JPH0860207A - Production of composite body of metal and oxide - Google Patents

Abstract

PURPOSE: To provide a method for producing a composite body of oxide and metal capable of obtaining a composite body of oxide and metal having an optional constitution by a simple device and simultaneously capable of joining a metallic body or a ceramic body. CONSTITUTION: The powder 2 of oxide as an oxygen feeding source required for the growth of a composite body and an aluminum powder press formed part 1 or a metallic lump are brought into contact and are heated, and by reaction sintering by a thermit reaction of the oxide and aluminum fed by a capillary phenomenon, the composite body is grown.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite of a metal such as aluminum and alumina and a metal oxide thereof and a composite of the composite and a metal body or a ceramic body.

[0002]

2. Description of the Related Art Conventionally, the heat resistance, corrosion resistance, wear resistance and high toughness of a metal oxide in an ordinary bonded body of the metal oxide and the metal have been investigated for mechanical, chemical and physical properties. In order to improve, wear resistance, toughness, or heat resistance is improved by adding flaky, granular, or fibrous carbide in an appropriate ratio. Utilizing the characteristics of this composite, it is widely used in applications such as cyclone liners, piston engine cams, burner tubes and other parts of heating furnaces.

Japanese Patent Publication No. 3-75508 discloses a method for producing such a composite, in which a base metal is oxidized by an oxidation reaction.
It is described that a ceramic matrix composite can be obtained in which an oxide ceramic of the base metal is formed and a base metal as a growth raw material is three-dimensionally reticulated in the formed oxide. .

Since the oxidation of the base metal is carried out by an oxidation reaction with a gas phase oxidant, it is necessary to introduce a gas phase oxidant of oxygen or air, and a special apparatus for introducing oxygen gas into and out of the furnace. Therefore, there is a problem that the equipment cost increases, and a melting furnace or a molten metal reservoir is required because the base metal, which is the feedstock for the growth of the composite, melts into a molten metal, so a dedicated firing furnace is required. Therefore, there is also a problem that the firing work process and work management become complicated.

In addition, the method for producing such a composite has a fatal drawback that it cannot be joined to the metal body because the metal surface of the metal body is oxidized.

Furthermore, since the oxygen supply source is a gas, it is difficult to add alloying elements to the composite, and further, the composite cannot grow in the direction of interrupting the oxygen supply of the preform, and There is also the drawback that barriers have to be formed to prevent complex growth, so the dipping of the preform in the melting furnace is directional and care must be taken in furnace operation during firing. .

[0007]

DISCLOSURE OF THE INVENTION The present invention solves the above drawbacks in producing a composite of an oxide and a metal by oxidizing a metal substrate in an oxidizing atmosphere. Provided is a method for producing a complex of an oxide and a metal, which can obtain a complex of a metal and an oxide having an arbitrary configuration by a simple device and can simultaneously bond a metal body or a ceramic body. Especially.

[0008]

[Means for Solving the Problems] A matrix of a metal and an oxide, characterized in that an oxide powder as a source of oxygen required for growth of a composite and a metal lump or a press-molded product of the metal powder are brought into contact with each other and heated. And a method of joining the composite with a metal body or a ceramic body.

Further, as an oxide powder which is an oxygen supply source necessary for the growth of the composite, an oxide of an alloy element which is desired to be solid-solved or combined with the composite is used, and a composite containing the alloy element is used. You can build a body and improve the physical properties of the complex.

As a concrete example, the present invention is applied to the growth of a composite by reaction sintering by the thermite reaction between an oxide powder as an oxygen source necessary for the growth of the composite and aluminum supplied by a capillary phenomenon. can do.

As the firing atmosphere for the reactive sintering, oxygen existing in the form of a solid oxide is used without the need to supply gaseous oxygen, so that the firing atmosphere can be selected depending on the object to be treated. For example, when firing and joining together with a metal, an inert atmosphere is used, and when joining with ceramics or when manufacturing only a composite, from an atmosphere in which oxygen or air is introduced to an oxidizing atmosphere such as an air atmosphere or You can make a wide selection of inert atmospheres. Furthermore, depending on the type and composition of the oxide powder, it is possible to perform firing in an air atmosphere at a low cost.

As the oxides of these oxygen sources, Fe is used.
O, Fe ₂ O ₃ iron oxides, NiO, Cr ₂ O
One of the oxides such as ₃ may be used, or a mixture of two or more thereof may be used. Further, when heat resistance, corrosion resistance and wear resistance are required, these oxides may be nitrided. ,carbide,
It is also possible to mix borides. However, oxides, nitrides, carbides, and borides, which have a weaker oxygen affinity than Al, such as alumina, zirconia, and calcia, do not serve as an oxygen supply source, so that the content of the oxide powder filler in the oxide powder filler is 98%.
% Should not be exceeded.

[0013]

[Function] A filler containing two or more kinds of oxide powders including magnesium oxide as a source of oxygen required for growth of a complex is brought into contact with a metal lump or a press-formed product of the metal powder, heated, and supplied by a capillary phenomenon. The metal is reduced to reduce the oxide, and at the same time, the metal forms a new oxide. At that time, in the newly formed oxide that was reduced due to the presence of the magnesium oxide powder, a melt passage having a three-dimensional network structure was simultaneously formed, and a complex of the metal supplied by the capillary and the newly formed oxide was formed. As the reaction is repeated, the reaction is repeated and laminated to grow a composite layer.

For example, when the metal substrate is aluminum,
When the equilibrium oxygen partial pressures of aluminum, oxygen, and alumina at the firing temperature are examined, most of the alloying elements that improve the physical properties are higher than the equilibrium oxygen partial pressure of aluminum. for that reason,
The elements that make up the oxide by the thermite reaction of aluminum and oxides are reduced to form elemental solids and evaporate. Not to make a separation layer,
By blending various oxides, composites having different properties can be obtained.

In the bonding using this oxide, the growth of the composite is performed by the Thermite reaction. Therefore, due to the heat of reaction, the reaction interface must be at least 2000.
When the reaction interface grows to the joint, the joint is exposed to high temperature and the base metal is aluminum, depending on the type and composition of the oxide. The form of joining will change.

I. When the compounded oxide raw material is mainly FeO or Fe ₂ O ₃ 2Al + 3FeO = Al ₂ O ₃ + 3Fe 2Al + Fe ₂ O ₃ = Al ₂ O ₃ + 2Fe Normally, alumina and iron are separated by the above-mentioned thermite reaction. Although iron having a large specific gravity sinks downward, in the present invention, iron is extruded at the leading edge of the growth of the composite.
Therefore, in joining with a metal, the iron members come into contact with each other at the joining interface, and the joining portion is melted and joined.

As described above, it is better to consider that the joining using an iron oxide such as FeO or Fe ₂ O ₃ as a raw material is a joining of metals.

II. When the main raw material is an oxide such as NiO or Cr ₂ O ₃ other than iron-based oxides such as FeO or Fe ₂ O ₃ 2Al + Fe ₂ O ₃ = Al ₂ O ₃ + 2Fe 2Al + 3NiO = Al ₂ O ₃ + 3Ni 2Al + Cr ₂ O ₃ = Al ₂ O ₃ + 2Cr As described above, the oxygen source is Fe ₂ O ₃ , NiO, Cr ₂ O ₃
However, when the proportion of Fe ₂ O ₃ is small, not only Cr but also Ni and Fe do not separate from the composite as described in I to form an extruded metal layer. . In this case, most of Cr evaporates, but Ni and Fe both form a solid solution in the complex or form a compound and remain. Therefore, the joint interface is aluminum or aluminum compound in which Ni, Cr, and Fe are solid-solved, which rises due to the capillary phenomenon, and the metal or ceramic as the joint partner.

When the joining partner is a metal, it is bonded by diffusion with aluminum and its compound in which Ni, Cr, and Fe which are leached by a capillary tube are dissolved, and when the complex in a high temperature state melts the metal. It may be melt-bonded.

In the case of joining with ceramics, aluminum and aluminum compound in which Ni, Cr, and Fe are solid-dissolved, which appear at the joining interface, are diffused to join.

Further, the present invention has a meaning that not only a molten metal produced by melting a metal block but also a pressed metal powder product can be used as a metal base material for a growth material of a composite. Even if the temperature is higher than the melting point of the metal, the metal powder is melted because it is covered with the oxide film.
The molten metal is supplied to the oxide powder only inside the powder, and because the powder forms a passage for the molten metal in a state where a part of the oxide film is fractured and connected by thermal stress.
Storage container for oxide powder filler or part of it because it does not burn through. The above functions are fulfilled.

[0022]

EXAMPLE An explanation will be given based on an example in which aluminum powder is used as the metal substrate of the present invention.

FIG. 1 shows a general cross-sectional view of a mixed powder component before firing. In the figure, reference numeral 1 denotes a powder compact obtained by press-molding aluminum powder having an average particle diameter of 0.3 mm into a cylindrical shape at a pressure of 500 Kg / cm ² . Reference numeral 2 denotes a filler containing oxide powder, which changes the type and composition of the oxide depending on the material of the storage cylinder 3. Reference numeral 3 denotes a storage cylinder, which is made of steel pipe, but the storage cylinder 3 may be an alumina pipe or unfired alumina green. Moreover, 4 shows a mount.

Example 1 Production Example of Composite for Jointing with Metal (Table 1) FIG. 2 shows that in FIG. 1, the storage cylinder 3 is made of SUS304 stainless steel pipe, and the filler 2 containing oxide powder is used. To Fe ₂
The following shows the state during firing when a mixed powder filler of 92% by weight of O ₃ and 8% by weight of fine MgO is used. Argon gas was used as the atmosphere, and the atmosphere was maintained at a firing temperature of 1100 ° C. for 8 hours. In this firing process, molten aluminum inside the powder particles of the aluminum powder press product 1 shown in FIG. 2 is leached toward the oxide powder 2 in a state where the oxide film is broken and connected, and comes into contact with the oxide. The thermite reaction of the following formula (1) occurred.

2Al + Fe ₂ O ₃ = 2Fe + Al ₂ O ₃ (1) Formula Aluminum supplied by this capillary phenomenon reacts with the oxide filler 2 to form the complex 5 and the molten iron 6 leached separately from the complex. At the last stage where the oxide powder 3 is consumed by growing toward the stainless steel pipe wall 3,
Molten iron 6 in a high-temperature molten state and stainless steel pipe wall 3 are contact-melted and joined. When the proportion of the iron-based oxide such as Fe ₂ O ₃ is large as in this case, the composite and iron are separated as shown in FIG. 2, and as a result, the iron serves as a joint.

Further, the oxide powder 2 is FeO 46%, Ni
In the case of a filler containing O ₂ 46% and MgO 8%, N
When the ratio of iO is 46%, Cr ₂ O _{3 is} 46%, and MgO is 8%, the growing composite body 5 and the molten iron 6 are not separated from each other.

2Al + 3FeO = 3Fe + Al ₂ O ₃ (2) Formula 2Al + 3NiO = 3Ni + Al ₂ O ₃ 2Al + 3NiO = 3Ni + Al ₂ O ₃ (3) Formula 2Al + Cr ₂ O ₃ = 2Cr + Al ₂ O _{3 In} the case of the above formula (2), melting of FIG. Fe and Ni correspond to iron 6, but Fe is only slightly separated on the surface and both Fe and Ni are contained in the composite 5.

In the case of the above formula (3), Ni and Cr correspond to the molten iron 6 in FIG. 2, but in this case, most of Cr is evaporated, but both Cr and Ni are in the composite body 5. It will be in a state of being contained inside.

Immediately, when the ratio of the oxides of other elements is higher than the ratio of the iron-based oxides or the ratio of the iron-based oxides is low, one layer of composite 5 grows as shown in FIG. Just do.

In this case, the joining in the cases of (2) and (3) is
At the joint interface, leaching to the interface, F
Bonding by diffusion of aluminum and its compound containing e, Ni or Ni, Cr as a solid solution, or melting of the metal by the complex in a high temperature molten state by the thermite reaction is carried out and bonded.

In summary, the way of bonding depends on the type and composition of the oxide. As in the case of FIG. 2, the joining in which the molten iron 6 and the composite body 5 are separated is a metal-to-metal joining, and as in the case of FIG. 3, the original gold element including iron dissolves in the composite body 5 as a solid solution. Bonding is a metal-composite bond.

Example 2 Production Example of Composite for Jointing with Ceramics In the case of ceramics, the iron-based oxide represented by the formula (1) described in the production example of composite for joining with metal is used. As shown in FIG. 2, the mixture containing a large amount of substances is divided into two layers of 5 and 6 to join the molten iron of 6 and the ceramic, and in the case of joining with the ceramic, such a composition is not desirable. .

Further, in the case of blending the oxides represented by the formulas (2) and (3), immediately when the proportion of the iron-based oxide is small or not at all, as shown in FIG. , 6 without separating into two layers, and only one layer of the composite grew as shown in 5 of FIG. 3 and when it became a bonding interface, Fe, Ni or Ni, Cr leaching out was dissolved. Diffusion bonding of aluminum and its compound, or diffusion and fusion bonding with a complex in a high-temperature molten state including the leached metal thereof are performed with ceramics.

Example 3 Example for the purpose of producing a composite only, not for joining, in this case, a method of forming a preform from a filler containing an oxide and immersing it in a molten metal is also possible. As described above, a method using an aluminum powder pressed product is also possible, but in this case, the storage cylinder indicated by 3 need not be metal or ceramics. Any material that holds a ceramic green body, a calcined product, or a filler such as graphite carbon may be used.

However, it is necessary to pay attention to the generation of gas, the reaction with the atmosphere, and the reaction with the growing complex.

The aluminum powder press-molded products shown in FIGS. 1, 2, and 3 do not burn through even though they are heated above the melting point of aluminum and retain their outer shapes. It was confirmed that there was no need for a pool of molten metal and it was economical in terms of equipment.

However, when it is treated with a metal, it must be fired in an inert atmosphere, and the oxide film of each powder forming the aluminum powder press-formed product can prevent burn-through in an inert atmosphere. Since it did not grow to the thickness of 1), it was partially burned out and the outer shape could not be retained. Therefore, when firing in an inert atmosphere, it is necessary to make the oxide film thick beforehand.

Table 1 demonstrates that growth to fillers containing oxides is possible.

[0039]

[Table 1] Since these oxides have higher partial oxygen partial pressure than aluminum, it was confirmed that aluminum and these oxides undergo a thermite reaction to form a composite by reaction sintering.

Examples 12 to 16 were oxide powders 10.
It was a mixture of nitride and carbide in an amount of 50 to 900% with respect to 0%, but was in a state of being dispersed in the composite as an aggregate.

Table 2 shows the measured physical properties of the composites obtained by the examples of Table 1.

[0042]

[Table 2] Reference Example 1 shown in the same table is a composite obtained by the vapor phase oxide method and is made of Si.
It is a wear resistant material in which C is dispersed in an amount of 70% or more as an aggregate. Reference Example 2 is also a composite obtained by the vapor phase oxidation method, but since it was grown by blowing oxygen gas, it is a composite of only alumina and aluminum. Therefore,
The wear resistance of Reference Example 1 is dramatically improved from that of Reference Example 2. However, the bending strength is significantly reduced. Example 8 according to the present invention has a high bending strength but a fracture toughness value of 16 MP√m and F
It is shown that it is increased by the addition of alloy elements such as e, Ni, and CrMg.

On the other hand, Example 9 according to the present invention is a reference even though the composite contains only Ni, Cr and Mg but does not contain SiC as an aggregate to enhance wear resistance. The wear property is improved by about 50% as compared with Example 1. Further, the flexural strength and fracture toughness are also high, and the inclusion of alloying elements improves various physical properties.

[0044]

According to the present invention, the following effects can be obtained.

(1) No need for introduction and supply of vapor phase oxidizer. All of the piping from outside the furnace to the inside of the furnace, the oxygen supply container around the preform body, etc. are unnecessary. Except when joining with a metal, it can be processed in a general heating furnace, does not require special technical equipment, and can simultaneously perform firing and joining of a composite at a low cost and easily. It also leads to the use of metals and expansion of applications.

Further, in the conventional method, the gas phase oxidant must be accurately supplied to the reaction interface where the complex is growing, the equipment inside and outside the furnace is complicated, and a dedicated furnace is required, and it becomes a fired product. Molding of the preform and barrier treatment to the preform are also required. However, in the present invention, only when an inert atmosphere is required, the airtightness for holding the atmosphere needs to function, and the firing furnace, the apparatus, and the configuration thereof do not particularly need to be devised.

(2) Simple equipment When using a powder press shape as the aluminum raw material, the oxide film of the powder keeps the shape of the pressed product at the firing temperature and does not burn through. There is no need for a puddle, and no special equipment is required in this respect.

(3) No Atmosphere Control Needed In the method for producing a composite according to the present invention, the atmosphere can be either oxidative or inert, and it can be either in the air, but the atmosphere is controlled except for simultaneous firing with a metal. No air atmosphere (no oxygen or air introduced into the furnace) is sufficient.

(4) It is not necessary to make a preform when using an aluminum powder press-molded product.

In the conventional method, since the aluminum raw material becomes a molten metal, a preform had to be prepared. However, in the present invention, a powder aluminum pressed product can be used. Therefore, the pressed product is brought into contact with and adjacently filled with an oxide. You don't have to make a preform.

(5) Any alloying element can be added.

When the alloy element is contained in the composite, the bending strength, fracture toughness value, wear resistance and other physical properties can be improved.

(6) Bonding with metals and ceramics is possible.

In the conventional method, when attempting to bond with a metal or ceramics, the growth direction of the composite advances in the direction of blocking the vapor phase oxidant, and at the last stage, the boundary between the metal or ceramics and the growth interface of the composite. Since oxygen cannot be supplied as a driving force for growth and bonding, bonding becomes impossible. However, in the case of metal, in the conventional method, the joint surface is oxidized and cannot be joined, whereas in the present invention, all or part of the preform or the filler is an oxygen supply source, and therefore a gas phase oxidizer is not required. Since oxygen is preliminarily arranged in the form of an oxide at the bonding interface, which is difficult to supply, the thermite reaction occurs, and the heat of reaction causes the diffusion of ceramics or metal and the phenomenon of melting to cause bonding. At that time, when the joining target is a metal, the joining is performed in an inert atmosphere.
When the object to be joined is a ceramic body, when the mixture ratio of the oxide powder that forms one layer of the composite shown in 5 of FIG. 3 does not separate iron from the composite even in an oxidizing atmosphere, iron is oxidized. Since it is not performed, the activated state is maintained at the bonding interface and bonding is performed.

(7) Oxidized structure by the solid-phase oxidizing agent becomes fine.

Comparing the microstructure of the composite by the simple oxidation reaction with the gas phase oxidant of the conventional method and the microstructure of the composite by the thermite reaction of the solid-phase oxidant of the present invention, the microstructure of the present invention is aluminum tertiary The original network structure is fine, and the strength and toughness are high.

(8) The heating temperature can be lowered.

In the method for producing a complex by the thermite reaction of the solid-phase oxidant of the present invention, the firing temperature is 100 ° C. to 350 ° C. lower than that in the oxygen gas oxidation method, and the firing temperature with the metal is It could be maintained at 950 ° C to 1200 ° C. This decrease in heating temperature helps prevent the deterioration of the quality of the metal such as coarsening of crystal grains of carbon steel and stainless steel and the burning phenomenon of grain boundaries, and expands the metal material that can be co-fired.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a structure before firing.

FIG. 2 shows an example during firing.

FIG. 3 shows another example during firing.

[Explanation of symbols]

1 Aluminum Powder Pressed Product 2 Filler Containing Oxide Powder 3 Stainless Steel Pipe or Ceramics or Ceramics Green, etc. 4 Stand 5 Composite 6 Molten Iron

Claims (3)

[Claims] 1. A composite is grown by arranging an oxide powder as an oxygen supply source required for growth of a composite adjacent to a metal powder press-formed product or a metal block and heating the composite. A method for producing a composite of a metal and its oxide. 2. The oxide according to claim 1, wherein an oxide of an alloying element to be contained in the composite is used as the oxide powder which is an oxygen supply source necessary for growth of the composite.
A method for producing a complex of a metal and an oxide thereof, which comprises solid-solubilizing the same alloying element in the complex and combining them. 3. A composite is grown by arranging an oxide powder as an oxygen supply source necessary for the growth of the composite between the metal body or the ceramic body and the metal powder press-formed product or the metal lump and heating the composite. And a method for producing a composite of a metal and an oxide thereof, which comprises bonding with the metal body or the ceramic body.