DE2656073A1 - SILVER COMPOSITE MATERIALS AND METHOD OF MANUFACTURING THE SAME - Google Patents

Description

Silver composites and methods of making the same

The invention relates to silver composite materials with continuous silicon carbide fibers are reinforced and a method for producing the same, according to which materials are obtained in particular in which continuous silicon carbide fibers with very high hardness, mechanical strength at high Temperature, abrasion resistance, heat resistance, oxidation resistance and corrosion resistance closely connected to a matrix composed mainly of silver.

Silver is a metal with a high density of 10.5 g / ^cm », a melting point of 96O ⁰ C and the highest thermal and electrical conductivity among the elementary metals.

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Hammerability. Silver can therefore be processed excellently and it is used in a variety of ways in the electrical industry, such as as a material for electrical contacts, circuit breakers, various switches, as relay material, slippery material, material for public transport such as buses and the like. In addition, since it is resistant to water, oxygen, hydrochloric acid, alkali hydroxide and the like, silver is used in pipes and siphons for the production of drinking water, in taps and cocks for the production of acetate fibers, and in containers for strong alkali and Silver is also used as a material for bearing metals, for various plating and the like, since silver is the best heat conductor. In addition, silver and silver alloys are used for coinage, silver vessels, jewelry, in dental technology, for silver solder, photosensitive materials, for silver plating and widely used as an additional element for alloys.

When using silver as a material for the electrical industry or for chemical instruments and as Structural material, however, results in the difficulty that often high hardness and mechanical strength in addition to the properties characteristic of silver is required, while silver has a relatively low one Has a Brinell hardness of 2.5 and a tensile strength of 13-16 kg / mm, which makes the application of silver is pretty limited. In particular, materials for the electrical industry should have high abrasion resistance and have mechanical strength and studies have therefore been carried out and systems developed for which not only silver but also alloys of silver with tungsten, molybdenum, iron, nickel, copper, Cadmium and the like, and metal-ceramic type materials or particle dispersion type silver composites

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Carbon, cadmium oxide, lead oxide, tungsten carbide, molybdenum sulfide and the like. to be used. Now they have above-mentioned silver alloys have improved abrasion resistance, but their resistance to oxidation in air and mechanical strength at high temperature and in areas where the silver alloy is applied is very limited. On the other hand, the above composite materials of silver and non-metallic substances such as carbon, cadmium oxide, lead oxide, tungsten carbide etc. generally have a low level electrical conductivity and result from an agglomeration of the non-metallic substances coarser particles at high temperature or by reacting the non-metallic substances with silver the resulting product has moderate properties at high temperatures. Furthermore, the handling of systems with cadmium or lead generally critical from a public health point of view. The application and Production of silver alloys or composites with lead or cadmium are very limited. It therefore exists an increased interest in overcoming the numerous shortcomings of the aforementioned conventional composite materials with a matrix of silver or silver alloy or silver composite material and on the development new composite materials with high electrical conductivity, thermal conductivity, hardness and oxidation resistance as well as excellent mechanical properties at high temperature for widespread use such materials in electrical systems, as structural materials and materials for chemical Devices that require use under severe conditions such as high pressure, high temperature, very low temperature, can withstand corrosive environments, high electrical currents, high voltage and the like, whereby such materials were particularly in demand in recent years.

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As new composite materials having the above excellent properties, silver composite materials have emerged of the fiber reinforced type are considered inexpensive. Such fiber reinforced composite materials are better than composite materials of other types because the fiber-reinforced type has both the properties of the Base material as well as that of the fibers can be retained and such materials are particularly excellent have mechanical properties at high temperature. It was therefore presumed that composite materials could be produced with high performance if suitable reinforcing fibers were found. As a composite material of the fiber-reinforced type have already been used with aluminum oxide whiskers or silicon carbide whiskers (SiC whiskers) investigated reinforced silver composites. These whisker-containing composite materials have however, there are several disadvantages for the following reasons: The whisker production is very expensive and the production difficult of whiskers with uniform property. If short whiskers with a length of a maximum of about 30 mm can be used, the composite material are only strengthened locally and there are increased shear forces at the ends of the whiskers in the composite material on reducing the strength of the material as a whole. The arrangement and embedding of short whiskers is very complicated and such composite materials are difficult to mass-produce. For these reasons, the described whisker-reinforced silver composites have not heretofore been practical ι applied.

The aim of the invention is therefore a process for the production of new silver composite materials in which the above shortcomings of the known materials do not j occur.

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According to the invention, homogeneous, long, continuous Silicon carbide fibers, which can be easily and relatively inexpensively manufactured, for production of fiber reinforced silver composite material used, creating a silver composite material with excellent Properties can be obtained without the shortcomings of the conventional silver composite materials described above can. That is, according to the invention, there is provided a method of manufacturing one having continuous silicon carbide fibers reinforced silver composite material is provided, which has a high thermal and electrical conductivity, as they are peculiar to silver, and also has a high hardness. Abrasion resistance, mechanical strength at high temperature, having heat resistance, oxidation resistance and corrosion resistance, such as they are inherent in silicon carbide fibers.

It should also be noted that silicon carbide fibers are easily wettable with silver and even with Immersion of the fibers in molten silver does not react with the silver and does not decrease the mechanical Properties, oxidation resistance and other characteristics up to the melting point of the Silver of 960 ° C. Furthermore, within the framework of the Invention applied continuous fibers composed mainly of silicon carbide and fired obtained from spun fibers which are mainly composed of high molecular organo-silicon compound exist. The silicon carbide fibers can be manufactured relatively easily, as will be explained below and, moreover, the fibers are homogeneous and can be produced in any size and length, with their strength and their Young's modulus are markedly superior to those of conventional silicon carbide fibers.

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are made as follows:

(1) by chemical conversion of organosilicon compounds and hydrogen or silicon chloride silicon carbide formed and hydrocarbon in the vapor phase is deposited on W / B fibers, obtained by coating tungsten core wire with boron.

(2) A bundle of about 10,000 rayon fibers is made hydrated and then dipped in silicon chloride and the fiber bundle treated in this way is subjected to thermal decomposition and coking.

(3) - Made of halogenated u. Ammonia-containing compounds containing silazane are chemically treated in such a way that the compound can be spun into fibers ₉ which are then heated in an inert atmosphere to produce continuous fibers from a homogeneous mixture of silicon carbide and silicon nitride.

However, since the type (1) fibers have a tungsten core, their diameter is large (such as at least 100 µm) and they have a high density of at least 10 g / cm and a poor flexibility. Furthermore, since the strength and the modulus of the fibers depend on those of the tungsten core, the specific strength and the specific modulus of the fibers are considerably lower than in the case of the continuous silicon carbide fibers used in accordance with the invention. Moreover, the deposition from the vapor phase is a complicated process step and the fibers are expensive.

The type (2) fibers are silicon tetrachloride and hydrochloric acid during manufacture to handle and the educational process is therefore complicated and there are some problems related to the general

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my safety. Since this manufacturing process is also based on a bundle of rayon fibers Individual fibers difficult to remove. Furthermore, the strength and modulus of the fibers are as low as 1/3 to 1/5 of those of the silicon carbide fibers used according to the invention. The application of the fibers from Type (2) for the reinforcement of composite material is therefore very disadvantageous.

With the fibers of type (3), a very complicated process step is required in the production of spun fibers, and the production cost of the fibers is therefore high; the tensile strength of the fibers is 60 to 115 kg / mm and the modulus is (9 to 10) χ 10 x ⁵ kg / mm ² , which is about 1/3 to 1/4 of the tensile strength and modulus of silicon carbide fibers according to the invention . The use of fibers of type (3) for the reinforcement of composite material is therefore very disadvantageous.

On the other hand, the continuous silicon carbide fibers to be used in the context of the invention can be obtained at no great cost by a simpler process step than those mentioned above conventional fibers as described below. In addition, the fibers can be in the form of homogeneous and continuous fibers with selectable diameter and length can be obtained and the Fibers have very excellent strength and modulus. That is, the fibers are for most suitable for use as a reinforcing fiber for composite material. The use of fibers in manufacture of silver composite materials therefore forms the essential feature of the invention.

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materials according to the invention to be applied materials include not only silver but also silver alloys and silver composites. As the silver alloy and the silver composite, there are known silver alloys which are composed of Ag and a metal having a high melting point and hardness such as W, Mo or the like and which have high electrical conductivity and improved abrasion resistance, arc resistance and mechanical strength; Silver alloys of Ag and at least an addition of 1 to 15 wt.% Of carbon, 5 to 10 wt.% Cu, 5 to 50 wt. # Ni, not more than 10 wt. # Cd and 10 to 40 wt.% Of iron with a high electrical conductivity and improved low contact resistance, melt strength, toughness and mechanical "strength; particle dispersion type silver composites such as Ag-CdO, Ag-MgO, Ag-PbO or the like produced by internal oxidation of alloys such as Ag-Cd, Ag-Mg, Ag -Pb or the like, with a high electrical conductivity and a low contact resistance; they are wear-resistant and melt-resistant; silver composite materials of the metal-ceramic type made of Ag and WC or TiC are resistant to high voltage and high currents; silver alloys for electrical contacts are used by alloying Ag with Au, Pd or Pt in an effort to avoid contamination of the alloy surface as much as possible; and silver composites made of Ag with carbon or the like the MoSp are used as a material for brushes with good sliding properties. Such silver alloys or silver composites are used particularly advantageously as a matrix or base material according to the invention and lead to a silver composite material reinforced with silicon carbide fibers, which is superior to a composite material in which only silver is used as the base material in terms of mechanical properties and abrasion resistance.

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The invention is explained in more detail below.

The fibers to be used for the reinforcement of silver composite material according to the invention are continuous High strength fibers composed mainly of silicon carbide obtained by firing spun Fibers is obtained which are mainly composed of high molecular organo-silicon compound. According to the invention, a silicon carbide fiber reinforced silver composite material having high strength can be used by tightly binding the fibers with silver alone or with alloys or consisting mainly of silver Composites are preserved.

The continuous silicon carbide fibers are according to the patent application P 26 18 150.0 of the applicant obtained method described. The low molecular weight organosilicon compounds are used in the manufacture of the fibers of the following groups (1) - (10) was used as the starting material.

(1) Compounds in which the silicon is only bonded to carbon ("only with Si-C bond ¹¹ )»

(2) compounds with Si-H bond in addition to Si-C bond;

(3) compounds with Si-Hal bond;

(4) compounds with Si-N bond;

(5) compounds with Si-OR bond (R = alkyl or aryl);

(6) compounds with Si-OH bond;

(7) compounds with Si-Si bond;

(8) compounds with Si-O-Si bond;

(9) esters of organosilicon compounds;

(10) Peroxides of organosilicon compounds.

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From at least one of the low molecular weight organosilicon compounds belonging to groups (1) to (10) are high-molecular organosilicon compounds with silicon and carbon as the main structural components by polycondensation reaction using radiation, the action of heat and / or the addition of a polycondensation catalyst formed, such as the compounds with the following molecular structures:

(a) -Si-CC) n-Si-O-

Cb) -Si-O-CC) n-O-

Cc) -Si-CC) Ii-

(d) Compounds with the above structural components (a) to (c) as at least a partial structure in linear, annular and three-dimensional structures or mixtures of compounds with the mentioned structural components (a) to (c).

From at least one of the high molecular weight organosilicon compounds with at least one of the named molecular structures is - if necessary with the addition of or implementation with a small amount of at least one member from the group of organo-metallic Compounds, metal complexes and organic polymers derived from the above two compounds are different - a spinning fluid is produced, which then becomes fibers of different lengths and uniform strength can be spun. The spun fibers are in an oxidizing atmosphere to a low temperature in the range of 50

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^{heated to 400 ° C and then heated initially to a temperature of 600 to 1000 0} C to form the initially heated continuous silicon carbide fibers in at least one gas atmosphere from the group: vacuum, inert gas, CO gas, hydrocarbon gas, organosilicon compound gas and hydrogen. This initial heating can, however, also take place in the gas atmospheres mentioned, which contain at least one oxidizing gas, a hydrocarbon gas and / or hydrogen with a partial pressure of less than 10 Torr. The preliminarily heated fibers are then in at least one of the gas atmospheres: fired vacuum, inert gas, CO gas, hydrocarbon gas, organo-silicon compound gas and hydrogen to form a continuous silicon carbide fibers at 1000-2000 ⁰ C. Properties of continuous silicon carbide fibers obtained by firing at 1300 ^° C. in a vacuum are summarized in Table 1 below.

TABLE 1

Crystal grain size 33 Ä (mean diameter) density 2.6-3.1 g / cm ³ hardness 9 (Mohs) tensile strenght 300 - 400 kg / mm ² Young module (2.0-4.0) χ 10 ⁴ kg / mm ² Resistance to oxidation after 100 hours in air
1300 C is no weight
change observed. Thermal shock resistance soapy after> 1000 cycles
rapid heating up and down
quenching of 25 C 5 = ±
1000 C will not produce a texture
change observed.

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The silicon carbide fibers obtained by firing spun fibers composed mainly of high molecular organosilicon compounds usually contain more than 0.01 % by weight of free carbon. The amount of free carbon contained in the fibers depends on the firing temperature, the firing time, the firing atmosphere and other conditions. This free carbon reacts locally with silver at a temperature above 850 ^° C. with the formation of very small amounts of a solid solution of silver with carbon or Ag ₂ C ₂ at the interface between the silicon carbide fibers and silver. As a result, the silicon carbide fibers are bound more tightly or more firmly to the silver, not only through the adhesion of the fibers to the silver due to the wettability and mutual diffusion of fibers and silver, but also through the adhesion of the fibers to the silver as a result of the local chemical reaction of the free carbon with the silver at the interface between silver and fibers ·. This free carbon therefore plays a very important role in the binding of SiC-Ag in the context of the invention. The silicon carbide fibers to be used according to the invention have a crystal grain size of about a few 10 Å, as indicated in Table 1 and the number of microscopic unevenness per unit area of the fiber surface is therefore very high and molten or sufficiently soft silver penetrates into the unevenness, whereby the adhesion between the fibers and the silver becomes very strong through wettability and mutual diffusion. This is an advantage of the invention. As indicated above, the fibers and silver to be used in the present invention are most suitable starting materials for the production of silver composite material having high strength due to the close bond between fibers and silver.

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4>

For the production of composite material from the silicon carbide fibers and silver or alloy or Composites, which are mainly composed of silver, have different approaches. Be with advantage however, the following four methods were used within the scope of the invention:

a) Evenly arranged fiber bundles are melted in a vacuum or in an inert atmosphere Matrix material permeated or soaked;

b) an assembly composed of matrix material and fibers becomes the tight bond of matrix and fibers sintered or hot pressed in vacuo or in an inert atmosphere;

c) Foils or thin sheets or plates of matrix material and fibers are placed evenly on top of one another arranged and hot pressed or hot rolled in vacuum or in an inert atmosphere for a Diffusion of the matrix and fibers into one another, whereby the matrix and fibers are closely bonded together;

d) Matrix material is sprayed or sprayed onto the individual fibers with a plasma torch or the like applied and the resulting fibers collected and placed in vacuum or in an inert atmosphere hot pressed.

The above methods can be used to produce homogeneous and solid composite materials made of fibers and matrix material can be obtained without pore formation at the boundary between fibers and matrix.

The silicon carbide fiber content of the silicon carbide / silver composite material according to the invention is preferably from 5 to 70% by weight . With silicon carbide fiber contents below 5% by weight, the reinforcement effect is through

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the fibers low. On the other hand, if the fiber content is over 70% by weight, those are the silver (or mainly Alloys or composites made of silver) have their own electrical and thermal conductivity reduced in the resulting composite material, which is also difficult to work or process.

The following are examples to further illustrate the invention.

example 1

This example shows the production of the continuous silicon carbide fibers to be used in accordance with the invention explained.

Dimethyldichlorosilane and sodium were converted to dimethylpolysilane. 250 g of dimethylpolysilane were placed in an autoclave with a capacity of 1 l and the air in the autoclave was replaced by argon. The contents were then ^{reacted at 470 °} C. for 14 hours. After the reaction had ended, the polycarbosilane formed was taken out as a solution in η-hexane. The solution was filtered to remove impurities. Then η-hexane was evaporated off under reduced pressure, after which the residue was ^{heated for 2 hours in an oil bath at 280 °} C. in vacuo to bring about a concentration. Polycarbosilane was obtained in a yield of 40 % (based on dimethyldichlorosilane). The average molecular weight (number average) of the formed polycarbosilane was 1700. Under A _n application of a conventional spinning device was heated the polycarbosilane in argon and at 33O ° C melted to form a spinning melt, which was spun at a rate of 200 m / min to polycarbosilane . The fibers were heated in 6 hours in air at 20 ⁰ C to 19O ⁰ C and

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For 1 hour "held at that temperature to make them infusible. The thus treated fibers were at a temperature rise rate of 1OO ° C / hr in a vacuum of 10" heated ^"5 Torr to 130o ⁰ C and the formation of silicon carbide fibers 1 hour kept at this temperature for a long time. The silicon carbide fibers formed had an average diameter

ser of 15 µm, an average tensile strength of 350 kg / mm,

• χ ρ

an average Young's modulus of 23 x 10 ^D kg / mm and a specific weight of 2.70 g / cm.

Five different composite materials were produced with silver as the sole matrix material and bundles of the silicon carbide fibers obtained as described with a length of 50 mm with the weight ratios given in Table 2. The silicon carbide fiber bundles were placed in an alumina crucible (0: 12 mm; i : 50 mm) which was suspended in the upper region of a vacuum heating chamber which was connected to a vacuum line of 10 Torr. Silver was placed in an alumina container located at the bottom of the heating chamber. The silver in the container was heated from outside the container and melted at about 1000 ° C. The crucible was then moved downward and immersed in the molten silver for 1 minute and then withdrawn. The resulting silicon carbide / silver composite material was processed into a rod 10 mm × 40 mm long, which served as a test specimen. The properties of the silicon carbide / silver composite are shown in Table 2.

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TABLE 2

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^ v amount of fiber
^ \ (Wt.tf)
Eigen- ^ v.
shafts ^ \ 10 20th 30th 50 70 Density (g / cm) 9.7 9.0 8.2 6.7 5.2 medium hardness
(Mohs) 3-4 4-5 5-6 6-7 7-8 tensile strenght
in air
(kg / mm)
Room temperature
300 ⁰ C
500 ⁰ C 20-25
16-21
10-15 48-78
39-61
30-48 96-130
87-110
69-97 170-210
150-190
110-140 200-240
180-220
160-200 more specific
resistance
(Xl.cm) 2.3 x
ΙΟ " ⁶ 3.2 χ
io- ⁶ 4.3 x
10 " ⁶ 7.8 χ
io- ⁶ 16.1 χ
ΙΟ " ⁶ Thermal conductivity
capability
(cal / cm · S- ⁰ C) 0.73 0.56 0.45 0.30 0.21 Oxidation
strength
up to 700 ⁰ C Well Well Well excellent
draw* excellent
b draws

As can be seen from Table 2, the silicon carbide continuous fiber reinforced has silver composite material with increasing fiber content, it has a higher hardness and strength, and it also shows a relatively slight decrease in electrical and thermal conductivity due to reduced silver content. The composite material

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therefore, it has excellent properties for use as an electrical material, a material for chemical equipment and a construction material, and it can be widely used for practical purposes. In the case of the cut material, no pores were observed on microscopic observation of the adhesion area between silicon carbide fibers and silver, but a very thin texture layer on the fiber surface. This thin layer is the formation of very small ^Ag 2 ^C 2 ~ ^{quantities durcn} l l ^e ° ^ka chemical reaction of the free carbon contained in the fibers with silver back. It has been found that the adhesion between silicon carbide fibers and silver is improved by the presence of this reaction product in combination with the adhesion by wettability and mutual adhesion: the composite material according to the invention has an improved mechanical strength.

Example 2

A mixture of 80 Gew.?6 silver, 15 wt.% Of molybdenum and 5 wt.% WC was processed into powder having a particle size of not more than 75 pm (200 meshes). Bundles of silicon carbide fibers obtained as described above and having a length of 40 mm were embedded in the powder mixture in one direction, which was then formed into prismatic compact bodies of 10 χ 10 χ with a molding press under a pressure of 300 kg / cm 40 mm with a matrix to fiber weight ratio of 30/70 with the fiber bundles oriented parallel to the longitudinal direction of the body. The continuous body was sintered for 2 hours at ⁰ C in an SOO at maintained at 1 atmosphere of argon. The composite material obtained had a hardness of about 7 (Mohs), an electrical resistance of 2.1 χ 10 Xl. cm and a thermal conductivity of 0.15 cal / cm.s. ° C. When checking the

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bund material as a material for electrical contacts essentially the same contact resistance was found as with pure silver and very little melting phenomena and very little material transport through arc discharge at high current and high voltage, a very small increase in temperature and abrasion at the contact point, with the service life as an electrical contact was about 30 to 50 times as long as the service life of an electrical contact made of pure silver. That is, the silver composite material produced according to the invention by powder metallurgical processes is suitable for practical purposes as a material for electrical contacts, sliding materials and materials for various Switch very suitable. Furthermore, the mechanical and other properties were as obtained in this example The composite material is practically the same as the composite material with 70 wt% silicon carbide fibers according to Table 2. Microscopic examination of the composite material showed that pores inside the same were very small. The composite material can be used as structural material and material for chemical devices in addition can be used in the electrical field.

Example 3

ρ A square sheet of 30 χ 30 mm and 0.05 mm

Thicknesses of 80 wt.% Silver and 20 wt. Silicon carbide fibers. The composite was 30 minutes with 200 kg / cm in an argon atmosphere at 93O ⁰ C hot-pressed (ie, 30 ⁰ C under the lying at 96O ⁰ C melting point of silver) to give a composite of silicon carbide and silver

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alloy. The composite material had a thickness of about 1.5 mm », a density of 9» O g / cm and a medium hardness of 6 (Mohs). The composite material had virtually the same mechanical and other properties as one Composite material with 20% by weight silicon carbide fibers according to Table 2. Following the procedure of this example thin plates of silver composite material reinforced with silicon carbide fibers can be obtained, and that Composite material can be made into different shapes by machining and cutting and as electrical Material, chemical device material and structural material can be applied.

Example 4

Silicon carbide fibers obtained as described above and having a length of 30 mm were arranged flat and silver was sprayed by means of a plasma. The spraying process was repeated three times on the top and bottom of the flat fibers. Each of the thus treated fibers of silicon carbide and silver had a diameter of 0.1 to 0.5 mm. 10 layers of the planarly disposed fibers were placed in a graphite mold and hot pressed for 1 hour in an argon atmosphere at 93O ⁰ C under a pressure of about 200 kg / cm. The amount of silicon carbide fiber contained in the resulting silver composite material was 50% by weight, and its properties were practically the same as those of the silver composite material containing 50% by weight of silicon carbide fibers shown in Table 2. The resulting composite material contained practically no pores. It could be used in the same technical area as the composite materials described above.

The preceding examples show typical procedures for making silver composite material with silicon carbide fibers as reinforcement and

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typical shapes of the resulting composite material. However, composite materials can of course be used can be obtained with various shapes in different procedures.

As follows from the foregoing, according to the invention, a silver composite material reinforced with silicon carbide fibers with excellent mechanical properties, heat resistance, oxidation resistance, Abrasion resistance, electrical conductivity and thermal conductivity can be obtained and the composite material can advantageously be used in a wide range as electrical Material, chemical device material and structural materials can be applied.

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Claims (14)

& - B 7817 Claims 'Fiber-reinforced silver composite material, g e k e rTn is characterized by the following three essential components: (a) Continuous silicon carbide fibers mainly consisting of consist of β-type silicon carbide; (b) a silver matrix selected from the group consisting of silver, silver alloys and mainly consisting of silver Composites; and (c) by reacting free carbon contained in the fiber surface with the matrix metal Very small amounts of carbide or solid carbon solution formed in the matrix metal. 2. Silver composite material according to claim 1, characterized by a high resistance to oxidation and a hardness of 3 to 8 (Mohs scale), a tensile strength from 20 to 240 kg / mm (at room temperature), an electrical resistivity of (2.0 to 16.1) χ e:
0.21 cal / cm.s. ° C. 10 II.cm and a thermal conductivity of 0.85 to 3. Process for the manufacture of continuous silicon carbide fiber reinforced silver composites according to claim 1, characterized in that one consists mainly of silicon carbide continuous Fibers obtained by burning spun fibers, which are mainly made of high molecular weight Organosilicon compound consist closely, with a matrix consisting mainly of silver arrested. 4. The method according to claim 3, characterized in that the matrix material by at least one Representatives from the group of silver and alloys of 709824/0389 - B 7817 Silver is formed with tungsten, molybdenum, iron, nickel, chromium, cadmium, copper, gold, palladium, and platinum will. 5. The method according to claim 3, characterized in that the matrix by at least one representative from the group of composites of silver with carbon, cadmium oxide, lead oxide, titanium carbide, tungsten carbide, Molybdenum sulfide and magnesium oxide is formed. 6. The method according to claim 4, characterized in that the amount of metal to be alloyed with silver is 1 to 30 Ge \ i.% (Based on the weight of the alloy). 7. The method according to claim 5, characterized in that which is to be mixed with the silver amount of carbon, oxide, sulfide or carbide (based on the weight of the composite) at 1 to 30 wt.%. 8. The method according to claim 3, characterized in that the spun fibers of high molecular weight Organosilicon compounds are formed with silicon and carbon as the main framework components, that of at least one of the low molecular weight orgaho silicon compounds of the following groups (1) to (10) (1) compounds in which the silicon is only bonded to carbon; (2) compounds with Si-H bond in addition to Si-C bond; (3) compounds with Si-Hal bond; (4) compounds with Si-N bond; (5) compounds with Si-OR bond (R = alkyl or aryl); (6) compounds with Si-OH bond; (7) compounds with Si-Si bond; 709824 / 038® B 7817 (8) compounds with Si-O-Si bond; (9) esters of organosilicon compounds and (10) Peroxides of organosilicon compounds by. Polycondensation using irradiation, Heating and / or polycondensation catalyst additive are formed. 9. The method according to claim 3, characterized in that the consisting mainly of silicon carbide continuous fibers contain at least 0.01 wt.% free carbon. 10. The method according to claim 3, characterized in that for the silver composite material 5 to 70 wt.% Resilient weather buckets consisting mainly of silicon carbide will. 11. The method according to claim 3, characterized in that that mainly composed of silver molten matrix material into the spaces between evenly arranged bundles of continuous silicon carbide fibers in a vacuum or in an inert Atmosphere for a close connection of the fibers with the matrix is admitted. 12. The method according to claim 3, characterized in that a composite arrangement of matrix material and continuous silicon carbide fibers for tightly connecting the matrix to the fibers in a vacuum or sintered or hot pressed in an inert atmosphere. 13. The method according to claim 3, characterized in that that foils or thin sheets of the matrix material and continuous silicon carbide fibers are uniform arranged one above the other and in a vacuum or one 709824/0389 - 7817 inert atmosphere with diffusion of matrix metal and fibers into one another and close adhesion of matrix metal and fibers are hot pressed or hot rolled. 14. The method according to claim 3, characterized in that the matrix material by plasma coating is applied or sprayed onto the individual continuous silicon carbide fibers, after which the resulting Fibers are collected and hot pressed in vacuo or in an inert atmosphere. 709824/0389