JPS6124458B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a hollow composite metal material having an arbitrary cross-sectional shape such as a cylinder, a rectangular tube, or a gear shape.

The inventor of the present application filed a patent application dated May 16, 1982.
-064956 discloses a method for manufacturing composite metal materials.

In this method, a cast alloy (referred to as a first metal) is maintained at a temperature range where solid and liquid phases coexist, a second metal is placed on one surface, and the second metal is By pressurizing the molten metal, the liquid phase is expelled from the other side of the solid phase of the first metal forming the dendrite network, and at the same time, the second metal is press-fitted into the first metal.
A method for obtaining a composite metal material in which the liquid phase part of the metal is replaced with a second metal was shown. However, subsequent research has revealed that this method is not necessarily sufficient to obtain composite metal materials having general shapes such as cylindrical and plate shapes. In other words, depending on the method of pressurizing the second metal molten metal, a tensile force is generated within the first metal material, and even though a dendrite network is formed that is considered to have a certain degree of mechanical strength. It was discovered that it breaks with an extremely small force and cannot be made into composites. In other words, as will be described later, when we conducted an experiment in which molten Pb was placed inside a cylindrical alloy sample A and the Pb was compounded by internal pressure, the Pb was composited by a tensile force in the circumferential direction before almost any pressure was applied. Vertical cracks occurred, and Pb flowed out from the cracks, making it impossible to form a composite.

As described above, in a solid-liquid coexistence state, although it has a certain degree of mechanical strength against compression, it breaks under tension with a force that is much smaller than the force generated when the pressure necessary for composite is applied. Moreover, it has no ductility and is extremely brittle. There is no data on the tensile properties of these alloys at solid-liquid coexistence temperatures, and furthermore, under the special situation where the coexisting liquid phase is expelled from the solid phase by the pressure of the second molten metal, it is difficult to determine how the solid phase behaves. No published data can be found regarding whether it has tensile properties.

The present inventor has further improved this method by pressurizing the second molten metal so that when performing the composite, a quasi-hydrostatic pressure state, that is, no tensile force is generated within the first metal material and a stress state close to hydrostatic pressure is created. In particular, we have developed a method for manufacturing general hollow composite metal materials such as cylindrical shapes by compounding the second metal without destroying the solid phase of the first metal material.

1 to 4 conceptually illustrate the method of manufacturing these according to the present invention. Hereafter, for ease of explanation, the first
The methods shown in FIGS. 4 to 4 will be referred to as processes, respectively. In FIG. 1 (process), a second metal is placed outside a hollow first metal material 1 having a solid-liquid coexistence state, and the second metal melts at a composite temperature, that is, a solid-liquid coexistence temperature of the first metal. It is held by the outer cylinder 3 in order to be in the state. For the outer cylinder 3, refractory ceramics, heat-resistant metal materials, or porous materials thereof (provided that the porous materials do not wet with the molten second metal and do not allow the molten second metal to pass through) are used. Predetermined composite ratio (defined as the weight percent of the second metal to the composite material after composite)
When the second molten metal is pressurized after being held at a predetermined composite temperature so as to obtain a It is possible to obtain a hollow composite material in which the liquid phase is simultaneously discharged and the liquid phase is replaced with the second metal. The reason why the axis of the hollow metal material is held horizontally is that if the axis is vertical, a pressure difference will occur between the upper and lower parts of the second molten metal due to the water head difference, and the composite ratio will become uneven (the upper This is to prevent problems in which the composite ratio is small) or the upper part is not composited. For example, in an experimental method described in detail in the examples below, an A-5wt% Si casting alloy (15 mm outer diameter x 6 mm inner diameter x 30 mm height) was used, Pb was used as the second metal, and the temperature was 595°C (solid phase ratio 0.5). ) at
When we conducted an experiment to compound Pb, we found that the external pressure required for compounding was approximately 0.1 atm, and when we examined the microstructure of a longitudinal section of a compound cylinder sample, we found that the higher the top, the more Pb was absorbed.
The content was decreasing. However, the cause of this is 0.1 atm at the upper end, but 0.1 Kg/cm ² + at the lower end.
11.34gr/cm ³ (specific gravity of Pb) x 3cm (height of head)
= 0.134 atm, which can be determined from the fact that there is a pressure difference of 34%. Although this level of sample height does not cause significant non-uniformity, it is clear that when a composite material with a length of actual operation level is required, it is not possible to produce a composite material that is uniform in the axial direction with the vertical type. be.

To overcome this difficulty, the inner surface of the hollow metal material has a resistance (resistance when the liquid phase enters the filter) that is greater than the combined pressure at the bottom end, and the top end has a resistance to the pressure difference due to the head difference. Installing filters with lower resistance in stages,
Alternatively, a method may be considered in which the part to be composited with the second metal and the hollow metal material are moved relatively to each other so as to be composited continuously, but this method is more complicated than the horizontal method and is not a good idea.

The reason for the next rotation is the non-uniformity of the composite ratio in the circumferential direction caused by the ratio of specific gravity of the first metal and the second metal and the shape ratio (ratio of wall thickness to outer diameter) of the first metal material. This is to avoid.

Furthermore, another important reason for adopting the horizontal rotation method is to obtain a uniform temperature distribution over the entire sample, which is one of the important control conditions in manufacturing, and to extend the life of heat-resistant jigs such as the outer cylinder. It is also essential from the perspective of transformation. In other words, in ordinary heating methods such as electric furnaces, uneven temperature distribution in the circumferential direction of the heating element is unavoidable, and thermal stress distortion occurs in these jigs, which, together with creep deformation, shortens the life of the jigs. Composite becomes difficult. This tendency becomes more severe as the diameter or length of the product increases or as the temperature increases.

Next, in the process according to the present invention (FIG. 2), a second metal 2 is placed inside the first hollow metal material 1, and the second metal molten metal is pressurized to form a composite material. At this time, as mentioned above, if there is no contact support by the filter 4, the first
The tensile force created within the hollow metal (usually very small) causes the hollow metal 1 to rupture, from which the second
Molten metal flows out and cannot be combined. That is, the filter 4 serves to discharge the liquid phase and the second molten metal and also to prevent breakage. The hollow member 3 provided inside the second metal is similar to process 3, but in connection with dimensions 1 and 2 it is not necessary.

The reason for adopting the horizontal rotation method and the combination method are the same as the process described above.

3 (process) is the same as the process (FIG. 1) except that a filter 4 is provided between the hollow metal material 1 and the second metal 2. The reason why the filter 4 is provided to contact and support the hollow metal material 1 is to prevent the hollow metal material 1 from becoming elongated and breaking due to bending in a state where there is almost no resistance to tension at the solid-liquid coexistence temperature. Although the second metal molten metal may be in contact with the first metal surface at the composite temperature, in order to increase the composite efficiency, it is desirable to select a filter that can make this contact area as large as possible. An example of such a filter is one in which a large number of holes are drilled into the pipe material to increase the contact area, or in an extreme example, only the lower part of the filter 1 may be supported by a long and narrow stiffener. . In short, anything can be used as long as it prevents breakage. Another reason for providing the filter 4 is to prevent erosion of the first metal by the molten second metal. For example, Pb was placed on the outside of an A-10 wt% Cu alloy (15 mm outer diameter x 9 mm inner diameter x 30 mm height) using the experimental method described below, and when it was held for about 20 mm at 588 °C (solid phase ratio 0.6), it was heated. Before pressing, a rather large hole was made at the bottom of the cylindrical sample, and Pb leaked out, making it impossible to form a composite. This is thought to be due to erosion caused by the solubility of Cu in the Pb melt being approximately 1 wt% (and A being approximately 0.1 wt%). In this way, depending on the combination of the first metal and the second metal, it is necessary to prevent erosion. Therefore, in this case, the filter should be sufficiently fine to prevent the intrusion of the second metal molten metal until the pressure is applied. It must not come into contact with metal. Such filters include porous ceramic and porous metal filters. Another method for preventing erosion is to saturate the molten second metal with the first metal element in advance.

The final process (FIG. 4) is similar to the process (FIG. 2) except that a filter 5 as described above is provided between the first metal and the second metal.

Examples of these methods according to the invention will now be described in detail.

FIG. 5 is a schematic cross-sectional view of the experimental apparatus used in the method of the present invention. This case was manufactured in such a way that complex experiments can be conducted using internal and external pressures, and it has a double-tube rotating system consisting of a stainless steel outer tube 2 and a stainless steel inner tube 3 that holds and supports the sample. It consists of a split-type nichrome heater electric furnace 1, an argon gas piping system (gas source not shown), and a temperature measurement system. Further, to explain in detail the case of compounding due to external pressure (process, Fig. 1) as an example, the part indicated by the broken line of the inner cylinder 5 has large windows open on three sides, and the inner diameter of the tip is Connected to the screw part. 4 is a sample support part provided inside the inner cylinder 3, 5 is a ring that supports the cylindrical first metal sample 8, the cylindrical second metal 7, and the filter 6, and one ring is provided with a ring to prevent pressure leakage. It has a retaining edge. 9 is a screw, and 10 is a pipe for taking out the liquid phase part of the sample 8 and the second molten metal 7 to the outside of the sample after compounding, and is heated to avoid a drop in temperature. 11 is a flange for connecting the inner and outer cylinders, 12 is a cap 13 and 14 fixed to the rotating double pipe.
Although it cannot maintain complete airtightness, it can sufficiently prevent pressure leaks, and there are no problems in experiments. 15 is a stainless steel pipe, 16 is a turning roller, 17 and 1
8 is a stainless steel pipe 1 for taking out the sample temperature measuring thermocouple 25 to an external temperature recorder 26.
The sheath heater 34 wrapped around the external power source 3
Brass slip ring and carbon brush for extraction to 5, 19, 20, 21, 22 are piping system valves, 23 and 24 are 10Kg/cm ² pressure gauge, 2
7, 28, and 30 are pipes, 29 is a copper pipe wound around the pipe 15, and 31, 32, and 33 are beakers containing water. Next, we will discuss the experimental method. Set one set of samples (namely 6, 7 and 8) in a predetermined position and tighten with screws 9. Valves 19 to 22 are opened to replace the air in internal chambers 40 and 50 with argon gas. Valve 22 after replacement
and adjust the valves to close the sample interior 40 and 50.
A very small amount of argon was flowed through the tube (argon was used to prevent oxidation of the sample). Start heating up,
Drive the motor (not shown) to rotate the double tube (approximately 0.5 rpm). Heating rate is approximately 15℃/min
It was hot. 10-15 after reaching the predetermined solid-liquid coexistence temperature
After holding for a minute and allowing it to heat up sufficiently, speed up the rotation (about 0.2r.
ps), adjust valves 20 and 23 to pressurize.
When a certain pressure is reached, the liquid phase of the first cylindrical sample is separated and discharged, and at the same time, the second metal is combined. At this time, the argon gas inside the sample is
Since the pipe 10 is sufficiently preheated, the first
The liquid phase of the metal and the second molten metal are discharged into the beaker 33 without solidifying in the middle of the pipe. It is also effective to create a slight slope to facilitate discharge. The pressure is increased slightly, and when the discharge stops, it can be confirmed that the compounding process has been completed.The pressure is then reduced, the power is turned off while a very small amount of argon is allowed to flow, the furnace is opened, the furnace is cooled to room temperature, and the sample is taken out. The second metal molten metal that was outside of sample 1 when the composite was completed does not remain inside or outside sample 1, and the second metal liquid phase that has entered between the dendrites of sample 1 is further exposed to argon gas. Therefore, in order to separate and discharge, a pressure several times or more than that required for the composite is required, so there is no fear that the composite second metal will be separated again.

The reason for speeding up the rotation during compounding is to promote uniform compounding in the circumferential direction, and the "compound speed"
It is necessary to be sufficiently fast compared to .

In the case of compounding by internal pressure (process), the discharge pipe 10 is not necessary, and the sample may be set in a predetermined position as shown in FIG. 2 or 4 and the internal pressure applied.

Examples will be described in detail below.

In these examples, the first cylindrical sample was A-2, which was normally cast in a sand mold ( _CO2 process mold).
Using 5wt%Si and A-15wt%Cu casting alloys, they were processed to predetermined dimensions and used as test materials.

Furthermore, Pb was used as the second metal. As already mentioned, the A-Cu alloy has a large erosion with respect to molten Pb, whereas the A-Si alloy has a considerably small effect of erosion, and there was no problem during the heating and holding period in this example. This is thought to be because Si does not alloy with Pb.

In addition, the filter used in these Examples was a 10 to 15 vol.
An A-3wt% Si material having a porosity of 100% was processed to a predetermined size, and "clogging" caused by processing was removed by etching with a sodium hydroxide solution.

Example 1 (process) A-5wt%Si sample (outer diameter 15 x inner diameter 6 mm x length
30mm) Pb (outer diameter 24.9mm x inner diameter 15.1mm x length 30
mm), A-3wt%Si porous filter (outer diameter 32
mm x inner diameter 25 mm x length 30 mm) were set as shown in Figure 6 (enlarged view of the sample holding part) (6, 7, and 7, respectively).
8). 3 is a refractory fiber flex inserted as a cushion to prevent pressure leakage, etc. 2 is the sample support ring with an edge as described above, and an aluminum foil ring is inserted between the edge and the support part 1 to prevent pressure. This prevents this from happening. non-equilibrium coagulation
It was heated to a temperature at which the solid phase ratio was 60% calculated based on Scheil's formula, that is, 583°C, held for about 15 minutes, and then pressurized and composited. Compounding was started at an external pressure of about 0.1 atm, and the final pressure was about 0.15 atm. The Pb content of the obtained sample was 47 wt%. If the liquid phase was completely replaced with Pb, Pb would be 74wt%, but in reality, 63% of this was replaced, and the existing liquid phase was not completely replaced with Pb.

It should be noted that molten Pb did not leak through the A-3% Si filter during heating and holding.

Example 2 (Process) From the inside, A-3wt%Si filter (outer diameter 7 mm x inner diameter 4 mm x length 30 mm), Pb (outer diameter 14.9 mm)
× 7.1 mm inner diameter × 30 mm length), A-5wt% Si sample (23 mm outer diameter × 15 mm inner diameter × 30 mm length), and a stainless steel support filter with many 3 mmφ drill holes (25 mm outer diameter × 23.05 mm inner diameter × length) 30 mm) was set in the specified position as shown in Figure 2. The effective area (ratio of the total hole area to the total internal surface area) of the stainless steel filter is 0.45. Solid phase rate 60% i.e.
Composite was performed at 583°C and an internal pressure of approximately 0.1 atm. Pb of sample
The content was 28wt%. The reason why the composite ratio is lower than that in Example 1 is thought to be due to the difference in internal pressure and external pressure, the effect of the effective area of the outer support filter, etc.

Example 3 (Process) In this example, A-15wt% was used as the sample.
Using Cu (outer diameter 15 mm x inner diameter 6 mm x length 30 mm),
Pb as the second metal (outer diameter 24.9mm x inner diameter 20.1mm x
Insert an A-3wt% porous filter (20mm outer diameter x 15.1mm inner diameter x 30mm length) between the sample and the A-3wt% Si porous filter (32mm outer diameter x 30mm inner diameter) on the outside. 25mm x length 30mm),
It was set in the predetermined position as shown in Figure 3. After being held at a temperature of 550°C for about 15 minutes, which corresponds to a solid fraction of about 0.6,
It was combined at about 0.4 atm. The Pb content of the composite sample was 25wt%. The amount of Pb is considerably smaller than in Example 1, and this is thought to be due to the inclusion of the filter, which reduces the contact area between the molten Pb and the sample surface at the time of compounding.

Example 4 (Process) Using A-15wt%Cu as a sample, the sample and Pb
A-3% Si porous filter (outer diameter
15.9 mm x inner diameter 12.1 mm x length 30 mm) (according to this, the inner diameter of the sample and the outer diameter of Pb are 16.0 mm and 12.0 mm, respectively). It was set in the predetermined position according to the instructions shown in Figure 4. The solid phase ratio was 0.6 and the temperature was maintained at 550°C for about 10 minutes to form a composite under pressure. It was pressurized at approximately 0.4 atm. The Pb content of the composite sample was 17wt%. Although the Pb content is quite low, this is thought to be due to the combination of the outer tube stainless steel support filter, A/Si porous filter, and internal pressure direction as described above.

When we observed the cross-sectional microstructures of the composite samples obtained in these examples, we found that all of them were uniformly Pb.
were compounded. FIG. 7 shows, as an example, a cross-sectional microscopic structure of a composite sample in which A-5wt%Si and 47wt% Pb were combined in Example 1. The dark black part is Pb, and the final solidification part between the dendrites (A
)+Si eutectic is crystallized into a matrix in which Pb is homogeneously composited. The hollow composite metal material described in this example is useful as a so-called friction material such as an oil-free bearing. It is clear in principle and from this example that hollow composite metal materials having various industrially useful cross-sectional shapes can be produced.
In addition, when performing gas pressurization compounding, it is possible to slowly increase the pressure by gradually increasing the pressure (or it is easy to control the compounding speed by applying pressure mechanically). ,
Materials that are partially composited in the thickness direction can also be easily produced. That is, depending on the application such as a friction material, a hollow composite metal material can be obtained in which the inner surface or the outer surface is partially composited with the second metal. Furthermore, the hollow composite metal material obtained by the method according to the present invention is characterized in that the composite second metals are interconnected, and by controlling the solidification structure of the hollow casting alloy. (e.g. unidirectional solidification), composite materials with various morphologies can be obtained.

As described above, the method for producing a hollow composite metal material according to the present invention is easier than the powder metallurgy technique, which cannot be obtained by conventional metallurgical methods or is technically complicated, and has different characteristics. It provides a composite metal material, and is expected to be used in the future.

[Brief explanation of the drawing]

1 to 4 show a method for manufacturing a hollow composite metal material according to the present invention, 1... hollow first metal, 2...
...second metal, 3...outer cylinder. Fig. 2 shows a method of compounding by internal pressure, 1...Hollow first metal, 2...Second metal, 3...Inner cylinder, 4...Filter. Fig. 3 shows a method of compounding by external pressure, 1...Hollow first metal, 2...Second metal, 3...Outer cylinder, 4...Filter. Figure 4 shows a method of compounding using internal pressure.
Metal, 2...Second metal, 3...Inner cylinder, 4 and 5...
...It's a filter. FIG. 5 is a schematic cross-sectional view of the apparatus used in the method of the present invention. DESCRIPTION OF SYMBOLS 1... Split type electric furnace, 2... Stainless steel outer cylinder, 3... Stainless steel inner cylinder, 4... Sample support part, 5... Sample support ring, 6... Filter, 7... Cylindrical Pb, 8...
... Cylindrical sample, 9 ... Tightening screw, 10 ... Discharge pipe, 11 ... Outer cylinder, inner cylinder connecting flange, 1
2... Connection section using a dynamic O-ring seal for connecting and sealing the rotary cylinder 2 and fixed caps 13 and 14, 13 and 14... Fixed cap, 15...
Stainless steel support pipe, 16... Turning roller, 17... Brass slip ring, 18... Carbon brush, 19, 20, 21 and 22...
...Valves, 23 and 24...Pressure gauge, 25...Thermocouple for measuring sample temperature, 26...Temperature recorder, 27,
28, 29 and 30...Plumbing pipe, 31, 32
and 33...beaker containing water, 34...sheath heater for heating the pipe 10, 35...external power source, 40 and 50...inner and outer chambers of the sample, respectively.
FIG. 6 is an example of a partial cross-sectional view of the main parts of the apparatus used in the example (FIG. 5), including 1...sample support section, 2...sample support ring with edges, 3... Refractory fiber flex, 4...
Sample support ring, 5... Alumel-chromel thermocouple, 6... Cylindrical A alloy sample, 7... Cylindrical
Pb, 8...A-3%Si porous filter. Figure 7 shows A-5%Si+ in Example 1.
This is a micrograph (18.7x magnification) of a cross section of a Pb composite cylindrical sample.

Claims (1)

[Claims] 1. A hollow first metal material made of an alloy in which a solid phase and a liquid phase coexist at a predetermined temperature and having an arbitrary cross-sectional shape such as a cylinder, a square tube, or a gear shape. and maintaining the metal material at the solid-liquid coexistence temperature while rotating the metal material while holding the axis of the metal material substantially horizontally; The materials are placed in contact with each other, the second metal is in a molten state at the temperature, and the liquid phase portion of the first metal is maintained in a quasi-hydrostatic state by pressurizing the molten metal. A method for manufacturing a hollow composite metal material having an arbitrary cross-sectional shape as described above, comprising the step of discharging and simultaneously obtaining a composite material in which a liquid phase portion of the first metal is replaced with a second metal. 2. The method for manufacturing a hollow composite metal material according to claim 1 is characterized in that a filter is disposed between the first hollow metal material and the second metal. 3. A hollow first metal material made of an alloy in which a solid phase and a liquid phase coexist at a predetermined temperature and having an arbitrary cross-sectional shape such as a cylinder, a rectangular cylinder, or a gear shape is provided, and the first Supporting the first metal by placing a filter in contact with the outside of the metal, holding the axis of the first metal substantially horizontally, and maintaining the first metal at the solid-liquid coexistence temperature while rotating the first metal. and a second metal inside the first metal.
The second metal is in a molten state at the temperature, and the molten second metal is pressurized to maintain the first metal in a quasi-hydrostatic pressure state while passing through the filter and applying the second metal to the first metal. A method for producing a hollow composite metal material having an arbitrary cross-sectional shape as described above, comprising the step of discharging a liquid phase portion of the metal and simultaneously replacing the liquid phase portion of the first metal with a second metal. 4. The method for manufacturing a hollow composite metal material according to claim 3 is characterized in that a filter is disposed between the first hollow metal material and the second metal.