JP2967840B2 - Method for producing particle-dispersed composite material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a particle-dispersed composite material of a matrix metal and powder particles.

[0002]

2. Description of the Related Art Particle-dispersed composite materials have recently attracted attention because of their excellent wear resistance as sliding members of machines.
In particular, a material having a low volume ratio of the powder particles to the matrix metal as a reinforcing material is required. However,
Conventionally, in order to produce a composite material having such a low volume ratio, a method of mixing powder particles into a molten metal of a matrix metal, mechanically stirring the mixture, pouring the mixture into a mold, and solidifying the mixture. Was taken.

[0003]

However, in the above-described conventional method, a high-temperature and long-time treatment is required, and especially when the volume ratio is small, the reinforcing material tends to be unevenly distributed. However, there is a problem that it is difficult to obtain a homogeneous composite material.

[0004]

In order to solve the above-mentioned problems, according to the present invention, a mold having a volume of 5 to 10 times is required.
% Of the powder particles having a volume equivalent to the volume of the matrix metal, the molten metal of the matrix metal is injected into the mold to disperse the powder particles in the matrix metal, and then solidified to obtain a low volume fraction particle dispersion type. Manufacture composite materials.

In the present invention, powder particles having a volume corresponding to 5 to 10% of the volume of a mold are inserted into a closed mold, and a molten metal of a matrix metal is injected into the mold to form a matrix. After dispersing the powder particles in the metal, the mixture is unidirectionally solidified from the bottom of the mold while applying a high pressure to produce a low volume fraction particle-dispersed composite material.

[0006]

As described above, in the present invention, powder particles having a volume corresponding to 5 to 10% of the volume of the mold are inserted into the mold, and the molten metal of the matrix metal is injected into the mold. The powder force can be uniformly dispersed in the matrix metal by the spraying force.

Further, after dispersing powder particles having a volume corresponding to 5 to 10% of the mold volume in the molten matrix metal, the molten metal is unidirectionally solidified from the bottom of the mold while applying high pressure. Before the powder particles sink to the bottom of the matrix metal melt, the melt can be solidified from the bottom.

Therefore, according to the present invention, it is possible to easily produce a low volume fraction particle-dispersed composite material in a short time, which has conventionally been considered difficult to produce. A composite material having excellent heat resistance can be obtained.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, the volume ratio to the matrix metal is 5
%, Alumina particles were uniformly dispersed in aluminum. The alumina particles used in this experiment were pure alumina powder manufactured by Meller, and had a particle size of 3.0.
μm one was used. As the matrix metal, industrial pure aluminum (99.7%) was used. Note that whiskers may be used as the powder particles used in the present invention.

FIG. 1 shows an integrated mold 1 used in an experiment. This mold 1 is formed by cutting a mild steel material having a diameter of 70 mm and a length of 110 mm with a lathe and forming a composite having a diameter of 32 mm and a length of 50 mm at a lower portion. There is a part 1a,
In addition, an injection part 1b for pouring a matrix melt having a diameter of 50 mm and a length of 45 mm is formed at the upper part. A disc-shaped jet plate 2 having an outer diameter of 50 mm and a hole 2a having a diameter of D mm at the center is provided between the upper injection part 1b and the lower composite part 1a. The value of the diameter D of the hole 2a is changed in each experiment. This hole 2a is for ejecting the molten metal. After casting, the inside of the mold 1 is coated with dicrine so that the sample can be easily taken out of the mold 1. In the figure, reference numerals 1c and 1d denote thermocouple insertion holes.

FIG. 2 and FIG. 3 schematically show the apparatus used in the experiment, and the same reference numerals as those described above denote the same components. That is, in the figure, 1 is a mold, 2 is a jet plate,
Reference numeral 3 denotes a fixed pedestal, and 4 denotes a water jacket mounted on the fixed pedestal 3 via a cushion 5 such as a coil spring. Cooling water enters as shown by an arrow A and is discharged as shown by an arrow B. I have.

Reference numeral 6 denotes a lift frame which surrounds the water jacket 4 and is elastically supported so as to be able to move up and down within a certain range. The mold 1 is mounted on the upper surface of the lift frame 6. A heating furnace 7 is mounted on the lifting pedestal 6 via the marinite 8 so as to surround the mold 1.

Reference numeral 9 denotes a graphite lid that is press-fitted into the injection portion 1b of the mold 1, and reference numeral 10 denotes a ram of a press device for pressing the graphite lid 9 via an insulating plate 11 such as asbestos. T ₁ and T ₂ are thermocouples inserted into the holes 1 c and 1 d provided in the mold 1.

In order to produce a composite material using the above-described apparatus, as shown in FIG. 3, the above-mentioned pure alumina powder 12 manufactured by Meller Co., Ltd. After that, a molten metal 13 of industrial pure aluminum is injected as a matrix metal into the injection portion 1b on the jet plate 2 and then sealed with a graphite lid 9 from above. Press down with ram 10.

Thus, the molten metal 13 is jetted from the holes 2a (small holes of 0.5 to 1.5 mmφ) provided in the jet plate 2. The powder particles 12 are melted by the jet flow of the melt 13.
It mixes well with the powder 13 so that the powder particles 12 are distributed almost uniformly in the matrix metal melt 13. Therefore, according to the present invention, the powder particles are almost uniformly distributed in the matrix metal.
A composite material with 12 distributions is obtained.

In the apparatus shown in FIGS. 2 and 3, when the ram 10 is pushed down, the elevating pedestal 6 is lowered via the mold 1, so that the bottom surface of the mold 1 comes into contact with the upper surface of the water jacket 4. Therefore, the molten metal 13 in the mold 1 cools rapidly from the bottom of the composite portion 1a and solidifies in one direction upward from below. That is, the powder particles 12 serve as a matrix metal melt.
Since the molten metal 13 can be solidified from the bottom before sinking to the bottom of the 13, the composite material in which the powder particles are uniformly distributed in the matrix metal can be obtained according to the present invention.

Next, a specific example of an experiment will be described. The alumina particles 12 which have been sufficiently dried at 423 K in advance are directly put into the composite portion 1 a below the mold 1, and the mold 1 is set in the heating furnace 7. At this time, a marinite partition plate 14 (FIG. 2) is used to keep heat between the mold 1 and the water jacket 4.
See). The water in the water jacket 4 is always kept flowing during the experiment.

The mold 1 is heated to a predetermined temperature. When the temperature reaches the predetermined temperature, the partition plate 14 is peeled off, and the molten metal 13 of the matrix metal, which has been heated to a predetermined temperature in another furnace, is placed on top of the mold 1. Of the graphite lid 9 having a thickness of 40 mm.
Put on top. The graphite lid 9 is composed of the molten metal 13 and the graphite lid 9 and the mold 1.
1.3mm from the inner diameter of the upper part of mold 1 so as not to leak from between
It's getting bigger.

In order to prevent heat from escaping to the ram 10 of the press machine, a 5 mm thick asbestos insulating plate 11 is placed on the graphite lid 9 and the ram 10 is pressed at a pressure of 39.2 × 10 ³ MPa. Pressurizes and ejects molten metal 13 from hole 2a of jet plate 2,
The alumina particles 12 are dispersed. At this time, the pressure is applied to the ram 10, and at the same time, the heating furnace 7 and the elevating gantry 6 on which the mold 1 is placed are lowered, the bottom of the mold 1 comes into contact with the water jacket 4, and cooling starts from under the mold 1. A cushion 5 is provided under the jacket 4 so as to be in constant contact therewith to enhance the cooling effect.
As a coil spring.

When the temperature of the upper part of the mold 1 becomes lower than 723 K, the pressure is released and the mold 1 is taken out of the heating furnace 7. Next, the composite was taken out of the mold 1 and used as a sample. The sample taken out was cut vertically into two pieces by a micro cutter, and the cross section was polished up to # 1500 with emery paper and observed.

In the above experiment, the experiment was carried out by changing the melt temperature, the mold temperature, the hole diameter of the jet plate, and the ram speed in various ways. FIG. 4 shows the time course of the experiment, in which the mold 1 was removed from the heating furnace 7 after the partition plate 14 was removed.
The change of temperature, pressure, solidification height, and ram speed of each part until it is taken out from the machine.
It is taking seconds.

The jet plate 2 has a hole diameter of 2.0 mm,
When the mold and molten metal temperature are varied at a ram speed of 8.6 cm / s and the mold temperature is 873K and the molten metal temperature is 1173K, the molten metal cannot enter the lower part because the mold temperature is lower than the solidification temperature of pure aluminum. A hole was seen at the top of the sample. When the mold temperature was 973K, the melt temperature was 1123K, and the temperature was 1173K, the alumina particles were not rolled up. At a mold temperature of 1003K and a molten metal temperature of 1193K, there were portions where the alumina particles were not dispersed, but the alumina particles sprang up to the upper part of the sample. Further, when the mold temperature is 1023K and the melt temperature is 1233K, the temperature of the mold and the melt is high, so that the graphite lid 9 is not used.
And the molten metal squirted out from between the mold 1 and the graphite lid 9, and the sample had many holes due to insufficient pressure. From the above, mold temperature 1003K, molten metal temperature 1193
It was found that K would cause alumina particles to fly. Therefore, all subsequent experiments were performed at this temperature.

In order to disperse the alumina particles, the ejection speed of the molten metal is important. First, ram speed 8.6 cm / s
When the hole diameter φD was changed by φ, the sample had an alumina dispersion portion at the upper and lower portions of the sample and a non-dispersion portion at the upper portion at φ2.0 mm. In the range of φ1.0 mm to φ1.5 mm, alumina particles were slightly unevenly distributed in the upper part, but the alumina particles were uniformly dispersed throughout. When the diameter was 0.8 mm, the uneven distribution ratio of the alumina particles on the upper part of the sample became considerably large. In order to evaluate this state, the area ratio of the uniformly dispersed portion of the alumina particles was calculated at each point from the cross section of the top, center, and bottom of the sample.

FIG. 5 shows the relationship between the hole diameter and the uneven distribution ratio. The average value at the top, center, and bottom is 1.0%.
It was found that the mm type had the least uneven distribution. this is,
Relational expression of injection power (F), F = γ · Q · v / g As the value of v increases as the hole diameter decreases, the value of F
It turns out that the value of becomes large. FIG. 6 shows this relationship.

That is, when the jetting power F is large, the force for dispersing the alumina particles increases, and at the same time, the force for pressing the particles to the upper part also increases. Therefore, when φ 0.8 mm, the uneven distribution ratio of the alumina particles increases. It is presumed to be.

Conversely, if the hole diameter is large, the molten metal falls spontaneously from the hole in the jet plate between the time the molten metal is poured and the time the pressure is applied (about 40 seconds). This ratio is shown in FIG. That is, when the hole diameter is 2.0 mm, 20% drops from the lower part of the mold, and when the hole diameter is 1.0 mm, the molten metal does not drop. From this, it can be seen that when the molten metal falls, the molten metal interrupts the dispersion of the alumina particles.

Another factor that changes the injection speed of the molten metal is the ram speed. Therefore, when the ram speed was changed, a sample with an ejection speed of 95.5 m / s or more was obtained. However, the dispersion changed when the ram speed fell below 53.7 m / s. In addition, the equation of injection power F = γQv /
As can be seen from g, when the ram speed is reduced, the value of the flow rate Q is also reduced. As an example, if the hole diameter is 1.0 mm,
When the ram speed was 2.15 cm / s, the ejection power was weak due to the small value of F, and the particles did not disperse. Also the hole diameter
In the case of 1.5 mm and a ram speed of 4.84 cm / s, the particles were dispersed throughout because the value of F was sufficient to elevate the particles. A sample with good dispersibility was obtained even when the hole diameter of the jet plate was 1.0 mm and the ram speed was 8.6 cm / s. FIG. 8 is a diagram showing the relationship between the ram speed and the ejection speed when the hole diameter of the jet plate is changed.

FIG. 9 shows the relationship between the dispersion ratio, uneven distribution ratio, and volume ratio of alumina particles. When the volume ratio is 2,3%, the alumina particles are small and it is difficult to uniformly disperse the particles throughout. Have difficulty. Conversely, when the volume ratio is 8 to 10%, the alumina particles are large and the uneven distribution ratio of the particles is large. This shows that the volume ratio is preferably about 5%. However, even when the volume ratio is 8 to 10%, if the alumina particles are directly introduced into the lower part of the mold, the alumina particles come close to the jet plate, so that it is not necessary to increase the jetting power. If this is the case, a sample in which the proportion of uneven distribution of alumina particles may be reduced can be obtained.

The relationship between the volume ratio of the powder particles to the matrix metal and the hardness is shown in FIG.
3% has a higher hardness than that of 3%, and 5% has a higher hardness than 3%.

FIGS. 11 to 13 show that the samples having a volume ratio of 1%, 3% and 5% are extracted from the above samples, and the longitudinal section of each sample is shown on the abscissa. In addition to dividing into 13 equal parts and dividing into 21 equal parts on the ordinate, the hardness in each section is measured, and the hardness distribution ratio is arranged on the abscissa by hardness.

A in the figure indicates a range of hardness of 32 HV or more,
Indicates a range of hardness 25 to 32 HV, C indicates a range of hardness 24 to 25 HV, and D indicates a range of hardness 24 HV or less. FIG. 11 shows the case where the volume ratio is 1%, and FIG.
%, And FIG. 13 shows a case where the volume ratio is 5%. From these, those with a volume ratio of 5% seem to be the most stable.

[0032]

As described above, in the present invention, powder particles having a volume corresponding to 5 to 10% of the mold volume are inserted into the mold, and the molten matrix metal is injected into the mold. The powder force can be uniformly dispersed in the matrix metal by this spraying force. After dispersing powder particles having a volume equivalent to 5 to 10% of the mold volume in the molten matrix metal, the molten metal was unidirectionally solidified from the bottom of the mold with high pressure applied. Before sinking to the bottom of the matrix metal melt, the melt can be solidified from the bottom. Therefore, according to the present invention, a particle-dispersed composite material having a low volume ratio, which has conventionally been considered difficult to produce, can be easily produced in a short period of time, whereby wear resistance, specific strength and heat resistance can be reduced. The advantage is that an excellent composite material can be obtained.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view showing a mold used in the present invention.

FIG. 2 is a partial cross-sectional view of a composite material manufacturing apparatus used in the present invention.

FIG. 3 is a partial sectional view showing a step subsequent to FIG. 2;

FIG. 4 is a diagram showing a time course of an experiment.

FIG. 5 is a diagram showing a relationship between a hole diameter of a jet plate and an uneven distribution ratio of alumina particles.

FIG. 6 is a diagram showing a relationship between a jet power of a molten metal and a hole diameter of a jet plate.

FIG. 7 is a diagram illustrating a relationship between a hole diameter of a jet plate and a rate at which molten metal falls naturally.

FIG. 8 is a diagram showing the relationship between the ram speed and the ejection speed when the hole diameter of the jet plate is changed.

FIG. 9 is a diagram showing the relationship between the dispersion ratio, uneven distribution ratio, and volume ratio of alumina particles.

FIG. 10 is a diagram showing a relationship between a volume ratio and hardness.

FIG. 11 is a diagram showing a hardness distribution of a sample having a volume ratio of 1%.

FIG. 12 is a diagram showing a hardness distribution of a sample having a volume ratio of 3%.

FIG. 13 is a diagram showing a hardness distribution of a sample having a volume ratio of 5%.

[Explanation of symbols]

1 molds 1a composite portion 1b injection section 2 jet plate 2a Hole 3 fixing base 4 water jacket 5 cushion 6 elevating frame 7 furnace 8 Marinaito 9 graphite lid 10 ram 11 insulation board T _1, T ₂ thermocouple 12 alumina powder 13 melt 14 Partition plate

────────────────────────────────────────────────── (5) Int.Cl. ⁶ Identification symbol FI B22D 27/20 B22D 27/20 Z (56) References JP-A-62-6759 (JP, A) JP-A-57-85662 ( JP, A) JP-A-63-295052 (JP, A) JP-A-63-295053 (JP, A) JP-A-62-116740 (JP, A) JP-A-2-15136 (JP, A) JP-A-1-259138 (JP, A) JP-A-50-92235 (JP, A) JP-A-3-91966 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B22D 18 / 02 B22D 19/14 B22D 19/16 B22D 27/04 B22D 27/09 B22D 27/20

Claims (2)

(57) [Claims] 1. Powder particles having a volume equivalent to 5 to 10% of the volume of a mold are inserted into a mold, and a molten metal of a matrix metal is injected into the mold to disperse the powder particles in the matrix metal. A method for producing a low-volume-ratio particle-dispersed composite material, wherein the composite material is coagulated. 2. A mold having a volume of 5 to 10 in a closed mold.
% Of the powder particles is inserted into the mold, and the molten metal of the matrix metal is injected into the mold to disperse the powder particles in the matrix metal. A method for producing a low-volume-ratio particle-dispersed composite material, comprising coagulating.