JPH0257135B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing fiber reinforced metal (FRM).

[Conventional technology]

In recent years, in various mechanical parts and structural materials,
Various composite materials such as metal reinforced with fibers
FRM is used. The reinforcing fibers used in FRM do not easily wet the base metal (matrix), especially aluminum alloys and magnesium alloys, but once they get wet, they react and deteriorate, causing the fibers to deteriorate. For this reason, reinforcing fibers are generally subjected to surface treatment. Examples of the treatment method include CVD method and plating method. In these methods, the surface of the reinforcing fibers is uniformly coated with metal or ceramic in the form of a film, but peeling occurs due to the difference in thermal expansion coefficient between the reinforcing fibers, reducing the effectiveness of the surface treatment, or the coating If the reinforcing fibers are made too thick, there are many problems, such as the reinforcing fibers losing their flexibility and becoming hard and brittle, making the fibers more likely to be damaged. Furthermore, in order to perform surface treatment on each fiber, a complicated device is required, which is disadvantageous in terms of cost. Furthermore, when FRM is manufactured by high-pressure coagulation casting using these reinforcing fibers, the fibers tend to be lopsided and the distribution of fibers tends to be coarse in some areas and dense in others.
For this reason, it is difficult to control the fiber volume fraction (Vf) in FRM, and especially when Vf is small, it is difficult to obtain an FRM in which reinforcing fibers are uniformly dispersed, and the degree of freedom in design, which is an original feature of FRM, is lost. was. In addition, FRM reinforced only with continuous fibers has a large anisotropy in strength; for example, in the carbon continuous fiber reinforced aluminum alloy produced by the high-pressure solidification casting method, the strength in the longitudinal direction of the fibers is over 130 kg/mm ² . However, in the direction perpendicular to that, it is only a few kg/ ^mm2 . Although FRM using only short fibers is isotropic, its strength is generally low.

Furthermore, methods have been proposed in which a combination of continuous fibers or long fibers and short fibers or whiskers is used as reinforcing fibers for composite materials. For example, there is a method of using long fibers on the inside of the FRM member and short fibers on the outside.

[Problem to be solved by the invention]

However, even in the conventional example, the method of using long fibers and short fibers selectively inside and outside the member, for example, requires a complicated manufacturing process. Also, the strength is not sufficient. Furthermore, in the method of mixing long fibers and short fibers during prepreg production, short fibers can be attached to the surface of the long fiber bundle by brushing, etc., but the short fibers can be attached to the surface of each long fiber inside. It is difficult to uniformly adhere the fibers to the fibers, resulting in uneven quality of the resulting fibers.

The present invention is intended to solve the problems in the prior art described above, and its purpose is to:
By uniformly dispersing continuous fibers in the base metal, the fiber volume fraction can be controlled, and by combining continuous fibers, short fibers, whiskers, or powders with different characteristics, it is possible to improve anisotropy, residual stress, and wear resistance. It is an object of the present invention to provide a manufacturing method that can easily obtain fiber-reinforced metal with improved mechanical properties such as wear resistance.

[Means to solve the problem]

That is, the method for manufacturing fiber reinforced metal of the present invention is as follows:
Ceramics such as silicon carbide, silicon nitride, alumina, silica, alumina-silica, zirconia, beryllia, boron carbide, titanium carbide, carbon, metals,
Continuous fibers made of at least one kind selected from heat-resistant substances such as intermetallic compounds, silicon carbide, silicon nitride, alumina, silica,
At least one kind of short fibers, whiskers, or powders made of at least one kind selected from ceramics such as alumina-silica, zirconia, beryllia, boron carbide, and titanium carbide, and heat-resistant substances such as carbon, metals, and intermetallic compounds. by immersing the continuous fibers in a treatment solution in which they are suspended, and applying vibrations to at least the continuous fibers using ultrasonic waves to attach at least one of the short fibers, whiskers, or powder to the continuous fibers, A fibrous body consisting of the continuous fiber and at least one of the short fibers, whiskers, or powder interposed between the fibers or a preformed body consisting of the fibrous body is prepared, and then the fibrous body or the fiber is prepared. The method is characterized in that a preformed body consisting of a body is placed in a cavity of a casting mold, and then a molten base metal is poured into the cavity and then cooled and solidified.

Further, in the method of the present invention, it is preferable to prepare the fibrous body by attaching at least one of short fibers, whiskers, or powder to the surface of each continuous fiber and aligning the continuous fibers.

Continuous fibers include the above-mentioned ceramics, heat-resistant nonmetallic elements such as carbon, boron, or heat-resistant metals, alloys, or intermetallic compounds such as molybdenum, tungsten, steel, stainless steel, CuZn,
Fibers made of materials such as FeAl can be used alone or in combination. Properties such as fiber thickness and cross-sectional shape are selected depending on the application.

Note that among the above short fibers, it is desirable to use metals, intermetallic compounds, alloys, etc. as heat-resistant substances. This is because when applying the fibrous body to a composite material, the fibers do not disappear due to a chemical reaction or the like with the molten or high-temperature metal that becomes the matrix in the compositing step.

Further, it is desirable to use a heat-resistant nonmetallic element as the whisker. This is because, like the short fibers, they have excellent chemical and thermal stability with respect to the matrix metal.

Furthermore, it is desirable to use an intermetallic compound as the powder. This is due to the same reason as in the case of the short fibers and whiskers.

The amount of short fibers, whiskers, or powder interposed between continuous fibers depends on the properties of both fibers and the manufactured FRM.
The volume ratio of continuous fibers, short fibers, whiskers, or powder to continuous fibers is 0.5 to 500% when used for mechanical parts or structural materials, although it varies depending on the application.
It is preferable to set it as approximately.

More preferably, the volume ratio of short fibers, whiskers or powder to continuous fibers is within the range of 1 to 9%. Within this range, the volume fraction of the continuous fibers can be maintained at an appropriate level, making it possible to produce FRMs with high strength in both directions parallel and perpendicular to the fiber axis.

Further, it is preferable that at least one of the short fibers, whiskers, and powder is uniformly adhered to the continuous fibers in the longitudinal direction.

Base metals that can be used in the method of the present invention include aluminum, magnesium, or alloys containing these as main components. The ratio of the base metal and the reinforcing fiber body can be varied depending on the types of the base metal and the reinforcing fiber body, the use of the produced FRM, and the like.

In the method of the present invention, the method for producing the fibrous body is a suspension dipping method from the viewpoint of simplicity and wide applicability. As an example of the suspension dipping method, for example, a continuous fiber wound around a bobbin or a continuous fiber bundle obtained by bundling an appropriate number of continuous fibers is unwound.
At least one of short fibers, whiskers, or powder
Examples include a method in which seeds are immersed in a liquid in which they are suspended, the short fibers, whiskers, or powder are attached to the surface of each of the continuous fibers, the fibers are aligned, and the fibers are wound up again on a bobbin.

When using a continuous fiber bundle, the number of fibers is not particularly limited, but the smaller the number, the better, since short fibers can be evenly attached to each fiber.
Further, the liquid in which the continuous fiber bundle with a large number of fibers is immersed is vibrated by ultrasonic waves to uniformly adhere to each fiber up to the fibers inside the fiber bundle. Ultrasonic waves may be applied to at least the continuous fibers through the outer wall by an ultrasonic adder provided outside the melter containing the liquid,
Alternatively, an appropriate number of ultrasonic transducers, such as ceramic transducers, may be appropriately placed in the liquid and applied directly to the liquid. The ultrasonic irradiation pattern may be continuous or pulsed. The strength, frequency and irradiation time are determined by continuous fibers, short fibers attached to these,
The selection depends on the type of whiskers or powder, the concentration of the deposits in the liquid, the immersion time of the continuous fibers, and other processing conditions, but for example, the frequency is 10 KHz or more.
Approximately 2000KHz is easy to use.

The treatment liquid for suspending the substance to be deposited may be water, but organic solvents such as ethanol, methanol, acetone, and especially ethanol are preferred. In particular, when a sizing agent is applied to the surface of continuous fibers, using an organic solvent such as ethanol will dissolve the sizing agent, making it easier for short fibers to adhere, and the volatility is higher than that of water. This has the advantage of faster drying and improved productivity. or,
Mixtures of the organic solvents mentioned above and water may also be used.

The concentration of deposits in the treatment liquid is not particularly limited, but
If it is too small, uniform adhesion will not be observed on the continuous fibers and the effect will be reduced, and if it is too large, the amount of adhesion will be larger than necessary. When treating a continuous fiber bundle of yarn, the silicon carbide whisker concentration is preferably about 0.5 g/-30 g/.

When a bundle consisting of a large number of continuous fibers is immersed in a treatment liquid, it is desirable to spread the fiber bundle by applying a blower to the fiber bundle before dipping. It is preferable to adjust the discharge flow rate of the blower depending on the number of fibers and the intensity of ultrasonic vibration to the processing liquid. A blower is not necessarily required when the number of fibers is small or when sufficiently strong ultrasonic vibrations are applied to the processing liquid.

The number of processing tanks containing processing liquid may be one, but
When using a plurality of deposits, a plurality of treatment tanks in which each deposit is suspended may be used. The immersion time can be adjusted by a conventional method such as using a movable roll. If necessary, the treated continuous fiber bundle is dried using a drying oven, an infrared dryer, a hot air dryer, etc. before winding it onto a bobbin.

Next, the fibrous body produced by the above method is cut into an appropriate length, or the fibrous body is preliminarily cut into a desired length.
A preformed body with a size and shape appropriate for the FRM product is placed in the cavity of a casting mold. A combination of different types of fibers may be used.

This preform is preheated to a predetermined temperature, for example, 700 to 800°C, and then a molten base metal heated to approximately the same temperature as the preform is poured into the cavity. Next, this molten metal is heated to a predetermined pressure, for example 400Kg/cm ² to 900Kg/cm 2 .
The base metal is solidified by cooling to room temperature while applying pressure to Kg/cm ² . Furthermore, if necessary, the obtained product may be subjected to surface treatment or machining.

Commercially available products can be used as they are for the continuous fibers used in the present invention, short fibers, whiskers or powders, and base metals to be attached to the surface of the continuous fibers.

FIG. 1 shows an example of fiber-reinforced metal manufactured by the method of the present invention. In the figure, 13 is a whisker (or short fiber), 14 is a continuous fiber, and 15 is a base metal.The whisker 13 is placed between the continuous fibers 14, and the remaining space is filled with the base metal 15. have By selecting the type and property of the whiskers 13, the conditions at the time of attachment, or the filling conditions of the continuous fibers 14 to which the whiskers 13 are attached, the whiskers 13 can be uniformly arranged in the spaces between the whiskers 13, or the continuous fibers 14 can be arranged uniformly.
They can also be placed centrally around the Although the base metal 15 is strengthened by the whiskers 13, it is also possible to add a predetermined amount of a desired element to further strengthen it. In this case, the alloy composition of the base material is not limited. By arranging the whiskers 13 between the continuous fibers 14, there is an advantage that contact between the continuous fibers 14 can be prevented, and by changing the amount of the whiskers 13, the continuous fibers 1
The volume ratio of 4 can be controlled.

Furthermore, due to the presence of whiskers 13, the continuous fiber 1
Since the strength in the direction perpendicular to 4 is improved, the anisotropy of the fiber-reinforced metal is reduced. The use of whiskers 13 having a coefficient of thermal expansion smaller than that of the base metal 15 has the effect of reducing thermal residual stress.

That is, since the thermal expansion coefficient of the base metal 15 is larger than that of the continuous fibers 14, the continuous fibers 14 and the base metal 15 are
Misalignment or peeling occurs between the two. However, if the thermal expansion coefficient of the whiskers 13 interposed between the continuous fibers 14 is smaller than that of the base metal 15, the whiskers 13 act as a buffer for thermal expansion at the interface between the continuous fibers 14 and the base metal 15. As a result, the difference in coefficient of thermal expansion between the continuous fibers 14 and the base metal 15 is reduced. Therefore, thermal residual stress is reduced. Furthermore, by using the whisker 13 having wear resistance, a fiber-reinforced metal with excellent wear resistance can be obtained.

〔Example〕

The invention will be explained in further detail in the following examples. Note that the present invention is not limited to the following examples.

Example 1 FIG. 2 shows an example of a manufacturing apparatus for a reinforcing fiber body used in the present invention. Silicon carbide whiskers (average diameter approx.
0.2μm, average length about 100μm) 5g with ethanol
After putting it into the processing tank 1 containing 1000 c.c., ultrasonic vibration was applied by the ultrasonic adder 2 to suspend it, and the processing liquid 3 was prepared. Toray Industries, Inc. M40 carbon fiber bundle (fiber diameter 7-8 μm, number of fibers 6000, with sizing agent)
4 is unwound from the bobbin and passed through the processing liquid 3 while being immersed in the processing liquid 3 while adjusting the immersion time by the movable rollers 6 and 7 so that the immersion time is about 15 seconds while the ultrasonic waves are still being applied. After being pressed by a roller, it was wound up again onto the bobbin 10 and dried at room temperature in the atmosphere.

In the figure, 11 is a blower, 12 is a drying oven,
Use as needed.

The fibers, which were black before the treatment, took on a light gray color after the treatment, and as a result of electron microscopy (SEM) observation, it was observed that whiskers 13 were attached to the continuous fibers 14, as shown in FIG. In addition, as a result of weighing after treatment, it was found that 0.15 g of whiskers (volume ratio to continuous fibers: 2.3%) was attached per 10 m of fiber bundle length.

Next, as shown in FIG. 4A, the fibrous body 16 produced by the above method was cut into a length of 150 mm.
The final bundle was inserted into the steel pipe 17. Then B
As shown in C, a steel pipe 17 is preheated to 760°C in nitrogen gas by a heater 18, and then placed in a casting mold 19 as shown in C, and molten pure aluminum 20 heated to 760°C is injected. Punch 21
Pressure was applied at 500 Kg/cm ² for 60 seconds using a

FIG. 1 shows a cross-sectional view of the metal structure of the continuous fibers of the obtained fiber-reinforced metal in a direction perpendicular to the fiber axis. As is clear from the figure, the continuous fibers 14 were uniformly dispersed in the base metal 15, and almost no mutual contact was observed. Furthermore, the presence of a large number of whiskers 13 was confirmed between the fibers.

Example 2 Silicon carbide whiskers (same as those used in Example 1) and silicon nitride whiskers (average diameter approximately 0.3μ
m, average length approximately 200 μm) was put into the treatment tank 1 containing 1000 c.c. of ethanol as shown in Fig. 2, and then suspended by applying ultrasonic vibration with the ultrasonic adder 2, and then treated. Solution 3 was prepared. A continuous fiber body with whiskers attached was produced in the same manner as in Example 1 except that the same carbon fiber bundle as in Example 1 was used and the immersion time was 20 seconds. g (volume ratio to continuous fibers: 3.1%) of whiskers were attached.

Next, as shown in FIG. 4A, the fibrous body 16 produced by the above method was cut into lengths of 150 mm, bundled into 100 pieces, and inserted into a steel pipe 17. Then, B
As shown in the figure, the steel pipe 17 is placed in nitrogen gas.
Preheat to 720℃, and then as shown in C, cast mold 1.
9, inject a pure magnesium molten metal 20 heated to 720℃, and use a punch 21 to
Pressure was applied at Kg/cm ² for 60 seconds.

The cross-sectional view of the metal structure of the obtained fiber-reinforced metal in the direction perpendicular to the fiber axis of the continuous fibers is similar to that shown in Figure 1, and a large number of whiskers are observed between the fibers, indicating that the continuous fibers are in contact with each other. were significantly less.

Bending strength measurement test: Using the same method as in Example 1, fiber-reinforced metal was produced by the method of the present invention with different whisker attachment conditions, and a bending test was performed in the direction perpendicular to the fiber axis of the continuous fibers. Ivy. The results are shown in Figure 5.
The fiber-reinforced metal produced by the method of the present invention using continuous fibers with whiskers attached has approximately 2 to 5 times higher bending strength than conventional fiber-reinforced metal that does not use whiskers, demonstrating a clear hybrid effect. It appears in Furthermore, the effect of applying ultrasonic waves and the effect of using ethanol as a treatment liquid are also clear, and it can be seen that large bending strength can be obtained by appropriately selecting the conditions during deposition.

[Effects of the Invention] As described above, the method for producing a fiber-reinforced metal of the present invention can produce a fiber body made of continuous fibers and short fibers, whiskers, or powder interposed between the continuous fibers, or a fiber body made from the fibers. This is a method in which a preformed body is prepared, the fibrous body or a preformed body made of the fibrous body is placed in a cavity of a casting mold, and then molten metal of the base metal is poured into the mold and then cooled and solidified. Therefore, it is simple and has high production efficiency. Furthermore, in addition to applying ultrasonic waves to the treatment liquid during the production of reinforced fiber bodies, various modifications such as adding ultrasonic waves to the molten metal of the base metal and using organic solvents as the treatment liquid are also carried out. This method allows the amount of adhesion to be controlled, making it possible to manufacture various types of reinforcing fiber bodies in the same equipment, and preforming various shapes of preforms using these fiber bodies. Therefore, fiber-reinforced metals with various properties can be easily obtained.

[Brief explanation of the drawing]

FIG. 1 is an optical micrograph of the metal structure of an example of fiber-reinforced metal manufactured by the method of the present invention, FIG. 2 is a schematic diagram of an example of an apparatus for manufacturing a reinforced fiber body in the manufacturing method of the present invention, and FIG. FIG. 2 is an electron micrograph showing the shape of the fibers in the fibrous body produced using the apparatus shown in FIG. 5 are graphs showing the whisker adhesion conditions and bending strength of the fiber-reinforced metal manufactured by the method of the present invention and the bending strength of the conventional fiber-reinforced metal. In the figure, 1... treatment tank, 2... ultrasonic adder, 3
...Treatment liquid, 4...Carbon fiber bundle, 5,10...Bobbin, 6,7...Movable roller, 8,9...Pressure roller, 11...Blower, 12...Drying oven, 13...
... Whisker, 14 ... Continuous fiber, 15 ... Base metal, 16 ... Fibrous body, 17 ... Pipe, 18 ...
Heater, 19... Casting mold, 20... Molten metal, 21...
…punch.

Claims (1)

[Claims] 1 Silicon carbide, silicon nitride, alumina, silica, alumina-silica, zirconia, beryllia,
Ceramics such as boron carbide and titanium carbide, carbon,
Continuous fibers made of at least one kind selected from heat-resistant substances such as metals and intermetallic compounds, silicon carbide, silicon nitride, alumina, silica,
At least one kind of short fibers, whiskers, or powders made of at least one kind selected from ceramics such as alumina-silica, zirconia, beryllia, boron carbide, and titanium carbide, and heat-resistant substances such as carbon, metals, and intermetallic compounds. by immersing the continuous fibers in a treatment solution in which they are suspended, and applying vibrations to at least the continuous fibers using ultrasonic waves to attach at least one of the short fibers, whiskers, or powder to the continuous fibers, A fibrous body comprising the continuous fibers and at least one of the short fibers, whiskers, or powder interposed between the fibers or a preformed body consisting of the fibrous bodies is prepared, and then the fibrous bodies or the fibers are prepared. 1. A method for producing a fiber-reinforced metal, which comprises placing a preformed body consisting of a preform in a cavity of a casting mold, and then injecting a molten base metal into the cavity, followed by cooling and solidifying. 2. The fiber-reinforced metal according to claim 1, characterized in that the fibrous body is prepared by attaching at least one of short fibers, whiskers, or powder to the surface of each continuous fiber and aligning the fibers. Production method.