JPH11107848A - Cylinder liner made of powder aluminum alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide such a thin-walled and lightweight cylinder liner made of an aluminum alloy that a gap is not produced on an interface between a cylinder liner and an engine block body, even after a cylinder liner made of a powder aluminum alloy is cast in an engine block body made of a molten aluminum alloy, and is good for actual use. SOLUTION: This cylinder liner made of a powder aluminum alloy cast in an engine block made of a molten aluminum alloy, uses such a cylinder linear made of an aluminum alloy that the thermal expansion factor of a powder aluminum alloy of which a cylinder line consists is αC and the thermal expansion factor of a molten aluminum alloy of which an engine block consists is αB, the cylinder liner made of an aluminum alloy satisfies formulas of 14×10<-6> deg.C<=αC<=20×10<-6> / deg.C and 1×10-6/ deg.C<=αB-αC<=8×10<-6> / deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder liner made of a powdery aluminum alloy used for automobiles, motorcycles, snowmobiles, personal watercrafts, and the like. The present invention relates to a powdered aluminum alloy for a cylinder liner suitable for casting a cylinder liner.

[0002]

2. Description of the Related Art Lightening of parts for automobiles or motorcycles that frictionally slide in lubricating oil can be expected to greatly improve fuel efficiency by reducing friction and driving torque. It is very effective to reduce the weight of the aluminum part.

However, if the lubricating oil is not sufficiently present at the sliding interface during operation for some reason, the aluminum portion has a problem such as seizure or adhesion. For example, the piston itself is made of an aluminum alloy, and the seizure phenomenon is suppressed by using a cast aluminum alloy with a hard plating of nickel, chromium, iron, etc. on the sliding surface as the mating material of the cylinder liner for internal combustion engines. Was considered.

However, since the aluminum alloy constituting the base material has insufficient heat resistance, it cannot be used as a liner material, and there is a problem in terms of economy.

[0005] Therefore, in order to improve the wear resistance and heat resistance of the aluminum alloy, by using a powdered aluminum alloy having a microstructure obtained by a rapid solidification method, these characteristics are improved, and the aluminum alloy is put into practical use as a cylinder liner material. A possibility was found. For example, according to the techniques disclosed in Japanese Patent Publication No. 6-21309 and Japanese Patent Application Laid-Open No. 1-256541, aluminum alloy powder having a special alloy composition is mixed with fine and nearly spherical alumina hard particles and lubricating components. We have proposed a cylinder liner material for internal combustion engines that can be mixed and added with graphite powder and solidified by hot extrusion.

Further, in the technique disclosed in Japanese Patent Application Laid-Open No. 1-271053, a method has been proposed in which a cylinder liner made of a powdered aluminum alloy is cast into an engine block body made of an aluminum alloy.

[0007]

However, when such an aluminum alloy cylinder liner is cast into an aluminum alloy engine block body by an aluminum high pressure casting method, the casting is completed in a relatively short time. The outer peripheral surface does not weld or bond with the engine block body. When the engine block is cooled to room temperature in this state, a gap is generated at the contact interface between the cylinder liner and the engine block due to the coefficient of thermal expansion. As a result, there is a problem that the cylinder liner comes off from the engine block body.

[0008] On the other hand, in the conventional technique, the outer peripheral surface of the cylinder liner is subjected to a fall prevention process such as a groove process. However, this drop-off prevention processing is
The cylinder liner must be made thicker, causing problems such as an increase in the cost of the cylinder liner and an increase in the size and weight of the engine block body.

Accordingly, an object of the present invention is to prevent a gap from being formed at an interface between a cylinder liner and an engine block body even after the cylinder liner is cast into an engine block body made of a molten aluminum alloy and to prevent the cylinder block from falling off. An object of the present invention is to provide a thin and light-weight powdered aluminum alloy cylinder liner that can withstand actual use without requiring any processing for the purpose.

[0010]

According to a first aspect of the present invention, there is provided a powder aluminum alloy cylinder liner cast into a molten aluminum alloy engine block, Assuming that the thermal expansion coefficient of the powder aluminum alloy cylinder liner is α _C and the thermal expansion coefficient of the molten aluminum alloy engine block is α _B , the relationship between the two is 14 × 10 ⁻⁶ / ° C ≦ α _C ≦ 20.
× 10 ⁻⁶ / ° C. and 1 × 10 ⁻⁶ / ° C. ≦ α _B −α
_C ≦ 8 × 10 ⁻⁶ / ° C.

Further, in the invention according to claim 2,
2. The cylinder liner made of a powdered aluminum alloy according to claim 1, wherein the cylinder liner made of a powdered aluminum alloy is cast into the engine block made of a smelted aluminum alloy by a high-pressure aluminum casting method.

As described above, according to the first and second aspects of the present invention, no gap is generated at the contact interface between the cylinder liner and the engine block due to the relationship between the coefficient of thermal expansion and the engine block. As a result, it is possible to prevent the cylinder liner from falling off the engine block.

Next, in the invention according to claim 3,
The cylinder liner made of a powdered aluminum alloy according to claim 1 or 2, wherein the powdered aluminum alloy of the cylinder liner contains aluminum nitride and Si, and the total content thereof is for the cylinder liner on a weight basis. It is 5% or more and 30% or less with respect to the whole powder aluminum alloy.

This makes it possible to achieve both an appropriate range of the coefficient of thermal expansion and excellent wear resistance.

Next, in the invention according to claim 4,
3. The cylinder liner made of a powdered aluminum alloy according to claim 1, wherein the powdered aluminum alloy of the cylinder liner contains 0.5% to 15% by weight of aluminum nitride, and the balance is aluminum. AlN dispersed aluminum alloy powder.

This makes it possible to obtain sufficient wear resistance and machinability. Next, in the invention as set forth in claim 5, the powdered aluminum alloy cylinder liner according to claim 1 or 2, wherein the powdered aluminum alloy of the cylinder liner is 0.1% by weight of nitrogen. %
This is an AlN-dispersed powdered aluminum alloy containing not less than 5%, the balance being aluminum, and the nitrogen being bonded to the aluminum.

This makes it possible to produce an appropriate amount of AlN, and as a result, it is possible to obtain a cylinder liner made of a powdered aluminum alloy having excellent heat resistance, abrasion resistance, seizure resistance and machinability. Becomes

Next, in the invention according to claim 6,
The powdered aluminum alloy cylinder liner according to claim 1 or 2, wherein the powdered aluminum alloy of the cylinder liner contains 0.5% to 15% by weight of aluminum nitride and Mg by weight. Is an AlN-dispersed powdered aluminum alloy containing 0.05% or more, with the balance being aluminum.

Next, in the invention according to claim 7,
3. The cylinder liner made of a powdered aluminum alloy according to claim 1 or 2, wherein the powdered aluminum alloy of the cylinder liner contains 0.1% or more and 5% or less by weight of nitrogen, and Mg by weight. It is an AlN-dispersed powdered aluminum alloy containing 0.05% or more, the balance being aluminum, and the nitrogen is bonded to aluminum. This ensures that AlN is generated and dispersed in the powdered aluminum alloy. And an excellent AlN-dispersed powdered aluminum alloy can be formed.

Next, in the invention according to claim 8,
3. The cylinder liner made of a powdered aluminum alloy according to claim 1 or 2, wherein the powdered aluminum alloy of the cylinder liner includes aluminum nitride having a textured structure grown in one direction in a fibrous form, and the growth thereof is performed. When the thickness is set in the direction, the aluminum nitride has a layered particle shape of 3 μm or less.

As described above, when the thickness is 3 μm or less, it is possible to obtain excellent slidability as compared with conventionally used AlN particles without lowering the machinability.

Next, in the invention according to claim 9,
3. The cylinder liner made of a powdered aluminum alloy according to claim 1 or 2, wherein the powdered aluminum alloy of the cylinder liner includes aluminum nitride, and a boundary between the aluminum nitride and aluminum which is a matrix of the aluminum alloy base. It has a bonding interface with no gaps.

According to a tenth aspect of the present invention, there is provided the cylinder liner made of the powdered aluminum alloy according to the first or second aspect, wherein the powdered aluminum alloy of the cylinder liner is based on the entire aluminum alloy. 15 by volume ratio
% Or less.

Further, in the invention according to the eleventh aspect, there is provided the cylinder liner made of a powdery aluminum alloy according to the tenth aspect, wherein the porosity is not less than 3% by volume with respect to the entire aluminum alloy. % Or less.

As a result, the holes are dispersed on the sliding surface of the cylinder liner that comes into contact with the piston or the piston ring, so that the holes form concave pits with respect to the sliding surface. Is maintained, and oil film breakage at the sliding interface with the piston or the like is prevented, and excellent seizure resistance and wear resistance can be realized.

According to a twelfth aspect of the present invention, there is provided a cylinder liner made of a powdered aluminum alloy according to the first or second aspect, wherein the powdered aluminum alloy of the cylinder liner is made of graphite, MoS ₂ , It contains at least one or more lubricating components selected from the group consisting of WS ₂ and CaF in an amount of 5% or less on a weight basis.

According to a thirteenth aspect of the present invention, there is provided the cylinder liner made of a powdery aluminum alloy according to the twelfth aspect, wherein the content of the lubricating component is 1 on a weight basis.
% Or more and 3% or less.

Thus, graphite, MoS ₂ , WS ₂ , C
Solid lubricating powder such as aF is dispersed on its own lubricating performance and the sliding surface of the cylinder liner to form a concave oil reservoir like the above-mentioned holes, so that the sliding interface with the piston etc. It is possible to prevent the oil film from running out and to realize excellent seizure resistance and abrasion resistance.

According to a fourteenth aspect of the present invention, there is provided a cylinder liner made of a powdered aluminum alloy according to the first or second aspect, wherein the powdered aluminum alloy of the cylinder liner is made of Si, Fe, Ni , Cr, Ti, M
at least one selected from the group consisting of n and Zr
Contains more than one element and the content is 25% by weight
It is as follows.

This makes it possible to improve the mechanical properties such as wear resistance, seizure resistance, strength, hardness and rigidity of the powdered aluminum alloy for cylinder liners.

According to a fifteenth aspect of the present invention, there is provided the cylinder liner made of a powdered aluminum alloy according to the first or second aspect, wherein the powdered aluminum alloy for the cylinder liner is made of TiO ₂ , ZrO ₂ , SiO ₂ , Mg
It contains 5% by weight or less of at least one oxide spherical particle selected from the group consisting of O ₂ , Al ₂ O ₃ , and Cr ₂ O ₃ .

As a result, the hard particles are dispersed in the base material of the powdered aluminum alloy for a cylinder liner, like aluminum nitride and Si, and the wear resistance and seizure resistance can be improved.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A powder aluminum alloy cylinder liner according to the present invention will be described below in detail.

(1) Relationship between Cylinder Liner and Coefficient of Thermal Expansion of Engine Block and Its Effect When casting an aluminum alloy cylinder liner into the engine block body by low-pressure aluminum casting, the long-term operation at a high temperature exceeding 500 ° C. The outer periphery of the time aluminum alloy cylinder liner comes into contact with the molten aluminum. Therefore, the interface between the aluminum alloy cylinder liner and the engine block body is welded and joined. As a result, a good bonding interface is obtained between the two, and there is no problem that the aluminum alloy cylinder liner comes off from the engine block.

On the other hand, when casting such an aluminum alloy cylinder liner into an aluminum alloy engine block body by aluminum high pressure casting, the casting is completed in a relatively short time. Therefore, the outer peripheral surface of the aluminum alloy cylinder liner is not welded to the engine block main body, and as a result, a good bonding interface cannot be obtained between the two. As a result, the conventional cylinder liner has a problem of falling off from the engine block.

Here, the inventors of the present invention prevent the cylinder liner made of aluminum alloy from falling off from the engine block without any gap at the contact interface between the cylinder liner and the engine block due to the coefficient of thermal expansion. Invented technology that can do it.

That is, when cooling the engine block body to room temperature with the cylinder liner cast into the engine block by aluminum high-pressure casting, the coefficient of thermal expansion of the aluminum alloy for the cylinder liner depends on the thermal expansion coefficient of the aluminum alloy of the engine block body. When the expansion coefficient is somewhat smaller than the expansion coefficient, the engine block contracts more than the cylinder liner, and compressive residual stress acts on the joint interface between the cylinder liner and the engine block.

The residual stress causes the cylinder liner to be restrained by the engine block. as a result,
It is possible to avoid the problem that the cylinder liner comes off from the engine block main body without forming a gap at the contact interface between them.

On the other hand, the heat generated when the engine operates causes the engine block to expand more than the cylinder liner, and a tensile thermal stress acts on the contact interface between the two. As a result, the above-mentioned residual compressive stress is reduced, and there is a possibility that the cylinder liner may fall off. If the residual stress of the compression from the engine block is too large, the rigidity of the thin cylinder liner is not sufficient, so that the cylinder liner may be deformed and the roundness may not be obtained.

In view of these problems, the present inventors have optimized the correlation between the coefficient of thermal expansion between the cylinder liner and the engine block main body. As a result, α _B −α _C ≧ 1 × 10 ⁻⁶ / ° C and α _B −α _C ≦ 8 × 1
0 ^-6 / ° C α _B : Coefficient of thermal expansion of aluminum alloy for engine block α _C : Deformation of cylinder liner, falling off of cylinder liner during engine operation, etc., as long as the thermal expansion coefficient of aluminum alloy for cylinder liner is satisfied It has been found that the thickness of the cylinder liner can be reduced without the problem described above.

That is, when α _B −α _C <1 × 10 ⁻⁶ / ° C., the compressive stress at the contact interface between the cylinder liner and the engine block is not sufficiently large, so that the cylinder liner is not sufficiently moved from the engine block. A sufficient restraining force cannot be obtained, and at room temperature or at a high temperature during operation of the engine, a gap is generated at the contact interface between the two, and the cylinder liner falls off.

When α _B −α _C > 8 × 10 ⁻⁶ / ° C., the residual stress of the compression from the engine block becomes large as described above, so that the binding force to the cylinder liner can be sufficiently obtained. Since the rigidity of the cylinder liner having a small thickness (difference between the outer diameter and the inner diameter) is low, when an excessive compressive stress is applied, the cylinder liner is deformed in the radial direction, so that roundness cannot be obtained. Therefore, there arises a problem that the thinning of the cylinder liner is hindered.

However, as a specific value relating to the coefficient of thermal expansion of the powdered aluminum alloy used in the cylinder liner at this time, α _C is desirably 14 × 10 ⁻⁶ / ° C. to 20 × 10 ⁻⁶ / ° C.

In general, the coefficient of thermal expansion α _B of a molten aluminum alloy used for an engine block is 18 × 10 ⁻⁶ / ° C. to 22 ° C.
× for a 10 ^-6 / ° C. or so, the correlation coefficient of thermal expansion of the above-described cylinder liner and the engine block (1 × 10 ^-6
/ ° C ≦ α _B −α _C ≦ 8 × 10 ⁻⁶ / ° C.), the thermal expansion coefficient α _C of the cylinder liner is 14 × 10 ⁻⁶ /.
It is desirable that the temperature is not less than ° C.

As will be described later, with respect to aluminum nitride and Si which have a strong correlation with abrasion resistance, which is one of the important characteristics required for the cylinder liner, the total content thereof is desirably 5% or more. In this case, the coefficient of thermal expansion of the powdered aluminum alloy is 20 × 10 ⁻⁶ / ° C. or less. Therefore, the thermal expansion coefficient α _C of the powdered aluminum alloy for a cylinder liner when satisfying both the castability with the engine block and the wear resistance of the cylinder liner is 14 × 10 ⁻⁶ /
C. to 20.times.10.sup.- ⁶ / .degree. C. is desirable.

On the other hand, the inventors of the present invention have found that the total content of aluminum nitride and Si contained in the powdered aluminum alloy constituting the cylinder liner achieves both the above-mentioned appropriate range of the coefficient of thermal expansion and excellent wear resistance. We found the proper range necessary for this.

Specifically, the total content of aluminum nitride and Si contained in the powder aluminum alloy is 5% or more and 30% or less, more preferably 7% or more and 20% or less based on the weight of the entire powder aluminum alloy. % Or less.

Here, if the total content of aluminum nitride and Si is less than 5%, it becomes difficult to have the wear resistance required for a cylinder liner. On the other hand, when the total content of both exceeds 30%, the thermal expansion coefficient α _C of the cylinder liner becomes smaller than 14 × 10 ⁻⁶ / ° C., and the above-described problem occurs.

In particular, from the viewpoint of machinability, the total content of both is desirably 20% or less, and from the viewpoint of sliding characteristics with a piston or piston ring of a mating material, the total content is 7%. It is more desirable that this is the case. Therefore,
In the present embodiment, the total content of aluminum nitride and Si in the powdered aluminum alloy is 5% or more and 30% or less.

(2) Characteristics of aluminum nitride in AlN-dispersed powdered aluminum alloy and its functions and effects Since the cylinder liner slides with a mating material such as a piston or a piston ring, the abrasion resistance and seizure resistance at high temperatures are obtained. And opponent aggression are required. The powdered aluminum alloy used for the cylinder liner according to the present embodiment is thermally stable even at a temperature higher than 500 ° C. for the purpose of improving heat resistance, abrasion resistance, seizure resistance, and aggressiveness to a partner. It has been found that by producing and dispersing aluminum nitride (AlN) in an aluminum alloy, it has excellent heat resistance and frictional sliding characteristics as compared with conventional powdered aluminum alloys.

Further, in the present embodiment, instead of mixing AlN as powder (particles) with the aluminum alloy powder and adding and dispersing it in the sintered aluminum alloy as in the conventional powder metallurgy technique, It is characterized in that AlN is generated and dispersed in an aluminum alloy by reacting an aluminum component in the alloy powder with nitrogen gas.

That is, according to the conventional method, the added AlN particles have a gap at the contact interface with the aluminum alloy base, and the AlN particles are mechanically constrained in the base. In addition, AlN particles fall off when frictionally sliding with a mating material such as a piston or a piston ring to form hard wear powder, which causes problems such as seizure and galling.

On the other hand, according to the present embodiment, as described above, AlN reacts with aluminum in the aluminum alloy powder (hereinafter, referred to as direct nitridation reaction), so that the AlN particles are made of aluminum. There is no gap at the contact interface with the alloy base, and it has a structure in which it is bonded to the aluminum base, so that it tightly adheres. As a result, the heat resistance, wear resistance and seizure resistance of the aluminum alloy are significantly improved. Therefore, the powder aluminum alloy in the present embodiment, even when cast into the aluminum alloy engine block body by high pressure casting,
It can be sufficiently used as a cylinder liner.

As a specific method of manufacturing the cylinder liner according to the present embodiment, first, an aluminum alloy powder is stamped and formed by a hydraulic press, a cold isostatic press or the like to produce a green compact. By heating and sintering this green compact in a nitrogen gas atmosphere, AlN is generated and dispersed in the old powder grain boundary of the aluminum alloy sintered body by a nitriding reaction. It is also effective to improve the strength of the sintered body by performing a hot extrusion method or a hot forging method as required.

In the powdered aluminum alloy according to the present embodiment obtained by such a manufacturing method, an appropriate amount of AlN is 0.5% to 15% by weight with respect to the entire powdered aluminum alloy, and the wear resistance is high. -From the viewpoint of machinability, more preferably 1% or more and 7% or less. If the amount of AlN generated and dispersed is less than 0.5% by weight, sufficient heat resistance and abrasion resistance cannot be obtained. On the other hand, even if the amount of AlN generated and dispersed exceeds 15%, the wear resistance is not significantly improved, and instead, economical efficiency such as reduction in machinability, reduction in toughness of the sintered body, or prolongation of the sintering process is obtained. Problems arise.

In order to produce AlN in the above-mentioned appropriate range, the powdered aluminum alloy contains 0.1 to 5% by weight of nitrogen required for reacting with the aluminum component. . That is, if the nitrogen content is less than 0.1%, 0.5% or more of AlN cannot be generated, and the nitrogen content is 5%.
The inventors of the present application have confirmed that if the ratio exceeds 15%, AlN exceeds 15%.

As described above, the powdered aluminum alloy cylinder liner according to the present embodiment is provided with 0.5% to 15% AlN, and 0.1% to 5% AlN, based on the weight of the entire aluminum alloy. By containing nitrogen, it is excellent in heat resistance, wear resistance, seizure resistance and machinability, and can be used as a cylinder liner when cast into an aluminum alloy engine block body by aluminum high pressure casting. It becomes possible.

In order to allow the direct nitridation reaction to proceed to generate and disperse AlN in the powdered aluminum alloy as described above, it is preferable to contain 0.05% or more of Mg.
Mg is contained in the aluminum alloy powder in advance and has the effect of removing the aluminum oxide film covering the powder surface by a reduction reaction when heating and sintering the aluminum compact in a nitrogen gas atmosphere. . As a result, the nitrogen gas and the aluminum component in the powder react to generate AlN. Therefore, in the powdered aluminum alloy of the present embodiment, the Mg content needs to be 0.05% by weight or more. That is, when the Mg content is less than 0.05% by weight, the above-described reduction reaction by Mg does not sufficiently occur, and thus a problem arises in that AlN cannot be uniformly generated.

Further, as described above, AlN generated in the powdered aluminum alloy utilizing the direct nitridation reaction has a significantly different structure from the AlN particles added by the conventional method. Specifically, in the process of the direct nitriding reaction, AlN grows in one direction from the surface of the aluminum alloy powder in the green compact in a fibrous or dendritic manner. As a result, a layered film as shown in FIGS. 1 and 2 is formed and dispersed in the aluminum alloy.

On the other hand, in a conventional AlN particle-dispersed sintered aluminum alloy, as shown in FIG.
1N particles are dispersed. That is, AlN in the sintered aluminum alloy by the nitridation reaction method in the present embodiment is as shown in FIG.
The inventors of the present application have found out that they have excellent slidability by having a fibrous texture structure as shown in FIG. 2 as compared with AlN particles used in the conventional method.

Further, when the direction of fibrous growth is the thickness direction of AlN, the thickness of AlN produced by the nitriding reaction is preferably 3 μm or less, more preferably 1 μm or less. This is because the thickness of AlN is almost proportional to the amount of AlN produced. For example, when the amount of AlN produced is 15% by weight, the thickness of AlN is about 3 μm. The thickness of AlN produced by the reaction method is 3 μm or less. That is, when the thickness exceeds 3 μm, the amount of generated AlN is 1
It means that the content exceeds 5% by weight, and in that case, problems such as reduction in machinability and toughness of the sintered body occur as described above. In particular, from the viewpoint of machinability, the thickness of AlN is 1 μm.
m is more preferable.

(3) Porosity in powdered aluminum alloy and its function / effect The pores are dispersed on the sliding surface of the cylinder liner which comes into contact with the piston or the piston ring, so that the pores are located on the sliding surface. Thus, a concave pit is formed, and lubricating oil is held in this portion to prevent the oil film from being cut off at the sliding interface with the piston or the like, and it is possible to realize excellent seizure resistance and wear resistance.

In order to obtain such an effect, the porosity of the powdered aluminum alloy in the present embodiment is not more than 15% by volume, preferably not more than 3%, based on the whole aluminum alloy.
It is preferably at least 10%. 15% porosity
Exceeding the mechanical properties of the powdered aluminum alloy deteriorates.
For example, sufficient strength and rigidity as a cylinder liner cannot be obtained, and as a result, a problem arises in that the cylinder liner is deformed when cast into an engine block. Therefore, in order to achieve both excellent seizure resistance, wear resistance and mechanical properties, the porosity in the powdered aluminum alloy needs to be 15% or less, more preferably 3% or more. It was found that it was 10% or less.

(4) Solid Lubricating Components and Their Functions and Effects Solid lubricating powders such as graphite, MoS ₂ , WS ₂ , and CaF are dispersed on the sliding surface of the cylinder liner due to their own lubricating performance and the above-mentioned pores. Similarly, by forming a concave oil reservoir, preventing oil film breakage at the sliding interface with the piston, etc.
Excellent seizure resistance and abrasion resistance can be realized. The powdered aluminum alloy of the cylinder liner in the present embodiment contains at least one or two or more lubricating components selected from graphite, MoS ₂ , WS ₂ , and CaF on a weight basis of 5% or less, preferably 1% or more. % Or less.

When the content of the lubricating component exceeds 5% by weight, the bonding strength between the aluminum alloy powders constituting the aluminum alloy base material is reduced, so that the mechanical properties required as a cylinder liner cannot be sufficiently obtained, and In the hot extrusion method, which is one of the production methods of the liner, the liner surface after extrusion is in a crimped state (peeled state) due to insufficient bonding between the aluminum alloy powders, which causes a problem in production.

Therefore, in order to suppress the deterioration of the mechanical properties of the cylinder liner and to obtain excellent wear resistance and seizure resistance, graphite, MoS ₂ , WS ₂ , CaF ₂
It is necessary to contain at least one or two or more lubricating components selected from the group consisting of 5% or less, preferably 1% or more and 3% or less on a weight basis.

(5) Composition of Powdered Aluminum Alloy and Its Functions and Effects In the powdered aluminum alloy of the present embodiment, at least one or more of Si, Fe, Ni, Cr, Ti, Zr and Mn may be used, if necessary. By containing the element described above, the respective effects as described below can be realized.
However, in order to improve mechanical properties such as abrasion resistance, seizure resistance, strength, hardness and rigidity of powdered aluminum alloy,
It is desirable that at least one or more of the above elements be contained, and that the total content be 25% or less. Because the total content of each additive element is 25%
Even if it exceeds the above, each property does not significantly improve, and rather the problem that the toughness of the powdered aluminum alloy decreases, and the hardness and rigidity of the aluminum alloy become too large, so it is difficult to perform hot extrusion in the subsequent process. This causes problems in the manufacturing method.

In this embodiment, when each of the above elements is added to an aluminum alloy, an aluminum alloy powder is produced from a molten metal having a predetermined alloy composition by a rapid solidification method and used as a raw material powder. . In other words, a sintered aluminum alloy having a predetermined composition can be produced by forming a molten aluminum alloy composed of a predetermined alloy component into powder by a spraying method (atomizing method), and molding and heating and solidifying the aluminum alloy powder. Here, the characteristics of each of the above elements will be briefly described below.

(I) Si has the effect of dispersing in the aluminum alloy base to improve the wear resistance and seizure resistance of the alloy. However, even if added in excess of 25%, the properties are not further improved, but rather the toughness of the aluminum alloy is reduced, and the rigidity of the aluminum alloy is increased, so that an extruded body is created in hot extrusion. In this case, a high extrusion force, that is, a large-sized extrusion equipment is required, which causes a problem of economy.

(II) Fe, Ni, Cr, Ti, Zr These metal elements form a fine intermetallic compound with aluminum and are dispersed in the matrix, thereby improving the heat resistance, rigidity and hardness of the aluminum alloy. Has the effect of causing That is, by improving the heat resistance, the seizure with the mating material during sliding is greatly suppressed, so that the addition of these elements is effective.

Further, by dispersing such a thermally stable intermetallic compound finely and uniformly, it is possible to suppress the growth of Si crystals during heating and sintering. As a result, there is also an effect that the machinability of the aluminum alloy is greatly improved.

In order to obtain such an effect, F
The addition of e, Ni, Cr, Ti, and Zr is effective, and at that time, it is necessary to contain 1% or more of each. On the other hand, when these elements are added in an appropriate amount, the intermetallic compound with aluminum coarsens as described above, which causes a problem such as lowering the toughness and strength of the aluminum alloy, and producing aluminum alloy powder. In doing so, the melting point of the aluminum alloy melt rises, leading to an increase in manufacturing costs. As a result, there is also a problem of economics such as an increase in the price of the aluminum alloy powder. Therefore, in the present embodiment, as an appropriate addition amount of each element, Fe;
i; 1 to 8%, Cr: 1 to 6%, Ti; 1 to 4%, Z
r; 1-4% was set.

(III) Mn Similarly to the above-mentioned metal elements, an intermetallic compound with aluminum is formed and uniformly dispersed in the alloy base material, thereby obtaining the mechanical properties of the alloy and the resistance to the mating material during sliding. It has the effect of improving seizure. In order to realize these effects, it is necessary to contain 1% or more. However, if it exceeds 5%, the properties are not improved, and the toughness of the aluminum alloy is rather lowered.

(6) Hard Particles The powdered aluminum alloy for a cylinder liner in the present embodiment may be made of TiO ₂ , ZrO ₂ , SiO ₂ ,
At least one oxide spherical particle selected from MgO ₂ , Al ₂ O ₃ , and Cr ₂ O _{3 is} contained in an amount of 5% by weight or less.

The hard particles are dispersed in the base material of the powdered aluminum alloy like aluminum nitride and Si, and have an effect of improving wear resistance and seizure resistance. However, the addition amount of the hard particles is desirably 5% or less based on the weight of the entire aluminum alloy. Because, even if hard particles are added in excess of 5%, the wear resistance and seizure resistance are not significantly improved, but rather the machinability of the aluminum alloy is reduced,
Further, there is a problem that the opponent material is attacked.

The type of the hard particles is Ti
O ₂ , ZrO ₂ , SiO ₂ , MgO ₂ , Al ₂ O ₃ , C
Oxide particles such as r ₂ O ₃ are preferred. Among them, from the viewpoint of wear resistance and machinability of aluminum alloy, TiO ₂ ,
The present inventors have found that the addition of oxide spherical particles of SiO ₂ , MgO ₂ , and Al ₂ O ₃ is more effective.

[0077]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to tables.

(Example 1)

[0079]

[Table 1] In Table 1, "good without gaps" means that the cylinder liner does not fall out of the engine block even when the engine is running. Also, "with a gap" means that the cylinder liner falls out of the engine block at the stage when casting is completed.
Alternatively, it means that a gap is formed at the interface between the cylinder liner and the engine block at a high temperature during operation of the engine, and the cylinder liner falls off from the engine block.

After the aluminum alloy cylinder liner having the coefficient of thermal expansion α _C as shown in Table 1 above was cast into the engine block body by the aluminum high-pressure casting method, the bonding state of the contact interface between the cylinder liner and the engine block was obtained. Also, the presence or absence of deformation in the diameter direction of the cylinder liner was confirmed.

The casting experiment was performed without subjecting the cylinder liner to groove processing for preventing falling off.
Here, the alloy composition of the aluminum alloy engine block body manufactured by the aluminum high-pressure casting method is Al-17%.
Si-3Cu-1Mg (% by weight), and its coefficient of thermal expansion α _B is 19.5 × 10 ⁻⁶ / ° C. However, the value of the coefficient of thermal expansion described here is an average value from normal temperature to 200 ° C.

As shown in Table 1, α defined by the present invention is
_B− α _C ≧ 1 × 10 ⁻⁶ / ° C. and α _B −α _C ≦ 8 × 1
A combination number of a cylinder liner and an engine block satisfying a relational expression of a coefficient of thermal expansion such as 0 ^-6 / ° C. 1
-No. In 5, the outer peripheral surface of the cylinder liner after casting is firmly restrained by the engine block body due to compressive residual stress from the engine block.
There is no gap at the contact interface between the cylinder liner and the engine block body.

As a result, it can be understood that the problem of the cylinder liner falling off the engine block body does not occur even if the cylinder liner is not subjected to the drop-off prevention processing.

Further, since the restraining force from the engine block is an appropriate condition, the cylinder liner itself after casting has a roundness enough to be used as a cylinder liner without being deformed. Therefore, it can be confirmed that the cylinder liner can be made thinner.

On the other hand, No. 1 which does not satisfy the above-mentioned relational expression regarding the coefficient of thermal expansion between the cylinder liner and the engine block specified by the present invention. 6-No. In No. 8, it is confirmed that the following problem occurs.

No. 6: The cylinder liner is deformed because the restraining force due to the compressive stress from the engine block acts excessively because the coefficient of thermal expansion of the cylinder liner is too small.

No. 7; Since the coefficient of thermal expansion of the cylinder liner is too large, the restraining force due to the compressive stress from the engine block does not act sufficiently, so that the cylinder liner is not held by the engine block, and a gap is formed and falls off.

No. 8: Since the coefficient of thermal expansion of the cylinder liner is too large, the restraining force due to the compressive stress from the engine block does not sufficiently act, so that the cylinder liner is not held by the engine block, and a gap is formed and falls off.

(Embodiment 2)

[0090]

[Table 2] In Table 2, "good without gaps" means that the cylinder liner does not fall out of the engine block even when the engine is running. Also, "with a gap" means that the cylinder liner falls out of the engine block at the stage when casting is completed.
Alternatively, it means that a gap is formed at the interface between the cylinder liner and the engine block at a high temperature during operation of the engine, and the cylinder liner falls off from the engine block.

No. as shown in Table 2. 1 to No. After a cylinder liner made of an aluminum alloy having a coefficient of thermal expansion α _C shown in FIG. 7 was cast into the engine block body by aluminum high-pressure casting, the connection state of the contact interface between the cylinder liner and the engine block and the diameter direction of the cylinder liner were determined. Was checked for deformation.

The casting experiment was performed without subjecting the cylinder liner to groove processing or the like for preventing falling off. The alloy composition of the aluminum alloy engine block body manufactured by the aluminum high-pressure casting method is Al-11% Si-3.
Cu-0.5Mg (% by weight), and its thermal expansion coefficient α _B
Is 21 × 10 ⁻⁶ / ° C. However, the value of the coefficient of thermal expansion described here is an average value from normal temperature to 200 ° C.

As shown in Table 2, α is defined by the present invention.
_B− α _C ≧ 1 × 10 ⁻⁶ / ° C. and α _B −α _C ≦ 8 × 1
A combination of a cylinder liner and an engine block that satisfies the relational expression of the coefficient of thermal expansion such as 0 ⁻⁶ / ° C. 1 to
No. 6. The outer peripheral surface of the cylinder liner after casting is firmly restrained by the engine block main body due to the compressive residual stress from the engine block, so that no gap is generated at the contact interface between the cylinder liner and the engine block main body.

As a result, it can be seen that the problem of the cylinder liner falling out of the engine block body does not occur even if the cylinder liner is not subjected to the dropping prevention processing. In addition, since the restraining force from the engine block is an appropriate condition, the cylinder liner after casting has sufficient roundness without being deformed and being sufficiently usable as a cylinder liner. Therefore, it was confirmed that the thickness of the cylinder liner can be reduced.

On the other hand, No. 1 which does not satisfy the above-mentioned relational expression regarding the coefficient of thermal expansion between the cylinder liner and the engine block specified by the present invention. 6 and no. In the case of 7, it was confirmed that the following problems occurred.

No. 6: The cylinder liner is deformed because the thermal expansion coefficient of the cylinder liner is too small and a binding force due to the compressive stress from the engine block acts.

No. 7; Since the coefficient of thermal expansion of the cylinder liner is too large, the restraining force due to the compressive stress from the engine block does not act sufficiently, so that the cylinder liner is not held by the engine block, and a gap is formed and falls off.

(Embodiment 3)

[0099]

[Table 3] No. shown in Table 3 above. 1 to No. 18 to the aluminum alloy powder as needed, oxide spherical particles (average particle size of 5 to 10 μm).
m) and solid lubricating particles (average particle size of 5 to 15 μm) are mixed into a raw material powder, which is molded and then heated and sintered in a nitrogen atmosphere to form aluminum nitride (AlN) in an aluminum alloy sintered body. AlN) was produced, and a cylinder liner was produced from the sintered body by hot extrusion. Here, each oxide spherical particle, solid lubricating particle and AlN
The nitrogen content and the nitrogen content are shown as percentages by weight with respect to the entire sintered aluminum alloy. The porosity of the cylinder liner was adjusted to 3 to 5% depending on the extrusion conditions.

A sample for a wear test was prepared from a cylinder liner material, and the wear resistance of each sintered aluminum alloy under boundary lubrication conditions was evaluated using a smelted aluminum alloy (JISAC8A) as a mating material. In addition, the seizure resistance under the condition that the oil film was broken (the load when the seizure phenomenon occurred by increasing the pressing load) was evaluated. In addition, each characteristic was evaluated using the chip-on-disk abrasion test.

Further, the comparative material No. As No. 19, a cylinder liner using a smelted aluminum alloy (JIS AC8A material) was produced, and a hard Cr plating was applied to the sliding surface of the sample. Furthermore, the comparative material No. 20 was a cast iron material.
Table 4 shows the evaluation results of the wear amount and the seizure load of the liner material and the mating material after the wear test.

[0102]

[Table 4] As can be seen from Table 4, the sintered aluminum alloy for the cylinder liner according to the present embodiment has excellent wear resistance and little aggression to the mating material.
It turns out that it is equivalent to the aluminum alloy which performed the plating process. In addition, the seizure resistance is equivalent to that of the cast iron material, and is superior to that of the hard Cr-plated material from which the plating film has peeled off.

On the other hand, the comparative material No. 13-No. Regarding No. 18, the following problems were confirmed.

No. 13: Since it does not contain AlN, sufficient abrasion resistance and counterpart aggression cannot be obtained.

No. 14: Since the content of AlN is small, sufficient abrasion resistance and counterpart aggressiveness cannot be obtained.

No. 15: Since the AlN content was as large as 18%, the strength of the aluminum alloy was reduced, and the sample was damaged during pressurization.

No. 16: Since the content of the lubricating particles was as large as 6%, the strength of the aluminum alloy was reduced, and the sample was damaged during pressurization. The surface of the cylinder liner was peeled off during hot extrusion.

No. 17: Since the content of the hard particles is as large as 6%, it attacks the partner material and reduces the seizure resistance.

No. 18: Since the content of the hard particles is as large as 7%, it attacks the partner material and reduces the seizure resistance.

Note that the No. In No. 15, the content of AlN was In Nos. 17 and 18, since the content of the hard particles is larger than the appropriate amount specified by the present invention,
When processing into a friction test piece, the wear of the cemented carbide tool was more remarkable than the others.

Example 4 In Example 3, after processing the cylinder liner material into a predetermined cylindrical shape, the cylinder liner was cast into an aluminum alloy engine block by an aluminum high-pressure casting method, and each cylinder liner was subjected to a single endurance test. .

Note that the comparative material No. No. 19 produced a cylinder liner using a smelted aluminum alloy (JIS AC8A material), and provided a hard Cr plating on the sliding surface for the purpose of improving abrasion resistance and seizure resistance. In addition, the comparative material No.
No. 20 produced a cylinder liner of the same shape using an Fc cast iron material and cast it into an engine block. In addition, a molten aluminum alloy (JIS AC8A material) is used as the piston material, and the comparative material No. Only in the case of No. 19, in addition to a molten aluminum alloy (JIS AC8A material) as a piston material, a material having an outer peripheral surface sliding with a cylinder liner plated with Fe was also prepared.

After the endurance test, the state of breakage of the sliding surfaces of the cylinder liner and the piston was observed, and the presence or absence of wear and adhesion (seizure) was confirmed. Table 5 shows the results.

[0114]

[Table 5] As can be seen from Table 5 above, the sintered aluminum alloy for the cylinder liner according to the present embodiment has excellent wear resistance of the cylinder liner itself, and causes abrasion and adhesion without applying Fe plating to the piston. It has little aggression to the partner material and is equivalent to the current cast iron material.

On the other hand, the comparative material No. 13-No. Regarding No. 19, the following problems were confirmed.

No. 13: Since it does not contain AlN, sufficient abrasion resistance and counterpart aggression cannot be obtained.

No. 14: Since the content of AlN is small, sufficient abrasion resistance and counterpart aggressiveness cannot be obtained.

No. 15: Since the AlN content was as large as 18%, the amount of attack on the piston side increased.

No. 16: Since the content of the lubricating particles was as large as 6%, the strength of the aluminum alloy was lowered, and the wear resistance was slightly lowered.

No. 17: Since the content of hard particles was as large as 6%, the amount of attack on the piston side increased.

No. 18: Since the content of hard particles was as large as 7%, the amount of attack on the piston side increased.

No. 19: In the case of a smelted aluminum alloy, its sliding surface is hard-Cr-plated, and
If plating is not performed, problems such as abrasion and adhesion occur, and the plating cannot be used as a liner.

Note that the No. In No. 15, the content of AlN was In Nos. 17 and 18, since the content of the hard particles was larger than the appropriate amount specified by the present invention, the wear of the cemented carbide tool was more remarkable when processed into a cylinder liner shape.

As described above, the sintered aluminum alloy in this embodiment has sufficient wear resistance and seizure resistance as a cylinder liner without surface treatment such as hard Cr plating. It is also economical in that it can be used without performing Fe plating on the piston side.

Example 5 Si: 12% by weight, F
e; 1.5% of TiO ₂ particles (average particle size: 7 μm) and 1 of graphite powder (average particle size: 10 μm) with respect to an aluminum alloy powder containing 3%, Ni; 3%, and Mg; After forming the mixed powder, the sintered aluminum alloy is manufactured by heating and holding for 3 hours in a nitrogen atmosphere controlled at 540 ° C., and at that time, the entire sintered aluminum alloy is subjected to a nitriding reaction. As a result, a sintered body in which 4% AlN was formed was obtained. A cylindrical cylinder liner was produced from this material by hot extrusion.

At this time, by controlling the extrusion conditions (extrusion ratio), the porosity of the extruded cylinder liner material was changed, and the wear resistance and seizure resistance of each aluminum alloy were evaluated. Table 6 shows the results.

[0127]

[Table 6] As for the wear resistance, the performance under the boundary lubrication condition was evaluated by the chip-on-disk wear test described in the above Example 3. A molten aluminum alloy (JIS AC8A) was used on the disk side as the mating material.

Further, each cylinder liner was cast into the engine block main body by aluminum high-pressure casting, and it was confirmed whether or not the cylinder liner was deformed at that time. In addition, a cylinder liner using FC cast iron as a comparative material was also evaluated.

As can be seen from Table 6, in the cylinder liner using the sintered aluminum alloy having the porosity specified in the present invention, the abrasion resistance and the resistance to the same level as the current cylinder liner FC cast iron material are obtained. Has seizure properties.

In particular, it can be seen that the characteristics of sintered aluminum alloys having a porosity of 3% to 10% are more excellent. In addition, even when cast into the engine block, it can be seen that the roundness of the cylinder liner shape is ensured without being deformed by the restraining force from the engine block body side. On the other hand, the following problems were confirmed in the comparative material.

No. 6: Since the porosity was as large as 18%, the cylinder liner was deformed by the compressive stress acting on the cylinder liner side when cast into the engine block.

No. 7: Since the porosity was as large as 22%, the strength of the sintered aluminum alloy was reduced, and the sample was damaged in the friction test. Also, when cast into the engine block,
The cylinder liner was deformed by the compressive stress acting on the cylinder liner side.

Example 6 A hot-extruded sintered aluminum alloy (alloy composition: Al-12Si-2Ni-1Mg-2A) produced by the nitriding reaction method proposed in the embodiment
FIG. 1 shows a TEM image (taken at a magnification of 18,000) of the structure of the AlN particles formed and dispersed in (1N / wt%), and FIG. 2 shows a SIM image.

For comparison, a sintered aluminum alloy having the same composition was produced by a conventional method, that is, AlN particles (average particle size: 22 μm).
m) with aluminum alloy powder (composition: Al-12Si-2Ni)
-1Mg / wt%) was formed by molding, sintering, and hot extrusion, and a SIM image of AlN particles dispersed in the aluminum alloy is shown in FIG.

As shown in FIGS. 1 and 2, Al formed by the direct nitridation reaction method proposed in this embodiment is used.
It can be seen that N has a tissue structure grown in one direction in a fibrous or dendritic manner. In addition, the growth direction is changed to Al
As can be seen from the drawing, the thickness of AlN generated by the nitriding reaction method is about 1 μm.

On the other hand, as shown in FIG. 3, when AlN particles produced by the conventional production method are added, AlN has not a fibrous structure but a single crystal structure, and is clearly produced by the nitriding reaction method of the present invention. It turns out that it is different from AlN particles.

Example 7 FIG. 4 shows an optical micrograph of a sintered aluminum alloy produced by the nitriding reaction method proposed in the present embodiment after hot extrusion. Alloy composition is Al-1
2Si-2Ni-1Mg-2AlN / wt%).
For comparison, AlN particles (average particle size: 22 μm) were converted to aluminum alloy powder (composition: Al-12Si-2Ni-1Mg).
/ Wt%) to obtain a sintered aluminum alloy having the same composition as the material of the present invention by hot extrusion. FIG. 5 shows a photograph of the structure of the sintered body.

As shown in FIG. 4, the AlN particles (portions indicated by black arrows) produced by the nitridation reaction method of the present invention have a bonding interface with no gap at the boundary between the matrix and the aluminum alloy base material. Recognize. On the other hand, in the conventional method (the method of adding AlN particles) shown in FIG. 5, a gap (portion indicated by a white arrow marked Gap) is formed between the AlN particles (portion indicated by a black arrow) and the aluminum alloy base. ) Is present.

(Example 8) With respect to the sintered aluminum alloy produced in Example 6, the chip-on-disc type friction test was performed under boundary lubrication conditions, and the state of damage to the sliding surface of the sintered body and the mating material was evaluated. Was observed with an optical microscope. The results are shown in FIGS. 6A and 6B and FIGS. 7A and 7B. FIGS. 6A and 6B show a sintered aluminum alloy in which AlN produced and dispersed by the nitriding reaction method proposed by the present invention, and FIGS. 7A and 7B show AlN which is a conventional method. It is a sintered aluminum alloy obtained by adding particles. In addition, a smelted aluminum alloy (ADC12 material) was used as a mating material.

As shown in FIG. 6 (a), on the sliding surface of the sintered aluminum alloy produced by the nitriding reaction method proposed by the present invention, the adhesion / seizure phenomenon was observed to the extent that slight scratch marks were observed. Is not observed. No trace of the AlN particles falling off is observed on the sliding surface. Further, as for the mating material, as shown in FIG. 6 (b), no cohesion / seizure phenomenon was observed, and only slight scratch marks were present.

On the other hand, in FIG. 7 (a), holes where the AlN particles are dropped off (white arrows marked Hall) are present in various places in the sintered aluminum alloy, and deep sliding flaws are also observed. As for the mating material, as shown in FIG.
It can be seen that there are deep sliding flaws and adhesion areas (white areas marked as Seizure) attacked by the dropped AlN particles in various places.

Thus, the sintered aluminum alloy produced by the nitriding reaction method proposed by the present invention has an interface in which aluminum nitride (AlN) and the aluminum alloy as the matrix are tightly bonded without any gaps, so that the mating material can be obtained. It was confirmed that the AlN particles did not fall off even in the case of friction sliding, and had excellent abrasion resistance, seizure resistance and aggressiveness to the partner.

(Embodiment 9)

[0144]

[Table 7] No. 7 in Table 7 above. 1 to No. After molding an aluminum alloy powder having the alloy composition shown in 11, heating in a nitrogen atmosphere
By sintering, aluminum nitride (AlN) was generated in the aluminum alloy sintered body, and the sintered body was manufactured into a cylinder liner by hot extrusion. The porosity was adjusted to 3 to 5% depending on the extrusion conditions.

The contents of aluminum nitride and nitrogen are shown in Table 7 above in terms of percentage by weight with respect to the total sintered aluminum alloy. The remainder is all Al. Also,
The coefficient of thermal expansion is also shown in Table 7 above.

A sample for a wear test was prepared from a cylinder liner material, and the wear resistance of each sintered aluminum alloy under boundary lubrication conditions was evaluated using a smelted aluminum alloy (JISAC8A) as a mating material. In addition, the seizure resistance under conditions of oil film breakage (comparing the load when the seizure phenomenon occurs by increasing the extrusion load) was evaluated. In addition, each characteristic was evaluated using the chip-on-disk abrasion test.
Table 8 shows the evaluation results of the wear amount and the seizing load of the cylinder liner material and the mating material after the wear test.

[0147]

[Table 8] The coefficient of thermal expansion α _B is 22 × by aluminum high pressure casting.
Aluminum alloy melt at 10 ^-6 / ° C (composition: Al-8Si
(-3Cu-0.5Mg / wt%), each cylinder liner was cast into the engine block main body, and the bonding interface and the presence or absence of deformation of the cylinder liner were confirmed. The results are shown in Table 8 above.

As shown in Tables 7 and 8, the total content of aluminum nitride and Si in the powdered aluminum alloy satisfies the appropriate range defined by the present invention. 1 to No. 9
, The coefficient of thermal expansion α _C is 14 × 10 ⁻⁶ / ° C. to 2
It can be seen that the composition satisfies 0 × 10 ⁻⁶ / ° C. and has excellent wear resistance. In addition, the interface between the cylinder liner and the engine block main body after casting was in a good contact state, and no deformation of the cylinder liner was observed.

On the other hand, in Comparative Example No. In Examples 10 and 11, the following problems were confirmed. No. 10; sufficient wear resistance could not be obtained because the total content of AlN and Si was as small as 2%, and the coefficient of thermal expansion was 21.6 × 10 ⁻⁶ / ° C. because the total content of both was small. And a large value. Further, since the difference between the thermal expansion coefficients of the cylinder liner and the engine block was as small as 0.4 × 10 ⁻⁶ / ° C., a gap was confirmed at the interface between the cylinder liner and the engine block.

No. 11; the thermal expansion coefficient is as small as 13.0 × 10 ⁻⁶ / ° C. because the total content of AlN and Si is as large as 36%, and the difference between the thermal expansion coefficients of the engine block and the cylinder liner is 9 × 10 Due to the large ^-6 / ° C, the cylinder liner was deformed after casting. Further, it was recognized that the target material was slightly attacked because the total content of AlN and Si was as large as 36%.

[0151]

According to the present invention, claims 1 to 1 are based on the present invention.
According to the invention described in 5, due to the relationship between the thermal expansion coefficients of the cylinder liner and the engine block, no gap is generated at the contact interface between the two. As a result, it is possible to prevent the cylinder liner from falling off the engine block.

[Brief description of the drawings]

FIG. 1 is a TEM photograph of the structure of AlN particles generated and dispersed in a sintered aluminum alloy after hot extrusion.

FIG. 2 is a SIM photograph of the structure of AlN particles generated and dispersed in a sintered aluminum alloy after hot extrusion.

FIG. 3 shows the SI of the structure of AlN particles in a conventional production method.
It is an M photograph.

FIG. 4 is a micrograph of an AlN-dispersed sintered aluminum alloy obtained by a nitriding reaction.

FIG. 5 is a micrograph of a sintered aluminum alloy added with AlN particles.

FIGS. 6 (a) and (b) are micrographs of an AlN-dispersed sintered aluminum alloy obtained by a nitriding reaction according to the present invention.

FIGS. 7 (a) and (b) are micrographs of a sintered aluminum alloy added with AlN particles, which is a conventional method.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor ▲ Taka ▼ Yoshige 1-1 1-1 Kunyokita Kita, Itami-shi, Hyogo Sumitomo Electric Industries, Ltd. Itami Works

Claims (15)

[Claims] 1. A powder aluminum alloy cylinder liner cast into a molten aluminum alloy engine block, wherein the coefficient of thermal expansion of the powder aluminum alloy cylinder liner is α.
_C, when the thermal expansion coefficient alpha _B of the smelting aluminum alloy engine block, the relationship between the two 14 × 10 ^-6 / ℃ ≦ α
_C ≦ 20 × 10 ⁻⁶ / ° C. and 1 × 10 ⁻⁶ / ° C. ≦
Powder aluminum alloy cylinder liner that satisfies α _B -α _C ≤8 × 10 ^-6 / ° C. 2. The powder aluminum alloy cylinder liner according to claim 1, wherein the powder aluminum alloy cylinder liner is cast into the molten aluminum alloy engine block by an aluminum high-pressure casting method. 3. The powdered aluminum alloy of the cylinder liner contains aluminum nitride and Si, and the total content is 5% or more and 30% or less based on the entire powdered aluminum alloy for a cylinder liner on a weight basis. The cylinder liner made of a powdered aluminum alloy according to claim 1 or 2. 4. The powdered aluminum alloy of the cylinder liner contains aluminum nitride in an amount of 0.5% to 15% by weight.
The cylinder liner made of a powdered aluminum alloy according to claim 1 or 2, wherein the powdered aluminum alloy contains the following, and the balance is aluminum. 5. The powdered aluminum alloy of the cylinder liner contains 0.1% to 5% by weight of nitrogen, the balance being aluminum, and the nitrogen has a structure in which the nitrogen is bonded to the aluminum. The cylinder liner made of a powdered aluminum alloy according to claim 1 or 2, which is a dispersion type powdered aluminum alloy. 6. The aluminum alloy powder of the cylinder liner contains aluminum nitride in an amount of 0.5% to 15% by weight.
Below, containing 0.05% or more by weight of Mg,
The cylinder liner made of a powdered aluminum alloy according to claim 1 or 2, wherein the balance is an AlN dispersion type powdered aluminum alloy of aluminum. 7. The powdered aluminum alloy of the cylinder liner contains 0.1% or more and 5% or less by weight of nitrogen.
g is not less than 0.05% by weight, the balance is aluminum, and the nitrogen is an AlN-dispersed powdered aluminum alloy having a structure bonded to the aluminum. A cylinder liner made of the powdered aluminum alloy described. 8. The powdered aluminum alloy of the cylinder liner includes aluminum nitride having a textured structure grown in one direction in a fibrous form, and when the growth direction is set to a thickness, the aluminum nitride has a layer thickness of 3 μm or less. The cylinder liner made of a powdered aluminum alloy according to claim 1 or 2, which has a particle shape. 9. The powdered aluminum alloy of the cylinder liner includes aluminum nitride, and has a bonding interface having no gap at a boundary between the aluminum nitride and aluminum which is a matrix of the aluminum alloy base material. 4. A cylinder liner made of a powdered aluminum alloy according to item 1. 10. The cylinder liner made of a powdered aluminum alloy according to claim 1, wherein the powdered aluminum alloy of the cylinder liner has a porosity of not more than 15% by volume based on the entire aluminum alloy. 11. The powder aluminum alloy cylinder liner according to claim 10, wherein the porosity is 3% or more and 10% or less by volume based on the entire aluminum alloy. 12. The aluminum alloy powder of the cylinder liner contains 5% or less by weight of at least one lubricating component selected from the group consisting of graphite, MoS ₂ , WS ₂ and CaF. Alternatively, the powdered aluminum alloy cylinder liner according to claim 2. 13. The powder aluminum alloy cylinder liner according to claim 12, wherein the content of the lubricating component is 1% or more and 3% or less on a weight basis. 14. The aluminum alloy powder of the cylinder liner contains at least one element selected from the group consisting of Si, Fe, Ni, Cr, Ti, Mn, and Zr, and the content thereof is Not more than 25% by weight,
The cylinder liner made of a powdered aluminum alloy according to claim 1 or 2. 15. The powdered aluminum alloy of the cylinder liner is made of TiO ₂ , ZrO ₂ , SiO ₂ , MgO ₂ , Al
_3. The powder aluminum alloy cylinder liner according to claim 1, wherein the cylinder liner contains at least one kind of oxide spherical particles selected from the group consisting of ₂ O ₃ and Cr ₂ O ₃ in an amount of 5% by weight or less.