JPH04128331A - Silver-tin oxide composite material and its production - Google Patents

Abstract

PURPOSE:To produce the silver-tin composite material in which the fine particles of the desired tin oxide are bonded in a good wetting state with a silver base substrate and are uniformly dispersed in the silver base substrate by putting a silver-tin system into the state where a liquid phase and a solid phase coexist at the time of executing the internal oxidation of the system, thereby increasing the diffusion rate of oxygen. CONSTITUTION:The silver-tin oxide composite material which consists of the silver base substrate, (a) 1 to 20wt.%, in terms of metal, tin oxide, and further, (b) 0.01 to 8wt.%, in terms of metal, the oxide of at least one kind of the elements selected from a group consisting of Mg, Zr, Ca, Al, Ce, Cr, Mn, and Ti, and/or (c) 0.01 to 15wt.%, in terms of metal, the oxide of at least one kind of the element selected from the group consisting of Cd, Sb, In, Bi, Zn, and iron-group metals, depending upon cases, and in which the tin oxides in (a) and the oxide of the elements of the above-mentioned (b) and/or the above-mentioned (c), depending upon cases, are dispersed uniformly in the above-mentioned silver base substrate in the fine particle state having the dense crystal structures and in the bond state having the good wettability with the silver base substrate from the surface to the deep part of the silver base substrate is produced with excellent productivity.

Description

[Detailed description of the invention]

[0001]

[Industrial application field]

The present invention relates to a silver-tin oxide composite material and a method for producing the same, and more particularly to a silver-tin oxide composite material suitable for use as an electrical contact material, a welding electrode material, etc., and a method for producing the same. [0002]

[Conventional technology]

Silver-tin oxide composite materials, which are made by adding tin oxide to silver, have greatly improved strength and are used as electrical contact materials for AC and DC relays, switches, current circuit breakers, etc. used in the atmosphere. It is used as a suitable medium-load switching electrical contact material. Conventionally, silver-tin oxide composite materials have been manufactured by internally oxidizing a silver-tin alloy and by sintering silver powder and tin oxide powder using a powder metallurgy method. [0003]

[Problem to be solved by the invention]

The above internal oxidation method involves heating a solid solution alloy of silver-tin below its melting point, and then increasing the oxygen partial pressure to 'lN+4-IZ6.5t5
1 s&-ft, oxygen is diffused into the alloy, and tin (X/) having a relatively high oxygen affinity is precipitated as tin oxide in the form of fine particles in the silver matrix. However, the composite material that can be produced by this internal oxidation method has a silver content of up to about 4% by weight.
Since the diffusion rate of oxygen into the solid solution alloy is extremely low, it has the disadvantage that it takes a long time to manufacture. In order to increase the content of tin oxide to more than about 4% by weight or to increase the oxidation rate, elements that promote oxidation such as In and Bi are added and subjected to internal oxidation. However, even in this case, for example, a long time of about one month was required to oxidize an alloy with a thickness of about 2 mm. [0004] Furthermore, according to internal oxidation, the amount of oxygen diffused into the solid solution alloy decreases in inverse proportion to the square of the depth from the surface, so tin oxide particles become coarser closer to the surface, but at deeper depths. (It is inevitable that an alloy phase with few tiny tin oxide particles will be formed). Therefore, the obtained silver-tin composite material not only has a non-uniform distribution of tin oxide particles, but also a non-uniform particle size, which becomes smaller as the depth increases. Since the particle sizes of the tin oxide particles are irregular and segregated as described above, there is a limit to the improvement in the strength of the resulting composite material, and there has been a demand for improvement of the negative layer. [0005] The production of silver-tin oxide composite materials by powder metallurgy involves sintering highly heat-resistant SnO3 powder and silver powder at the same phase temperature as silver, so the interaction between the silver phase and tin oxide particles is difficult. A strong bond cannot be obtained between them, and defects in the crystal structure of tin oxide cannot be improved. Therefore, the resulting sintered body has low mechanical strength, especially strength at high temperatures, and this cannot be improved even by post-processing such as hot extrusion or forging. As a method for improving silver-tin oxide composite materials produced by the powder sintering method, attempts have been made to add W, Mo, etc., which form lower oxides, but conversely, when used as contact materials, they increase contact resistance. Also, since it becomes easier to weld, little improvement can be expected. Further, although improvements may be made by adding heat-resistant oxides such as MnO, Cab, ZrO, etc., these impair sinterability and, as a result, the mechanical strength of the sintered body is reduced. [0006] Therefore, an object of the present invention is to combine tin oxide fine particles with a bank matrix in a good monolithic state. Sakaihei 4-128331 (
5) To provide a silver-tin oxide composite material uniformly dispersed in a bank matrix and a highly productive manufacturing method capable of manufacturing such a composite material in a relatively short time. . [0007]

[Means to solve the problem]

The present invention makes it possible to increase the oxygen diffusion rate by placing the system in a state where a liquid phase and a solid phase coexist when carrying out internal oxidation of a silver-tin system, and furthermore, the target tin oxide fine particles can be produced. It has been found that it is possible to obtain a silver-tin oxide composite material in which the silver-tin oxide is bonded to the matrix substrate in a good wet state and uniformly dispersed in the bank matrix. [0008] In other words, the present invention provides a final substrate and (a) 1 in terms of metal.
~20% by weight of tin oxide and optionally present (b
) 0.01 to 8% by weight of Mg, Zr, C in terms of metal
a, an oxide of at least one element selected from the group consisting of Al, Ce, Cr, Mn, and Ti; and/or (c) 0.01 to 15% by weight of Cd, Sb in terms of metal.
, In, Bi, Zn, and an oxide of at least one element selected from the group consisting of iron group metals,
a) tin oxide and optionally present said (b)
) and/or the oxide of the element (c) is in a fine particle state having a hard and dense crystal structure, and is bonded to the base matrix from the surface of the base matrix to the deep part thereof, and has good wettability with the base matrix. A silver-tin oxide composite material is provided that is uniformly dispersed in a matrix. [0009] When the composite material of the present invention contains an oxide of the element (b) and/or an oxide of the element (c) in addition to the tin oxide, these oxides are usually It exists in the form of a conjugated oxide (that is, a composite oxide). [00103] The composite material of the present invention has excellent strength at high temperatures and is useful, for example, as an electrical contact material for AC/DC relay switches, current circuit breakers, etc. used in the atmosphere. Especially (b) above
Since the oxide of the element increases the heat resistance of the composite material, (b
) is suitable as an electrode material for electric welding, for example. In addition, the metal (e) has the effect of promoting the oxidation of tin etc. in the manufacturing method as described below, and this oxide forms a military oxide with tin etc. to stabilize the contact resistance in the low current region. It is effective for [0011] The composite material of the present invention preferably contains tin and, if it contains, oxides of the elements (a) and (b) in a total amount of about 50% by weight or less, preferably Approximately 30% by weight
It is as follows. If it exceeds about 50% by weight, the electrical conductivity of the composite material will be impaired. [0012] As explained below, the composite material of the present invention includes various embodiments. In either embodiment, (a)
The tin oxide, the oxide of the element (b) and/or the oxide of the element (c) present depending on the embodiment are uniformly dispersed in the silver matrix in the above-mentioned state. [0013] In a first embodiment of the composite material of the present invention, the composite material comprises a silver mother matrix and tin oxide in an amount of 1 to 20% by weight, calculated as tin metal. [0014] In a second embodiment of the composite material of the present invention, the composite material comprises a silver matrix, (a) tin oxide in an amount of 1 to 20% by weight, calculated as metal tin, and (b) tin oxide, calculated as metal tin. 0.01-8% by weight of Mg
, Zr, Ca, Al, Ce, Cr, Mn, and an oxide of at least one element selected from the group consisting of Ti, and these oxides (a) and (b) form a conjugated oxide. are doing. [0015] In a third embodiment of the composite material of the present invention, a silver mother matrix and (a
) tin oxide in an amount of 1 to 20% by weight calculated as metallic tin, and (c)
0.01 to 15% by weight of Cd, Sb, In in terms of metal
, Bi, Zn, and an oxide of at least one element selected from the group consisting of iron group metals, and these (
The oxides a) and (c) form a conjugated oxide. [0016] In a fourth aspect of the present invention, a silver mother substrate, (a) tin oxide in an amount of 1 to 20% by weight calculated as metal tin, and (b) tin oxide in an amount of 0.01 to 8% by weight calculated as metal tin. , Mg, Zr, Ca, Al
, Ce, Cr, Mn, and Ti, and (c) O001 to 15% by weight of Cd, Sb, In, and Bi in terms of metal.
, an oxide of at least one element selected from the group consisting of Zn and iron group metals, and these (a)
The oxides (b) and (c) form a conjugated oxide. [0017] In the second to fourth embodiments above, the formed conjugated oxide usually has a hard and dense crystal structure and is in the form of fine particles with a particle size of 0.1 μm or less on the surface of the base substrate. It is uniformly dispersed in the bank matrix in a bonded state with good wettability, that is, in a tightly bonded state with no voids, from the beginning to the deepest part of the base matrix. [0018] Acid. Nowa. In the method of the invention, starting materials containing silver and tin are placed in a coexistence of liquid and solid phases. In this state, a part of the system exists in a liquid phase, but this liquid phase plays the role of a good transport route for oxygen, so oxygen can diffuse more quickly than in conventional internal oxidation methods. oxidation progresses uniformly from the surface to the deep part in a relatively short period of time. [0019] (A) silver; and (a) 1 to 20% by weight of metallic and/or oxide tin, and optionally further (b) 0.01 to 8% by weight of metallic equivalent. % metallic and/or
Or oxide Mg, Zr, Ca, Al, Ce
, Cr, Mn, and at least one element selected from the group consisting of Ti and/or (c) 0.01 in terms of metal
~15% by weight of metallic and/or oxidic Cd, S
By heating a mixture containing at least one element selected from the group consisting of B, In, Bi, Zn, and iron group metals and increasing the oxygen partial pressure, a liquid phase and a solid phase coexist. This removes tin, if metallic, and optionally the (b)
) and/or the entire amount of the metallic form of the element (c) to be precipitated as oxides, and (B) then cooling the mixture thus treated and lowering the oxygen partial pressure. has. [0020] In this method, the mixture used as a starting material in step (A) contains, for example, silver, tin, and in some cases, the element (b) and/or the element (c) which is further added as necessary. ) may be in the state of an alloy consisting of the elements, or may be in the state of a sintered body produced by a powder metallurgy method. Said (
Element b) has a high affinity for oxygen and is effective in making precipitated oxide particles finer, thereby improving the fire resistance of the resulting composite material. There is relatively little tin, (
Mixtures with a high content of element b) are generally difficult to oxidize, but according to the method of the present invention, oxidation progresses easily, and a composite material with high fire resistance and suitable as a welding electrode material can be obtained. . The above element (c) is effective in promoting oxidation. There is almost no limit to the amount of oxide that can be included in the composite material, but as mentioned above, it is usually 50% by weight or less. [0021] The sintered body used as the starting mixture may be made of, for example, silver powder and an alloy powder consisting of silver, tin, and, if necessary, the element (b) and/or the element (c). Examples include manufactured sintered bodies. [0022] In addition, the above-mentioned sintered body as a starting mixture includes silver powder, (a) tin, and [0023] When carrying out the above method, a mixture of an alloy or a sintered body may be used. It is preferable to coat the surface with silver or a silver alloy mainly composed of silver (low concentration of other component metals of 1% by weight or less). This is because when high oxygen pressure is applied to a silver mixture containing 5 to 20% tin by weight, SnO3 accumulates on the surface, which may prevent oxygen from permeating or penetrating into the mixture. In order to prevent this, it is necessary to gradually increase the oxygen partial pressure to the target value, which requires a long time for the oxidation treatment. However, by applying the above-mentioned coating in advance, it is possible to prevent the accumulation of SnO□ on the surface layer, so the treatment can be started at the required oxygen pressure from the beginning, and the oxidation treatment can be completed in a short time. It has the advantage of being able to finish with [0024] By using the mixture, the composite material of the first aspect is obtained. [0025] Further, in this method, as a starting mixture, (a) 1 to 20% by weight of tin, and 0.01 to 8% by weight of the element (b) above.
The composite material of the second aspect can be obtained by using a silver mixture consisting of silver and silver. When the system is placed in a state where a liquid phase and a solid phase coexist, all of the metals (a) and (b) are precipitated as oxides as oxidation progresses. [0026] Further, in this method, as a starting mixture (a)
The composite material of the third embodiment is obtained by using a silver mixture consisting of 1 to 15% by weight of tin, 0.01 to 15% by weight of the element (c) above, and the balance silver. When the system is placed in a state where a liquid phase and a solid phase coexist, all of the metals (a) and (c) are precipitated as oxides as oxidation progresses. [0027] Furthermore, in this method, as the starting mixture,
(a) 1-20% by weight of tin, 0.01-20% of the above element (b)
The composite material of the fourth aspect is obtained by using a silver mixture consisting of 8% by weight, 0.01-15% by weight of element (c) above and the balance silver. When the system is placed in a state where liquid and solid phases coexist, as oxidation progresses (a)
All of the metals (b) and (c) are precipitated as oxides. [0028] In the production method of the present invention, each of tin, the element (b), and the element (c) used in the starting mixture used in step (A) is partially or completely Particle size 0.1
It may exist as an oxide with a size of μm or less. Therefore, in another embodiment of the method of the invention, the mixture used in step (A) comprises silver powder and (a) a particle size of 0.1 μm.
m or less, and if necessary, further oxide powder of the element (b) with a particle size of 0.1 μm or less and/or oxide powder of the element (c) with a particle size of 0.1 μm or less. One example is a method in which a sintered body manufactured from [0029] In the case of this embodiment, the tin oxide (a) dispersed in the final matrix and the optionally present oxide of the element (b) and/or the element (c) have a particle size of 0 in advance. It is used in the form of oxide powder of .1 μm or less. When the system is placed in a state where it partially becomes a liquid phase, the fine voids between and around the silver particles and oxide particles present in the sintered body, which is the starting material, are filled with the liquid phase, resulting in a dense structure. structure, and the strength of the resulting composite material is improved. [0030] In this aspect, when the sintered body is a sintered body manufactured from silver powder and 1 to 20% by weight tin oxide powder in terms of metal, the sintered body according to the first aspect A composite material is obtained. [0031] In addition, in this embodiment, the sintered body contains silver powder, (a) tin oxide powder of 1 to 20% by weight in terms of metal, and Mg of 0.01 to 8% by weight in terms of metal. When using a sintered body manufactured from an oxide powder of element (b) such as
A composite material according to the second aspect is obtained. [0032] Furthermore, in this embodiment, the sintered body contains silver powder, (a) 1 to 20% by weight of tin oxide powder in terms of metal, and 0.01 to 15% by weight of Cd in terms of metal. etc. (c)
When using a sintered body made from oxides of elements,
A composite material according to the third aspect is obtained. [0033] Furthermore, the sintered body may include silver powder, (a) tin oxide powder of 1 to 20% by weight in terms of metal, and 0.01 to 8% by weight in terms of metal (Kg, etc.). oxide powder of element b) and 0.01 to 15% by weight of Cd etc. in terms of metal (c)
When using a sintered body made from oxides of elements,
A composite material according to the fourth aspect is obtained. [0034]

[Effect]

FIG. 1 shows a temperature versus pressure phase diagram of the silver-oxygen system. In the method of the invention, the starting mixture is tin, (b) and/or (
When the element c) is contained in a metallic state, the phase diagram becomes more or less specific. However, the state diagram of FIG. 1 is helpful in understanding the method of the present invention. When the system is placed in a state where the liquid phase and the same phase coexist (the region shown as α in Figure 1), the silver phase is partially in the liquid phase, so oxygen is removed from the system by the oxygen pressure outside. It is easy to penetrate and diffuse into the body. This oxygen diffusion rate is significantly higher than the rate at which oxygen is diffused into the solid solution in conventional internal oxidation methods. Oxygen is transported through the liquid phase. If tin, element (b) and/or element (c) are present in the system in a metallic state, they will be oxidized. Oxidation proceeds from the surface of the system. For example, if tin is present in the system, as oxidation progresses, tin is oxidized from the silver-tin solution that has become a liquid phase and precipitated as SnO3 particles to form a pure silver phase. It is thought that this process progresses sequentially from the surface to the depths, and eventually the entire system becomes a state in which tin oxide fine particles are uniformly dispersed in the bank matrix. [0035] Since the temperature versus pressure phase diagram differs depending on the presence or absence and content of tin, the element (b) and/or the element (c), the temperature and pressure at which the liquid phase appears may vary in part. I can't say it. However, by increasing the temperature and pressure of a given starting mixture, the state changes from a state where only a solid phase is present to a state where a solid phase and a liquid phase coexist. can be found. If even a small portion of the system becomes liquid, the oxygen diffusion rate increases dramatically. Therefore, as long as a liquid phase exists, low pressure and temperature may be used. Such conditions are advantageous in that energy consumption is small. The solid phase and liquid phase coexist in a wide range of conditions (especially in a certain temperature range, there is no upper limit to the pressure);
It is practical to find coexistence conditions and carry out the method of the present invention in the range of 50 atmospheres. [0036] The method of bringing the starting mixture to the target temperature and oxygen partial pressure state is not limited at all, but for example, first the temperature is adjusted to the required temperature, and then the temperature is adjusted from the α region to the α-plus region. A method of controlling the oxygen partial pressure to a required value may also be used. Also, after increasing the oxygen partial pressure to a certain target, α + L from the α + Ag2O region
A method of gradually increasing the temperature toward the region may also be used. [0037]

【Example】

Examples 1 to 10 () Quantum 4-1 etc. F5t5t5jL (1t) Samples of each example were prepared by any of the following methods A to E. Table 2 shows the composition and manufacturing method of the samples of each example. Method A: A plate obtained by rolling a silver-tin alloy containing tin in a predetermined proportion to a thickness of 1 mm using a normal hot rolling method with a layer of pure silver 1/10 thick as the lining. Dimensions from 4.5mm
Punch out a disk with a diameter of 1 mm. A sample is prepared by silver plating the entire surface of this disk to a thickness of 3 microns using the barrel silver plating method. Method B: 1i before Mg, Zr, Cd, Sb, etc.
After casting a molten silver-tin alloy containing at least one of Group 12 (a) and/or Group (b) in a hole with a diameter of 4.5 mm and a depth of 1.0 mm provided in a carbon plate mold. , cool in a mold and make a disk with dimensions of 4.5 mmφ x 1 mm. The entire surface of the obtained disk was coated with a thickness of 5 mm using the barrel silver plating method.
Prepare the sample by silver plating the micron. Method C: A molten silver-tin alloy containing 30% by weight of tin was injected into nitrogen gas to form a powder. The obtained silver-alloy powder and silver powder are mixed so that the proportion of tin becomes a predetermined value, and then pulverized with a vibrating mill. The resulting mixed powder is molded into disks with dimensions 4.5 mm tl x 1.1 mm under a pressure of 1 ton. The obtained green compact was held at 750° C. for 1 hour in a nitrogen atmosphere for temporary sintering, and then remolded to a size of 4.5 mmφX 1. Adjust to 0mm and use as a sample. Method D: 75% by weight of tin and the balance Mg, Zr, Ca,
A molten metal of an intermetallic compound consisting of at least Al, Ce, Cr, Mn, and Ti was injected into nitrogen gas to form a powder. The obtained tin alloy powder and silver powder were mixed with tin and Ll.
After mixing so that the amount of g, etc. becomes a predetermined value, the mixture is pulverized using a vibrating mill. Method E: The obtained mixed powder is mixed with silver powder, tin oxide powder, and powder of other metal oxides used as necessary so that each component has a predetermined amount in terms of metal, and then processed with a vibrating mill. Smash. The obtained mixed powder is subjected to powder compaction, temporary sintering, and remolding in the same manner as Method C, and is used as a sample. The samples of Examples 1 to 10 were placed in a heat-resistant container made of heat-resistant stainless steel, sealed, and heated to 510 ° C. in an oxygen stream.
The oxygen partial pressure was gradually increased to 414 atm and maintained for 8 hours. Thereafter, the temperature was maintained at 500° C. and 500 atm for 10 minutes. Thereafter, the pressure was reduced and the mixture was gradually cooled. When the composite obtained in the above example was cut and the cut surface was inspected, it was found that the oxide particles with a particle size of 0.1 μm or less were uniformly dispersed and were in close contact with the final matrix without voids. [0038] Examples 11 and 12 Samples of Examples 11 and 12 were prepared by Method A described above. The composition of the sample is shown in Table 1. This sample was maintained at 700° C. and oxygen partial pressure of 200 atmospheres for 5 hours. Next, the pressure was increased to 350 atm, maintained at this atmospheric pressure for 10 minutes, and then reduced to 1 atm and cooled. [0039] Comparative Examples 1 and 2 A silver alloy having the composition shown in Table 1 was heated at 700° C. and at an oxygen partial pressure of 1.
It was subjected to internal oxidation under conditions of 0 atm. [0040] Comparative Examples 3 and 4 Samples of Comparative Example 3.4 prepared in the same manner as Examples 11 and 12, respectively, were heated at 700°C and an oxygen partial pressure of 30 atm for 5 minutes.
Holds time. Oxidation stopped at a depth of 1 mm or less from the surface, and it was determined that oxidation was not possible. [0041] The hardness and electrical conductivity of the samples treated in the above Examples and Comparative Examples were measured. The results are shown in Table 1. [0042] Furthermore, the sample was made into a contact support alloy with Ag-In 15%-
It was welded with a silver solder having a composition of 13% (by weight) of 3n, and the following electrical conditions and tests were conducted. [0043] 1) Opening/closing test, test [0045] Table 1 No. Amount of other metals included in the method chain tZ Hardness 1 Conductivity H, R, F, 1. A, C, S7: Example I A Example 21A 1 Example 3B Example 41B Example 5C Example 6C Example 7D Example 8D Example 9E Example 10 E Sn 67; Sn 10Z Sn 7.57. , Ca 2.5X Sn 9Z Mg 1°/. Sn 13'4, CrO, 17:Sn 8'l,
N stone 1.0zSn 7.5'14. Ca
2.57: Sn 8'1. , Mg IZ Sn 8Z Zr 17: Sn 87; Cd 4X Table 1 (continued) No. 1 Method 1 Amount of other metals contained in silver tX 1 Hardness 1 Electrical conductivity lH, R, F, l 1. A, C, SZ Comparative Example 1 1 Sn 87: n 4Z Comparative Example 21 Cd la: Sn1.5Z 1 Example 11 l Sn 9'! . Zr0.3X Ni0.1°/. 1 Example 12 l Sn 9Z Cd 3Z Mg 0.15Z [0046] Table 2 No. IAsTM consumption mgr. Welding test, test mP Contact surface condition Example 1 Example 2 1 Example 3 Example 4 Example 5 Example 6 1 Example 71 Example 8 ) Example 9 Example 10 9,000 11.000 13, 500 14,000 18,000 8,000 10,500 11.000 9,500 9,000 1 Smooth surface 1 Smooth surface less 1 smooth, less silver all over gray smooth surface gray smooth surface gray smooth surface smooth surface H Table 2 (Continued) No. ASTM wear amount I welding test, test mgr, AmP Contact surface condition Comparative example 1 Comparative example 2 Example 11 1 Example 121 6,500 4,500 13,000 io, oo. White rough uneven surface Silver melting flame 1 White smooth surface 1 Smooth gray surface [0047] (Note) In the contact using the composite material of the embodiment of the present invention,
Compared to conventional products, the amount of arc was smaller and the interruption time was shorter. [0048]

【Effect of the invention】

The silver-tin oxide composite material provided by the present invention differs from those produced by conventional internal oxidation methods, in that tin oxide is produced from the surface of a bank matrix in the form of fine particles with a hard and dense crystal structure. Since it is uniformly dispersed in the silver matrix in a bonded state with good wettability to the bank matrix, its strength is physically and chemically degraded. Also,
The conventional internal oxidation method could only add about 4% by weight of tin oxide, but the composite material of the present invention can add 1 to 15% by weight.
It is possible to further improve the strength by incorporating tin oxide. [0049] Furthermore, in the conventional internal oxidation method, it took a long time to oxidize tin and the like. In particular, it has been difficult to manufacture thick-walled materials. However, compared to this, according to the method of manufacturing a composite material of the present invention, manufacturing can be carried out in a significantly shorter time, productivity is greatly improved, and even thick composite materials can be easily manufactured.

[Brief explanation of the drawing]

[Figure 1] FIG. 2 is a temperature versus pressure phase diagram of a silver-oxygen system.

[Document core]

[Figure 1] drawing Procedural amendment March 26, 1991

Claims (8)

[Claims] Claim 1: A silver mother matrix, (a) 1 to 20% by weight of tin oxide in terms of metal, and (b) 0.01 to 8% by weight of Mg, Zr, in terms of metal, optionally present. Ca, Al,
An oxide of at least one element selected from the group consisting of Ce, Cr, Mn, and Ti and/or (c) 0.01 to 15% by weight of Cd, Sb, In, Bi, and Zn in terms of metal.
and an oxide of at least one element selected from the group consisting of iron group metals, the tin oxide of (a) and the oxide of the metal of (b) and/or (c) present in some cases. Silver is uniformly dispersed in the silver mother matrix in the form of fine particles with a particle size of 0.1 μm or less in a bonded state with good wettability from the surface to the deep part of the silver mother matrix.
Tin oxide composite material. 2. The composite material according to claim 1, comprising:
a) tin oxide and (b) element oxide and/or (
A composite material in which the oxide of the element c) is dispersed to form a conjugated oxide. 3. (A) silver; (a) 1 to 20% by weight of tin in metal and/or oxide form, and optionally further (b) 0.01 to 20% by weight of tin in metal terms 8% by weight of metallic and/or oxidic Mg, Zr, Ca, Al,
At least one element selected from the group consisting of Ce, Cr, Mn and Ti and/or (c) 0.01 in terms of metal
~15% by weight of metallic and/or oxidic Cd, Sb
, In, Bi, Zn, and at least one element selected from the group consisting of iron group metals is heated and the partial pressure of oxygen is increased to bring the mixture into a state where a liquid phase and a solid phase coexist. , thereby precipitating the entire amount of tin as an oxide, as well as the optionally present metallic material of the element (b) and/or the element (c); 2. The method for producing a silver-tin oxide composite material according to claim 1, further comprising the step of (B) cooling the thus treated mixture and lowering the oxygen partial pressure. 4. The method of claim 3, wherein the mixture used in step (A) contains silver, tin, and optionally the elements of (b) and/or the elements of (c). A method that is an alloy of elements. 5. The method of claim 3, wherein the mixture used in step (A) contains silver, tin, and optionally the elements of (b) and/or the elements of (c). A method in which the sintered body is made of elements. 6. The method according to claim 5, wherein the sintered body comprises:
silver powder, silver, tin, and if necessary further the above (b)
and/or an alloy powder consisting of the element (c). 7. The method of claim 5, wherein the sintered body comprises:
A method in which a sintered body is produced from a silver powder and an alloy powder consisting of (a) tin, and the element (b) and/or the element (c). 8. The method of claim 3, wherein the mixture used in step (A) comprises silver powder, (a) tin oxide powder with a particle size of 0.1 μm or less, and if necessary, the mixture further comprises ( The oxide powder of the element b) with a particle size of 0.1 μm or less and/or the element (c
) and an oxide powder having a particle size of 0.1 μm or less.