JP4788878B2 - Whisker coating material and manufacturing method thereof - Google Patents

Description

  The present invention relates to a whisker coating material and a manufacturing method thereof, and more particularly to a whisker coating material having high adhesion strength between a base material and a whisker and a large surface area and a manufacturing method thereof.

Conventionally, a whisker-coated composite powder has been proposed in which a whisker is grown in all directions on the surface, using a powder composed of at least one of metal and ceramics as a core, and the whisker is a carbide of Ti, Zr, Hf, nitrided The core portion was a mixture or solid solution containing at least one of Co, Ni, Mn, P, and B (see, for example, Patent Document 1). .)
Also, a filter made of fibrous ceramics or carbon fibers with whiskers formed on the surface, the whisker composition of carbon, silicon carbide, silicon nitride, titanium carbide, titanium nitride and mixtures thereof has been proposed. (For example, refer to Patent Document 2).
Japanese Patent No. 3004672 Special table 2003-521368 gazette

However, conventional whisker-coated composite powders and the like have limited whisker materials for the purpose of using them as reinforcing materials.
Moreover, since the composition of the whisker and the core material is different, it is still insufficient as a material for achieving the purpose according to various uses.

The inventors of the present invention, for example, when applying a wet surface decoration treatment such as support to a conventional whisker-coated composite powder (when TiC whiskers are formed on a ceramic containing Ni), the difference in wettability From the fact that ceramics is hydrophilic and TiC is hydrophobic, we have obtained technical knowledge that it may not be possible to uniformly treat the core and whiskers.
In other words, when the conventional whisker-coated composite powder is used as an electrode material after surface decoration treatment, the current density is uneven, or a sufficient electrochemical surface area (reaction site) cannot be secured. It was an obstacle to maintain quality.

  The present invention has been made in view of the above-described problems of the prior art, and further, the above technical knowledge. The object of the present invention is to provide a whisker coating with high adhesion strength between a base material and whiskers and a large surface area. An object of the present invention is to provide a whisker coating material and a method for producing the same, which can achieve the object according to the material, particularly various uses.

The present inventors have made intensive studies to achieve the above object, a given substrate, the inert gas per minute 0.1~5L supplying inert gas flow in the melting point of the substrate The present inventors have found that the above object can be achieved by heat treatment at a lower temperature to form whiskers on the surface of the substrate, and the present invention has been completed.

That is, in the whisker coating material of the present invention, a base material containing an alloy containing nickel and one metal element selected from manganese and chromium is grown on the surface of the base material from the base material. And a whisker having an oxide trunk containing one metal element selected from chromium and a metal head containing nickel and one metal element selected from manganese and chromium located at the tip of the oxide trunk The main constituent elements of such whiskers are the same as the constituent elements of the surface portion of the base material .
In a further method of manufacturing a whisker coating material of the present invention is a method for producing the whisker coating material of the present invention, including alloys containing a one kind of metal element and nickel selected from manganese and chromium The substrate is heat-treated at a temperature lower than the melting point of the substrate in an inert gas flow supplying 0.1 to 5 L of inert gas per minute, and selected from manganese and chromium on the surface of the substrate. Forming a whisker having an oxide trunk containing one kind of metal element and a metal head containing nickel and one kind of metal element selected from manganese and chromium located at the tip thereof; This is a method for obtaining a whisker coating material .

According to the present invention, a base material including an alloy containing one metal element selected from manganese and chromium and nickel, in an inert gas flow for supplying 0.1 to 5 L of inert gas per minute. And an oxide trunk containing one metal element selected from manganese and chromium on the surface of the substrate by heat treatment at a temperature lower than the melting point of the substrate, and manganese and chromium located at the tip thereof because and this to form whiskers having a metal head comprising one kind of metal element and nickel which more selected high adhesion strength between the substrate and the whiskers, large whisker coating material of the surface area, especially a variety of applications It is possible to provide a whisker coating material and a method for producing the whisker coating material that can achieve the object according to the above.

Hereinafter, the whisker coating material of the present invention will be described. In the present specification, “%” represents mass percentage unless otherwise specified.
As described above, in the whisker coating material of the present invention, the base material containing a metal, an alloy or ceramics and any mixture thereof includes a whisker containing one or more constituent elements of the base material on the surface of the base material. The main constituent element of the whisker is the same as the constituent element of the surface portion of the base material.
Here, the shape of the base material is not particularly limited, and for example, various shapes such as a spherical shape, a scale shape or a column shape generally called a powder, and a fiber / fiber shape can be used. .
In addition, the term “main” means that when the whisker has a head at its tip, the composition of the head is almost the same as the composition inside the base material, while the trunk occupies most of the whisker. This is because the composition of is substantially the same as the composition of the substrate surface portion.

Although the whisker coating material of the present invention is not particularly limited, the whisker coating material of the present invention is produced by a method described in detail below. Therefore, the adhesion strength between the base material and the whisker is high, and the size of the formed whisker is, for example, an average thickness. It is very fine such as 50 nm in length and 100 μm in length, and the surface area is remarkably large. Such a large surface area can drastically improve the catalytic activity when used as a catalyst support with high social demand.
In addition, since the formation density of whiskers is remarkably improved, it becomes easy to get entangled and easy to contact each other. For example, when used for a filter or a shock absorbing material, it is processed into an arbitrary shape without a step such as sintering. be able to.

  Since the main constituent element of the whisker provided is the same as the constituent element of the surface portion of the base material, the adhesion strength between the base material and the whisker is further increased, and the surface composition of the entire whisker coating material Is almost uniform, for example, when the whisker itself is a functional material, the whisker coating material as a whole, it is easy to demonstrate the functionality that has, on the other hand, even when subjected to surface support treatment, It becomes easy to obtain a uniform surface composition.

Moreover, in the whisker coating material of the present invention, it is desirable that the composition of the inside and the surface portion of the base material be different. In other words, since it is produced by the method described in detail later, the element having a high vapor pressure contained in the base material is evaporated by the heat treatment, and is reattached to the base material surface to form a layer having a composition different from the inside. There is. Moreover, it is not necessary for the whole base material to have the same composition from the stage before the heat treatment, and for example, it may be coated with a composition containing an element for which whisker is to be formed on an arbitrary metal powder surface.
In this way, the elements necessary for the formation of whiskers are gathered on the surface in particular. Therefore, when forming whiskers of a functional material, elements that inhibit the function can be confined inside.

Furthermore, in the whisker coating material of the present invention, the diameter of the whisker (DW) and the minimum diameter (DS) of the substrate are expressed by the following formula (1).
DW / DS ≦ 1/10 (1)
It is preferable to satisfy the relationship represented by these.
Here, “minimum base material diameter (DS)” means, for example, the diameter when the base material is spherical, the thickness when it is scaly, and the fiber diameter when it is fiber / fibrous. .
With such a structure, when the whisker coating material is handled as a powder, the strength of the structure can be maintained more easily, and the effect of increasing the surface area can be further exhibited.

In the whisker coating material of the present invention, the base material may contain a metal element related to silicon, manganese, aluminum, chromium, indium, silver, gallium, tin, copper, scandium, germanium, and any combination thereof. desirable.
These metals are metals with high vapor pressure, and when they evaporate and deposit on the substrate surface, whiskers can be formed.

Furthermore, in the whisker coating material of the present invention, it is desirable that the base material contains a metal element related to nickel, iron or cobalt and any combination thereof.
These metals have a function of acting catalytically, that is, a function of promoting the formation of whiskers, and it becomes possible to obtain particularly finer and densely formed whiskers. Thereby, a surface area can be increased more.

Moreover, in the whisker coating material of the present invention, the whisker provided is a metal element according to silicon, manganese, aluminum, chromium, indium, silver, gallium, tin, copper, scandium, germanium, nickel, iron, cobalt, and any combination thereof. It is desirable that it is a metal or oxide containing.
These metals are metals with high vapor pressure, and when they evaporate and deposit on the substrate surface, whiskers can be formed. Moreover, when oxygen exists in the atmosphere at the time of precipitation, it may precipitate as an oxide.

Next, the manufacturing method of the whisker coating material of this invention is demonstrated.
As described above, the method for producing the whisker coating material of the present invention is a method for producing the above whisker coating material of the present invention, wherein a substrate or substrate precursor containing a metal, an alloy, ceramics, and a mixture thereof is used. This is a method for obtaining a desired whisker coating material by forming a whisker on the surface of the substrate by performing a heat treatment in an inert gas atmosphere at a temperature lower than the melting point of the substrate or substrate precursor. .
Here, “base material or base material precursor” is described in consideration of the case where the composition of the base material changes due to heat treatment.

  Thus, it is not necessary to supply whisker raw materials from the outside as in CVD, for example, by a simple method such as heat treatment at a temperature at which the base material or base material precursor does not melt in an inert gas atmosphere. In addition, a desired whisker coating material can be obtained.

  It is also possible to form whiskers by heat treatment in an inert gas flow. The amount of inert gas introduced at that time is determined according to the size and shape of the reaction furnace and the raw material substrate. For example, when the reactor capacity is 3 L, the inert gas is reduced to 0 per minute. It is desirable to supply about 1-5L. In this case, a whisker having a trunk grown from the base material, or a trunk grown from the base material and a head located at the tip thereof can be obtained.

Furthermore, when the supply flow rate of the inert gas is in the above range, the “wool whisker” can be formed by supplying the inert gas in an arbitrary low flow rate range. This “wool-like whisker” has, for example, a shape as shown in FIG. 5 and has a trunk grown from the base material and a head located at the tip thereof, and a plurality of trunks are mutually connected. The plurality of trunks share one head while being gathered together to twist.
That is, normal whiskers are composed of a pair of spherical heads and columnar trunks, but “wool-like whiskers” are composed of a plurality of trunks for one head, and the trunks twist each other. It is formed to fit.
The “wool-like whisker” may be formed by twisting a plurality of trunks mutually twisted together.

  By forming such a woolen whisker, not only the surface area of the whisker coating material is further increased, but also has a higher strength than ordinary whiskers even if the trunk is the same thickness, and the inside of the whisker is also periodic and very fine. A void is formed. For this reason, for example, when used as a carrier such as a catalyst, a carrier having a higher catalytic effect can be obtained.

The flow rate of the inert gas for forming such a woolen whisker varies depending on the elements of the whisker raw material, but for example, in the case of silicon oxide, it is desirable to supply 0.1 to 1 L.
Moreover, although it is necessary to perform the treatment at a temperature lower than the melting point of the whisker to be formed, the temperature at the time of the heat treatment varies depending on the composition of the whisker to be formed, and is typically in the range of 700 to 1200 ° C.

  Hereinafter, the present invention will be described in detail with reference to some examples, but the present invention is not limited to these examples.

(Example 1)
A whisker coating material of this example was obtained by using Mn—Ni alloy powder as a raw material, firing at 1100 ° C. for 1 hour while supplying argon as an inert gas at 1 L / min, and then cooling.
Composition analysis of the formed whiskers by energy dispersive X-ray fluorescence analysis (EDX) revealed that only Mn and oxygen (O) were detected in the trunk and Ni and Mn were detected in the head.
FIG. 1 is a scanning electron microscope (SEM) photograph of the obtained whisker coating material. 2A is an SEM photograph showing the appearance of the whisker coating material, and FIG. 2B is an SEM photograph showing the appearance of the whisker portion where the whisker coating material is formed.
Compared with the whisker of Comparative Example 1 shown below (see FIG. 2), fine whiskers can be densely grown when Ni is mixed.

( Comparative Example 1 )
The whisker coating material of this example was obtained by using 100% Mn powder as a raw material, firing at 1100 ° C. for 1 hour while supplying argon as an inert gas at 1 L / min, and then cooling.
The composition of the formed whiskers was analyzed by EDX, and only Mn and O were detected.
FIG. 2 is an SEM photograph showing the appearance of the whisker portion on which the obtained whisker coating material is formed.

(Example 3)
Using a Cr—Ni alloy powder as a raw material, while supplying argon as an inert gas at 1 L / min, firing was performed at 1000 ° C. for 1 hour, followed by cooling to obtain a whisker coating material of this example.
When the composition of the formed whiskers was analyzed by EDX, only Cr and O were detected in the trunk and Cr and Ni were detected in the head.
FIG. 3 is an SEM photograph of the obtained whisker coating material. 2A is an SEM photograph showing the appearance of the whisker coating material, and FIG. 2B is an SEM photograph showing the appearance of the whisker portion where the whisker coating material is formed.

( Reference Example 4)
Using an Al—Fe alloy powder (fibrous) as a raw material, while supplying argon as an inert gas at 1 L / min, firing was performed at 1000 ° C. for 1 hour, followed by cooling to obtain a whisker coating material of this example. .
The composition of the formed whiskers was analyzed by EDX, and only Al and O were detected. The head was not observed.
FIG. 4 is an SEM photograph of the obtained whisker coating material. 2A is an SEM photograph showing the appearance of the whisker coating material, and FIG. 2B is an SEM photograph showing the appearance of the whisker portion where the whisker coating material is formed.

( Reference Example 5)
While using as a raw material a porous sintered metal of Ni powder (manufactured by Kojundo Chemical Laboratory Co., Ltd.) mixed with Mn powder at a rate of 10%, while supplying argon as an inert gas at 1 L / min, The mixture was baked at 1000 ° C. for 1 hour and then cooled to obtain the whisker coating material of this example.
When the composition analysis of the formed whisker was performed, only Mn and O were detected.

( Reference Example 6)
A material obtained by sputtering a Ni film on the Si substrate surface (sputtering pressure 1 Pa, DC 250 W using Ar gas) is used as a raw material, and argon is supplied at 0.5 L / min as an inert gas for 1 hour at 1000 ° C. Firing and then cooling were performed to obtain the woolen whisker coating material of this example. An SEM photograph of this whisker coating material is shown in FIG.
When composition analysis of the formed whiskers was performed, only Si and O were detected.

  The whisker coating material of the present invention has high adhesion strength between the base material and the whisker and has a large surface area, and can be used as, for example, a catalyst-supporting base material for supporting a catalyst. Moreover, since the formation density of whiskers is remarkably high, it can be used, for example, as a filter material or a shock absorbing material. Furthermore, it is easy to carry out wet surface decoration treatment such as support on whiskers, and it is used not only as a support substrate for a catalyst, but also as an electrode material that is less likely to be biased in current density and can ensure a sufficient electrochemical surface area. be able to.

2 is a SEM photograph of the whisker coating material of Example 1. 4 is a SEM photograph showing an appearance of a whisker portion of a whisker coating material of Comparative Example 1. 4 is a SEM photograph of the whisker coating material of Example 3. 6 is a SEM photograph of the whisker coating material of Reference Example 4. 10 is a SEM photograph of the whisker coating material of Reference Example 6.

Claims (2)

A substrate including an alloy containing nickel and one metal element selected from manganese and chromium is one metal selected from manganese and chromium grown from the substrate on the surface of the substrate. A whisker having an oxide trunk containing an element and a metal head containing nickel and one metal element selected from manganese and chromium located at the tip of the oxide trunk;
The whisker coating material, wherein the main constituent element of the whisker is the same as the constituent element of the surface portion of the substrate.   In producing the whisker coating material according to claim 1, a base material containing an alloy containing one kind of metal element selected from manganese and chromium and nickel, and 0.1 to 5 L of inert gas per minute. One metal element selected from manganese and chromium grown from the base material on the surface of the base material by heat treatment at a temperature lower than the melting point of the base material in the supplied inert gas flow A whisker-covering material, characterized by forming a whisker having an oxide trunk containing nickel and a metal head containing nickel and one metal element selected from manganese and chromium located at the tip thereof Method.

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