JPH0222430A - Production of grain dispersion-strengthened alloy - Google Patents

Abstract

PURPOSE:To easily produce a grain dispersion-strengthened alloy in which grains are uniformly dispersed by blowing a dispersed and mixed solution consisting of surface-treated grains for dispersed phase and a surface treatment solution or a volatile medium into a previously melted molten metal. CONSTITUTION:A metal, such as Al, is melted in a crucible 3 disposed in a heating furnace 2 equipped with heating units 1, by which a molten metal 4 is prepared. On the other hand, the grains 8 of ceramics, etc., to be added as dispersed phase to the above molten metal are subjected to surface treatment to improve wettability, and these grains 8 are dispersed into a solvent, as a dispersion medium, consisting of surface treatment solution or volatile medium with low boiling point, such as water, by which a mixed solution 9 is prepared. While agitating the molten metal 4 in the above crucible 3 by means of an agitating device 5 equipped with an agitation blade 6, the above mixed solution 9 is blown into this molten metal 4 via a spray gun 10. By this method, the grains 8 can be uniformly dispersed into the molten metal 4 easily and inexpensively in high yield, by which the grain dispersion-strengthened alloy of high quality can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing a particle dispersion strengthened alloy.

[Conventional technology]

Dispersion-strengthened alloys, in which particles of ceramic or the like are dispersed in metal, are widely used as monofunctional materials. Dispersion-strengthened alloys are often produced by a sintering method in which metal powder and particles to be dispersed are mixed, followed by powder compaction, sintering, extrusion, f'1 HIP treatment, and machining. Since the royal power is complicated, the capital investment is large, and the metal powder is also expensive, so manufacturing by melting method has recently been considered.

The melting method is a method of casting by adding particles to molten metal, and can be further divided into the portex method, injection method, composite casting method, injection method, etc., but there are many points that are not technically established. Commercially available dispersion strengthened alloys include, for example, Dura k (Dur
Al) Company [Subsidiary of Alcan Company]
An example of this is a dispersion-strengthened alloy in which SiC particles with a particle size of 10 to 20 μm are dispersed in aluminum, but the details of the manufacturing method are unknown. In addition, if the wettability between the particles to be dispersed in the metal and the molten metal is poor, the properties of the obtained particle dispersion strengthened alloy will deteriorate. For example, metal plating is also used.

In the melting method, as a means of adding all the particles to the molten metal,
It is common to spray particles together with a carrier gas while stirring the molten metal.

The present applicant has proposed a method of dispersing fine particles as a dispersed phase onto the surface of molten metal at a speed of 5+n/sec while stirring the molten metal in a non-oxidizing atmosphere.
We have proposed a method for producing a particle dispersion strengthened alloy characterized by injection at a temperature of 800 to 2,500° C. or higher.

[Problem to be solved by the invention]

However, the conventional melting method described above has many problems as described below.

1) Particles tend to aggregate. That is, the finer the particles, the stronger their tendency to aggregate, and if they enter the molten metal as aggregates, they cannot be separated by stirring, making it difficult to disperse them uniformly. For this reason, it is not possible to sufficiently improve the properties such as tensile strength and Young's modulus of the particle dispersion strengthened alloy.

2) Particles are limited to coarse powder. That is, coarse particles with an average particle diameter of 10 μm or more are generally used because fine particles tend to scatter together with the carrier gas and are difficult to mix into the molten metal.

For this reason, and because many of the particles added are made of hard materials, the resulting particle dispersion strengthened alloy has extremely poor rigidity. For example, lathe cutting requires the use of expensive diamond-coated tools.

3) Poor yield. That is, many of the particles to be added scatter along the flow of the carrier gas, and do not penetrate into the molten metal very much, resulting in a poor yield. Particularly fine particles are bad.

4) Carrier gas is required. That is, it is necessary to use an expensive gas such as N, gas, or irradiated gas so as not to oxidize the molten metal.

5) Additional equipment is required. That is, as mentioned above, the particles are scattered together with the carrier gas, resulting in dusty work and a poor working environment. Therefore, ancillary equipment such as a dust collector is required.

6) Taking plating treatment as an example of surface treatment for particles,
If the plating process is complicated, the recovery rate of fine powder will be poor. That is, when plating particles, the electroless plating method is generally used, and the particles are usually put into a plating solution, then collected with a filter, and dried before use. When using a filter, some particles may pass through the filter's openings, while others may clog the filter's openings, resulting in a poor collection rate and poor work efficiency due to the clogging of the filter. Further, equipment and time for drying the particles are also required. Furthermore, normally, the finer the powder, the more strongly the particles stick together during the drying process, making it difficult to disperse the particles in the molten metal.

The present invention is intended to solve the above-mentioned problems in the prior art, and its purpose is to uniformly disperse particles in metal without causing agglomeration even if the average particle size is small. It is an object of the present invention to provide a method for producing a particle dispersion strengthened alloy, which can be easily carried out, and has improved wettability between particles and molten metal.

[Means for solving problems]

That is, the method for producing a particle dispersion-strengthened alloy of the present invention includes a liquid mixture consisting of surface-treated particles to be added as a dispersed phase into a metal and a surface-treated liquid or a vaporizable liquid as a dispersion medium for the particles. It is characterized by injecting into molten metal that has been melted in advance.

The particles may be made of ceramic, metal, or the like whose melting point is higher than the temperature of the molten metal. The material, size, shape, etc. of the particles are selected depending on the required characteristics of the intended particle dispersion strengthened alloy. Note that the term "particles" in this text also includes whiskers, short fibers, etc. that can be used in the same manner. A single type of particles may be used, or a combination of two or more types may be used.

The surface treatment applied to the particles may be any treatment as long as it improves the wettability between the particles and the molten metal, and includes surface modification by physical or chemical means, formation of an affinity layer by plating, etc.

As the particle dispersion medium, the surface treatment liquid used for surface treatment may be used as is, or the surface treatment liquid may be replaced with a vaporizable liquid.

To explain specifically when plating is used as a surface treatment, particles are put into a plating solution, a plating layer is formed on the surface of the particles, and then a mixture of the plating solution and particles is directly injected onto the molten metal. A mixed liquid in which the soaking liquid is replaced with another vaporizable liquid may be injected into the molten gold metal. The plating agent is not particularly limited as long as it improves wettability.

As the vaporizable liquid, a liquid having a boiling point lower than the temperature of the molten metal can be used. For example, it is preferable to use something that is nonflammable and difficult to decompose, such as water.

The mixing ratio of the particles to the surface treatment liquid or vaporizable liquid is preferably 1 to 5 wt or more of the surface treatment liquid or vaporizable liquid relative to the weight of the particles. When the mixing ratio of the surface treatment liquid or the vaporizable liquid is less than 5 wt %, the force of the small explosion during instantaneous vaporization of the droplets is not sufficient to break up the mutual agglomeration of the particles.

It is desirable that the injection speed of the liquid mixture into the molten metal is 1 m/sec or more. If the injection speed is slower than this, the droplets will either evaporate before reaching the molten metal surface, or
The particles simply float on the surface of the molten metal while emitting steam, and the particles cannot be sufficiently dispersed in the molten metal.

The form in which the mixed liquid is sprayed onto the molten metal is not particularly limited. For example, the mixed liquid may be injected onto the surface or inside of the molten metal that is being stirred in a container, or the mixed liquid may be injected onto the surface or inside of the molten metal while it is falling or flowing down.

The liquid mixture may contain a gas such as air, if desired, in addition to the particles and the vaporizable liquid.

As the metal to be strengthened, a common metal such as aluminum or an alloy thereof can be used.

The weight of the particles added as a dispersed phase in the metal is 4 to so
wt arrow is preferable. If the amount is less than this, no improvement in the properties of the reinforced alloy will be observed even if the particles are added, and if the amount is more than this, the toughness will decrease.

[Effect]

By spraying a surface treatment liquid or a vaporizable liquid in which the particles are completely dispersed into the molten metal, the particles are uniformly dispersed in the molten metal by the explosive force caused by the rapid volumetric expansion of the vaporizable liquid in the molten metal. to be dispersed. Furthermore, surface treatment of the particles improves their wettability with molten metal.

〔Example〕

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

Example 1 In FIG. 1, an aluminum alloy (JIS A
7075 alloy) was melted to prepare molten metal 4. Separately, add Kchel's salt concentration to non-chemical nickel plating solution (01 mol), 10
Si (, 'particle 13 i 1
A uniform plating layer was formed on each particle by applying ultrasonic waves of 20 KHz (7) for 3 minutes to give slight vibrations.

Next, while stirring the molten metal 4 with a stirring blade 6 connected to the stirring device 5, a mixture 9 of the plating solution and the SIC particles 8 is sprayed onto the surface of the molten metal 4 by a spray gun 10 at a speed of 5 m.
Sprayed in 7 seconds. In this example, the thickness of the Ni plating layer on the particles was 0.05 μm, and injection was performed after the plating reaction was saturated. By directly spraying the plating solution, 100% of the plated SiC particles 8 can be utilized. Please note that direct injection is not possible depending on the composition of the plating solution.
In this case, the same effect can be obtained by precipitating the SiC particles 8 after plating, discarding the supernatant liquid, and adding water to inject a mixture 9 of plated SiC particles 8 and water. can get.

Example 2 In this example, as shown in FIG. 2, all of the molten aluminum alloy 4 is dropped from the ladle 11, and SiC
A mixture 9 of particles 8 and a plating solution was sprayed from a spray gun 10 and directly poured into a casting m12.

Example 6 In this example, as shown in FIG.
A mixture 9 of C particles 8 and a plating solution was sprayed from a spray gun 10 and poured into a mold 12 as it was.

Examples 2 and 3 have the advantage that there is no need to use the stirring device 5 as in Example 1, and only a simple spray device is required.

In addition, the spray gun used in Examples 1 to 3 used air and water (
The effects of the present invention were fully exhibited in both cases, using both a type in which surface treatment liquid (surface treatment liquid) and SiC particles were sprayed and a type in which only water (surface treatment liquid) and SiC particles were sprayed. Also, similar effects can be obtained by using other spraying means instead of the spray gun.

〔Effect of the invention〕

As mentioned above, the method for producing the particle dispersion strengthened alloy of the present invention includes:
A mixture of surface-treated particles to be added as a dispersed phase in the metal and a surface treatment liquid or a vaporizable liquid as a dispersion medium for the particles is injected into the pre-melted molten metal, so that the reinforcing alloy is The uniform dispersibility of the particles and the wettability between the particles and the molten metal were improved, and as a result, the tensile strength and other properties of the reinforced alloy were improved. Furthermore, since fine particles, which were difficult to use in conventional methods, can be used, the stiffness of the reinforced alloy is improved.

For example, an aluminum alloy to which SiC particles with an average particle diameter of α3 μm are added can be cut with a normal carbide tool without using a diamond-coated tool. Moreover, the yield of particles was improved. That is, the yield when adding SiC particles with an average particle size Q of 3 μm to an aluminum alloy using the conventional method was 10 to 20 wt%, but the yield was improved to 60 to 80 wt% with this method. In addition, because there is no need for incidental equipment such as carrier gas or dust collectors, manufacturing costs are lower and the working environment is better. In addition, since surface-treated particles such as plated particles are used without isolation, they can be used 100%, and there is less loss of plated particles compared to when plated particles are used in the conventional production method of particle dispersion strengthened alloys. This eliminates the need for equipment and time for collection and drying, resulting in cost reduction and improved workability.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of Example 1 of the method for producing a particle dispersion strengthened alloy of the present invention, FIG. 2 is an explanatory diagram of Example 2 of the method of the present invention, and FIG. 6 is an explanatory diagram of Example 3 of the method of the present invention. FIG. In the figure, 1... Heating element 2... Heating furnace 3... Crucible 4... Molten metal 5... Stirring device 6... Stirring blade 7.13... Container 8... Particles 9 ...Mixed liquid 10...Spray gun 11...Ladle 1
2... Mold 14... Figure 1 Figure 2 Patent applicant Toyota Motor Corporation

Claims (1)

[Claims] A liquid mixture consisting of surface-treated particles to be added as a dispersed phase into the metal and a surface treatment liquid or a vaporizable liquid as a dispersion medium for the particles is injected into a molten metal that has been melted in advance. A method for producing a particle dispersion strengthened alloy.