metal is smaller than that of the conventional one, the occurrence of aluminum adhesion is prevented. Further, since the cutting resistance is small due to the presence of the solid lubricant, the machinability is good.

In the manufacturing method of the third invention, the sliding portion is manufactured by spraying a mixed powder of the iron-based metal powder, the solid lubricant and the powder of aluminum or aluminum alloy. In the case of thermal spraying, the solid lubricant is 1
It is exposed to a high temperature of 000 to 1500 ° C. However, the presence of the coating layer prevents decomposition of the solid lubricant. The composition of the sliding member formed according to the first invention or the third invention may be such that the volume ratio of the iron-based metal is 40 to 70%, the solid lubricant is 1 to 20%, and the aluminum based metal is 10 to 50%. For example, the volume ratio of the aluminum-based metal is smaller than in the past, aluminum adhesion is prevented, and the presence of the solid lubricant provides excellent machinability.

[0013]

【Example】

[Examples of the invention] The iron-based metal material is selected from iron or iron-based alloys such as carbon steel, tool steel, bearing steel, and heat-resistant steel,
It is desirable that the sliding portion contains 40 to 70% by volume. If it is less than 40% by volume, the hardness will be low and plastic flow will easily occur in the surface layer when sliding with the mating member, and the oxide film on the surface will be destroyed and the new surface will be exposed. Wearing is easy to occur. Again 7
If it is more than 0% by volume, the machinability will be lower than that of the conventional Al-based MMC material even if a solid lubricant is blended.

The aluminum-based metal material is selected from aluminum and aluminum-based alloys, and it is desirable that the sliding portion contains 10 to 50% by volume.
If the amount of aluminum-based metal is more than 50% by volume, plastic flow is likely to occur in the surface layer portion, the oxide film on the surface is destroyed, and the new surface is exposed, so that aluminum adhesion occurs with the mating member. .

On the other hand, if it is less than 10% by volume, the interfacial strength with the sintered body becomes low because the amount of the aluminum-based metal impregnating the pores in the first invention is small. This is due to the difference in the thermal expansion coefficient between the base material and the sintered body when used in combination with an aluminum-based base material. To reduce this difference and maintain high interfacial strength, 10% by volume or more. Impregnation is required. Further, in the third invention, when the aluminum-based metal is less than 10% by volume, when an aluminum-based base material is used, interfacial peeling occurs between the base material and the sprayed layer due to the difference in thermal expansion coefficient. Furthermore, the adhesion efficiency during thermal spraying is extremely reduced, and mass productivity is also reduced.

Solid lubricants include MoS ₂ , WS ₂ ,
BN or the like is used. This solid lubricant has 1
Used in the range of up to 20% by volume. If it is less than 1% by volume, it becomes difficult to reduce the cutting resistance, and if it is more than 20% by volume, the strength is lowered and the solid lubricant is dropped from the matrix. If it is 10% by volume or more, transfer of the solid lubricating film to the mating material occurs and high sliding performance can be obtained, so it is desirable to set it to 10 to 20% by volume.

The coating layer may be a metal coating film of Fe, Mo, Cu or the like, a ceramic coating film of TiN, CrN or the like, or a plating film of Ni-P, Ni-B or the like. The film thickness is preferably 5 to 20 μm. If it is less than 5 μm, the film thickness tends to be non-uniform, and the solid lubricant may be decomposed by heat in a thin portion. If the thickness is more than 20 μm, cracks may occur in the coating layer and the coating time becomes long, which is not preferable. As a coating method, a known method such as a PVD treatment method such as sputtering or vapor deposition, an electroless plating method can be used. [Examples] Hereinafter, specific examples will be described. Example 1 First, a coating layer made of Fe was formed on the surface of MoS ₂ powder by a sputtering method. The film thickness of the coating layer is 5 μm.

Next, Fe-1% C high carbon steel powder and MoS ₂ powder having the above coating layer were mixed in a volume ratio of 49: 1, packed in a mold and pressed to form a compact. Obtained. Then, the molded body was heated to 800 to 1200 ° C. under pressure to manufacture a porous sintered body. This sintered body is placed in a predetermined portion of a mold, and an aluminum alloy (AC
The molten metal of 8A) was cast under high pressure. At the time of casting, the molten metal was impregnated into the pores of the sintered body, and a test piece having a predetermined shape was obtained in which the sintered body was integrally bonded to the base material.

The material composition of the sliding portion of the test piece was 49: volume ratio iron-based metal, solid lubricant and aluminum-based metal.
The ratio is 1:50. Next, using this test piece, workability and aluminum adhesion resistance were evaluated. The workability was evaluated by cutting using a test piece in which a cylindrical sintered body was integrated with the outer peripheral portion of a cylinder having an outer diameter of 90 mm. Cutting tip is "BN-100" (Sumitomo Electric Co., Ltd.)
(Made by the manufacturer) was used and the processing speed was 100 to 200 m / min and the cutting depth was 0.04 mm / rev. Then, measure the main component force, feed component force and back force component with a cutting dynamometer,
The cutting resistance was calculated by calculating the square root of the sum of squares and determining the combined force. Then, the cutting resistance at each cutting speed was calculated, the average value was calculated, and the results are shown in Table 3.

To evaluate the aluminum adhesion resistance, a ring-on-plate type tester (beating-sliding) was used, and the plate-shaped test piece and the ring of the mating material (SUS430-equivalent material were subjected to nitriding treatment and surface hardness). Hv1000 or more)
Then, it was slid under the conditions of Table 1 and examined for aluminum adhesion.
The results are shown in Table 3.

[0021]

[Table 1] (Examples 2 to 4) Test pieces were manufactured in the same manner as in Example 1 except that the compounding amounts of the high carbon steel powder and MoS ₂ powder and the impregnated amount of AC8A were changed as shown in Table 3, and the same. The cutting resistance and the presence or absence of aluminum adhesion were measured and the results are shown in Table 3. (Examples 5 to 6) The coating layer was formed by sputtering of Mo, and the blending amount of the high carbon steel powder and MoS ₂ powder and AC8.
A test piece was manufactured in the same manner as in Example 1 except that the impregnation amount of A was changed as shown in Table 3, and the cutting resistance and the presence or absence of aluminum adhesion were measured in the same manner, and the results are shown in Table 3. . (Example 7) BN powder was used in place of MoS ₂ , and bearing steel (SUJ2) powder was used in place of the high carbon steel powder.
A test piece was manufactured in the same manner as in Example 1 except that the volume ratio of the iron-based metal to the solid lubricant and the aluminum-based metal was 40:10:50, and cutting resistance and aluminum adhesion were similarly prepared. The presence or absence was measured and the results are shown in Table 3. (Example 8) A tool steel (SKD11) powder, a WS ₂ powder having a coating layer in which TiN was formed to a thickness of 5 μm by a PVD method, and an Al-Si alloy powder were mixed in a volume ratio of 7
Mixed powders were prepared by mixing so as to be 0:20:10.

Next, the sprayed portion of the test piece of AC8A was cleaned by shot blasting, and then METOC was used.
The mixed powder was sprayed under the conditions shown in Table 2 using a plasma spraying apparatus manufactured by Company O to form a test piece having a sprayed layer.

[0023]

[Table 2] With respect to the obtained test piece, cutting resistance and the presence or absence of aluminum adhesion were measured in the same manner as in Example 1, and the results are shown in Table 3. (Examples 9 to 11) Tool steel powder of the sprayed layer and WS ₂ and A
A test piece was manufactured in the same manner as in Example 8 except that the composition ratio of the 1-Si alloy powder was changed as shown in Table 3, and the cutting resistance and the presence or absence of aluminum adhesion were determined in the same manner as in Example 1. The measurement results are shown in Table 3. (Example 12) First, a coating layer made of CrN was formed on the surface of WS ₂ powder by a PVD treatment method. The thickness of the coating layer is 5
μm.

Next, the tool steel (SKD11) powder and the WS ₂ powder having the above-mentioned coating layer were mixed in a volume ratio of 45: 5, packed in a mold and pressed to obtain a molded body. Using this molded body, a test piece was manufactured in the same manner as in Example 1, and the cutting resistance and the presence or absence of aluminum adhesion were measured in the same manner, and the results are shown in Table 3. (Examples 13 to 14) A tool steel (SKD61) powder, a MoS ₂ powder and a Al-Si alloy powder having a coating layer in which Ni-P was formed to a thickness of 10 μm and 20 μm by electroless plating, respectively, Mixed powders were prepared by mixing in the ratios shown in 3. Then, a test piece having a sprayed layer was formed in the same manner as in Example 8, the cutting resistance and the presence or absence of aluminum adhesion were measured in the same manner as in Example 1, and the results are shown in Table 3. (Examples 15 to 16) Tool steel (SKD61) powder, MoS ₂ powder and A having a coating layer on which Ni-B was formed by electroless plating to a thickness of 5 μm and 10 μm, respectively.
The 1-Si alloy powder was mixed in the ratio shown in Table 3 to prepare a mixed powder. Then, a test piece having a sprayed layer was formed in the same manner as in Example 8, the cutting resistance and the presence or absence of aluminum adhesion were measured in the same manner as in Example 1, and the results are shown in Table 3. Comparative Example 1 First, a coating layer made of Cu was formed on the surface of MoS ₂ powder by sputtering. The thickness of the coating layer is 5
μm.

Next, the tool steel (SKD61) powder and the MoS ₂ powder on which the above-mentioned coating layer is formed are in a volume ratio of 49.5:
The mixture was mixed to be 0.5, filled in a mold and pressurized to obtain a molded body. Using this molded body, a test piece was manufactured in the same manner as in Example 1, and the cutting resistance and the presence or absence of aluminum adhesion were measured in the same manner, and the results are shown in Table 3. The sliding part of the test piece is made of tool steel and M
The volume ratio of oS ₂ and ACA8 is 49.5: 0.5: 50.
It is composed of a ratio of. (Comparative Examples 2-3) Tool steel (SKD61) powder and MoS ₂
A test piece was manufactured in the same manner as in Example 1 except that the compounding amount of the powder and the impregnated amount of AC8A were changed as shown in Table 3, and the cutting resistance and the presence or absence of aluminum adhesion were measured in the same manner, and the result Is shown in Table 3. (Comparative Examples 4 to 6) Except that the coating layer was formed by sputtering Fe and the compounding amounts of the tool steel (SKD61) powder and MoS ₂ powder and the impregnation amount of AC8A were changed as shown in Table 3. A test piece was manufactured in the same manner as in Example 1, and the cutting resistance and the presence or absence of aluminum adhesion were measured in the same manner, and the results are shown in Table 3.
Shown in (Comparative Examples 7 to 8) Tool steel (SKD61) powder, MoS ₂ powder and Al-S having a coating layer in which Mo is formed by sputtering to have a thickness of 3 μm and 25 μm, respectively.
The i alloy powder was mixed in a volume ratio shown in Table 3 to prepare a mixed powder.

This mixed powder was sprayed in the same manner as in Example 8 to form a test piece having a sprayed layer. With respect to the obtained test piece, cutting resistance and the presence or absence of aluminum adhesion were measured in the same manner as in Example 1, and the results are shown in Table 3. (Comparative Example 9) tool steel and (SKD61) powder, a mixed powder mixed in a ratio of 50:10:40 of MoS ₂ powder and Al-Si alloy powder having no coating layer in a volume ratio, Example 8 A test piece having a sprayed layer was formed in the same manner as in. With respect to the obtained test piece, cutting resistance and the presence or absence of aluminum adhesion were measured in the same manner as in Example 1, and the results are shown in Table 3. (Reference Examples 1 and 2) Test pieces were formed in the same manner as in Example 1 using BN powder having no coating layer and bearing steel (SUJ2) powder, and cutting resistance and the presence or absence of aluminum adhesion were measured in the same manner. The results are shown in Table 3. (Reference Examples 3 to 4) Test pieces were formed for Ni-resist cast iron and Al-based MMC material in which alumina-silica fiber was composited with aluminum-based metal, and cutting resistance and presence or absence of aluminum adhesion in the same manner as in Example 1. Was measured and the results are shown in Table 3.
Shown in

[0027]

[Table 3] (* Indicates that the surface is rough)

(Evaluation) From Table 3, the sliding member obtained by the manufacturing method of the present invention has a low cutting resistance and no occurrence of aluminum adhesion. Therefore, both the workability and the aluminum adhesion resistance are obtained. It is clear that it is superior to.

When a solid lubricant such as BN having stable performance up to high temperature as in Reference Examples 1 and 2 is used, good performance is exhibited without a coating layer, and the effect of the coating layer is not clear. . However, by comparing Comparative Example 9 with Examples 13 to 16, it is clear that the sliding member using a solid lubricant such as MoS ₂ has improved workability and aluminum adhesion resistance due to the presence of the coating layer. Is.

When the content of the solid lubricant is less than 1% by volume as in Comparative Example 1, the cutting resistance is high and the transfer of the solid lubricant to the mating material hardly occurs, so that the aluminum adhesion resistance is also poor.
On the other hand, if the solid lubricant exceeds 20% by volume as in Comparative Example 2, the proportion of the solid lubricant in the volume of the sliding member increases and the holding power decreases, causing the solid lubricant itself to drop off. Roughness occurs and cutting resistance is also high.

When the iron-based metal is less than 40% by volume as in Comparative Example 3, plastic flow cannot be prevented and aluminum adhesion occurs. On the other hand, if it exceeds 70% by volume as in Comparative Example 4, no improvement in machinability due to the solid lubricant can be observed. When the Al-based metal is less than 10% by volume as in Comparative Example 5, cracks are likely to occur at the interface between the sintered layer or the sprayed layer and the base material, and the cutting resistance is increased due to the increase in the iron-based metal. . On the other hand, when the Al-based metal exceeds 50% by volume as in Comparative Example 6, the iron-based metal cannot hold the Al-based metal, plastic flow occurs, and aluminum adhesion occurs.

From the comparison between Example 2 and Comparative Examples 7 to 8, it can be seen that the cutting resistance is high even if the coating layer is as thin as 3 μm or too thick as 25 μm. Further, as shown in Reference Examples 3 to 4, Niresist cast iron, which is a conventional material, exhibits good aluminum adhesion resistance, but has high cutting resistance, and Al-based MMC material has low cutting resistance, but is used when the operating environment is severe. Has aluminum adhesion. (Embodiment 17) An example in which the sliding member of the present invention is applied to the piston ring groove of an engine piston is shown below.

First, a coating layer made of Fe was formed on the surface of MoS ₂ powder by a sputtering method. The film thickness of the coating layer is 5 μm. Next, the high carbon steel powder of Fe-1% C and the MoS ₂ powder having the coating layer formed thereon were mixed at a volume ratio of 50: 2.
The mixture was mixed so as to be 0, filled in a mold, and pressurized to obtain a piston ring groove-shaped molded body.

Then, the molded body is pressed under a pressure of 800 to 1200.
It heated at 0 degreeC and manufactured the porous sintered compact. This sintered body was placed in a predetermined portion of a mold, and a molten aluminum alloy (AC8A) at 600 to 800 ° C. was subjected to high pressure casting to manufacture a piston ring. During casting, the molten metal was impregnated into the pores of the sintered body, and a piston ring having a predetermined shape was obtained in which the sintered body was integrally joined to the piston ring groove.

The material composition of the piston ring groove portion is such that the iron base metal, the solid lubricant and the aluminum base metal are 5 in volume ratio.
The ratio is 0:20:30, and the structure is the same as that of the third embodiment. (Example 18) A high carbon steel powder of Fe-1% C, a MoS ₂ powder having a coating layer in which Fe was formed to a thickness of 5 μm by sputtering, and an Al-Si alloy powder were mixed in a volume ratio of 50: Mixed powder was prepared by mixing so as to be 20:30.

Next, after the piston ring groove portion of the piston ring made of AC8A was cleaned by shot blasting, a plasma spraying apparatus manufactured by METOCO was used to obtain Table 2
The mixed powder was sprayed under the conditions shown in to form a sprayed layer in the piston ring groove. The thermal sprayed layer contains iron-based metal, solid lubricant, and aluminum-based metal in a volume ratio of 50: 20: 3.
The ratio is 0, which is the same as that of the third embodiment. Comparative Example 10 An AC8A piston having a piston ring groove formed of conventional Ni-resist cast iron was formed. (Test) Each of the above pistons was cut in the same manner as in Example 1 and the cutting resistance was measured. The results are shown in Table 5. Also, each was mounted on an actual machine, and the presence or absence of aluminum adhesion and the wear depth of the piston ring groove were measured under the test conditions shown in Table 4. The results are shown in Table 5.

[0037]

[Table 4]

[0038]

[Table 5] It is clear from Table 5 that the sliding member of the present invention does not cause aluminum adhesion like Niresist cast iron, has a lower cutting resistance and a smaller wear amount than Niresist cast iron.

[0039]

That is, according to the method for producing a sliding member of the present invention, the solid lubricant is prevented from being decomposed and dropped off, so that it is excellent in machinability using an iron-based metal and is resistant to aluminum adhesion. It is possible to easily and reliably manufacture a sliding member having excellent properties. That is, the sliding member obtained by the present invention has excellent wear resistance, and at the same time, extremely excellent machinability and lubricity.

Claims (4)

[Claims] 1. A molding step of molding a mixed powder of an iron-based metal powder and a solid lubricant having a coating layer coated with a metal or ceramics to obtain a molded body, and sintering the molded body to form an internal body. A method for manufacturing a sliding member, comprising: a sintering step of forming a sintered body having pores; and an impregnation step of impregnating the pores of the sintered body with an aluminum-based metal. 2. The sliding member has a volume ratio of 40 to 70% of the iron base metal, 1 to 20% of the solid lubricant, and 10 to 50% of the aluminum base metal. The method for manufacturing a sliding member according to claim 1. 3. Forming by spraying a mixed powder obtained by mixing iron-based metal powder, a solid lubricant having a coating layer coated with a metal or ceramics, and aluminum or aluminum alloy powder onto a material. A method for manufacturing a sliding member having the characteristics. 4. The sliding member has a volume ratio of 40 to 70% of the iron base metal, 1 to 20% of the solid lubricant, and 10 to 50% of the aluminum base metal. The method for manufacturing a sliding member according to claim 3.