JPS61166935A - Composite member superior in wear resistance and its manufacture - Google Patents

Abstract

PURPOSE:To decrease the cost of the titled member, by using compacted body of graphite bearing cast iron fiber as metallic porous body in a method in which said body is chilled internally with Al alloy by high pressure casting method, then intermetallic compd. formation heating treatment is applied. CONSTITUTION:Cast iron fiber compacted body obtd. by press compacting the cast iron fibers contg. dispersedly graphite having self lubrication property is held in metal mold. Molten Al alloy is poured into the mold, then said compacted body is chilled internally by high pressure solidification casting method at >=about 400kg/cm<2> pressing force. Said composite cast material is hated and held at about 450-550 deg.C for about 1-10hr, to form compound layer of Al and Fe components at boundary between Al alloy and said compacted body, to obtain composite member superior in wear resistance. Thereby, cost can be decreased,m compared with a case of using Ni foamed metal, etc. as metallic porous body.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a fiber-reinforced composite member in which metal and reinforcing fiber are combined to improve mechanical properties, physical properties, and particularly wear resistance. The present invention also relates to a method for manufacturing this composite member at low cost.

C. Prior Art] Conventionally, members used in high-temperature and high-pressure sliding conditions, such as the piston of a vehicle engine, have a low coefficient of thermal expansion and excellent wear resistance, such as aluminum alloy (JIS AC8A). etc.) are used. In this piston, for example, repeated loads from the piston ring due to gas pressure act on the ring carrier portion for the top ring, so the high temperature strength of this portion is further improved to improve wear resistance and set resistance. This is requested.

Conventionally, as a method to improve wear resistance, etc., there was a method of casting Ni sintered bodies etc. with A1 alloy by high pressure solidification casting method, but with this conventional method, the hardness was high and the wear resistance was improved. There was a problem in that an intermetallic compound layer, which is the main factor, was hardly formed, and the bonding strength between the Ni sintered body and the AI1 alloy was insufficient.

In another conventional method, a porous metal such as Ni is immersed in molten An, and the surface is coated with N1-An! by heat treatment.
There is a method in which a compound layer is formed and then the metal porous body is cast with A1 alloy, but this conventional method requires a complicated manufacturing process and increases costs, and the N1-Al compound is not deposited on the surface of the Ni porous body. Moreover, there was a problem that the bonding strength between the A1 alloy and the Ni--Al compound was insufficient.

Therefore, as a method for improving wear resistance and settling resistance, the applicant of the present application casts Ni, Cu, and Fe-based metal porous bodies with A1 alloy using a high-pressure casting method with a pressing force of 400 kg/cm2 or more. , then 1 at 450-550℃
An application has been filed for a method of manufacturing an aluminum alloy casting in which the cast body is subjected to an intermetallic compound generation treatment by heating and holding for up to 10 hours (see Japanese Patent Application No. 87197/1983). The above manufacturing method according to this application has the advantage that it can increase the bonding strength between the metal porous body and the AJ gold alloy, generate an intermetallic compound layer to increase high temperature strength, and improve wear resistance. There is a problem in that the materials such as Ni foam metal are expensive.

[Purpose of the invention]

An object of the present invention has been made in view of the above-mentioned conventional problems, and is to provide a composite member that can significantly improve wear resistance and set resistance, and reduce costs, and a method for manufacturing the same.

[Structure of the invention]

Therefore, in order to achieve the above object, the inventor of the present application proposed that if the A1 alloy is reinforced with cast iron fibers containing graphite, which is low cost and has self-lubricating properties, high temperature strength can be achieved without increasing the cost. This method focuses on the fact that the wear resistance can be improved.

That is, the first invention of the present application is a fiber-reinforced composite member in which a molded body made of cast iron fibers containing dispersed graphite having self-lubricating properties is cast in A1 alloy, and the matrix A1 alloy and the reinforcing member are cast together. An intermetallic compound layer of AJ and an iron component is formed at the boundary with a certain cast iron fiber molded body, and as a result, in this first invention, an intermetallic compound layer with high hardness is generated and self- The presence of graphite, which has lubricating properties, improves the settling resistance and wear resistance.

Further, the second invention of the present application is a method for manufacturing the above-mentioned composite member, in which a cast iron fiber molded body formed by compression molding cast iron fibers containing dispersed graphite is held in a mold, and the molded body is compressed under pressure. By using a high-pressure solidification casting method of 400 kg/cm2 or more, one alloy is cast, and the cast composite casting material is heated and held at a temperature of 450 to 550°C for 1 to 10 hours to form Aj! An at the boundary between the alloy and the cast iron fiber compact
This is an intermetallic compound generation treatment that generates a compound layer of iron and iron components, and as a result, this second
In the invention, the cast iron fiber molded body serving as the strength member and the A1 alloy serving as the matrix are firmly adhered to each other, and a composite member in which the intermetallic compound layer and graphite are dispersed and contained can be reliably obtained.

Here, the pressurizing force in the above high pressure solidification casting method was set to 400 k.
The reason why it is set to be more than g/cm2 is as follows.

(If the pressure is less than 11,400 kg/cm2, the effect of pressurization on the solidified structure and mechanical properties of the A1 alloy casting itself is small, and it is difficult to guarantee its quality.

(2) Below 400 kg/cm2,
The adhesion between the cast iron fiber molded body and the A1 alloy was insufficient, and during the intermetallic compound generation treatment, a good Al alloy was formed at the boundary between the two.
It is difficult to generate an intermetallic compound layer with iron and iron components.

Moreover, in the above-mentioned intermetallic compound generation treatment, the treatment temperature was set at 450 to 550° C., and the heating holding time was set at 1 to 10 hours for the following reason.

(1) If the heating temperature is lower than 450°C, it will take a long time to generate intermetallic compounds, and if this compound generation treatment is also used as solution treatment for A1 alloy, sufficient solution treatment will not be possible; If it exceeds 1, the strength of the 1-alloy casting die will decrease.

(2) If the heating time is less than 1 hour, a sufficient intermetallic compound layer cannot be formed, and the amount of intermetallic compound layer produced is almost saturated after 10 hours, so it is not economical to heat for more than 10 hours.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Figures 1 to 5 are part 1 of the present application. This is for explaining a piston for a diesel engine which is a composite member according to the first embodiment of the second invention and a method for manufacturing the same, the piston 11 is formed using A1 alloy (AC8A), and the piston body is At the upper outer periphery of 12, there are annular top rings 3. Secondary ring groove 14. An oil ring groove 15 is recessed, and this top ring groove 13 is constituted by a ring carrier 16 which is a composite member of this embodiment.

FIG. 1 showing the metal structure of the ring carrier 16 portion,
In FIG. 2 showing the micrograph, 1 is a cast iron fiber as a reinforcing member in which pearlite 3 and graphite 4 are dispersed in a ferrite 2 base, and 5 is an A1 alloy (5) as a matrix filled between the cast iron fibers 5. JIS AC8A
), and the above cast iron fiber l has a diameter of 10100 l and a length l.
It is a fibrous ductile cast iron (FCD50) of about Qmm, and its chemical components are as shown in Table 1. The fiber 1 is located at the boundary between the Af gold alloy and the cast iron fiber 1.
An intermetallic compound layer 6 of the iron component and A/ is generated.

Next, a method of manufacturing the A1 alloy piston 11 will be explained with reference to FIG.

(I) First, cast iron fibers are formed by, for example, chatter vibration cutting, and the cast iron fibers are press-molded into a ring carrier 16 which is an annular fiber molded body shown in FIG. 4 (21). Here, the cast iron fiber has a diameter of 10100 II as described above.
It is desirable that the ring carrier 16 has a length of about 10 mm and contains 1.5% or more of graphite, and the fiber volume content Vf of the ring carrier 16 shown in Table 1 is 20% in this embodiment, but it is 10 to 10%. 70% is desirable. If this fiber volume content Vf is less than 10%, it will be difficult to produce a molded body, and also from the amount of dispersion of the graphite and intermetallic compound layer (preferably an area ratio of 0.5% or more), VflO
% or more, and if Vf is 70% or more, it becomes difficult to fill the pores of the compact with the A1 alloy.

(I[) The ring carrier 16 is sintered at, for example, 1150° C. in an inert gas atmosphere or in a vacuum. This sintering treatment is performed in order to increase the shape retention of the molded body and prevent the shape from collapsing during casting.

Note that this sintering treatment is not necessarily necessary depending on the required shape retention strength of the fiber molded body.

(III) Next, in order to further improve the filling properties of the A4 alloy molten metal into the ring carrier (&ili fiber molded body), the ring carrier 16 is heated to about 300° C.
It is attached to a predetermined position of the mold 22 shown in FIG. 2(b). This mold 22 is composed of an upper mold 22a, a middle mold 22b, and a lower mold 22c, and the space surrounded by these molds is a cavity 23 having the same shape as a piston, and the ring carrier 16 is inserted into this cavity. It is located at a portion corresponding to the top ring portion of No. 23. Note that heating the ring carrier 16 as described above is not necessarily necessary.

(IV) Inside the cavity 23, /1 alloy (AC8A'
) The molten metal is supplied from the molten metal supply port 22d formed in the lower die 22c, and then the molten metal is heated to a rate of 400 kg/cm2 or more,
In this example, a pressure of 1000 kg/cm2 is applied. Then, due to this pressurization, the molten metal of the A1 alloy is filled between all the fibers of the ring carrier 16, thereby forming a composite casting material in which the ring carrier 16 is cast with the A1 alloy by the high-pressure solidification casting method.

, (■) Then, the above composite casting material is charged into a heat treatment furnace and subjected to an intermetallic compound generation treatment. This treatment is to generate Fe-Al1 intermetallic compound at the boundary between the cast iron fiber and the AJ gold alloy, and the composite casting material is
This is done by heating and holding at a temperature of ~550°C for 1 to 10 hours, and in this example, in order to also serve as solution treatment for the A1 alloy, water quenching is performed after holding at 510°C for 6 hours, and further Tempering treatment (T-6 treatment) is performed by holding at 170° C. for 7 hours. As a result, a piston material 21 having the metal structure shown in FIGS. 1 and 2 was obtained in the ring carrier 16 portion, and the graphite content after this heat treatment was about 2.3%.

(Vl) Finally, the piston material 21 is cut into the top ring groove 1 shown by the two-dot chain line in FIG. 4(b).
3. Secondary ring groove 14. An oil ring groove 15 is formed. Then, the A1 alloy piston 11 shown in FIG. 3 is obtained.

FIG. 5 shows pins for explaining the effect of improving the wear resistance of the ring carrier 16 portion which is a composite member according to the above embodiment.
The results of a wear test using the disk method are shown.A cast iron disk is rotated at a circumferential speed of 0.5 m/3, and a test specimen pin is pressed against it with a load of 300 g to determine the friction distance. The wear amount (cm3) of the test piece was measured against (km).

In the figure, curve A shows the wear amount of the cast iron fiber composite member according to this example, and curves B, C, and D show the wear amount of the Niresist cast iron, carbon steel (S 45 c) fiber composite member, and A/
The wear amount of gold alloy AC8A) subjected to T-6 treatment is shown.

As is clear from the figure, for example, when compared at a friction distance of 2.0 km, the amount of wear of the composite member of this example (curve A) is lower than that of the case where T-6 treatment is applied to A1 alloy (curve D). Approximately 1
15, about 1/2 of the carbon steel fiber composite member (curve C)
Thus, it can be seen that the wear resistance of this example is significantly improved compared to these. The reason why there was such a large difference in the amount of wear was that in the case of A1 alloy, T-6
This is because even if the treatment is applied, total interflexural compounds, which are the main factor for improving wear resistance, are not generated, and when reinforced with carbon steel fibers, graphite, which has self-lubricating properties as in this example, is not produced. This is because it does not exist.

In addition, Niresist cast iron (curve B) has slightly less wear than the composite member of this example, but this Niresist cast iron has A1
When the alloy base material is subjected to T-6 treatment, the bondability with the base material is poor, and from this point of view, the composite member of this example is more advantageous.

FIG. 6 is part 1 of the present application. A piston pin 31 for a gasoline engine according to a second embodiment of the second invention is shown, and in the figure, 31b is the pin body, which is 5% A/! A sliding part 31a is formed on the outer surface of both ends of the pin body 31b, and this sliding part 31a is a composite member made of A1 alloy reinforced with cast iron (FCD40) fibers. The chemical components of AC8B and FCD40 are shown in Table 1.

The fiber volume content Vf of this example is 50%, the high pressure solidification casting pressure is 1000 kg/cm2,
Heat treatment was performed by heating and holding at 515°C for 5 hours, and after water quenching,
Tempering was performed by holding at 170°C for 7 hours. In this example, the graphite content after heat treatment was approximately 2.3%, and both wear resistance and set resistance were significantly improved.

FIG. 7 is part 1 of the present application. An adjusting disc 41 according to a third embodiment of the second invention is shown, which is installed between an engine cam and a valve.
8A) is made of SiC whiskers, and the upper part 41a is made of cast iron (FC
D70) is reinforced with fibers, and the chemical components of this FCD70 are as shown in Table 1.

The fiber volume content vr of this example is 70% in the upper part 41a.
The lower portion 41b is 10%, and the heat treatment is the same as in the first embodiment. In this example, the graphite content of the upper part 4a after heat treatment was about 2.3%, and it was possible to improve the sliding characteristics and wear resistance, and also to achieve improvement in high-temperature strength and weight reduction.

In the first to third embodiments described above, the present invention was applied to a piston, a piston pin, and an adjusting disk, but the present invention is of course applicable to other devices, such as the connecting rod 51 shown in FIG. It can also be applied to

In this conorod 51, the sliding portion 51 of the small end 51a
If the sliding portion 51d of the large end portion 51c and the sliding portion 51d of the large end portion 51c are formed of a cast iron fiber composite member, the wear resistance and set-off resistance of these portions can be improved.

〔Effect of the invention〕

As described above, in the first invention of the present application, cast iron fibers containing graphite dispersed therein, which are low in cost and have self-lubricating properties, are used as reinforcing members, and A1 and iron components are added at the boundary between the cast iron fibers and the A1 alloy. Since an intermetallic compound layer is formed with the F e -A 1 compound having high hardness and graphite which has self-lubricating properties and reduces the friction coefficient, it has the effect of improving wear resistance and set resistance. , and also has the effect of reducing costs.

In addition, in the second invention of the present application, a cast iron fiber molded body containing dispersed graphite is cast with A2 alloy by high pressure solidification casting method, and this I-Grounded composite casting material is made of A7! Since the treatment was carried out to generate an intermetallic compound layer between
6 alloy is sufficiently filled throughout the cast iron fiber molded body and firmly adheres to the cast iron fiber, and Fe-Aβ intermetallic compound is generated throughout the cast iron fiber molded body, and the bonding force with the A/gold alloy cast iron fiber is strong. This has the effect of providing a composite member with excellent wear resistance and set resistance at low cost.

[Brief explanation of the drawing]

FIG. 1 is part 1 of the present application. A diagram showing the metallographic structure of a composite member according to the first embodiment of the second invention, FIG. 2 is a photomicrograph in place of a drawing showing the metallographic structure, and FIGS. For explanation purposes, Fig. 3 is a cross-sectional front view of the piston, Fig. 4 (al is a perspective view of the ring carrier, and the crest in Fig. 4) is a sectional view of the mold in the high-pressure solidification casting method. Figure 4 (C1 is a sectional view of the ring carrier portion of the piston material, Figure 5 is a friction distance vs. wear amount characteristic diagram for explaining the effect, and Figures 6 to 8 are each a cross-sectional view of the ring carrier portion of the piston material. They are a sectional view, a perspective view, and a side view for explaining other embodiments of the invention of No. 2. 1... Cast iron fiber, 4... Graphite, 5... A1 alloy,
6...Fe-AJ compound layer, 11,31,41.51
... Piston, piston pin, adjusting disc, stove 7 (composite member), 1G... ring carrier (cast iron fiber molded body), 22... mold. Patent applicant Ken Hayase, agent of Mazda Motor Corporation - Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Friction tread/km - Fig. 6 fs7 Fig. I! +1 1b Figure 8

Claims (2)

[Claims] (1) A cast iron fiber molded body whose pores are filled with aluminum alloy and cast, graphite dispersed in the cast iron fiber molded body, and graphite formed at the boundary between the cast iron fiber molded body and the aluminum alloy. A composite member with excellent wear resistance, characterized in that it is composed of a compound layer of aluminum and the iron component of a cast iron fiber molded body. (2) A compression-molded cast iron fiber molded body containing dispersed graphite is held in a mold, and molten aluminum alloy is injected into the mold, followed by high-pressure solidification casting with a pressing force of 400 kg/cm^2 or more. A composite casting material is formed by casting the above-mentioned cast iron fiber molded body by the method, and then the composite casting material is
An intermetallic compound generation treatment is performed by heating and holding at a temperature of 50 ° C. for 1 to 10 hours to generate a compound layer of aluminum and the iron component of the molded product at the boundary between the cast iron fiber molded product and the aluminum alloy. A manufacturing method for composite parts with excellent wear resistance.