Silver-based contact material containing composite conductive ceramic reinforced phase and preparation method of silver-based contact material

Abstract

The invention discloses a silver-based contact material containing a composite conductive ceramic reinforced phase and a preparation method of the silver-based contact material, and belongs to the technical field of silver-based contact materials. The preparation method of the silver-based contact material comprises the following steps: carrying out chemical co-deposition reaction on composite slurry obtained by carrying out high-energy ball milling on specially prepared ITO conductive ceramic powder and ATO conductive ceramic powder according to the mass ratio of 7: 2-2: 7, silver nitrate and sodium hydroxide to obtain composite wet powder with a uniformly dispersed reinforced phase and a core-shell structure; and roasting the obtained composite wet powder, and then carrying out isostatic compaction, sintering and extrusion procedures to obtain the composite material. The contact material prepared according to the method is low in resistivity and high in welding resistance, and the purpose of saving silver can be achieved.

Description

Technical Field

[0001] This invention belongs to the technical field of silver-based contact materials, specifically relating to a silver-based contact material containing a composite conductive ceramic reinforcing phase and its preparation method. Background Technology

[0002] Silver-based contact materials possess excellent electrical and thermal conductivity. However, pure silver has relatively weak resistance to welding, leading to adhesion issues during the application of electrical contact materials, thus affecting the lifespan of electrical appliances. Existing research shows that adding metal oxides (MeO, where Me represents Bi, In, or Sb, etc.) or conductive ceramics as reinforcing phases to the silver matrix can improve the electrical properties of electrical contact materials, including weld resistance, electrical life, and resistance to arc burn-off.

[0003] ITO (Indium Tin Oxide) is an N-type semiconductor conductive ceramic composed of In2O3 and SnO2 in a specific ratio (typically with SnO2 doping at 5-10 wt%). Its powder exhibits high conductivity (resistivity 10 wt%). -4 ~10 -2 With high permeability (Ω·cm), high light transmittance (visible light transmittance > 85%), and good dispersibility, it is widely used in transparent conductive coatings, electronic component electrodes, sensors, and composite modification of high-end electrical switch contact materials. For example, patent application CN109136633A discloses a high-resistance soldering electrical contact material comprising the following raw materials in parts by weight: 78-85 parts silver powder, 4-7 parts nickel powder, 0.8-1.2 parts graphite powder, 0.1-0.2 parts tritiium tetranitride, 0.1-0.2 parts niobium carbide, 0.05-0.1 parts diamond micropowder, 0.05-1 part zirconium diboride, 0.03-0.06 parts indium tin oxide, and 0.01-0.03 parts aluminum nitride. This invention, by adding synergistically acting tritiium tetranitride, niobium carbide, zirconium diboride, and indium tin oxide, not only improves the hardness of the electrical contact material but also enhances its resistance to soldering.

[0004] Currently, the oxide content of widely used silver-tin oxide contact materials is generally below 15%, meaning the silver content is above 85%. Common oxide contents are 12% or less, while silver contents can reach 88% or more. With the increasing depletion of precious metal resources and the continuous rise in silver prices, developing contact materials with high-performance reinforcing phase content can, on the one hand, reduce the use of silver to achieve silver conservation, and on the other hand, improve the material's resistance to welding and corrosion.

[0005] The present invention aims to use ATO and ITO composite conductive ceramics as the reinforcing phase of Ag-based electrical contact materials. Through the complementary and synergistic effects of the two conductive ceramics, a novel Ag-ATO·ITO contact material with excellent electrical properties containing composite conductive ceramic reinforcing phase is obtained, and the purpose of saving silver is achieved. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a silver-based contact material containing a composite conductive ceramic reinforcing phase with low resistivity, high resistance to welding and silver saving, and a method for preparing the same.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] A method for preparing a silver-based contact material containing a composite conductive ceramic reinforcing phase includes the following steps:

[0009] 1) Preparation of ITO conductive ceramic powder:

[0010] In2O3 powder and SnO2 powder were weighed at a mass ratio of 95:5 and placed in a high-energy ball mill. Grinding balls and water were added for ball milling. After ball milling, the material was removed, dried, and then dispersed to separate the grinding balls, thus obtaining powder I. The obtained powder I was then calcined at high temperature and pulverized to obtain ITO conductive ceramic powder.

[0011] 2) Preparation of ATO conductive ceramic powder:

[0012] Sb2O3 powder and SnO2 powder were weighed at a mass ratio of 5:95 and placed in a high-energy ball mill. Grinding balls and water were added for ball milling. After ball milling, the material was removed, dried, and then dispersed to separate the grinding balls, thus obtaining powder II. The obtained powder II was calcined at high temperature and pulverized to obtain ATO conductive ceramic powder.

[0013] 3) Weigh ITO conductive ceramic powder and ATO conductive ceramic powder in a mass ratio of 7:2 to 2:7 and place them in a high-energy ball mill. Add grinding balls and water for ball milling. After ball milling, remove the material and separate the grinding balls to obtain ITO·ATO composite conductive ceramic powder slurry.

[0014] 4) Add water or not to the obtained ITO·ATO composite conductive ceramic powder slurry, and then add silver nitrate and sodium hydroxide to carry out a chemical co-deposition reaction. After the reaction is completed, filter and wash the residue with water to obtain composite wet powder.

[0015] 5) The obtained composite wet powder is calcined and then crushed to obtain calcined powder;

[0016] 6) The obtained calcined powder is subjected to isostatic pressing, sintering, and extrusion processes to obtain the silver-based contact material containing the composite conductive ceramic reinforcing phase.

[0017] Further, in step 1), zirconia balls are used as grinding balls, with a ball-to-material ratio typically between 3:1 and 10:1. During ball milling, the milling speed is 100-200 r / min, and the milling time is 30-50 h. The material after milling includes a slurry of In₂O₃ powder, SnO₂ powder, and water, as well as the grinding balls. The dried material is preferably dispersed by ball milling and then sieved to separate the grinding balls. In this step, the high-temperature calcination temperature is 1500-1800℃, and the calcination time is 4-6 h.

[0018] Further, in step 2), zirconia balls are used as grinding balls, with a ball-to-material ratio typically between 1:1 and 5:1. During ball milling, the milling speed is 200–400 r / min, and the milling time is 10–20 h. The material after milling includes a slurry of Sb₂O₃ powder, SnO₂ powder, and water, as well as the grinding balls. The dried material is preferably dispersed by ball milling and then sieved to separate the grinding balls. In this step, the high-temperature calcination temperature is 800–1000 °C, and the calcination time is 2–4 h.

[0019] Further, in step 3), zirconia balls are used as grinding balls, with a ball-to-material ratio typically between 1:1 and 50:1. During ball milling, the milling speed is 100–400 r / min, and the milling time is 1–10 h. After ball milling, the grinding balls are separated by sieving.

[0020] In step 4), the amount of silver nitrate is calculated based on the material ratio of the target contact to be prepared, and the amount of sodium hydroxide is calculated based on the determined amount of silver nitrate. The silver nitrate can be added in solid or aqueous solution form. When silver nitrate is added in solid form, it is preferable to first dilute the composite slurry obtained in step 3) with water before adding the silver nitrate to facilitate its dissolution and the full progress of subsequent reactions. When silver nitrate is added in aqueous solution form, it is first prepared into a 20-40 wt% silver nitrate aqueous solution with water before addition. The sodium hydroxide is added in aqueous solution form, typically by preparing a 10-30 wt% sodium hydroxide aqueous solution with water.

[0021] In step 4), the retentate is washed with water until pH < 10, more preferably until pH < 8.

[0022] In step 5), the roasting and crushing operations are the same as in the prior art. Preferably, the roasting process is as follows: holding at 100~300℃ for 10~20h, then raising the temperature to 400~600℃ and holding for 0.5~10h. Crushing is preferably carried out in a mixer (such as a double cone mixer), and the crushing time is controlled at 0.1~10h.

[0023] The isostatic pressing, sintering, and extrusion processes involved in step 6) are all the same as in existing technologies. Specifically, the pressure during isostatic pressing is preferably 30~300MPa; the sintering temperature is 500~650℃, and the time is 0.5~96h; the extrusion temperature is 300~900℃. After extrusion, the wire is then drawn to the required size using conventional drawing processes.

[0024] The present invention also includes a silver-based contact material containing a composite conductive ceramic reinforcing phase prepared by the above method.

[0025] Compared with the prior art, the present invention is characterized by:

[0026] I. Core characteristics of the ATO and ITO composite system:

[0027] 1. Using ATO and ITO composite conductive ceramics as the reinforcing phase, the complementary and synergistic effects of the two conductive ceramics result in comprehensive properties superior to those of a single ceramic reinforcing phase. These core properties can be summarized in three dimensions: "performance balance, structural stability, and cost controllability," as detailed below:

[0028] 1.1 Synergistic balance between conductivity and temperature resistance: The composite system combines the high conductivity of ITO (resistivity as low as 5×10⁻⁶) with the high conductivity of ITO. -5 The composite ceramic exhibits excellent high-temperature stability (softening point 1630℃) with ATO (Ω·cm). By optimizing the ATO / ITO ratio (typical range 2:7 to 7:2), the resistivity of the composite ceramic can be controlled at 1×10⁻⁶. -4 ~5×10 -4 It has a resistance of Ω·cm, while maintaining an upper temperature limit of over 1200℃, thus solving the shortcomings of single ITO in terms of temperature difference resistance (softening point 1170℃) and single ATO in terms of conductivity.

[0029] 1.2 Improved dispersion uniformity and interfacial compatibility: ATO (density 6.95 g / cm³) 3 ) and ITO (density 7.17 g / cm³) 3 The density difference between the two ceramics is only 3.2%, which is much smaller than the density difference between traditional ceramics and metals. After high-energy ball milling, they can form a uniformly dispersed "island-like" distribution at the nanoscale in the Ag matrix, and the particle agglomeration rate is reduced by 40% compared with the single ATO system. At the same time, both ceramics are oxide semiconductors, with good interfacial wettability with the Ag matrix, and the interfacial bonding energy is improved by 25-30% compared with the single ATO-reinforced system.

[0030] 1.3 Precise Matching of Cost and Performance: By replacing 30-70% of ITO with ATO, the cost of the reinforcing phase raw materials can be reduced by 30-60% while maintaining conductivity close to that of a pure ITO-reinforced system (since the price of In is more than 50 times that of Sn). For example, Ag-based materials reinforced by ATO / ITO (5:5) composites have conductivity only 12% lower than ITO / Ag materials, but the raw material cost is reduced by 45%, achieving the desired match of "high-end performance and mid-range cost".

[0031] 1.4 Enhanced environmental adaptability: The chemical stability of the composite system is better than that of the single ceramic. In the neutral salt spray test (5% NaCl solution, 48h), the surface corrosion rate is only 65% ​​of that of the single ITO reinforced system. In a wide temperature range of -40~150℃, the contact resistance fluctuation is less than 15%, which is suitable for application requirements under extreme working conditions.

[0032] 2. ATO and ITO composite ceramics achieve a comprehensive improvement in the performance of Ag-based electrical contact materials through multiple mechanisms, including "synergistic conductive network, superimposed arc modulation, and complementary interface strengthening." The core mechanisms can be divided into the following four aspects:

[0033] 2.1 The composite ceramic forms a dual conductive network in the Ag matrix: "ITO-dominant conductivity - ATO-assisted conductivity": highly conductive ITO particles serve as the main channel for current transmission, reducing the overall resistance; ATO particles fill the gaps between ITO particles, avoiding the "bottleneck" of current transmission, while inhibiting the formation of oxide film on the Ag matrix.

[0034] 2.2 The inhibitory effect of the composite system on arc erosion is manifested as the synergistic effect of "energy layer absorption - double protection barrier": Under the action of high temperature (3000℃) of arc, ITO first absorbs part of the arc energy through lattice vibration (absorption efficiency of about 20%), and then ATO forms a continuous high temperature resistant ceramic protective layer (thickness 1~3μm) on the contact surface with its high melting point characteristics, blocking the direct burning of the Ag matrix by the arc.

[0035] 2.3 The composite system enhances anti-fusion welding performance through the dual effects of "rigid support and grain refinement": The high melting point of ATO allows it to remain solid when the Ag matrix melts (melting point 961℃), forming a "skeleton" rigid support structure that prevents the flow and aggregation of molten Ag; ITO particles refine Ag grains through heterogeneous nucleation, reducing the fluidity and surface tension of molten Ag and reducing the bonding strength of the fusion welding area.

[0036] 2.4 The interface bonding between the composite ceramic and the Ag matrix adopts a dual mode of "physical interlocking-chemical adsorption": high-energy ball milling generates a large number of hydroxyl groups and unsaturated bonds on the surface of ceramic particles, which form chemical adsorption bonds with Ag atoms; at the same time, the nanoscale size of the ceramic particles allows them to embed into the pits on the surface of the Ag matrix, forming a physical interlocking structure.

[0037] Therefore, ATO and ITO composite conductive ceramics, through complementary and synergistic effects, significantly improve the conductivity, arc erosion resistance, weldability, and mechanical properties of Ag-based electrical contact materials. Their core advantage lies in constructing a "dual conductive network" and a "dual protective barrier," achieving a balance between performance and cost, while also possessing good process adaptability. The research on composite reinforcement systems not only addresses the shortcomings of single ceramic reinforcement but also expands the application boundaries of Ag-based contact materials.

[0038] II. Construction of Core-Shell Structures via Chemical Co-deposition

[0039] A silver layer was deposited in situ on the surface of ITO·ATO composite particles using a chemical co-deposition method. This core-shell structure effectively reduces interfacial resistance by lowering interfacial bonding energy, further reducing the material resistivity; at the same time, the silver layer prevents direct contact between particles, solving the problem of nanomaterial agglomeration and ensuring uniform dispersion of the reinforcing phase.

[0040] III. Isostatic Pressing-Sintering Densification Control

[0041] A high-density green body is obtained by isostatic pressing. After high-temperature sintering, the silver layer deposited in situ on the surface of the ITO·ATO composite particles promotes the densification process. The superplastic flow of the silver matrix fills the micro-gaps, ultimately resulting in a green body with low porosity and high density.

[0042] In summary, this invention systematically solves the contradiction between conductivity, arc resistance, and cost control through the optimized combination of core processes, achieving a triple breakthrough in performance: firstly, effectively reducing contact resistance; secondly, reducing welding force and increasing electrical life; and thirdly, maintaining good conductivity and processability even with an oxide content as high as 16%, thus achieving silver-saving goals. Attached Figure Description

[0043] Figure 1 This is a metallographic diagram of the contact material prepared in Example 1 of the present invention.

[0044] Figure 2 This is a metallographic diagram of the contact material prepared in Comparative Example 1-1 of the present invention.

[0045] Figure 3 This is a welding force diagram of the contact material prepared in Example 1 of the present invention.

[0046] Figure 4This is a welding force diagram of the contact material prepared in Comparative Example 1-1 of the present invention.

[0047] Figure 5 This is a comparison chart of the simulated electrical lifetime cycles of the contact materials prepared in Example 1 and Comparative Example 1-1 of the present invention. Detailed Implementation

[0048] To better explain the technical solution of the present invention, the present invention will be further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited thereto.

[0049] The grinding balls described in the following embodiments are all zirconia balls.

[0050] Example 1: Preparation of Ag-ITO·ATO (18) contacts (material chemical formula is AgSnO2 (14)In2O3 (4))

[0051] 1) Preparation of ITO conductive ceramic powder:

[0052] In₂O₃ powder and SnO₂ powder were weighed at a mass ratio of 95:5 and placed in a high-energy ball mill. Grinding balls and water were added for ball milling, with a ball-to-material ratio of 3:1. The amount of water added was equal to the sum of the weights of the In₂O₃ powder and SnO₂ powder. The ball milling speed was 200 r / min, and the ball milling time was 40 h. After ball milling, the material was removed and placed in an oven to dry at 150 °C for 10 h. The dried material was then fed into a ball mill jar for ball milling and dispersing (ball milling speed was 100 r / min, and the ball milling time was 0.5 h). The grinding balls were separated to obtain powder I. Powder I was then calcined at 1600 °C for 4 h. The resulting material was pulverized and sieved (100 mesh) to obtain ITO conductive ceramic powder.

[0053] 2) Preparation of ATO conductive ceramic powder:

[0054] Sb₂O₃ powder and SnO₂ powder were weighed at a mass ratio of 5:95 and placed in a high-energy ball mill. Grinding balls and water were added for ball milling, with a ball-to-material ratio of 3:1. The amount of water added was equal to the sum of the weights of the Sb₂O₃ powder and SnO₂ powder. The ball milling speed was 200 r / min, and the ball milling time was 10 h. After ball milling, the material was removed and placed in an oven to dry at 150 °C for 10 h. The dried material was then fed into a ball mill jar for ball milling and dispersing (ball milling speed was 100 r / min, and the ball milling time was 0.5 h). The grinding balls were separated to obtain powder II. Powder II was then calcined at 800 °C for 2 h. The resulting material was pulverized and sieved (100 mesh) to obtain ATO conductive ceramic powder.

[0055] 3) Weigh 0.9 kg of ITO conductive ceramic powder prepared in step 1) and ATO conductive ceramic powder prepared in step 2) at a mass ratio of 2:7 and place them in a high-energy ball mill. Add grinding balls and water for ball milling. The ball-to-material ratio is 3:1, the amount of water added is 1.5 kg, the ball milling speed is 200 r / min, and the ball milling time is 2 h. After ball milling, remove the material and sieve it to separate the grinding balls, and obtain ITO·ATO composite conductive ceramic powder slurry.

[0056] 4) Weigh out 6.454 kg of silver nitrate and 1.519 kg of sodium hydroxide, and prepare a 22 wt% sodium hydroxide aqueous solution with water for later use;

[0057] Then, 25L of water was added to the ITO·ATO composite conductive ceramic powder slurry obtained in step 3) for dilution, and then weighed silver nitrate was added to it. The mixture was ultrasonically dispersed evenly, and then the prepared sodium hydroxide aqueous solution was added to it under stirring to carry out a co-deposition reaction. After the reaction was completed, the mixture was filtered, and the residue was washed with water until the pH was <8 to obtain composite wet powder.

[0058] 5) The obtained composite wet powder is loaded into a tray for segmented calcination. The calcination process is: 200℃×15h+ 400℃×6h. The calcined material is placed in a double cone mixer for crushing for 0.5h to obtain calcined powder.

[0059] 6) The obtained calcined powder is pressed into a green body under an isostatic pressing pressure of 300 MPa. The green body is then sintered in a sintering furnace at 910℃ for 2 hours to obtain a sintered ingot. The sintered ingot is extruded into a wire (φ6mm) at 700℃. The wire is then drawn to the required size using a conventional drawing process to obtain the silver-based contact material containing the composite conductive ceramic reinforcing phase. Its metallographic structure is as follows: Figure 1 As shown.

[0060] Comparative Example 1-1: AgSnO2(14)In2O3(4) wire prepared by conventional alloy internal oxidation method

[0061] 1) Preparation of AgSnIn alloy: Ag ingots, Sn ingots and In ingots were weighed in a mass ratio of 85:11.5:3.5 and melted in a medium-frequency melting furnace and cast into AgSnIn alloy ingots; then AgSnIn alloy wire with a diameter of φ1mm was obtained by extrusion and drawing.

[0062] 2) The AgSnIn alloy wire prepared in step 1) is placed in a high-pressure oxidation furnace for high-temperature and high-pressure oxidation, wherein the oxidation temperature is 750℃, the oxidation time is 96h, and the oxidation pressure is 2MPa. After oxidation, AgSnO2(14)In2O3(4) wire in oxidized state is obtained.

[0063] 3) Take the AgSnO2(14)In2O3(4) wire prepared in step 2) and place it on a shearing bed to cut it into pieces, wherein the size of the broken wires is 20mm×φ1.0mm;

[0064] 4) Take the AgSnO2(14)In2O3(4) shredded wire prepared in step 3) and place it in a steel mold. Press it into AgSnO2(14)In2O3(4) shredded wire ingots under a pressure of 500 tons, wherein the ingot diameter is φ85mm.

[0065] 5) Take the AgSnO2(14)In2O3(4) shredded ingots prepared in step 4) and place them in a 1000-ton extruder for hot extrusion to produce AgSnO2(14)In2O3(4) wire with a diameter of φ6mm;

[0066] 6) Take the φ6mm AgSnO2(14)In2O3(4) wire prepared in step 5) and perform drawing plastic processing. Then, the wire is drawn to the required size according to the conventional drawing process to obtain the AgSnO2(14)In2O3(4) contact material.

[0067] The metallographic structure of the contact material obtained in this example is as follows: Figure 2 As shown.

[0068] The resistivity, contact resistance, and electrical life of the contact materials prepared in Example 1 and Comparative Example 1-1 were tested, and the results are shown in Table 1 and Table 2 below, respectively.

[0069] Table 1 Resistivity and Contact Resistance

[0070]

[0071] As shown in Table 1, the resistivity of the Ag-ATO·ITO material in Example 1 is as low as 2.55 μΩ·cm, which is about 14% lower than that of the traditional AgSnO2In2O3 material (2.98 μΩ·cm); the contact resistance is reduced to 0.834 mΩ, which is 24% lower than that of the traditional AgSnO2In2O3 material, effectively reducing the temperature rise during the electrical contact process and suppressing arc-induced material welding from the source.

[0072] Table 2 Simulated Electrical Life Cycles

[0073]

[0074] This application utilizes the ATO·ITO reinforcing phase, which decomposes into SnO2, Sb2O3, and In2O3 under high-temperature electric arc, absorbing part of the arc energy, inhibiting arc-concentrated erosion, and significantly reducing the welding tendency of the contact surface. In the simulated electrical life test of the Ag-ATO·ITO (18) material in Example 1 under 220VAC / 25A resistive load conditions, the maximum welding force was reduced to below 15g (e.g. Figure 3 As shown), the maximum fusion welding force of traditional AgSnO2In2O3(14) material is 40g (as shown). Figure 4 (As shown in Table 2) decreased significantly. Figure 5 As shown, the average number of electrical lifetime cycles of the contact material described in Example 1 is increased by 26%.

[0075] Comparative Examples 1-2: Preparation of Ag-ITO·ATO (18) contacts (material chemical formula is AgSnO2 (14)In2O3 (4))

[0076] Unlike Example 1, in step 3), the ITO conductive ceramic powder is replaced with commercially available ITO.

[0077] Comparative Examples 1-3: Preparation of Ag-ITO·ATO (18) contacts (material chemical formula is AgSnO2 (14)In2O3 (4))

[0078] Unlike Example 1, in step 3), ATO conductive ceramic powder is replaced with commercially available ATO.

[0079] Comparative Examples 1-4: Preparation of Ag-ITO·ATO (18) contacts (material chemical formula is AgSnO2 (14)In2O3 (4))

[0080] Unlike Example 1, only ITO conductive ceramic powder was used as the reinforcing phase, that is, the amount of ATO conductive ceramic powder used in step 3) was 0 kg.

[0081] Comparative Examples 1-5: Preparation of Ag-ITO·ATO (18) contacts (material chemical formula is AgSnO2 (14)In2O3 (4))

[0082] Unlike Example 1, only ATO conductive ceramic powder was used as the reinforcing phase, that is, the amount of ITO conductive ceramic powder used in step 3) was 0 kg.

[0083] Comparative Examples 1-6: Preparation of Ag-ITO·ATO (18) contacts (material chemical formula is AgSnO2 (16)In2O3 (2))

[0084] Unlike Example 1, in step 3), ITO conductive ceramic powder and ATO conductive ceramic powder are weighed in a mass ratio of 2:8, and the total amount remains unchanged.

[0085] Comparative Examples 1-7: Preparation of Ag-ITO·ATO (18) contacts (material chemical formula is AgIn2O3 (16)SnO2 (2))

[0086] Unlike Example 1, in step 3), ITO conductive ceramic powder and ATO conductive ceramic powder are weighed in a mass ratio of 8:2, and the total amount remains unchanged.

[0087] Example 2: Preparation of Ag-ITO·ATO (18) contacts (material chemical formula is AgIn2O3 (9)SnO2 (9))

[0088] The difference from Example 1 is:

[0089] In step 3), weigh out ITO conductive ceramic powder and ATO conductive ceramic powder (0.9 kg in total) in a 5:5 mass ratio.

[0090] In step 4), the amounts of silver nitrate and sodium hydroxide weighed are 6.454 kg and 1.519 kg, respectively.

[0091] Example 3: Preparation of Ag-ITO·ATO (18) contacts (material chemical formula is AgIn2O3 (14)SnO2 (4))

[0092] The difference from Example 1 is:

[0093] In step 3), weigh out ITO conductive ceramic powder and ATO conductive ceramic powder (total 1.6 kg) at a mass ratio of 7:2.

[0094] In step 4), the amounts of silver nitrate and sodium hydroxide weighed are 13.22 kg and 3.2 kg, respectively.

[0095] The resistivity and simulated electrical lifetime cycles of the contact materials prepared in Examples 2-3 and Comparative Examples 1-2 to 1-7 were tested (under the same test conditions as before), and the results are shown in Table 3 below.

[0096] Table 3 Resistivity and Simulated Electrical Life Cycles

[0097]

[0098] As can be seen from Table 3, the contact material prepared by the method described in this invention has a better electrical lifetime. Although Comparative Example 7 also obtained an excellent electrical lifetime, the amount of ITO conductive ceramic powder used was large, which significantly increased the cost, making it significantly higher than that of Example 1.

Claims

1. A method for preparing a silver-based contact material containing a composite conductive ceramic reinforcing phase, comprising the following steps: 1) Preparation of ITO conductive ceramic powder: In2O3 powder and SnO2 powder were weighed at a mass ratio of 95:5 and placed in a high-energy ball mill. Grinding balls and water were added for ball milling. After ball milling, the material was removed, dried, and then dispersed to separate the grinding balls, thus obtaining powder I. The obtained powder I was then calcined at high temperature and pulverized to obtain ITO conductive ceramic powder. 2) Preparation of ATO conductive ceramic powder: Sb2O3 powder and SnO2 powder were weighed at a mass ratio of 5:95 and placed in a high-energy ball mill. Grinding balls and water were added for ball milling. After ball milling, the material was removed, dried, and then dispersed to separate the grinding balls, thus obtaining powder II. The obtained powder II was calcined at high temperature and pulverized to obtain ATO conductive ceramic powder. 3) Weigh ITO conductive ceramic powder and ATO conductive ceramic powder in a mass ratio of 7:2 to 2:7 and place them in a high-energy ball mill. Add grinding balls and water for ball milling. After ball milling, remove the material and separate the grinding balls to obtain ITO·ATO composite conductive ceramic powder slurry. 4) Add water or not to the obtained ITO·ATO composite conductive ceramic powder slurry, and then add silver nitrate and sodium hydroxide to carry out a chemical co-deposition reaction. After the reaction is completed, filter and wash the residue with water to obtain composite wet powder. 5) The obtained composite wet powder is calcined and then crushed to obtain calcined powder; 6) The obtained calcined powder is subjected to isostatic pressing, sintering, and extrusion processes to obtain the silver-based contact material containing the composite conductive ceramic reinforcing phase.

2. The preparation method according to claim 1, characterized in that, In step 1), the ball-to-material ratio is 3:1 to 10:1, the ball mill speed is 100 to 200 r / min, and the ball milling time is 30 to 50 h.

3. The preparation method according to claim 1, characterized in that, In step 2), the ball-to-material ratio is 1:1 to 5:1, the ball mill speed is 200 to 400 r / min, and the ball milling time is 10 to 20 h.

4. The preparation method according to claim 1, characterized in that, In step 1), the high-temperature calcination temperature is 1500~1800℃, and the calcination time is 4~6h; In step 2), the high-temperature calcination temperature is 800~1000℃, and the calcination time is 2~4h.

5. The preparation method according to claim 1, characterized in that, In step 4), the silver nitrate is added in the form of a solid or an aqueous solution, and the sodium hydroxide is added in the form of an aqueous solution.

6. The preparation method according to claim 1, characterized in that, In step 4), the retentate is washed with water until pH < 10.

7. The preparation method according to claim 1, characterized in that, In step 5), the roasting process is as follows: keep warm at 100~300℃ for 10~20h, and then raise the temperature to 400~600℃ and keep warm for 0.5~10h.

8. The preparation method according to claim 1, characterized in that, In step 6), the pressure during isostatic pressing is 30~300 MPa.

9. The preparation method according to claim 1, characterized in that, In step 6), the sintering temperature is 500~650℃ and the sintering time is 0.5~96h; the extrusion temperature is 300~900℃.

10. A silver-based contact material containing a composite conductive ceramic reinforcing phase prepared by the method according to any one of claims 1 to 9.

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