CN113764211B - Reinforced phase material of low-Cd electrical contact, low-Cd silver-based composite electrical contact material and preparation method - Google Patents
Reinforced phase material of low-Cd electrical contact, low-Cd silver-based composite electrical contact material and preparation method Download PDFInfo
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- CN113764211B CN113764211B CN202111079978.8A CN202111079978A CN113764211B CN 113764211 B CN113764211 B CN 113764211B CN 202111079978 A CN202111079978 A CN 202111079978A CN 113764211 B CN113764211 B CN 113764211B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H1/00—Contacts
- H01H1/02—Contacts characterised by the material thereof
- H01H1/021—Composite material
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/02—Making metallic powder or suspensions thereof using physical processes
- B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/04—Making non-ferrous alloys by powder metallurgy
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/04—Making non-ferrous alloys by powder metallurgy
- C22C1/0466—Alloys based on noble metals
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/04—Making non-ferrous alloys by powder metallurgy
- C22C1/047—Making non-ferrous alloys by powder metallurgy comprising intermetallic compounds
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C20/00—Alloys based on cadmium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C5/00—Alloys based on noble metals
- C22C5/06—Alloys based on silver
- C22C5/10—Alloys based on silver with cadmium as the next major constituent
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H1/00—Contacts
- H01H1/02—Contacts characterised by the material thereof
- H01H1/021—Composite material
- H01H1/023—Composite material having a noble metal as the basic material
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H11/00—Apparatus or processes specially adapted for the manufacture of electric switches
- H01H11/04—Apparatus or processes specially adapted for the manufacture of electric switches of switch contacts
- H01H11/048—Apparatus or processes specially adapted for the manufacture of electric switches of switch contacts by powder-metallurgical processes
Abstract
The invention discloses a low-Cd electric contact reinforced phase material, a low-Cd silver-based composite electric contact material and a preparation method thereof, belonging to the technical field of electric contact materials, wherein the low-Cd electric contact reinforced phase material comprises Ti and Cd with the element molar ratio of 2:1, belonging to one of Ti/Cd intermetallic compounds, and the Ti is as follows 2 Cd for preparing Ag/Ti 2 The Cd content in the composite electrical contact material is reduced by more than 38 percent compared with the Cd content in the Ag/CdO of the same component, and the Cd composite electrical contact material has obvious attenuation effect. The method can be suitable for relays and contactors of military electronic and electric equipment, aerospace and the like in a large scale after industrialization, and can effectively promote the low Cd and low toxicity processes of low-voltage switch electrical contact materials in the future.
Description
Technical Field
The invention relates to the technical field of electrical contact materials, in particular to a low-Cd electrical contact reinforced phase material, a low-Cd silver-based composite electrical contact material and a preparation method thereof.
Background
The energy source must be converted into electric energy for human use, the electric energy output to the terminal equipment must be distributed and controlled by switches, such as relays, contactors, circuit breakers and the like, which play a key role in the circuit system, and the "core" of the switches is an electric contact, and the quality and performance of the electric contact directly determine the service life and the use safety of the electric equipment. In the middle and later stages of the last century, the electric contact for the low-voltage switch is mainly made of Ag-based composite materials, and the universal electric contact 'Ag/CdO' occupies most of the market of the piezoelectric device due to the lower resistivity and excellent arc erosion resistance. However, the Ag/CdO service process generates a large amount of toxic Cd steam, is harmful to human bodies and the environment, and is against the increasingly severe environmental protection policy (ELV direct 2000E.U.; WEEE direct 2002E.U.; roHS direct 2003 E.U.) in the world, so that the Ag/CdO service process must exit the electric contact material market in the future. At the end of the last century, cd-free electrical contact materials (such as Ag/SnO2, ag/ZnO, ag/Ni, ag/C and the like) which are to replace Ag/CdO still have a series of problems of poor processability, large contact resistance, high temperature rise, large material loss and the like, and the performance of the material is still a larger gap than that of an Ag/CdO material, so that most countries and regions worldwide still use a small amount of Ag/CdO composite electrical contact materials. However, in the fields of aerospace and military industry, cd-containing electrical contacts remain the first choice. Therefore, the search for novel silver-based composite electrical contact materials with low Cd content and performance which are not inferior to Ag/CdO in some special fields is obviously the development direction with the strongest practicability. However, a suitable low Cd electrical contact material has not been found to replace Ag/CdO.
Disclosure of Invention
The invention aims to solve the technical problems and provide an electric contact reinforced phase material Ti with low Cd content 2 Cd, preparation method thereof and Ag/Ti 2 Cd composite electrical contact material and a preparation method thereof.
In order to achieve the above object, the present invention provides the following solutions:
one of the purposes of the invention is to provide an electric contact reinforcing phase material with low Cd content: a reinforced phase material of a low-Cd electrical contact comprises Ti and Cd in element composition, wherein the element molar ratio of the reinforced phase material is 2:1, and the reinforced phase material belongs to one of Ti/Cd intermetallic compounds.
Further, the reinforcing phase material element is Ti 2 Cd particles, the electric contact reinforcing phase material is sphere-like, the particle size is adjustable within the range of 1-50 mu m, the electric contact reinforcing phase material has high purity, and the prepared Ti 2 The purity of the Cd phase is above 98%.
The second purpose of the invention is to provide a preparation method of the low Cd electrical contact reinforced phase material, which comprises the following steps:
s1, weighing Ti powder and Cd powder according to a molar ratio;
s2, fully mixing the Ti powder and the Cd powder in the step S1 to obtain uniform mixed powder;
s3, sintering the mixture powder in the step S2 under the protection of inert gas, heating to a set temperature at a certain heating rate, and preserving heat for a period of time;
and S4, taking out the sample sintered in the step S3, grinding and sieving to obtain the low-Cd electric contact reinforcing phase material.
Further, in the preparation method of the low Cd electrical contact reinforced phase material, the purity of the Ti powder in the step S1 is more than 90%, and the grain diameter is 1-100 mu m; the purity of the Cd powder is more than 90 percent, and the particle size is 1-200 mu m; the molar ratio of Ti to Cd is (2-2.9) to (1-1.75).
Further, in the preparation method of the low Cd electrical contact reinforced phase material, the full mixing in the step S2 means mixing for 20-30 hours in an omnibearing three-dimensional powder mixer; in the step S3, the inert gas is Ar gas or N gas 2 The temperature rising rate is 3-30 ℃/min, the set temperature is 300-1200 ℃, and the heat preservation time is 0.5-4h; and S4, grinding and sieving with a 80-600 mesh sieve.
The invention further aims to provide a low Cd silver-based composite electrical contact material prepared from the low Cd electrical contact reinforced phase material.
Further, ag base accounts for 50-95% of the mass of the low Cd silver-based composite electrical contact material, and reinforcing phase material accounts for 5-50% of the mass of the low Cd silver-based composite electrical contact material. Compared with the Ag/CdO commercial electrical contact composed of mass fractions, the Cd content in the novel low-Cd silver-based composite electrical contact is over 38 percent lower.
The invention aims at providing a preparation method of the low Cd silver-based composite electrical contact material, which comprises the following steps:
s1, weighing Ag powder and prepared Ti according to mass percent 2 Cd powder, medium liquid and grinding balls;
s2, mixing the powder, the medium liquid and the grinding balls weighed in the step S1 in a ball mill, and drying the mixture after ball milling to obtain a mixture;
s3, placing the mixture in the step S2 into a die capable of being electrified, and controlling the temperature of the die by adjusting the current;
s4, preparing the composite block material from the mixed powder in the step S3 under the protection of inert gas by a dynamic pressure sintering technology.
Further, in the preparation method of the low Cd silver-based composite electrical contact material, the purity of the Ag powder in the step S1 is more than 90%, and the particle size is 1-100 mu m; ti (Ti) 2 Cd powderThe purity is more than 90 percent, and the grain diameter is 1-50 mu m; the medium liquid comprises alcohol, acetone and deionized water, wherein the purity of the alcohol and the acetone is more than 95%, and the resistivity of the deionized water is 1-5 mu S/cm; grinding ball diameter 1-8mm, alcohol, acetone, deionized water= (1-1.2), 0.85-1, 0.9-1.05); the mass ratio of the grinding ball to the medium liquid to the powder is (1-3) to (0.5-3) to 1.
Further, in the preparation method of the low Cd silver-based composite electrical contact material, ball milling time in the step S2 is 10-100min, and drying is carried out for 8-30h.
Further, in the preparation method of the low Cd silver-based composite electrical contact material, the power-on current in the step S3 is 6-24A, the heating rate is 5-25 ℃/min, and the die temperature is 300-800 ℃; the energizable die is preferably square, and the square die has a length x width x height of (20-50 mm) × (10-30 mm) × (5-10 mm).
Further, in the preparation method of the low Cd silver-based composite electrical contact material, the inert gas in step S4 is Ar gas or N gas 2 The dynamic pressure burning technology refers to repeated pressing-pressure maintaining-pressure releasing operation in the process of electrifying and heating, wherein the pressing pressure is 50-800MPa, the pressure maintaining time is 1-40min, the pressure releasing speed is 5MPa/s, and the operation times are 2-6 times.
The fifth purpose of the invention is to provide the application of the low Cd silver-based composite electrical contact material in the preparation of a low-voltage switch, wherein the low-voltage switch comprises a relay, a contactor, a circuit breaker and the like.
The invention discloses the following technical effects:
(1) The novel low Cd reinforced phase Ti obtained by the invention 2 The preparation process of Cd is simple, ti 2 The purity of Cd powder is high (more than 98%), the particle size is adjustable within the range of 1-50 mu m, the preparation cost is low, and the application range is wide;
(2) The invention adopts the dynamic pressure sintering technology to prepare the Ag/Ti 2 In the Cd composite electrical contact material, ti 2 The Cd reinforced phase material has low Cd content, the Cd content in Ag/CdO is 43.8 percent, which is reduced by more than 38 percent compared with Ag/CdO, and the release of toxic Cd in the electric contact service process can be effectively reduced;
(3) Metallographic and SEM micrographs both show Ti 2 Cd in silverThe dispersion in the matrix is good, the combination with the matrix is tight, the improvement of the integral strength of the composite material is facilitated to a certain extent, and the arc mechanical damage resistance is enhanced;
(4) Ag/Ti obtained by the invention 2 The density of the Cd composite electrical contact material is high (9.10-9.33 g/cm) 3 ) The electric conductivity is good (the resistivity is 2.07-3.8 mu omega cm), the microhardness is moderate (90-97 HV), the tensile strength is high (218-235 MPa), the arc erosion resistance is outstanding, and the current can be effectively opened and closed more than 10000 times under the severe acceleration condition. The novel low Cd silver-based composite electrical contact material reaches the application standard, is suitable for batch production and is used in main low-voltage switches such as relays, contactors and circuit breakers, and has huge application prospects in the future, especially in power grid distribution, aerospace and military equipment.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the drawings that are needed in the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 shows the reinforcing phase material Ti prepared in example 5 2 XRD pattern of Cd phase composition;
FIG. 2 is a reinforcing phase material Ti of example 5 2 A low-power SEM image and a high-power SEM enlarged image of the morphology of the Cd powder;
FIG. 3 is a diagram of Ag/Ti prepared in example 5 2 Microstructure morphology graph of Cd composite electrical contact material and Ti 2 High-power SEM image of compact combination of Cd and silver matrix;
FIG. 4 is a graph of example 5 Ti uniformly distributed in silver matrix 2 EDS spectra of Cd.
Detailed Description
Various exemplary embodiments of the invention will now be described in detail, which should not be considered as limiting the invention, but rather as more detailed descriptions of certain aspects, features and embodiments of the invention.
It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. In addition, for numerical ranges in this disclosure, it is understood that each intermediate value between the upper and lower limits of the ranges is also specifically disclosed. Every smaller range between any stated value or stated range, and any other stated value or intermediate value within the stated range, is also encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.
It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the invention described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from consideration of the specification of the present invention. The specification and examples of the present invention are exemplary only.
As used herein, the terms "comprising," "including," "having," "containing," and the like are intended to be inclusive and mean an inclusion, but not limited to.
Example 1
17.035g of Ti powder (purity > 90%) and 20.000g of Cd powder (purity > 90%) are respectively weighed according to the mol ratio of Ti to Cd of 2:1, put into an omnibearing three-dimensional powder mixer, mixed for 20h, put into a sintering furnace after the powder mixing is finished, and heat treated for 0.5h at the speed of 3 ℃/min to 300 ℃ under the protection of Ar gas to prepare Ti 2 The Cd powder (phase purity 98%) was milled and sieved through a 80-mesh sieve with a particle size of 50. Mu.m.
According to Ag:Ti 2 Cd accounts for 50 percent to 50 percent of the mass of the whole material, 5g of Ag powder (purity is more than 90 percent and grain diameter is 1 mu m) and Ti are respectively weighed 2 5g of Cd powder, and weighing 25g of a sphere with the diameter of 1mm according to the mass ratio of grinding sphere to medium liquid of 2.5:2:1, wherein 20g of medium liquid (96% alcohol, 98% acetone, deionized water with resistivity of 1 [ mu ] S/cm, volume ratio of 1:1:1); ball milling in a ball mill for 10min, taking out, and drying in a drying oven for 10h; putting the powder into a square die with length, width and height=50 mm, 10mm and 5mm, introducing 6A current, heating to 300 ℃ at a heating rate of 5 ℃/min, introducing Ar gas for protection, maintaining the pressure for 1min under a pressure condition of 50MPa, releasing pressure at a speed of 5MPa/s after the pressure maintaining is finished, and repeating the operation for 2 times to directly obtain the low Cd silver-based composite electrical contact material, wherein the Cd content is 27.0%.
Example 2
16.539g of Ti powder (purity is more than 90%) and 20.341g of Cd powder (purity is more than 90%) are respectively weighed according to the molar ratio of Ti to Cd of 2.1:1.2, put into an omnibearing three-dimensional powder mixer, mixed for 22h, put into a sintering furnace after the powder mixing is finished, and put into N 2 Heating to 500 ℃ at a speed of 8 ℃/min under the protection of gas, and performing heat treatment for 1h to prepare Ti 2 The Cd powder (phase purity: 98%) was pulverized and then sieved through a 100-mesh sieve, and the particle size was 45. Mu.m.
According to Ag to Ti 2 Cd accounts for 60 percent to 40 percent of the mass of the whole material, 7.2g of Ag powder (purity is more than 90 percent and grain diameter is 10 mu m) and Ti are respectively weighed 2 4.8g of Cd powder, and weighing 26.4g of a sphere with the diameter of 2mm according to the mass ratio of grinding sphere to medium liquid to powder of 2.2:1.8:1, wherein 21.6g of medium liquid (97% alcohol, 97% acetone, deionized water with the resistivity of 2 mu S/cm volume ratio=1.05:0.95:1); ball milling in a ball mill for 30min, taking out, and drying in a drying oven for 12h; placing the powder into square mold with length, width and height of 45mm, 15mm and 6mm, introducing 10A current, heating to 400deg.C at 10deg.C/min, and introducing N 2 And (3) protecting the gas, maintaining the pressure for 5min under the pressure condition of 100MPa, releasing the pressure at the speed of 5MPa/s after the pressure maintaining is finished, and repeating the operation for 3 times to directly obtain the low Cd silver-based composite electrical contact material, wherein the Cd content is 21.6%.
Example 3
14.516g of Ti powder (purity is more than 90%) and 20.141g of Cd powder (purity is more than 90%) are respectively weighed according to the molar ratio of Ti to Cd of 2.2:1.3, put into an omnibearing three-dimensional powder mixer, mixed for 24 hours, put into a sintering furnace after the powder mixing is finished, and put into N 2 Heating to 600 ℃ at a speed of 10 ℃/min under the protection of gas, and performing heat treatment for 1.5h to prepare Ti 2 The Cd powder (phase purity: 99%) was pulverized and then sieved through a 150-mesh sieve, and the particle size was 40. Mu.m.
According to Ag to Ti 2 Cd accounts for 70 percent to 30 percent of the mass of the whole material, 7.7g of Ag powder (purity is more than 90 percent and grain diameter is 20 mu m) and Ti are respectively weighed 2 3.3g of Cd powder, and weighing 22g of spherical balls with the diameter of 3mm according to the mass ratio of grinding balls to medium liquid to powder of 2:1.5:1, wherein 12.65g of medium liquid (96% alcohol, 98% acetone, deionized water with the resistivity of 3 mu S/cm volume ratio=1.05:0.95:1.05); ball milling in a ball mill for 45min, taking out, and drying in a drying oven for 15h; putting the powder into a square die with length, width and height of 40mm, 20mm and 7mm, introducing 12A current, heating to 500 ℃ at a heating rate of 12 ℃/min, introducing Ar gas for protection, maintaining the pressure for 10min under a pressure condition of 200MPa, releasing pressure at a speed of 5MPa/s after the pressure maintaining is finished, and repeating the operation for 4 times to directly obtain the low Cd silver-based composite electrical contact material, wherein the Cd content is 16.2%.
Example 4
14.792g of Ti powder (purity is more than 90%) and 21.141g of Cd powder (purity is more than 90%) are respectively weighed according to the molar ratio of Ti to Cd of 2.3:1.4, put into an omnibearing three-dimensional powder mixer, mixed for 26 hours, put into a sintering furnace after the powder mixing is completed, and put into N 2 Heating to 650 ℃ at a speed of 15 ℃/min under the protection of gas, and performing heat treatment for 2 hours to prepare Ti 2 The Cd powder (phase purity: 99%) was pulverized and then sieved through a 200-mesh sieve, and the particle size was 40. Mu.m.
According to Ag to Ti 2 Cd accounts for 75 percent to 25 percent of the mass of the whole material, 12g of Ag powder (purity is more than 90 percent and grain diameter is 40 mu m) and Ti are respectively weighed 2 4g of Cd powder, and weighing 25.6g of a ball with a diameter of 3.5mm according to the mass ratio of grinding balls to medium liquid of 1.6:1.2:1, wherein 19.2g of medium liquid (97% alcohol, 99% acetone, deionized water with resistivity of 4 mu S/cm volume ratio=1.05:0.95:0.95); ball milling in ball mill for 60min, taking outDrying in a drying oven for 20h; placing the powder into a square mold with length, width and height of 35mm, 25mm and 8mm, introducing 15A current, heating to 550deg.C at 15 deg.C/min, and introducing N 2 And (3) protecting the gas, maintaining the pressure for 15min under the pressure condition of 300MPa, releasing the pressure at the speed of 5MPa/s after the pressure maintaining is finished, and repeating the operation for 5 times to directly obtain the low Cd silver-based composite electrical contact material, wherein the Cd content is 13.5%.
Example 5
14.578g of Ti powder (purity is more than 90%) and 23.532g of Cd powder (purity is more than 90%) are respectively weighed according to the mol ratio of Ti to Cd of 2.4:1.65, put into an omnibearing three-dimensional powder mixer, mixed for 27h, put into a sintering furnace after the powder mixing is finished, and heat treated for 2.5h at the speed of 18 ℃/min to 700 ℃ under the protection of Ar gas to prepare Ti 2 The Cd powder (phase purity: 99%) was pulverized and then sieved through a 300-mesh sieve, and the particle size was 35. Mu.m.
According to Ag to Ti 2 Cd accounts for 80 percent to 20 percent of the mass of the whole material, 10g of Ag powder (purity is more than 90 percent and grain diameter is 50 mu m) and Ti are respectively weighed 2 2.5g of Cd powder, and weighing 21g of balls with the diameter of 4mm according to the proportion of grinding balls to medium liquid, wherein the proportion of grinding balls to medium liquid is 1.5:1:1, and 14g of medium liquid (98% alcohol, 99% acetone, deionized water with the resistivity of 5 mu S/cm, and the volume ratio of deionized water is 1.1:0.9:1); ball milling in a ball mill for 70min, taking out, and drying in a drying oven for 22h; putting the powder into a square die with length, width and height of 30mm, 30mm and 9mm, introducing 18A current, heating to 600 ℃ at a heating rate of 18 ℃/min, simultaneously introducing Ar gas for protection, maintaining the pressure for 20min under a pressure condition of 400MPa, releasing the pressure at a speed of 5MPa/s after the pressure maintaining is finished, and repeating the operation for 6 times to directly obtain the low Cd silver-based composite electrical contact material, wherein the Cd content is 10.8%.
The reinforcing phase material Ti prepared in this example 2 XRD patterns of Cd phase components are shown in figure 1, and the reinforced phase material Ti 2 The low-power SEM image and the high-power SEM enlarged image of the morphology of the Cd powder are shown in figure 2, ag/Ti 2 Microstructure morphology graph of Cd composite electrical contact material and Ti 2 High-power SEM image of compact combination of Cd and silver matrix is shown in FIG. 3, ti is uniformly distributed in silver matrix 2 EDS spectrum of Cd is shown in 4. Metallographic and SEM micrographs both show Ti 2 Cd in silver matrixGood dispersibility and tight combination with the matrix, is favorable for improving the integral strength of the composite material to a certain extent, enhancing resistance to arc mechanical failure.
Example 6
12.947g of Ti powder (purity is more than 90%) and 19.456g of Cd powder (purity is more than 90%) are respectively weighed according to the molar ratio of Ti to Cd of 2.5:1.6, put into an omnibearing three-dimensional powder mixer, mixed for 28h, put into a sintering furnace after the powder mixing is finished, and put into N 2 Heating to 800 ℃ at a speed of 20 ℃/min under the protection of gas, and performing heat treatment for 3 hours to prepare Ti 2 The Cd powder (phase purity: 99%) was pulverized and then sieved through a 400-mesh sieve, and the particle size was 30. Mu.m.
According to Ag to Ti 2 Cd accounts for 85 percent to 15 percent of the mass of the whole material, 11.9g of Ag powder (purity is more than 90 percent and grain diameter is 70 mu m) and Ti are respectively weighed 2 2.1g of Cd powder, and weighing 19.6g of medium liquid (98% alcohol, 96% acetone, deionized water with resistivity of 3 mu S/cm in volume ratio of 1.2:0.8:1.05) with diameter of 4.5mm according to the mass ratio of 1.4:0.8:1 of the medium liquid to the grinding balls; ball milling in a ball mill for 80min, taking out, and drying in a drying oven for 24h; placing the powder into square mold with length, width and height of 40mm, 25mm and 10mm, introducing 20A current, heating to 650deg.C at 20deg.C/min, and introducing N 2 And (3) protecting the gas, maintaining the pressure for 25min under the pressure condition of 500MPa, releasing the pressure at the speed of 5MPa/s after the pressure maintaining is finished, and repeating the operation for 4 times to directly obtain the low Cd silver-based composite electrical contact material, wherein the Cd content is 8.1%.
Example 7
13.976g of Ti powder (purity is more than 90%) and 23.456g of Cd powder (purity is more than 90%) are respectively weighed according to the mol ratio of Ti to Cd of 2.6:1.7, put into an omnibearing three-dimensional powder mixer, mixed for 29 hours, put into a sintering furnace after the powder mixing is finished, and heat treated for 3.5 hours at the speed of 25 ℃/min to 1000 ℃ under the protection of Ar gas to prepare Ti 2 The Cd powder (phase purity: 99%) was pulverized and then sieved through a 500-mesh sieve, with a particle size of 25. Mu.m.
According to Ag to Ti 2 10 percent of Cd accounts for 90 percent of the mass of the whole material, 10.8g of Ag powder (purity is more than 90 percent and grain diameter is 90 mu m) and Ti are respectively weighed 2 1.2g of Cd powder and grinding the powder into medium liquidThe mass ratio of the powder is 1.2:0.6:1, 14.4g of spheres with the diameter of 4.5mm are weighed, and 7.2g of medium liquid (99% alcohol, 97% acetone, deionized water with the resistivity of 2 mu S/cm and volume ratio=1.15:0.95:0.9) is obtained; ball milling for 90min in a ball mill, taking out, and drying in a drying oven for 26h; putting the powder into a square die with length, width and height of 45mm, 20mm and 8mm, introducing 22A current, heating to 700 ℃ at a heating rate of 22 ℃/min, simultaneously introducing Ar gas for protection, maintaining the pressure for 30min under a pressure condition of 600MPa, releasing the pressure at a speed of 5MPa/s after the pressure maintaining is finished, and repeating the operation for 2 times to directly obtain the low Cd silver-based composite electrical contact material, wherein the Cd content is 5.4%.
Example 8
13.855g of Ti powder (purity is more than 90%) and 19.632g of Cd powder (purity is more than 90%) are respectively weighed according to the molar ratio of Ti to Cd of 2.9:1.75, put into an omnibearing three-dimensional powder mixer, mixed for 30h, put into a sintering furnace after the powder mixing is completed, and put into N 2 Heating to 1200 ℃ at a speed of 30 ℃/min under the protection of gas, and performing heat treatment for 4 hours to prepare Ti 2 The Cd powder (phase purity: 99%) was pulverized and then sieved through a 600-mesh sieve, with a particle size of 20. Mu.m.
According to Ag to Ti 2 Cd accounts for 95 percent to 5 percent of the mass of the whole material, 15.2g of Ag powder (purity is more than 90 percent and grain diameter is 100 mu m) and Ti are respectively weighed 2 0.8g of Cd powder, and weighing 16g of balls with the diameter of 4.5mm according to the mass ratio of grinding balls to medium liquid to powder of 1:0.5:1, wherein 8g of medium liquid (99% alcohol, 98% acetone, deionized water with the resistivity of 4 mu S/cm, volume ratio=1.2:0.85:1.05); ball milling in a ball mill for 100min, taking out, and drying in a drying oven for 30h; placing the powder into a square mold with length, width and height of 40mm, 10mm and 10mm, introducing 24A current, heating to 800deg.C at a rate of 25deg.C/min, and introducing N 2 And (3) protecting the gas, maintaining the pressure for 40min under the pressure condition of 800MPa, releasing the pressure at the speed of 5MPa/s after the pressure maintaining is finished, and repeating the operation for 6 times to directly obtain the low Cd silver-based composite electrical contact material, wherein the Cd content is 2.7%.
Performance tests were carried out on the low Cd silver-based composite electrical contact materials prepared in examples 1-8 (wherein the electrical contact performance was tested under the conditions of 380V/50A/AC-3 on the national standard (GB 14048.4-2010)), and the test results are shown in table 1.
Table 1 examples 1-8 composite electrical contact material performance
| Performance of | Example 1 | Example 2 | Example 3 | Example 4 | Example 5 | Example 6 | Example 7 | Example 8 |
| Density (g/cm) 2 ) | 9.10 | 9.12 | 9.17 | 9.28 | 9.31 | 9.33 | 9.25 | 9.21 |
| Resistivity (mu omega cm) | 2.07 | 2.27 | 3.11 | 3.29 | 3.56 | 3.74 | 3.36 | 3.21 |
| Microhardness (HV) | 90 | 92 | 94 | 93 | 97 | 95 | 91 | 93 |
| Tensile strength (MPa) | 218 | 212 | 219 | 217 | 235 | 231 | 223 | 220 |
| Electric life (secondary) | ＞10000 | ＞10000 | ＞10000 | ＞10000 | ＞10000 | ＞10000 | ＞10000 | ＞10000 |
As can be seen from Table 1, the present invention prepares Ti by pressureless rapid sintering 2 The Cd powder is tightly combined with the silver matrix, so that the composite material has higher density (9.10-9.33 g/cm 3 ) The uniformity of the composite material is ensured, and the actual production and application are facilitated. Ti (Ti) 2 The Cd powder is uniformly dispersed in the silver matrix to play a remarkable reinforcing effect, so that the composite material has good microhardness (90-97 HV) and is ensured to have good mechanical properties such as tensile strength (218-235 MPa). Ti (Ti) 2 The Cd has outstanding conductivity, and after being compounded with the Ag matrix, the Cd ensures the excellent conductivity (resistivity is 2.07-3.8 mu omega cm) of the composite electrical contact, so that the electrical contact has good conductivity and heat transfer in the service process, low contact resistance and small temperature rise, and further ensures the excellent arc erosion resistance (the electrical life is more than 1 ten thousand times). Thus Ti is 2 The Cd-reinforced silver-based composite electrical contact has excellent comprehensive performance, the Cd content is more than 38% lower than that of Ag/CdO, the low toxicity is outstanding, and the silver-based composite electrical contact has remarkable application advantages in the aspects of aviation, aerospace, navigation, military and the like in the future. The silver-based electrical contact material is expected to replace Ag/CdO, further promotes the low Cd in the field of silver-based electrical contact materials, and lays a foundation for the future Cd-free process.
Comparative example 1
Ti 2 The preparation process of Cd powder is the same as that of example 6, and the powder is prepared according to the ratio of Ag to Ti 2 Cd accounts for 85 percent to 15 percent of the mass of the whole material, 11.9g of Ag powder (purity is more than 90 percent and grain diameter is 70 mu m) and Ti are respectively weighed 2 2.1g of Cd powder, weighing 19.6g of balls with the diameter of 4.5mm according to the mass ratio of grinding balls to powder of 1.4:1, placing the balls into a powder mixer for mixing for 24 hours, directly placing the mixed powder into a circular die with the diameter of 15mm, and maintaining the pressure for 10 minutes under the pressure of 500MPa for molding to obtain Ag/Ti 2 Cd composite electrical contact material.
Comparative example 2
According to Ag to Ti 3 SiC 2 The weight percentage of the whole material is 85 percent to 15 percent, 11.9g of Ag powder (purity is more than 90 percent and grain diameter is 70 mu m) and Ti are respectively weighed 3 SiC 2 Powder 2.1gThe other steps were the same as in example 6.
Comparative example 3
According to Ag to Ti 3 C 2 The weight percentage of the whole material is 85 percent to 15 percent, 11.9g of Ag powder (purity is more than 90 percent and grain diameter is 70 mu m) and Ti are respectively weighed 3 C 2 Powder 2.1g, the other steps being the same as in example 6.
Comparative example 4
According to the mass fraction of Ag to CdS accounting for 85 percent of the total material to be 15 percent, 11.9g of Ag powder (purity is more than 90 percent, particle size is 70 mu m) and 2.1g of CdS powder are respectively weighed, and other steps are the same as those of example 6.
The composite electrical contact materials prepared in comparative examples 1 to 4 were subjected to performance tests (wherein the electrical contact performance was tested under the condition of 380V/50A/AC-3 on the national standard basis), and the test results are shown in Table 2.
TABLE 2 composite electrical contact materials and commercial Ag/CdO Synthesis Properties of comparative examples 1-4
| Performance of | Comparative example 1 | Comparative example 2 | Comparative example 3 | Comparative example 4 | Commercial Ag/CdO |
| Density (g/cm) 2 ) | 8.86 | 8.90 | 8.73 | 8.96 | 9.08 |
| Resistivity (mu omega cm) | 3.79 | 3.64 | 3.71 | 3.83 | 3.59 |
| Microhardness (HV) | 79 | 80 | 83 | 84 | 88 |
| Tensile strength (MPa) | 145 | 153 | 167 | 157 | 209 |
| Electric life (secondary) | 7000 | 6000 | 4000 | 5000 | 8500 |
As can be seen from Table 2, the density, resistivity, hardness, tensile strength, and arc erosion resistance life in comparative examples 1, 2, 3, and 4 are all less excellent than commercial Ag/CdO composite electrical contact materials. Under the same condition, ag/Ti prepared by dynamic discharge experiment 2 The Cd composite electrical contact material has high density and resistanceThe composite electrical contact material prepared by the method has the advantages of low rate, moderate hardness, excellent tensile strength, high arc erosion resistance and better comprehensive performance than that of Ag/CdO composite electrical contact materials prepared by other experimental methods and materials, and specific commercial application value and potential.
The above embodiments are only illustrative of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention, and various modifications and improvements made by those skilled in the art to the technical solutions of the present invention should fall within the protection scope defined by the claims of the present invention without departing from the design spirit of the present invention.
Claims (7)
1. The preparation method of the low Cd electrical contact reinforced phase material is characterized by comprising the following steps of:
s1, weighing Ti powder and Cd powder according to a molar ratio;
s2, fully mixing the Ti powder and the Cd powder in the step S1 to obtain uniform mixed powder;
s3, sintering the mixture powder in the step S2 under the protection of inert gas, heating to a set temperature at a certain heating rate, and preserving heat for a period of time;
s4, taking out the sample sintered in the step S3, grinding and sieving to obtain the low Cd electric contact reinforcing phase material;
the reinforcing phase material element is Ti 2 Cd particles are sphere-like and have a particle size of 1-50 μm;
the inert gas in the step S3 is Ar gas or N gas 2 The temperature rising rate is 3-30 ℃/min, the set temperature is 300-1200 ℃, and the heat preservation time is 0.5-4h.
2. The method according to claim 1, wherein the Ti powder in step S1 has a purity of more than 90% and a particle size of 1 to 100 μm; the purity of the Cd powder is more than 90 percent, and the particle size is 1-200 mu m; the molar ratio of Ti to Cd is (2-2.9) to (1-1.75).
3. The low Cd silver-based composite electrical contact material is characterized in that the low Cd electrical contact reinforced phase material obtained by the preparation method of claim 1 or 2 is prepared.
4. The low-Cd silver-based composite electrical contact material of claim 3, wherein Ag-based comprises 50% -95% by mass of the low-Cd silver-based composite electrical contact material, and wherein the reinforcing phase material comprises 5% -50% by mass of the low-Cd silver-based composite electrical contact material.
5. A method of making a low Cd silver-based composite electrical contact material according to claim 3 or 4, comprising the steps of:
s1, weighing Ag powder and prepared Ti according to mass percent 2 Cd powder, medium liquid and grinding balls;
s2, mixing the powder, the medium liquid and the grinding balls weighed in the step S1 in a ball mill, and drying the mixture after ball milling to obtain a mixture;
s3, placing the mixture in the step S2 into a die capable of being electrified, and controlling the temperature of the die by adjusting the current;
s4, preparing the composite block material from the mixed powder in the step S3 under the protection of inert gas by a dynamic pressure sintering technology.
6. The method according to claim 5, wherein the purity of the Ag powder in step S1 is more than 90%, and the particle size is 1 to 100 μm; ti (Ti) 2 The purity of the Cd powder is more than 90 percent, and the particle size is 1-50 mu m; the medium liquid comprises alcohol, acetone and deionized water, wherein the purity of the alcohol and the acetone is more than 95%, and the resistivity of the deionized water is 1-5 mu S/cm; the diameter of the grinding ball is 1-8mm; the mass ratio of the grinding ball to the medium liquid to the powder is (1-3) (0.5-3) 1; in the step S3, the power-on current is 6-24A, the heating rate is 5-25 ℃/min, and the temperature of the die is 300-800 ℃.
7. Use of the low Cd silver-based composite electrical contact material of claim 3 or 4 for the preparation of a low voltage switch.
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