JPS6173846A - Porous fiber reinforced metallic composite material and its manufacture - Google Patents

Abstract

PURPOSE:To obtain the titled composite material having improved strength and heat resistance by infiltrating a molten metal into an aggregate of fibers, solidifying it, remelting the resulting composite material, and making holes in the material so that they are dispersed among the fibers. CONSTITUTION:A molten metal such as molten Al (alloy) is infiltrated into an aggregate of fibers such as alumina, carbon or glass fibers, and a fiber reinforced metallic composite material is formed by forging or other method. The whole or part of a block of the composite material is remelted by heating, and holes are made in the material so that they are distributed among part of the fibers having the stuck molten metal. The resulting porous composite material can be utilized as a sound absorbing member, a filter member or the like used at a relatively high temp.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a porous fiber-reinforced metal composite material and its! Regarding the 1-making method. The porous fiber-reinforced metal composite material of the present invention can be used for sound absorbing members, sound reducing members, filter members, etc. that are used at relatively high temperatures. It can also be used as a base member for a ceramic sprayed layer, a lightweight member, etc.

[Prior art 1] Conventionally, porous metal materials have been provided such as foamed metals, sintered metal powders, and materials in which hollow bodies such as glass balloons are mixed into a base metal. .

However, the above-mentioned materials have low strength because they have pores in the normal metal structure that does not contain fibers, and
The heat resistance also did not exceed that of the base metal.

[Problems to be Solved by the Invention] The present invention has been made in view of the above-mentioned conventional techniques, and improves the strength and heat resistance of conventional porous metal materials.

[Means for Solving the Problems] The porous fiber-reinforced metal composite material of the first invention comprises a fiber aggregate, a metal attached to the fiber aggregate, and a fiber m* aggregate to which the metal is attached. It is characterized by being composed of pores dispersed between some of the constituent fibers.

The fiber aggregate refers to a large number of reinforcing fibers that are entangled or aligned.

Although the porous fiber-reinforced metal composite material of the present invention is porous, it has high strength because it is reinforced with reinforcing fibers. Furthermore, even when the porous fiber-reinforced metal composite material of the present invention is heated at high temperatures, due to the presence of reinforcing fibers,
Deformation of the outer shape can be suppressed. As the above-described reinforcing fibers, reinforcing fibers conventionally used in metal matrix composite materials can be used. Both short U&fiber and long L miscellaneous can be used. In order to improve the bondability between the metal and the reinforcing fibers, reinforcing fibers coated with a substance that has good wettability to molten metal or the same metal as the molten metal may be used. It is preferable that the reinforcing fiber has a higher melting point than the metal. The main reason for this is that when the porous fiber-reinforced metal composite material of the present invention is manufactured by the melt forging method as described below, if the melting point of the reinforcing fibers is lower than the melting point of the metal, the fibers will melt. be. Therefore, as the reinforcing fibers, alumino fibers, alumina silica mu, zirconia fibers, silicon nitride fibers, carbon fibers, silicon carbide fibers, glass fibers, boron fibers, metal fibers, etc. can be used as the reinforcing fibers. Stainless steel fibers can be used as the metal fibers. Whiskers may be used as reinforcing fibers. The whisker is preferably a ceramic whisker. This is because ceramics have a higher elastic modulus. Ceramic whiskers include silicon carbide whiskers, silicon nitride whiskers,
Alumina whiskers, zirconia whiskers, etc. can be used. Depending on the conditions of use, not only the ceramic whiskers described above but also metal whiskers and graph 1 whiskers may be used.

The orientation and blending amount of the reinforcing fibers forming the fiber aggregate can be arbitrarily determined depending on the application. Note that the volume percentage of the fibers is desirably about 2 to 30% when the whole is 100% by volume. If the volume fraction of the fibers is 2% or less, the reinforcing effect of the fibers will be small, and if it is 30% or more, the formation of pores will be restricted and it will be difficult to form pores. Although the distribution of fibers is generally uniform, the volume fraction of fibers may be made small in certain parts and large in other predetermined parts, if necessary. In this case, the change in fiber volume fraction may be continuous or stepwise.

The metal adheres to the reinforcing fibers constituting the fiber aggregate to form a fiber-reinforced metal composite material. The metal is generally a light metal. Conventional light metals can be used. For example, aluminum, magnesium, aluminum-based alloys, magnesium-based alloys, etc. can be used.

The pores are dispersed among some HAHs constituting the fiber aggregate to which the metal is attached. The pores can be formed by heating the metal that makes up the porous Al fiber reinforced metal composite near or above the melting point. The pores provide the porous fiber-reinforced metal composite material with sound absorption, sound reduction, and weight reduction effects. The pores also serve to reduce the coefficient of thermal expansion and thermal conductivity of the porous fiber-reinforced metal composite material. The reason why pores reduce the coefficient of thermal expansion is that the thermal expansion of the metal is regulated by the fibers, so the thermal expansion of the metal is absorbed into the pore spaces without being able to escape outward. This is presumed to be because the amount of thermal expansion at the top becomes smaller. It is desirable that these pores are uniformly distributed within the porous U & fiber reinforced metal composite material. The volume percent of pores varies depending on the required strength, heat resistance, heat insulation, etc., but when the void is 1.00 volume percent, it is preferably 5 to 50 volume percent. Here, the volume percent of the pores is measured based on the pore area ratio of the cross section measured by an image analysis device. The size of the pores varies depending on the required strength, heat resistance, and heat insulation, but is between 5 and 10
It can be about 0μ. The pores may have approximately the same size, or a combination of large-diameter pores and small-diameter pores may be used.

Various specific methods can be considered for manufacturing the porous fiber-reinforced metal composite material of the first invention as described above, but the most desirable manufacturing method among them, that is, the manufacturing method according to the second invention of the present application, is as follows. Explain.

The manufacturing method of the second invention includes a first step of impregnating and contacting a molten metal into a fiber aggregate and solidifying the metal to form a block, and heating the block to form a block. A second step of dispersing and forming pores between some of the fibers constituting the fiber aggregate to which the molten metal is attached by melting is carried out in sequence.

In the first step, a block in which reinforcing fibers are embedded is formed by impregnating and contacting molten metal into the fiber aggregate and then solidifying the metal. Specifically, in the first step, as in the conventional method, a fiber aggregate is arranged in the cavity of a mold, and in that state, a molten metal such as the above-mentioned aluminum alloy or magnesium alloy is placed in the cavity of the mold. This can be done by injecting a molten metal such as an alloy to impregnate and adhere between the fibers, and then solidifying the molten metal as it is. In this way, the metal and the fiber aggregate can be easily integrated. In this case, it is desirable to use a molten metal forging method (also called high pressure casting method or pressure casting method) in which high pressure is applied to the molten metal injected into the metal and the pressure is maintained until solidification. The pressurizing means is generally a plunger, but in some cases gas pressure may be used. When using the molten metal forging method using a plunger, the pressure is usually 5
00 to 200 kU/am2. In the first step, a vacuum casting method, a die casting method, or a melt field infiltration method, which does not apply particularly high pressure unlike the molten metal forging method, may be used depending on the case. Incidentally, the above-mentioned fiber aggregate can be formed by a conventionally used official sealing method, such as a vacuum forming method or a compression molding method.

In the second step, the block is heated and melted to a temperature higher than the melting point of the metal, and pores are dispersed in the metal between the fibers. In this case, even when heated to a temperature higher than the melting point of the metal, changes in the external shape and dimensions of the porous fiber-reinforced gold film composite material itself of the present invention are caused by the surface tension of the metal interposed between the reinforcing fibers. This can be suppressed by the action of The block is preferably heated in a reducing atmosphere or an inert gas atmosphere such as argon or helium. Here, the entire block may be heated, or a portion thereof may be heated to a temperature equal to or higher than the melting point of the metal (eg, aluminum alloy). In the second step, when the reinforcing fibers are alumina-silica rectangular fibers and the metal is JIS-ACOA aluminum alloy, the heating temperature is set to 600-600℃.
The temperature can be about 800°C. Here, the higher the heating temperature, the more pores there are, so the ratio of pores can be adjusted by adjusting the heating temperature. In the second step, the means for partially heating the block include means for generating an arc by bringing an electrode close to the surface of the 10 blocks, means for irradiating the surface portion of the block with a laser beam, and means for heating the block with an electron beam. Means for irradiating surface portions can be used.

Note that if the entire block is placed in a heat treatment furnace and heated, the entire block becomes a porous body. Arc again,
By partially heating the surface of the block with a laser beam, electron beam, etc., only the parts heated above the melting point become porous, making it possible to form a porous fiber-reinforced metal composite material with pores formed only in the necessary parts. As a means for generating the above-mentioned arc, a TIG arc method can be used in which an arc is generated between a tungsten electrode and the block in an inert gas. In the TIG arc method, the electrode diameter is about 3.2 mm, the arc length is about 6 mm, and the current is 15 mm.
Approximately 0 to 12 OA, voltage approximately 14, argon gas flow ff
125 liters/min.

In the means for irradiating the laser beam, an auxiliary gas can be flowed together with the laser beam irradiation, and a pulsed laser can be used to reduce the size of the processed layer due to heat.

[Effect of the invention] The porous fiber-reinforced metal composite material of the present invention has fibers 9P, 8
One body and the said I! It is characterized by being composed of metal adhered to the Zato laminate and pores dispersed in some of the fibers constituting the fiber aggregate to which the metal is adhered.

Therefore, conventionally provided porous metal scrap materials that do not contain reinforcing fibers, such as foamed metal materials, sintered compact materials obtained by sintering metal powder as a compact, and hollow bodies such as glass balloons. Compared to materials that have a metal structure mixed with them, the outer shape is less likely to collapse, and in this sense, the heat resistance is improved.

In addition, the strength is improved due to the presence of reinforcing fibers.

Further, according to the manufacturing method of the present invention, a porous fiber-reinforced metal composite material having excellent properties as described above can be manufactured relatively simply and easily.

Furthermore, if the second step is performed by heating with an arc, a laser beam, or an electron beam, pores can be formed only in the surface portion of the porous fiber-reinforced metal composite material.

E Example 1 (first step) First, A12 was used as reinforcing fiber at ■m%.
Using alumina-silica short fibers with an average fiber diameter of 1 to 20 μm and a length of 10 to 100 μm and having a composition of 0350%-8iOz50%, a diameter of 100 mm was formed by vacuum forming.
A disk-shaped fiber aggregate with a thickness of 3Q mm was formed. The fiber packing density of this fiber assembly was 0.17 g/cc.

Next, this 41M aggregate was placed in a corresponding portion of the cavity of a mold for molten metal forging. In this case, the mold was preheated to 300°C and the fiber aggregate to 800°C. Next 700
A molten JIS-AC8A aluminum alloy melted at ℃ was poured into the cavity, and a pressure of 1500 atmospheres was applied to impregnate and contact the molten metal between the fibers of the S fiber aggregate, thereby performing molten metal forging. As a result, a fiber-reinforced metal composite material in which the volume percentage of alumina-silica fibers was 6 to 8% was formed.

(Second Step) Three blocks No. 1, No. 2, and No. 003 were appropriately cut out from the above-described porous fiber-reinforced metal composite material.

The size of each block is 40 mm (length) x 30
The dimensions were mm (width) x 10 mm (thickness). Then, the block No. 1 was placed in an electric furnace maintained at 600°C and heated for 1 hour.
A hole was formed in the block. Thereafter, the N091 block taken out from the electric furnace was air cooled.

Similarly, blocks No. 2 were placed in an electric furnace maintained at 700° C., holes were formed in the same manner, and then air-cooled. Similarly, the NO.3 block was charged into an electric furnace maintained at 800° C., holes were formed, and then the air cooling section was placed.

As a comparative example, a J15-AC8A alloy was formed by molten metal forging, and this was used as a No. 4 block (not containing reinforcing fibers), and was charged into an electric furnace maintained at 600°C as in the case of N091. did. Block No. 4 as a comparative example is the same as No. 1 except that it does not contain fibers.
~No., manufactured under almost the same conditions as block No. 3. Note that the holding time in the electric furnace is the same for No. 1 to No. 4, 1 hour.

(Rating 8) Table 1 shows the results of the external shape and the degree of pore formation when heated in an electric furnace. Here, as shown in Table 1, the external shapes of No. 1 to No. 3 were maintained as they were.

FIG. 1 is a side view showing the external shape of block No. 1 after heating, and it can be seen that the block external shape is hardly deformed.

In No. 4 as a comparative example, the external shape changed significantly and collapsed as shown in FIG. In addition, as shown in Table 1, the volume percent of pores is 10 to 20% in the case of No. 1 (there is a slightly different width depending on the cut surface), and No. 2, it is 15-25%, and N
In the case of O33, it was 20-35%, and as is clear from Table 1, the higher the temperature at which the block was heated, the more vacancies there were.

Furthermore, Fig. 3 and Fig. 4 are photographs showing the microscopic metal structure of blocks No. 1, and Fig. 3 has a magnification of 100 times
The figure has a magnification of 400x. In FIGS. 3 and 4, the irregularly shaped black parts indicate pores, which are circular, spindle-shaped,
The black part of the line represents the fiber, and the remaining part represents the aluminum alloy. Further, in Comparative Example No. 4, no pores were formed even though the heating temperature was the same as in No. 1.

From the results in Table 1 above, the following (1) and (2) can be understood.

(1) Even when heated to 800°C, which is above the melting point, the shape of the porous block is maintained without losing its shape. Even if heated to 800℃, which is above the melting point,
The reason why the shape is maintained almost without deformation is presumed to be due to the effect of surface tension generated in the metal between the fibers.

Therefore, the porous fiber-reinforced metal composite material of the present invention hardly loses its outer shape or does not deform much even when heated above the melting temperature, and in this sense has good heat resistance.

(2) Comparing the No. 1 block heated to the same temperature as 600°C and the No. 14 block, 10 to 20% of pores were formed in the No. 11 block that contained fibers, but the fibers No pores were formed in the block containing N014. From this, it is inferred that the presence of fibers greatly contributes to the formation of pores.

Next, the porous fiber-reinforced gold WrS composite material produced through the first and second steps described above was cut out and No. 1
Several blocks with numbers 1 to 0.14 were formed. Furthermore, N
o, block size of 11 to N0.14 let, 80
mm (length) x 80 mm (width) x 10
Measured in millimeters (thickness). Then, heat these blocks to 600℃, 700℃, and E300℃ in the same way as above.
Thereafter, tensile test pieces and heating test pieces were prepared by cooling and opening processing, and tensile tests and heating tests were performed. Specifically, the heating test was carried out by placing a heated test piece on an alumina boat and charging it into a tubular furnace heated to a predetermined temperature. Specifically, the tensile test was carried out at a tensile rate of 1 mm/min using a 20-ton universal test bench with a strain gauge attached to the parallel portion of the test piece. The tensile test piece had a parallel part diameter of 5 mm, a parallel part length of 20 mm, and a gage distance of 25 mm.

The heating test piece was 40 mm (length) x 30 mm (width) x 8 mm (thickness).

As a comparative example, a compacted body was formed from aluminum alloy powder, and the compacted body was sintered at 580 to 590°C for 20 to 30 minutes to form a sintered body of N0914 with a pore volume percentage of about 30%. This sintered body No. 14 was also subjected to a tensile test and a heating test in the same manner as described above. No, 11～No,
The results of the 14 tests are shown in Table 2. The following can be understood from this test result.

N0513 and N with almost the same pore volume % (about 30%)
Comparing No. 14 with fiber-reinforced No. 13, the tensile strength is 9 kllJ/mm2 and the Young's modulus is 5020 kC/mm2, which are high. This is presumed to be due to the reinforcing effect of the fibers contained in No. 13. From this fact, the porous fiber-reinforced metal composite material of the present invention has improved strength compared to conventional porous metal materials. I know that there is.

L Example 2j In Example 1, the entire block is heated to form pores, but in Example 2, the surface of the block (length 40 mm, width 30 mm, thickness 10 mm) is partially heated. There are some that form pores by heating.

In Example 2, 1) A tungsten electrode is brought close to the surface of the diblock marked ζ■, thereby generating an arc between the block and the electrode, thereby partially heating the metal on the surface of the block above the melting point. It melted, thereby forming pores on the surface. The pore formation conditions were: voltage 14V, current 120△,
This was carried out at a block moving speed of 3 mm/sec and argon gas of 25 liters/min, and the surface of the block was melted to a width of 5 mm, depth i, and 91T1 m. As a result, it was found that the surface of the block contained 43% by volume of pores.

[Brief explanation of the drawing]

FIG. 1 is a side view showing the external shape of block No. 1, which is an example of the present invention, after heating, and FIG. 2 is a side view showing the external shape of block No. 4, which is a comparative example, after heating. It is a diagram. FIG. 3 is a micrograph (100x magnification) showing the structure of block No. 1, which is an example of the present invention.
Figure 4 shows the same micrograph at different magnifications (400 magnification).
times).

Claims (11)

[Claims] (1) It is characterized by being composed of a fiber aggregate, a metal attached to the fiber aggregate, and pores dispersed between some of the fibers constituting the fiber aggregate to which the metal is attached. Porous fiber reinforced metal composite material. (2) The porous fiber-reinforced metal composite material according to claim 1, wherein the volume percent of pores is 5 to 50 volume percent when the total volume is 100 volume percent. (3) The porous fiber-reinforced metal composite material according to claim 1, wherein the pores have a size of 5 to 100 microns. (4) The porous fiber-reinforced metal composite material according to claim 1, wherein the metal is aluminum or an aluminum-based alloy. (5) The fiber aggregate is composed of at least one of alumina fiber, zirconia fiber, silicon nitride fiber, silicon carbide fiber, carbon fiber, alumina silica fiber, boron fiber, and glass fiber. porous fiber-reinforced metal composite material. (6) A first step of forming a block by impregnating and contacting the molten metal with the fiber aggregate and solidifying the metal; and a first step of forming a block by heating the block and melting the metal. A method for manufacturing a porous fiber-reinforced metal composite material, which comprises sequentially carrying out a second step of dispersing and forming pores between some of the fibers constituting the fiber aggregate to which molten metal is attached. (7) The method for producing a porous fiber-reinforced metal composite material according to claim 6, wherein the first step is performed by a molten metal forging method. (8) The second step is performed by heating the entire block or a part of the block.
A method for producing a porous fiber-reinforced metal composite material as described in Section 1. (9) The second step is performed by heating with an arc, a laser beam, or an electron beam.
A method for producing a porous fiber-reinforced metal composite material as described in Section 1. (10) The method for producing a porous fiber-reinforced metal composite material according to claim 6, wherein the metal is aluminum or an aluminum-based alloy. (11) The fiber aggregate is composed of at least one of alumina fiber, zirconia fiber, silicon carbide fiber, silicon nitride fiber, carbon fiber, alumina silica fiber, boron fiber, and glass fiber. A method for producing porous fiber-reinforced metal composite materials.