JP2008007844A - Method for producing metal-coated ceramics fiber, method for producing formed body and method for producing composite material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently produce metal-coated ceramics fiber at low cost, for efficiently obtaining a composite material in which ceramics fiber is incorporated into a base material metal at low cost. <P>SOLUTION: Only the negative pole of a DC. power source is electrically connected to ceramics fiber, thereafter, the ceramics fiber is subjected to electroless plating, or, an organic metal salt is stuck to the surface of the ceramics fiber, and, thereafter, the organic metal salt is thermally decomposed so as to be turned to a metal, thus the surface of the ceramics fiber is provided with a metal film, to obtain metal-coated ceramics fiber, and further, the metal-coated ceramics fiber is subjected to molding, to obtain a formed body 26. During the molding, or after the completion thereof, the formed body 26 is energized. Next, a metal is infiltrated into the formed body 26, resulting in obtaining the composite material. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a metal-coated ceramic fiber, a method for producing a molded body using the metal-coated ceramic fiber, and a method for producing a composite material using the molded body.

  As a kind of composite material including ceramics and metal, a material in which ceramic fibers are dispersed in a base metal is widely known. This type of composite material is produced, for example, by first providing a formed body of ceramic fibers and then infiltrating the metal into the formed body preheated to about 500 to 800 ° C. In addition, when the metal is infiltrated, a molten metal to which a predetermined high pressure is applied is supplied to the molded body. For this reason, after giving predetermined intensity | strength by giving a baking process to a molded object, it is common to perform the said infiltration.

  Here, the reason why the compact is preheated and the high pressure is applied to the molten metal is that the wettability of the ceramic fiber to the molten metal is not so great. However, preheating the molded body to a high temperature consumes energy and causes an increase in cost. In addition, energy for raising the temperature and maintaining the temperature is also required for the firing treatment for avoiding the collapse of the molded body when the high-pressure molten metal is supplied, and the cost also increases in this respect. In addition, since the firing process takes a long time, the production efficiency of the composite material also decreases.

  From such a viewpoint, Patent Document 1 proposes to provide a Ni film, that is, a metal film, on the surface of the SiC particles by plating. Patent Document 2 discloses that Ni is attached to the surface of SiC particles. Both techniques attempt to improve the wettability with respect to the molten metal by allowing the metal to be present on the surface of the particles in contact with the molten metal.

JP-A-2-22430 Japanese Patent Laid-Open No. 3-146627

  However, in the method described in Patent Document 1, it is difficult to say that the formation of a metal film on ceramic fibers is still more efficient.

  The present invention has been made to solve the above-described problems, and a metal-coated ceramic fiber manufacturing method, a molded body manufacturing method, and the like, capable of forming a metal film on the surface of the ceramic fiber efficiently and at low cost. And it aims at providing the manufacturing method of a composite material.

In order to achieve the above object, the present invention is a method for producing a metal-coated ceramic fiber in which a metal film is formed on the surface of the ceramic fiber,
Electrically connecting only the negative electrode of the DC power source to the ceramic fiber;
Providing a metal film on the surface of the ceramic fiber by applying electroless plating to the ceramic fiber;
It is characterized by having.

Further, the present invention is a method for producing a metal-coated ceramic fiber in which a metal film is formed on the surface of the ceramic fiber,
Electrically connecting only the negative electrode of the DC power source to the ceramic fiber;
Attaching an organometallic salt to the surface of the ceramic fiber;
Providing a metal film on the surface of the ceramic fiber by thermally decomposing the organometallic salt into a metal; and
It is characterized by having.

  That is, in the present invention, after the ceramic fiber is electrically connected only to the negative electrode of the DC power supply, the electroless plating or the organic metal salt once adhered to the surface is thermally decomposed, thereby A film is formed. By using ceramic fibers electrically connected only to the negative electrode of the DC power supply, a metal film having a substantially uniform thickness can be efficiently formed.

  This is presumably because the ceramic fibers that are negatively charged by supplying a negative charge from the negative electrode of the DC power supply electrically attract metal ions and organometallic cations that are positive ions. In addition, it is considered that the removal of the gas component adsorbed on the surface of the ceramic fiber along with the supply of the negative charge effectively works.

  In addition, as a suitable example of a metal film, any of Cu, Zn, Ni, and Fe can be mentioned.

Further, the present invention is a method for producing a molded body comprising a metal-coated ceramic fiber in which a metal film is formed on the surface of the ceramic fiber,
Electrically connecting only the negative electrode of the DC power source to the ceramic fiber;
Electroless plating is performed on the ceramic fiber, or an organic metal salt is attached to the surface of the ceramic fiber, and then the organic metal salt is pyrolyzed to form a metal, thereby forming a metal on the surface of the ceramic fiber. Providing a film to form a metal-coated ceramic fiber;
A step of forming the metal-coated ceramic fiber to form a molded body;
Have
The molded body is energized during or after the molding process.

  That is, the manufacturing method of the molded object which concerns on this invention is implemented using the metal-coated ceramic fiber obtained by said manufacturing method. In this case, since the metal-coated ceramic fibers are energized, the metal coatings are welded to each other, whereby the metal-coated ceramic fibers are connected to each other. As a result, it is possible to easily obtain a molded article exhibiting high strength while having a relative density of about 18 to 40%.

  As described above, any one of Cu, Zn, Ni, and Fe is suitable as the metal film.

Furthermore, the present invention is a method for producing a composite material in which a metal is infiltrated into a molded body made of a metal-coated ceramic fiber having a metal film formed on its surface,
Electrically connecting only the negative electrode of the DC power source to the ceramic fiber;
Electroless plating is performed on the ceramic fiber, or an organic metal salt is attached to the surface of the ceramic fiber, and then the organic metal salt is pyrolyzed to form a metal, thereby forming a metal on the surface of the ceramic fiber. Providing a film to form a metal-coated ceramic fiber;
A step of forming the metal-coated ceramic fiber to form a molded body;
Infiltrating metal into the molded body;
Have
The molded body is energized during or after the molding process.

  That is, in this case, the molded body produced as described above is used. Since the metal coating is present on the surface of the metal-coated ceramic fiber forming the molded body, the wettability to the molten metal is good, so the preheating temperature of the molded body is low and the molten metal pressure is low. However, the molten metal penetrates the molded body efficiently. For this reason, according to the present invention, the energy consumption and thus the cost is reduced, while the production efficiency of the composite material is improved.

  In addition, since the metal-coated ceramic fibers are bonded to each other by energization, a molded body exhibiting high strength is used, so that the firing treatment performed for the purpose of improving the strength of the molded body can be omitted. From this point, it is possible to reduce the cost and improve the production efficiency of the composite material.

In addition, you may make it produce a composite material from the molded object which couple | bonded metal-coated ceramic fibers with binder resin. That is, the present invention is a method for producing a composite material in which a metal is infiltrated into a molded body made of a metal-coated ceramic fiber having a metal film formed on its surface,
Electrically connecting only the negative electrode of the DC power source to the ceramic fiber;
Electroless plating is applied to the ceramic fiber, or an organic metal salt is attached to the surface of the ceramic fiber, and then the organic metal salt is thermally decomposed to become a metal, thereby forming a metal on the surface of the ceramic fiber. Providing a film to form a metal-coated ceramic fiber;
A step of providing a molded body by bonding the metal-coated ceramic fibers through a binder resin;
Infiltrating metal into the molded body;
It is characterized by having.

  Also in this manufacturing method, since the wettability of the metal-coated ceramic fiber (molded body) to the molten metal is good, the molten metal is efficiently used even when the preheating temperature of the molded body is low and the molten metal pressure is low. It penetrates into the molded body. Accordingly, in this case as well, energy consumption and thus cost are reduced, while production efficiency of the composite material is improved.

  In addition, Al or Al alloy can be mentioned as a suitable example of the metal to infiltrate. On the other hand, as described above, any one of Cu, Zn, Ni, and Fe is suitable as the metal film of the metal-coated ceramic fiber. These metal films have very good wettability to Al or Al alloys.

  According to the present invention, since the ceramic fiber is electrically connected only to the negative electrode of the DC power source, a metal film having a substantially uniform thickness can be efficiently formed on the surface of the ceramic fiber.

  In addition, when the metal-coated ceramic fiber is subjected to a molding process or by energization after completion, a molded body having a high strength can be obtained while the relative density is relatively low. Therefore, before the metal is infiltrated, it is possible to omit the firing treatment for the molded body.

  Furthermore, since the wettability of the molded body made of the metal-coated ceramic fiber provided with the metal film to the molten metal is good, even if the preheating temperature of the molded body is low and the molten metal pressure is low, Penetration into the molded body efficiently.

  From the above, it is possible to efficiently produce metal-coated ceramic fibers, molded articles thereof, and composite materials at low cost.

  Hereinafter, preferred embodiments of the manufacturing method of a composite material according to the present invention will be described in relation to the molded body constituting the composite material and the respective manufacturing methods of ceramic fibers constituting the molded body, and the accompanying drawings. Will be described in detail with reference to FIG.

  First, the composite material that is the final product will be described. This composite material is configured by infiltration of a base metal into a molded body made of metal-coated ceramic fibers.

  The metal-coated ceramic fiber has a metal film formed on the surface of the ceramic fiber. The ceramic fiber is not particularly limited, and suitable examples include aluminum oxide (alumina), mullite, aluminum boride, silicon carbide, and the like.

  On the other hand, a material having good wettability with respect to a molten metal serving as a base metal is selected as the material of the metal film. For example, when the base metal is Al or an Al alloy, copper (Cu), zinc (Zn), nickel (Ni), iron (Fe), or the like is preferable.

  The molded body is produced by molding the metal-coated ceramic fiber thus configured into a predetermined shape. The molten metal permeates into the molded body and then hardens to form a composite material in which the base metal is infiltrated into the molded body.

  Next, the manufacturing method of this composite material will be described.

  First, the above metal-coated ceramic fiber is prepared. Here, the metal-coated ceramic fiber is a manufacturing method for providing a metal film by electroless plating (hereinafter referred to as a first fiber manufacturing method), or a manufacturing method for providing a metal film by thermally decomposing a film made of an organic metal salt. (Hereinafter referred to as the second fiber manufacturing method).

  The first fiber manufacturing method includes a first step 1-1 in which only a negative electrode of a DC power source is electrically connected to ceramic fibers, and a second step 2-1 in which electroless plating is performed on the ceramic fibers.

  In the 1-1st step, after the ceramic fibers are accommodated in a conductive container or placed on a conductive mounting table, only the negative electrode of the DC power source is connected to the container or the mounting table, for example, via a lead wire. Are electrically connected. That is, the positive electrode of the DC power source is not electrically connected to the container or the mounting table, and therefore the DC power source and the ceramic fiber are in an electrically open circuit state.

After a predetermined time has elapsed, the ceramic fiber is electrically cut off from the negative electrode of the DC power source. Then, in the 2-1 step, electroless plating is performed. When a Cu metal film is provided, for example, plating containing 10 g / liter of CuSO ₄ .5H ₂ O, 50 g / liter of sodium tartrate, 10 g / liter of sodium hydroxide, and 10 × 10 ⁻³ g / liter of 37% formalin. A liquid may be used.

  When only electroless plating is performed, it takes a relatively long time to form the metal film. In other words, it is not easy to efficiently form a metal film on the surface of the ceramic fiber. Also, the thickness of the metal film is generally uneven.

  On the other hand, when the step 2-1 (electroless plating) is performed after the step 1-1 (electrical connection to the negative electrode of the DC power supply) is performed, a metal film having a substantially uniform thickness is efficiently formed. Is done. This is because, when only the negative electrode of the DC power supply is electrically connected, a negative charge is supplied to the ceramic fiber, and this negative charge releases the gas component adsorbed on the surface of the ceramic fiber. It is assumed that the metal ions that are positive ions are attracted electrically in the process.

  On the other hand, in the second fiber manufacturing method, the 1-2 process of electrically connecting only the negative electrode of the DC power source to the ceramic fiber, and the 2-2 process of attaching an organometallic salt to the surface of the ceramic fiber, And 3-2 step of thermally decomposing the organometallic salt to form a metal film.

  The 1-2 process is the same as the 1-1 process. Thereafter, in the second fiber manufacturing method, an organic metal salt is once attached to the surface of the ceramic fiber, and the metal film is provided by using the organic metal salt as a metal.

  In the case of forming the Cu film, in the step 2-2, for example, the ceramic fiber may be immersed in an alcohol solution of copper formate and copper acetate. By this immersion, copper metal formate and copper acetate, which are organic metal salts, adhere to the surface of the ceramic fiber.

  If filtration etc. are performed after predetermined time passes, the ceramic fiber with which copper formate and copper acetate adhered to the surface will be isolate | separated from an alcohol solution. If this ceramic fiber is subjected to a heat treatment in step 3-2, copper formate and copper acetate undergo thermal decomposition and a Cu film is formed.

  Also in the second fiber manufacturing method, a metal film having a substantially uniform thickness can be efficiently formed. It is assumed that the ceramic fibers are negatively charged, so that the gas adsorbed on the surface is released and the organometallic cations are attracted efficiently.

  Using the metal-coated ceramic fiber thus produced, a molded body is then produced. In this Embodiment, a molded object is manufactured by the manufacturing method which performs a shaping | molding process, energizing.

  In this molded body manufacturing method, for example, a molding apparatus 10 shown in FIG. 1 is used. The forming apparatus 10 includes a cylindrical die 12, a metal outer fitting ring 14 that fits the die 12, and a lower punch 16 and an upper punch 18 that are passed through a through hole of the die 12. 12, the lower punch 16 and the upper punch 18 form a cavity 20.

  Among them, the die 12 is made of an insulating ceramic having good wear resistance, while the lower punch 16 and the upper punch 18 are made of metal. Sliding contact portions 22 and 24 made of conductive ceramics are connected to the tip portions of the lower punch 16 and the upper punch 18 facing each other. Further, a through hole forming core 28 for providing a through hole in the formed body 26 is fitted into the support concave portion 27 of the sliding contact portion 22 of the lower punch 16, and the sliding contact portion 24 of the upper punch 18 is An insertion recess 29 for inserting the tip of the through hole forming core 28 is formed. Here, the through-hole forming core 28 is also formed of insulating ceramics having good wear resistance, like the die 12.

  The lower punch 16 and the upper punch 18 are electrically connected to an AC power supply 32 via lead wires 30a and 30b. In place of the AC power supply 32, a DC power supply may be adopted.

  When the molded body 26 is provided, when the upper punch 18 is separated from the die 12, the metal-coated ceramic fiber is accommodated in the lower punch 16, the through hole forming core 28, and the cavity 20 formed by the die 12. . After energizing the lower punch 16 and the upper punch 18 from the AC power supply 32, the upper punch 18 is inserted into the die 12, and the metal-coated ceramic fiber is pressed by the lower punch 16 and the upper punch 18. Of course, the lower punch 16 and the upper punch 18 may be energized after the pressing of the metal-coated ceramic fibers by the lower punch 16 and the upper punch 18 is started. Note that the side walls of the sliding contact portions 22 and 24 are in sliding contact with the inner wall of the die 12 during this pressing.

  When the metal-coated ceramic fiber is pressed, an electric current flows through the metal-coated ceramic fiber. The lower punch 16 and the upper punch 18 are made of metal, the slidable contact portions 22 and 24 provided at the respective tip portions are made of conductive ceramics, and the metal-coated ceramic fibers are in contact with each other through a metal film. It is.

  In this way, the metal-coated ceramic fibers that are supplied with current and pressed are connected to each other by causing the metal films to be welded together. As a result, a high-strength molded body 26 is produced, although the relative density is relatively small, about 18 to 40%.

  Alternatively, energization of the molded body 26 via the lower punch 16 and the upper punch 18 may be performed after the molded body 26 is obtained. Furthermore, the molded body 26 may be energized after the molded body 26 is removed from the cavity 20.

  Next, a composite material is manufactured using the molded body 26 thus obtained. That is, after filling the pores existing in the molded body 26 with a molten metal, the molten metal is solidified to form a base metal. In order to perform this filling (infiltration), for example, after the molded body 26 is accommodated in a sand mold, the molten metal may be made to reach the molded body 26 in the sand mold via a liner.

Here, 95% Al ₂ O ₃ -5% SiO ₂ (numbers are% by weight, the same applies hereinafter) fibers were formed into a 40 mm × 40 mm × 50 mm rectangular parallelepiped shape by a suction molding method, and this molded body was formed at 1000 ° C. for 90 minutes. FIG. 2 is a graph showing the relationship between the preheating temperature, the molten metal pressure, and the relative density of the fired body when ADC12, which is a kind of Al alloy, is infiltrated into the fired body formed by the firing treatment. Show. The molten metal was prepared in an inert gas atmosphere, and the pouring temperature was 680 ° C.

  From FIG. 2, it is understood that in order to obtain a composite material with a small amount of remaining pores, it is necessary to increase the preheating temperature of the fired body and the molten metal pressure.

On the other hand, FIG. 3 shows that after forming a Cu film by electroless plating on 95% Al ₂ O ₃ -5% SiO ₂ fiber, a molded body having the same dimensions as above is provided, and this molded body is fired. It is a graph which shows the relationship between the preheating temperature of a sintered compact, molten metal pressure, and relative density at the time of performing infiltration of ADC12 without.

Also, 95% Al ₂ O ₃ -5% SiO ₂ fiber is immersed in an alcohol solution of copper formate / copper acetate to separate the solvent, and then thermally decomposed by heating at 300 ° C. for 60 minutes in an inert atmosphere. Then, a Cu film was provided, and a molded body having the same dimensions as the above was provided from this Cu-coated 95% Al ₂ O ₃ -5% SiO ₂ fiber. ADC12 was infiltrated without baking this molded object, and the relationship with the preheating temperature of a sintered body, a molten metal pressure, and a relative density was investigated. The results are shown in FIG. 4 as a graph.

From these FIG. 3 and FIG. 4, in the molded body made of 95% Al ₂ O ₃ -5% SiO ₂ fiber having a Cu film, the preheating temperature is relatively low as 50 ° C. and the molten metal pressure is as low as 300 MPa. Even in such a case, it is clear that a composite material having a remarkably low porosity and a high relative density can be obtained. From this, it can be said that the wettability of the ADC 12 to the molten metal is improved by providing a Cu film on the 95% Al ₂ O ₃ -5% SiO ₂ fiber.

  In addition, in this case, it is possible to omit the firing treatment for the molded body.

  That is, according to the present embodiment, energy consumption can be reduced and the cost can be reduced, and the composite material can be manufactured efficiently. In addition, in addition to the high strength of the molded body, there is no need to make the molten metal high pressure when infiltrating a metal such as Al or an Al alloy.

  Note that the molded body used for infiltration may be a molded body in which metal-coated ceramic fibers are bonded together with a binder resin in place of the one that is energized during or after the production of the molded body. Good. For example, a styrene resin, a urethane resin, or an epoxy resin may be selected as the binder resin.

  That is, for example, a mixture obtained by adding a styrene resin and a foaming agent to metal-coated ceramic fibers is kneaded with a kneader or the like, and then molded while supplying steam, butane gas, or the like to obtain a foamed molded body.

  Next, after sand (for example, slurry containing 40% bentonite and 40% silica sand) is sprayed on the surface of the foamed molded product, it is embedded in a sand mold. When the molten metal is supplied from the sand mold gate, the styrene resin is vaporized and removed, while the molten metal penetrates into the foamed molded body. The infiltrated molten metal is cooled and solidified to obtain a composite material.

  When a foaming agent is used, there is an advantage that defects in the foamed molded product are suppressed and defects in the molten metal are also suppressed.

  The metal forming the metal film and the metal to be infiltrated may be selected in consideration of each other's wettability, and are particularly limited to Cu, Zn, Ni, Fe films and Al or Al alloys. is not.

It is a principal part schematic longitudinal cross-sectional view of the shaping | molding apparatus for performing a shaping | molding process, supplying with electricity with respect to metal-coated ceramic fiber. It is a graph which shows the relationship between the preheating temperature of a sintered compact, molten metal pressure, and relative density at the time of infiltrating ADC12 to the sintered compact consisting of ceramic fiber. It is a graph which shows the relationship between the preheating temperature, molten metal pressure, and relative density of a baking body at the time of infiltrating ADC12 to the molded object which consists of a metal-coated ceramic fiber produced by the 1st fiber manufacturing method. It is a graph which shows the relationship between the preheating temperature of a baked body, a molten metal pressure, and a relative density at the time of infiltrating ADC12 to the molded object which consists of a metal covering ceramic fiber produced by the 2nd fiber manufacturing method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Molding apparatus 12 ... Die 16 ... Lower punch 18 ... Upper punch 20 ... Cavity 22, 24 ... Sliding contact part 26 ... Molding body 28 ... Core 32 for through-hole formation ... AC power supply

Claims (9)

A method for producing a metal-coated ceramic fiber in which a metal film is formed on the surface of the ceramic fiber,
Electrically connecting only the negative electrode of the DC power source to the ceramic fiber;
Providing a metal film on the surface of the ceramic fiber by applying electroless plating to the ceramic fiber;
A method for producing a metal-coated ceramic fiber, comprising: A method for producing a metal-coated ceramic fiber in which a metal film is formed on the surface of the ceramic fiber,
Electrically connecting only the negative electrode of the DC power source to the ceramic fiber;
Attaching an organometallic salt to the surface of the ceramic fiber;
Providing a metal film on the surface of the ceramic fiber by thermally decomposing the organometallic salt into a metal; and
A method for producing a metal-coated ceramic fiber, comprising:   3. The method for producing metal-coated ceramic fibers according to claim 1, wherein a film made of any one of Cu, Zn, Ni, and Fe is provided as the metal film. A method for producing a molded body comprising a metal-coated ceramic fiber having a metal film formed on the surface of a ceramic fiber,
Electrically connecting only the negative electrode of the DC power source to the ceramic fiber;
Electroless plating is performed on the ceramic fiber, or an organic metal salt is attached to the surface of the ceramic fiber, and then the organic metal salt is pyrolyzed to form a metal, thereby forming a metal on the surface of the ceramic fiber. Providing a film to form a metal-coated ceramic fiber;
A step of forming the metal-coated ceramic fiber to form a molded body;
Have
A method for producing a molded body, wherein the molded body is energized during or after the molding process.   The manufacturing method according to claim 4, wherein a film made of any one of Cu, Zn, Ni, and Fe is provided as the metal film. A method for producing a composite material in which a metal is infiltrated into a molded body made of a metal-coated ceramic fiber having a metal film formed on its surface,
Electrically connecting only the negative electrode of the DC power source to the ceramic fiber;
Electroless plating is applied to the ceramic fiber, or an organic metal salt is attached to the surface of the ceramic fiber, and then the organic metal salt is thermally decomposed to become a metal, thereby forming a metal on the surface of the ceramic fiber. Providing a film to form a metal-coated ceramic fiber;
A step of forming the metal-coated ceramic fiber to form a molded body;
Infiltrating metal into the molded body;
Have
A method for producing a composite material, wherein the molded body is energized during or after the molding process. A method for producing a composite material in which a metal is infiltrated into a molded body made of a metal-coated ceramic fiber having a metal film formed on its surface,
Electrically connecting only the negative electrode of the DC power source to the ceramic fiber;
Electroless plating is performed on the ceramic fiber, or an organic metal salt is attached to the surface of the ceramic fiber, and then the organic metal salt is pyrolyzed to form a metal, thereby forming a metal on the surface of the ceramic fiber. Providing a film to form a metal-coated ceramic fiber;
A step of providing a formed body by bonding the metal-coated ceramic fibers through a binder resin;
Infiltrating metal into the molded body;
A method for producing a composite material, comprising:   8. The method of manufacturing a composite material according to claim 6, wherein Al or an Al alloy is infiltrated as the metal. The manufacturing method according to claim 6, wherein a film made of any one of Cu, Zn, Ni, and Fe is provided as the metal film.

Images