JPS61177353A - Wear resistant fiber reinforced metallic composite material - Google Patents

Abstract

PURPOSE:To obtain a wear resistant fiber reinforced metallic composite material for a sliding member having superior strength, toughness and wear resistance and wearing hardly an opposite member during sliding by dispersing alumina fibers having a high alpha-alumina content as a reinforcing material in a light metal such as Al or Mg. CONSTITUTION:Alumina fibers contg. >=60wt% alpha-alumina, colloidal silica and an org. binder such as starch are dispersed in water. The resulting slurry is vacuum-molded to form a discoidal fibrous molded body 1, and this molded body 1 is baked at 1,200 deg.C for 20min and put in a metallic mold 3. A light metal such as Al or Mg or an alloy thereof is melted, and the molten metal 5 is charged into the mold 3 and solidified under pressure applied by a plunger 6. The alumina fibers as a reinforcing material and dispersed in the light metal or alloy as a matrix, and a wear resistant fiber reinforced metallic composite material for a sliding member having superior wear resistance, strength and toughness and capable of reducing the extent of wear of an opposite member during sliding is obtd.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention relates to a fiber-reinforced metal composite material, which has particularly excellent sliding properties and is suitable for use as a sliding member for automobiles, for example. The present invention relates to a wear-resistant fiber-reinforced metal composite material that can

(Prior Art) Conventional #I fiber-reinforced metal composite materials include, for example, fibers having high strength and high elasticity such as polymer AM such as carbon, alumina, silica, silicon carbide, silicon nitride, glass, and aramid. Alternatively, there is one in which whiskers are used as a reinforcing material and this reinforcing material is compositely dispersed in a light metal matrix such as aluminum or magnesium. And #l like this
Regarding fiber-reinforced metal composite materials, for example, JP-A-58
JP-A-93835-6, JP-A-58-93838, JP-A-58-93840-1, JP-A-58-93948, JP-A-59-70734-6, etc.

(Problems to be Solved by the Invention) For example, conventional alumina-silica fibers are much harder than aluminum alloys as a matrix, and also have spherical particles as unfiberized parts due to the manufacturing method. is mixed between the fibers, so composite materials reinforced with alumina-silica fibers reduce the amount of wear on other mating members that come into contact with and slide relative to the composite material. There was a problem with increasing the amount. Particularly in composite materials reinforced with the fibers, there is a problem in that the lower the plane-parallel orientation ratio of the fibers on the sliding surface, the more pronounced the tendency for wear against the mating material. To explain in more detail, in the conventionally used alumina-silica fibers, Al
203/S i O2 composition ratio (weight%) is approximately 1
It is glassy under normal conditions, begins to crystallize at about 1000℃, and becomes mullite (3A or 203-2SiO□).
crystallizes, and at higher temperatures cristobalite (S
i 02 ) is precipitated. Furthermore, commercially available conventional polycrystalline alumina fibers have an AfL203 content of 70
~95% by weight, and the mineral composition of fibers with low A203 content is mainly mullite, and even high alumina fibers have α-A! The content of L203 is low,
Intermediate alumina crystals such as γ, δ, and 0-Alz03 are the main materials. Therefore, conventional fiber-reinforced metal-type composite materials in which these polycrystalline alumina fibers are used have a problem in that they have poor abrasion resistance not only to themselves but especially to the mating material.

This invention was made by focusing on the above-mentioned conventional problems, and it not only has excellent properties as a general fiber-reinforced metal composite material, such as strength and toughness, but also Especially when used as a sliding member,
The purpose of the present invention is to provide a fiber-reinforced metal composite material that not only has excellent wear resistance on its own, but also has low aggressiveness toward other members, making it possible to significantly reduce the amount of wear on the other members. It is something to do.

[Structure of the Invention] (Means for Solving the Problems) The present invention solves the conventional problems as described above, and provides an alumina fiber having an α-alumina content of 60% by weight or more. is used as a reinforcing material, and the reinforcing material is a light metal (including alloy) such as aluminum or magnesium.
It is characterized by being compositely dispersed in a matrix. More preferably, especially when used as a sliding member, the reinforcing fibers are oriented so that the plane-parallel orientation ratio of the reinforcing fibers on the sliding surface of the composite material is 50% or more, more preferably 70% or more. It is characterized by:

The alumina fiber used as a reinforcing material in this invention has an α-alumina content of 60% by weight or more. Here, the reason why the content of α-alumina is set to 60% by weight or more is because of the α-alumina among various crystal structures in alumina.
-Alumina has the most stable structure, has high hardness and elastic modulus, and when used as a sliding member, has good wear resistance and is less aggressive to the other material. It is effective in reducing the amount of wear on the mating member, and in order to obtain such an effect of α-alumina, the content of α-alumina is set to 60% by weight or more.

Furthermore, light metals (including alloys) such as aluminum and magnesium are used as the metal for the matrix, but are not particularly limited.

(Example 1) In this example, a wear-resistant fiber-reinforced metal composite material was manufactured using reinforcing alumina fibers A to D shown in Table 1. In addition, in Table 1, A.

B is alumina fiber manufactured by ICI (product name "Safil")
, and C, D, and E are alumina l manufactured by Nichias ■.
ilfm (trade name "Rubeel").

Therefore, we made sure that the contents of colloidal silica (manufactured by Nissan Chemical ■) and organic binder (starch) in the final molded body were 6% and 1%, respectively, and that the fiber bulk density was 0.
．． The above alumina fiber, so that it is 20g/c 3
A uniform slurry is produced by dispersing colloidal silica and an organic binder in an aqueous solution.Then, this slurry is used to form a disc as shown in Figure 1 with a diameter of 98 m and a thickness of 32 m by vacuum forming. A fibrous molded body 1 having the shape of the shape was prepared, and this fibrous molded body 1 was further baked under the conditions of 1200° C. x 20 cm to bond and mold with the inorganic binder silica. In this case, as shown in FIG. 1, the individual reinforcing fibers 2 in the fiber #I molded body 1
They are randomly oriented in the Y plane, and are stacked in the Z direction.

Next, as shown in FIG. 2, the fiber molded body 1 is placed in a mold cavity 4 of a mold device 3, and a molten metal (hot water temperature) of an aluminum alloy (JIS standard AC8A alloy) is placed in the mold cavity 4. 800℃) 5.
Next, the molten metal 5 is heated to 800 kgf by the plunger 6.
/ am2, and this pressurized state was maintained until the molten metal 5 was completely solidified. In this way, the outer diameter 1
A cylindrical solidified body with a diameter of 00 mm and a height of 70 cm was pressure cast,
Furthermore, the solidified body is subjected to heat treatment (T6 treatment), and as shown in FIG. Material 10 was produced.

Next, from the part reinforced with the reinforcing material 8 of the composite material 10 produced as described above, 5X5X10
A wear test piece 11 having a layer (tip radius: 7 mm) and having the shape shown in FIG. 4 was prepared. At this time, the wear test piece 11 was prepared for each sample shown in Table 1 so that the plane-parallel orientation ratio of reinforcing fibers on the worn surface was 10% or less and 90% or more, respectively.

In this specification, the plane-parallel orientation ratio of the reinforcing fibers means that the ratio of the major axis to the minor axis of the elliptical cross section of the inorganic fibers that crosses any plane in the portion reinforced by the reinforcing fibers is 3 or more. The number of fibers in the plane is divided by the total number of fibers crossing the surface, and the value is multiplied by 100. That is, this is the plane-parallel orientation rate, and this plane-parallel orientation rate was determined by processing an image (magnification: 800 times) obtained through a metallurgical microscope using a computer.

Next, each of the wear test pieces 11 prepared as described above was sequentially set in a set of three pieces in a disk-type friction and wear tester, and a disk test made of flake graphite cast iron (JIS standard FC25 equivalent material) as a mating member was performed. A wear test was performed for 10 minutes at a pressing force of 150 kg, sliding speed of 1, and 5 m for 1 sec while supplying motor oil (8-stone motor oil C) whose temperature was adjusted to 80°C to the contact area of each test piece. A wear test was conducted in which the piece 11 was rotated.

The results of this wear test are shown in FIG.

In FIG. 5, the right half is the worn surface 8 of the tip R7 of the three-wood wear test piece 11! The left half shows the average value of the results of measuring the wear cross-sectional area (X 10-30-3ts) at six locations on the disk test material, which is the mating member. This area measurement was determined for each specimen.

In addition, in FIG. 5, 90% or more and 10% or less indicate wear test pieces having the plane-parallel orientation ratio.

From the results shown in Figure 5, the wear amount of the alumina fiber-reinforced wear test piece is considerably smaller than that of the test piece made only of aluminum alloy AC8A, especially when the α-alumina content is 60%. M% or more (sample material, H
) and the plane-parallel orientation ratio is 90% or more, it can be seen that there is no wear of the mating material at all.

From the above wear test results, in order to suppress the amount of wear of both the composite material and its mating material to a low value, the content of α-alumina in the alumina fiber as a reinforcing material must be 60%.
% by weight or more, and the plane-parallel orientation rate on the sliding surface is 90
% or more is particularly preferable.

(Example 2) Next, test specimens A' to E' were produced in exactly the same manner as in Example 1, with the reinforcing fiber bulk density increased to 1.6517 cm<3>, and abrasion tests were conducted. The results are shown in FIG.

From the results shown in Figure 6, even when increasing the amount of reinforcing fibers in the wear test piece, in order to keep the amount of wear of both the composite material and its mating member to a low value, it is necessary to increase the amount of reinforcing fibers in the wear test piece. It can be seen that composite materials using However, when the bulk density of the reinforcing fibers is increased in this way, the amount of wear on the reinforcing fiber itself is further reduced, but the amount of wear on the mating member tends to increase slightly. Therefore, it is advantageous to use it in consideration of this tendency.

(Example 3) Next, fiber-reinforced metal composite material 1 using the reinforcing fibers shown in Table 1 was manufactured using the same manufacturing method as in Example 1.
0 was manufactured, and wear test pieces 11 having various plane-parallel orientation ratios as shown in Table 2 were manufactured. And wear test piece 11
A set of three pieces was sequentially set in a disc-type abrasion tester, and the same wear test as in Example 1 was conducted using a disc test material made of JISFC25 mating material as the mating member. The results of this wear test are shown in Figure 7. In Figure 7,
The vertical axis shows the average wear area of the wear test piece 11 and the average wear area of the disk test piece, and the horizontal axis shows the plane-parallel orientation rate.

From the results shown in Figure 7, the amount of wear of the disk test piece (Fe12), which is the mating member, is determined by the fact that the plane-parallel orientation rate of the fibers is 50%.
It can be seen that when the value exceeds the value, the size decreases rapidly, and at 70% there is almost no wear, and at 90% there is no wear at all. Also, the wear of composite materials.

It can be seen that it does not depend on the plane-parallel orientation ratio of the fibers, and that both values are small.

From the above wear test results, in order to reduce the wear of the composite material and the mating member, the plane-parallel orientation ratio of the reinforcing fibers must be 5.
It can be seen that 0% or more is desirable, and 70% or more is even more desirable.

Table 2 (Example 4) Using the same manufacturing method as in Example 1, this time JIS ADC12 was used instead of the aluminum alloy JISAC8A that became the metal matrix, and the reinforcing fibers A-E shown in Table 1 were used. A reinforced composite material 10 was manufactured using the composite material 10, and a disk test material (outer diameter 80s layer x thickness 10mm) was manufactured from this composite material 10.Next, the disk test material was similarly set in the wear tester. As a mating member, iron-based sintered materials (C: 0.2% by weight, Ni: 2% by weight, Cu
: 0.5% by weight, balance Fe, HRB near 0, density:
A disk 12 made of 6.8 g/c■3) having the shape shown in FIG. A wear test was conducted by rotating the disk 12 for one hour each with the sliding speed in the pattern shown in FIG. 9. The results of this wear test are shown in FIG.

In FIG. 10, the right half shows the average value of the wear amount (ILm) of the disk 12, which is the mating member, determined at 20 points, and the left half shows the wear cross-sectional area (ILm) of the disk test material, which is a composite material. The average value of the results of measuring X 10-3me2) at six locations is shown.

From the results shown in Figure 10, the wear amount of the disk test material reinforced with alumina fibers is significantly smaller than that of JIS ADC12 alloy alone, especially when the α-alumina content is 66% by weight or more (in the case of D and E). ) and the plane-parallel orientation ratio of the fibers is 90% or more, it is clear that the wear of the disk serving as the mating member is extremely small, and the results are similar to those of Example 1.

(Example 5) Next, a fiber-reinforced metal was prepared using the reinforcing m fibers and E shown in Table 1 used in the above-mentioned Example 1 as the reinforcing material 8, and using a magnesium alloy (JISAZ91) as the metal matrix 9. A mold composite material 10 was created in exactly the same manner as in Example 1, and wear test pieces similar to those in Example 1 were created from these composite materials.

Next, for these wear test pieces, flake graphite cast iron (
When a wear test using a disc test material manufactured using JIS FC25 (equivalent to JIS FC25 material) as a mating member was similarly carried out using a disc-type wear tester, the wear test piece composite-reinforced with reinforcing fibers and H It was observed that the wear amount of both the wear test piece and the disk test material was significantly smaller than that of the wear test piece made of only the disk.

Further, as a result of various studies on the causes of the difference in the amount of wear of the mating member due to the difference in the plane-parallel orientation ratio, it was assumed that, according to observation means such as an electron microscope, it was probably due to the difference in crystal morphology between the inside of the fiber and the surface.

[Effects of the Invention] As explained above, the wear-resistant fiber-reinforced metal composite material according to the present invention uses alumina fibers containing α-alumina of 60% by weight or more as a reinforcing material, and the reinforcing material is Since it is compositely dispersed in a metal matrix, it not only has excellent properties as a general fiber-reinforced metal composite material, such as strength and toughness, but especially when used as a sliding member. Not only does it have excellent wear resistance, but it is also less aggressive to the other member, making it possible to significantly reduce the amount of wear on the other member. A very excellent effect is brought about by exhibiting excellent properties.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of a slope of a fiber molded body produced in an example of the present invention, and Fig. 2 is a cross-sectional view of a mold device used to manufacture a fiber-reinforced metal composite material using the fiber molded body. Figure 3 is an explanatory diagram of the slope of the fiber-reinforced metal type composite material partially reinforced with the fiber molded body shown in Figure 1, and Figure 4 is an explanatory diagram of the wear test piece made from the composite material of Figure 3. . FIGS. 5 and 6 are graphs showing the results of wear tests when flake graphite cast iron was used as the mating member in Example 1 and Example 2 of the present invention, respectively, and FIG. 7 is a graph showing the results of wear tests in Example 3 of the present invention A graph showing the results of the wear test conducted,
FIG. 8 is an explanatory diagram of the slope of the disk, which is the counterpart member in the wear test conducted in Example 4 of the present invention, and FIG. 9 is an explanatory diagram showing the sliding speed pattern of the wear test conducted in Example 4. The 1θ diagram is a graph showing the results of the wear test in the same Example 4 when the mating member was made of iron-based sintered material. 8... Reinforcement material, 9... Metal matrix, 10... Fiber reinforced metal type composite material. Patent applicant Nissan Motor Co., Ltd. Patent applicant Nichias Co., Ltd. Patent attorney Yutaka Oshio 2 Figure 7 ε 0 20 40 60 80 100 (Z) in 74
Go orientation figure 9 θ leap (way)

Claims (1)

[Claims] (1) A wear-resistant fiber-reinforced metal composite material, characterized in that the reinforcing material is alumina fiber containing 60% by weight or more of α-alumina, and the reinforcing material is compositely dispersed in a light metal matrix.