JPH01180928A - Manufacture of metal-based composite material - Google Patents

Abstract

PURPOSE:To improve the quality of the title material at the time of the forming stage of a preform to which the molten metal of matrix metal is infiltrated by spraying specific amounts of water or others a reinforcing material in a form of whisker or inorganic short fiber. CONSTITUTION:The reinforcing material consisting of whisker or inorganic short fiber is sprayed with water or organic solvent, is pressurized and is dried to form a preform. At this time, the water or organic solvent contg. the amounts equivalent to the clearance volume in the reinforcing material in the compressive state at time of the above pressure forming is used. The molten metal of the matrix metal is then pressure-infiltrated to the obtd. preform, by which the metal-based composite material can be obtd.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a method for manufacturing a metal matrix composite material by impregnating a preform with a matrix metal molten metal.
In particular, the present invention relates to a method of manufacturing a metal matrix composite material with an improved preform forming process.

(Prior art) In recent years, for example, alumina (A, f203), silicon carbide (
S i C) fibers or ceramic materials such as whiskers are used as reinforcing materials, and aluminum (Δ1), magnesium (
Metal matrix composite materials with a matrix of light alloys such as Mg) alloys have been developed, and in addition to being lightweight, having high strength and high modulus of elasticity, they also have excellent heat resistance and abrasion resistance. It is expected to be applied to aircraft, automobiles, FA robot parts, etc.

Various methods have been considered for manufacturing this metal matrix composite material, among which the infiltration method, in which a preform is impregnated with a matrix metal molten metal, is a manufacturing method suitable for mass production.

The manufacturing method of metal matrix composite material by infiltration and removal begins with the preparation of a preform (m dark blue preform) with a shape close to the actual product using reinforcing material.
After sufficiently drying, insert into the mold, preheat with a heater, inject molten matrix metal, pressurize the molten metal with a piston, impregnate the preform, and pressurize and solidify in the mold. This is a method for obtaining a metal matrix composite material.

This infiltration method offers various advantages over other manufacturing methods, such as direct addition of fibers into molten matrix metal. For example, with the direct addition method, a reinforcing material with a fiber volume percentage of only about 5% can be obtained, whereas with the infiltration method, it is possible to obtain a reinforcing material with a fiber volume percentage of about 40%. In addition, the contact time between the fibers and the molten matrix metal is short, and there is little fiber deterioration due to reaction with the molten metal.

By the way, the preform molding method is disclosed in Japanese Unexamined Patent Application Publication No. 1986-
As disclosed in Japanese Patent No. 121196, a slurry in which a reinforcing material is suspended in water or an organic solvent is heated under reduced pressure.
10 to 20% by weight of sea urchin reinforced fibers using the pressure filtration method, J disclosed in JP-A No. 61-147824;
A method of spraying water or an organic solvent and then press-molding in a mold is known.

(Problems to be Solved by the Invention) However, in the former method of filtering and covering the reinforcing material suspension slurry, a large amount of filtration time is required when the #A string volume ratio becomes high, and there is also a problem that residual leakage may occur inside the preform during molding. This increases the amount of water or organic solvent, leading to problems such as a decrease in the strength of the preform, a prolonged drying process, or the occurrence of cracks during drying, resulting in low production efficiency of the preform.

On the other hand, the method of spraying 10 to 20% by weight of water or organic solvent on reinforced H and then pressure molding can shorten the molding time and shorten the drying time compared to the former method. Although it can prevent cracks from occurring during drying,
The difference in fiber volume percentage between the area near the pressurized surface and the center of the obtained preform becomes large, making it impossible to create a uniform preform, and in particular, it is difficult to obtain a preform with a low fiber volume percentage. (There were problems in that the quality of the metal matrix composite material deteriorated and the range of use was restricted.

The present invention has been made in view of the above circumstances, and it is possible to easily obtain a preform with a low fiber volume percentage, and with a uniform fiber volume percentage as a whole, without the occurrence of cracks.
The purpose of this invention is to provide a method for manufacturing metal matrix composite materials that can improve the quality of metal matrix composite materials and expand the range of their use.

(Structure of the Invention) (Means and Effects for Solving the Problems) In order to achieve the above-mentioned object, the present invention provides a method of spraying water or an organic solvent onto a reinforcing material made of inorganic fibers or whiskers. In a method of manufacturing a metal matrix composite material by forming a preform by pressurizing and drying and impregnating the preform with a molten matrix metal under pressure, the reinforcing material is added to the reinforcing material during the formation of the glyph 4-me. the amount of water or organic solvent to
It is characterized in that the amount is set to correspond to the volume of the gap in the reinforcing material under the compressed state when the preform is pressurized.

Such a method of the present invention was made based on the following findings. That is, the inventors have been conducting research on the causes of cracks occurring when the amount of water or organic solvent added to the reinforcing material during preform formation is small. As a result, the following was clarified as a function of water or organic solvent sprayed into the reinforcing material during the preform compression molding process.

(1) Water or an organic solvent serves as a pressure medium for transmitting the pressure applied to the press surface of the preform to the inside of the preform during compression molding.

(2) Water or organic solvent reduces the friction at the contact points between the reinforcing materials or between the reinforcing materials and the mold during preform compression molding, thereby smoothing the movement of the reinforcing materials during preform contraction. , the deflection of the reinforcing moon due to pressurization of the prism 71-m is reduced. Therefore, the amount of springback that occurs when the preform is depressurized is inversely proportional to the amount of water or organic solvent added, and when the amount added is small, the amount of springback is large and becomes non-uniform. If the amount of springback is large, defects such as cracks will occur on the surface of the preform.

Figure 1 is an enlarged schematic diagram of the inside of the preform to explain the function of water or organic solvent, and Figure (a) shows the case where the amount of water or organic solvent added is small. , and (b) in the same figure shows the case where the amount added is large.

As shown in these figures, reinforcing materials such as fibers and whiskers 1
Water or an organic solvent (hereinafter referred to as solvent) 2 is present in the gap between them.

When the amount of solvent 2 added is small, as shown in Figure 1(a), the solvent 2 is distributed in a scattered manner in the gaps between the reinforcing materials 1 due to surface tension, and there are many particles inside the preform. A void 3 exists. Therefore, the function of the solvent 2 as a pressure medium cannot be fully exhibited, and the pressurizing force during compression is not sufficiently transmitted to the inside of the preform. As a result, the fiber volume fraction in the pressing direction of the obtained preform is large in the vicinity of the pressing surface, and conversely becomes significantly small in the central portion. Furthermore, the lubrication between the reinforcing materials 1 or between the reinforcing materials and the mold becomes insufficient, and the amount of springback becomes large and uneven, which causes cracks to occur during pressure removal, making it impossible to form a good preform.

On the other hand, when the amount of solvent 2 added is large, Figure 1 (
As shown in b), the solvent 2 is uniformly and sufficiently dispersed between the reinforcing materials 1. Thereby, the pressure acting on the preform surface is sufficiently transmitted to the inside of the preform by the solvent 2 between the reinforcing materials 1, and the distribution of the fiber volume fraction can be made uniform by equalizing the pressure. In addition, the friction at the interface between the reinforcing materials 1 and the contact interface between the reinforcing material and the mold is reduced, reducing the amount of springback and making it more uniform, which prevents damage to the preform and the occurrence of defects when pressure is removed. 1: To be done.

Next, the optimum amount of solvent to be added will be considered. As the fiber volume percentage increases, the proportion of reinforcing material in the preform increases, and a large amount of springback occurs when the pressure is removed, which increases the compression ratio during pressure molding of the preform. I for retention! The gap between the i-fibers decreases as the fiber volume fraction increases.

Therefore, the optimal range for the amount of solvent added is based on the amount of springback when the pressure is removed, and is approximately equal to the volume of the part other than the fiber volume when the preform is compressed to an amount higher than the desired preform height, that is, the volume of the space where water enters. It is desirable to set them within the same range. As a result, during pressurization, the spaces between the fibers are almost filled with water, and the pressure applied to the preform is transmitted very well.

Note that if the amount of solvent added is too large, the reinforcing material will aggregate and become granular during solvent spraying, making it impossible to uniformly and finely disperse the reinforcing material.

Specifically, the amount of solvent added to the reinforcing material 1 is determined by the fiber volume on a graph with the fiber volume ratio of the preform on the horizontal axis and the solvent addition rate on the vertical axis, as shown in Figure 2. rate is 15
%, the addition rate is in the range of 100 to 130%, and the addition rate is in the range of 40 to 70% when the fiber volume percentage is 30%. The addition rate is preferably within the range of 100 to 130% when the fiber volume percentage is 15%, and 40 to 60% when the fiber volume percentage is 30% (shaded area). .

If the preform molding is performed with the solvent addition rate set within this range, the solvent 2 will be sufficiently present in the gaps between the reinforcing materials 1, as shown in Figure 1(b), and the preform will be formed in the pressure molding process. The fiber volume ratio between the pressurized surface and the inside is about 10%. In other words, the distribution of the fiber volume percentage within the preform becomes uniform, and as a result, even preforms with a low fiber volume percentage or high height can be molded into high quality products without cracking. In turn, it will be possible to improve the quality and diversify metal matrix composite material products.

(Example) An example of the present invention will be described below with reference to FIGS. 3 to 5.

First, the preform molding process will be explained with reference to FIGS. 3(a) to 3(d).

After weighing an arbitrary amount of the reinforcing material 1, the solvent 2 is sprayed while stirring (FIG. 4(a)). At this time, the amount of the solvent 2 to be sprayed is set depending on the fiber volume ratio of the preform to be molded, the material of the reinforcing material 1, and the aspect ratio.

Next, in order to uniformly and finely distribute the reinforcing material 1, it is covered with a sieve 5 having a predetermined mesh to remove aggregated lump-like reinforcing material (FIG. 2(b)).

Then, the homogenized wetted body 1a of the reinforcing material 1 is placed in a mold 6, and pressurized to a predetermined usage level with a piston 7.8 (see FIG.
C)). This pressurized state is maintained until the displacement of the piston 7.8 becomes constant, and then the mold is released and dried to obtain a preform 9 (FIG. 4(d)).

Next, the infiltrated culm will be explained with reference to FIGS. 4(a) to 4(d).

After sufficiently drying the preform 9 (Fig. 9(a)), which has a shape close to the actual product obtained from the above-mentioned Briform molded T culm,
Insert it into the mold 10 and preheat it with the heater 11 (see the same figure).
b)). After this, molten metal 1 to 71 is placed in the mold 10.
2 is injected, the molten metal is pressurized by the piston 13, and the preform 9 is impregnated under pressure (the shaded area 9a indicates the initial impregnation area).The solidified product in the mold 11 is then released, By cutting and removing the excess 71 helix metal parts, a metal matrix composite material 14 of matrix metal and reinforcing material is obtained.
1q ((d) in the same figure).

The inorganic short fibers or whiskers as the reinforcing material 1 include carbon (C), silicon carbide (SiC), and silicon nitride.
N4), alumina (A1203), titanium boride (Ti
B2), or nonolium ditanate (K2O・r)T
i 02 ) 'F;- can be used alone, in mixtures, or in various mixed materials mainly composed of these.

In addition, the 71 helix metal is aluminum (,'l
), magnesium (Mg) or these.

Alloys, other light metals or alloys are applicable.

<Example 1> SiC whiskers (length 10 to 50 μm, diameter 0.05 to 0.2 μm) were used as the reinforcing material 1, and water was sprayed thereon as a solvent at an addition rate of 100%, as shown in Fig. 2. height 10 in the way
A cylindrical preform with a diameter of 0 an and a diameter of 100# was prepared. A 50 mesh sieve was used, the pressing force was set at 10 kg/ci, and the fiber volume fraction of the brief Δ-me was set at -C 15% as a whole.

As a result, as shown in Fig. 5, we investigated the fiber volume percentages at several locations ■ to ■ from one end surface (one pressure surface) to the other end surface (the other pressure surface) of the preform. The fiber volume percentage at points ■ and ■ closest to the pressure surface is approximately 15.5%,
The fiber volume percentage in the center part (■) was approximately 14.5%, and the difference therebetween was less than 10%.

The crack occurrence rate in this case was 5%, as shown in Table 1 below, and it was confirmed that a good preform with almost no cracks could be formed.

Using such a preform, a metal matrix composite material was manufactured using A6061Δ1 alloy as a matrix metal by the pressure infiltration method shown in Figure 3, and a high-quality product with uniform reinforcement was obtained. I was given 1q.

<Example 2> A preform with a total fiber volume percentage of 15% was produced in the same manner as in Example 1 except that the water addition rate was 130%.

In this case, as shown in FIG. 5, the I string volume percentage at the point closest to the pressurizing surface of the preform is about 15.5%, as described above.
Each center portion was about 14.5%, and the difference was less than 10%.

As shown in Table 1 below, the crack occurrence rate was 5%, and the same effect as in Example 1 was observed in this case as well.

<Comparative Example 1> A preform having a total fiber volume ratio of 15% was prepared using substantially the same conditions as in Example 1 except that the water addition rate was 80%.

In this case, as shown in FIG. 5, the fiber volume percentage at the point closest to the pressurizing surface of the preform was high at about 18%, and that at the center was low at about 11%, the difference being over 40%.

The crack occurrence rate was as high as 80% as shown in Table 1 below, indicating a high crack occurrence rate. When a metal matrix composite material is manufactured using such a preform, the portion corresponding to the crack in the preform becomes only the matrix metal, and the effect of fiber reinforcement is reduced.

<Comparative Example 2> SIC whiskers similar to those in Example 1 were sprayed with water at an addition rate of 140%. In this case, the amount of SIC whisker aggregates generated is 95% or more, making filtration difficult and reducing practicality.

<Example 3> A brifform having a fiber volume percentage of 25% was prepared in substantially the same manner as in Example 1 except that the water addition rate was 50%.

In this case, as shown in FIG. 5, the fiber volume percentage at the point closest to the pressurizing surface of the preform was about 26%, and that at the center was about 24%, with a difference of less than 10%.

The crack occurrence rate was 10% as shown in Table 1 below, and the same effects as in each of the aforementioned Examples were observed in this case as well.

<Example 4> A preform having a fiber volume percentage of 25% was prepared in substantially the same manner as in Example 1 except that the water addition rate was 80%.

In this case, as shown in Figure 5, the m string volume fraction at the point closest to the pressure surface of the preform was approximately 26%, and that at the center was approximately 24%, with a difference of less than 10%. .

The crack occurrence rate was 5% as shown in Table 1 below, and the same effects as in the above-mentioned Examples were observed in this case as well.

<Comparative Example 3> A preform having a total fiber volume percentage of 25% was produced using substantially the same conditions as in Example 1 except that the water addition rate was 40%.

In this case, as shown in Figure 5, the fiber volume percentage at the point closest to the pressurized surface of the preform was high at about 32%, and that at the center was low at about 18%, the difference being over 50%. .

The crack occurrence rate was as high as 75% as shown in Table 1 below, indicating a high crack occurrence rate. When a metal matrix composite material is manufactured using such a preform, the portion corresponding to the crack in the preform becomes only the matrix metal, and the effect of fiber reinforcement is reduced.

<Comparative Example 4> Water was sprayed onto the same SiC whiskers as in Example 1 at an addition rate of 90%. In this case, the SIC whiskers become clay-like during pressure molding, making it difficult to release from the mold, and after release, the preform has high fluidity and deforms.

<Example 5> A preform having a fiber volume percentage of 30% was prepared using substantially the same conditions as in Example 1 except that the water addition rate was 40%.

In this case, as shown in FIG. 5, the fiber volume percentage at the point closest to the pressurized surface of the preform was about 32%, and that at the center was about 28%, with a difference of less than 10%.

The crack occurrence rate was 5% as shown in Table 1 below, and the same effects as in the above-mentioned Examples were observed in this case as well.

<Example 6> A preform having a fiber volume percentage of 30% was prepared in substantially the same manner as in Example 1 except that the water addition rate was 60%.

In this case, as shown in FIG. 5, the fiber volume percentage at the point closest to the pressurized surface of the preform was about 32%, and that at the center was about 28%, with a difference of less than 10%.

The crack occurrence rate was 5% as shown in Table 1 below, and the same effects as in the above-mentioned Examples were observed in this case as well.

<Comparative Example 5> A preform having a total fiber volume percentage of 30% was prepared using substantially the same conditions as in Example 1 except that the water addition rate was 30%.

In this case, as shown in FIG.
The product fraction of the X&fibre at the point closest to the pressure surface was high at about 37%, and that at the center was low at about 26%, with a difference of more than 35%.

The crack occurrence rate was as high as 95% as shown in Table 1 below, indicating a high crack occurrence rate. When a metal matrix composite material is manufactured using such a preform, the portion corresponding to the crack in the preform becomes only the matrix metal, and the effect of fiber reinforcement is reduced.

<Comparative Example 6> Water was sprayed onto the same SiC whiskers as in Example 1 at an addition rate of 70%. In this case, SiC Wisno J becomes clay-like during pressure molding, making it difficult to release from the mold, and after release, the preform has high fluidity and deforms.

According to Examples 1 to 6 shown in Table 1 and above, the difference in the fiber volume percentage of the preforms is within 10%, and the conventional method of adding only about 20% of the Il miscellaneous weight (Comparative Example 1゜3.5 ), the amount of solvent that is the pressure transmission medium is optimized, the fiber volume ratio of the preform is made uniform, and it is possible to obtain high quality preforms with a higher height and a smaller fiber volume ratio. , it is possible to eliminate problems such as a decrease in strength at the center of the preform and breakage during demolding, which have been observed in the past. Further, no condensation or deformation of the reinforcing material occurs as seen in Comparative Example 2.4.6.

In Examples 1 to 6, the reinforcing material was SiC whiskers, the matrix metal was alloyed with Δ, and the solvent was water. However, the reinforcing material was other inorganic fibers or whiskers, and the matrix metal was MQ. Even when an alloy is used or an organic solvent is used as the reinforcing material, substantially the same effects as in the above embodiment can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, the fiber volume in the preform is increased compared to the conventional method by spraying the optimum water or organic solvent, taking into consideration the voids in advance when forming the preform under pressure. As a result, preforms with a low fiber volume ratio and tall preforms that could not be molded using conventional methods can be formed without cracking, resulting in high quality and a wide range of applications. The effect is that a metal matrix composite material can be manufactured.

[Brief explanation of the drawing]

Figures 1 (a) and (b) are schematic diagrams of the inside of the preform for detailed explanation of the present invention, Figure 2 is a graph showing the addition ω of water or organic solvent according to the present invention, and Figure 3 (a). )～(
d> and FIGS. 4(a) to 4(d) are process diagrams showing one embodiment of the present invention, and FIG. 5 is a graph showing the effects of the embodiment. 1... Reinforcing material, 2... Solvent (water, organic solvent), 9.
··preform. Figure 2 ■■■■■ Enactment device Figure 5 (a) (b) Figure 3, i. Figure 4

Claims (1)

[Claims] 1. A preform is formed by spraying water or an organic solvent onto a reinforcing material made of inorganic short fibers or whiskers, pressurizing and drying the same, and pressurizing a molten matrix metal onto this preform. In the method of manufacturing a metal matrix composite material by impregnation, the amount of water or organic solvent added to the reinforcing material during the preform formation is adjusted to reduce the amount of water or organic solvent added to the reinforcing material to reduce the gap in the reinforcing material under the compressed state during the pressurized forming of the preform. A method for manufacturing a metal matrix composite material, characterized in that the amount is set to correspond to the volume. 2. The amount of water or organic solvent added is determined on a graph where the horizontal axis is the fiber volume fraction of the preform and the vertical axis is the addition rate of water or organic solvent. When the fiber volume fraction is 15%, the addition rate is 100%. The metal matrix composite material according to claim 1, wherein the metal matrix composite material is set within a band-shaped region and an extension region thereof, which are accommodated in a range of 130% to 130% and a range of 40 to 70% when the fiber volume percentage is 30%. manufacturing method.