Method for preparing silver tin oxide relay contact material from composite mixed powder

Abstract

A method for preparing a silver tin oxide relay contact material through composite mixed powder comprises the following steps that firstly, tin oxide is completely added into a powder mixing machine 1, then part of silver powder is added, the adding mass of the silver powder is larger than or equal to 1 / 3 of the total amount of the silver powder and smaller than or equal to 1 / 2 of the total amount of the silver powder, the powder mixing time ranges from 1.5 hours to 2 hours, and the rotating speed of the powder mixing machine 1 ranges from 100 revolutions per minute to 120 revolutions per minute; and 2, all the mixed materials in the powder mixing machine 1 are taken out and then added into a powder mixing machine 2, all the remaining silver powder is added, the powder mixing time is 2.5-3 hours, and the rotating speed of the powder mixing machine is 150-180 r / min. By adopting a composite powder mixing method, the oxidation process problem of silver tin oxide and the agglomeration problem of tin oxide in a silver matrix can be effectively solved, so that the microstructure of the silver tin oxide is fully uniform. According to a metallographic diagram of the silver tin oxide contact material, the microstructure of the silver tin oxide is uniform, and almost no defective tissue exists; and the physical performance and the electrical service life of the tested contact material can reach the design standard.

Description

Technical Field

[0001] The invention relates to a method for preparing a relay contact material, in particular to a method for preparing a silver tin oxide relay contact material by using a composite mixed powder. Background Art

[0002] Contact materials play a vital role in electrical equipment. They are directly related to the electrical conductivity, arc erosion resistance, and anti-oxidation and welding performance of the equipment. Silver tin oxide contacts are extremely critical and important contact components in electrical equipment such as relays and electrical switches. They are mainly responsible for connecting and disconnecting circuits and load currents. The quality of silver tin oxide contacts directly affects the life of relays and the safety and reliability of electrical equipment. Adding tin oxide as a reinforcing phase to the silver matrix can effectively enhance the arc erosion resistance and anti-welding performance of the silver tin oxide contact material. Therefore, the silver tin oxide electrical contact material is a metal composite material with tin oxide as a dispersion strengthening phase uniformly distributed in the silver matrix.

[0003] As electrical equipment develops towards miniaturization and high performance, the requirements for contact materials are becoming higher and higher. Domestic and foreign scholars usually use the internal oxidation method to prepare silver tin oxide electrical contact materials. The traditional internal oxidation preparation process has some problems, such as uneven oxidation composition, insufficient oxidation, and poor mechanical processing performance. Due to the presence of a dense tin oxide film during the oxidation process of the silver-tin alloy, it will hinder the further oxidation of the silver-tin alloy. At the same time, the entry of tin into the silver alloy lattice will seriously hinder the diffusion of oxygen atoms. Therefore, when preparing silver tin oxide electrical contact materials by the internal oxidation method, indium elements must be added to increase the internal oxidation rate of the silver-tin alloy. The internal oxidation method for preparing silver tin oxide electrical contact materials is to oxidize the silver-tin alloy at high temperature under certain oxygen pressure conditions. The detailed process flow is as follows. Figure 1 shown.

[0004] When preparing silver tin oxide contact materials by internal oxidation, the process conditions such as oxygen pressure, oxidation temperature, and oxidation time are extremely demanding. If the oxidation is insufficient, a large number of tin atoms in the microstructure of the silver tin oxide will not be oxidized, and the tin atoms cannot be oxidized to tin oxide as dispersion strengthening. If the oxidation is excessive, cracks or even holes will appear in the center of the silver tin oxide material, which will seriously affect the contact performance and electrical service life of the silver tin oxide contact. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a method for preparing silver tin oxide relay contact material by composite mixed powder, which can effectively solve the oxidation process problem of silver tin oxide and the agglomeration problem of tin oxide in the silver matrix, so as to make the microstructure of silver tin oxide uniform.

[0006] The technical solution adopted by the present invention to solve the technical problem is:

[0007] A method for preparing a silver tin oxide relay contact material by composite mixed powder comprises the following steps:

[0008] Powder mixing step 1: add all the tin oxide into the powder mixer 1, then add part of the silver powder, 1 / 3 of the total amount of silver powder ≤ the mass of the silver powder added ≤ 1 / 2 of the total amount of silver powder, mix the powder, the mixing time is 1.5 to 2 hours, and the speed of the powder mixer 1 is 100 to 120 rpm;

[0009] Powder mixing step 2: Take out all the mixed materials in the powder mixer 1, and then add all of them into the powder mixer 2, and add all of the remaining silver powder, mix the powder, the mixing time is 2.5 to 3 hours, and the speed of the powder mixer is 150 to 180 rpm.

[0010] The present invention adopts two powder mixing steps to ensure that the silver powder and the tin oxide powder can be fully and evenly mixed.

[0011] Furthermore, the powder mixer 1 is preferably a double-motion powder mixer. The powder mixer 2 is preferably a plowshare type powder mixer.

[0012] The powder mixer 1 is preferably a double-motion powder mixer. The double-motion powder mixer uses the eccentric rotary motion of the barrel and the high-speed stirring motion of the full-size rotary blades to make the powder roll up and down and convect left and right in the barrel space, achieving the mixing effect of "uniform in large areas" and "sufficient in small areas", which can solve the mixing problem of ultrafine tin oxide powder and silver powder. The powder mixer 2 is preferably a plow-type powder mixer. The high-speed rotation and discrete stirring of the plow blade can greatly increase the mixing speed, which can solve the workability and uniformity of the mixed powder of tin oxide powder-silver powder and the remaining silver powder material without segregation.

[0013] If too little silver powder is added to the powder mixer 1, the workability and uniformity of the mixed powder of tin oxide powder-silver powder and the remaining silver powder material in the powder mixer 2 will be affected, resulting in segregation. If too much silver powder is added to the powder mixer 1, the ultrafine tin oxide powder will not be fully mixed with the silver powder.

[0014] If the mixing time is too long, the energy consumption will increase. If the mixing time is too short, the mixing will be uneven. If the mixer speed is too high, the energy consumption and maintenance cost will increase. If the mixer speed is too low, the mixing will be uneven.

[0015] The specific steps include:

[0016] ① Powder drying: drying the silver powder and tin oxide powder;

[0017] Furthermore, in step ①, the mass percentage of silver powder is 87-89%, and the mass percentage of tin oxide powder is 11-13%. The drying temperature is 80-90° C., and the drying time is 2-3 hours.

[0018] ② Powder mixing step 1: Use a double motion powder mixer to mix the powder, add all the tin oxide into the powder mixing tank, and then add some silver powder, 1 / 3 of the total amount of silver powder ≤ the mass of silver powder added ≤ 1 / 2 of the total amount of silver powder, the mixing time is 1.5 to 2 hours, and the speed of the powder mixer is 100 to 120 rpm;

[0019] ③ Powder mixing step 2: Use a shovel-type powder mixer to mix the powder, take out all the mixed materials in the double-motion powder mixer, and then add all of them into the shovel-type powder mixer, and add all of the remaining silver powder. The mixing time is 2.5 to 3 hours, and the speed of the powder mixer is 150 to 180 rpm to obtain a mixed powder;

[0020] ④ Isostatic pressing: isostatically pressing the mixed powder obtained in step ③ to obtain a silver tin oxide mixed powder ingot;

[0021] Furthermore, in step ④, the isostatic pressing pressure is 15 to 20 MPa, and the holding time is 15 to 20 seconds.

[0022] ⑤ Sintering: The silver-tin oxide mixed powder ingot pressed in step ④ is sintered in air to obtain a silver-tin oxide alloy ingot, i.e., a silver-tin oxide embryo material.

[0023] Furthermore, in step ⑤, the silver-tin oxide mixed powder ingot is first heated to 300-500° C., then heated to 850-900° C., and kept warm for ≥2 hours.

[0024] The silver tin oxide embryo material obtained by the present invention can be used to prepare wires and sheets, and the specific steps are as follows:

[0025] Option 1: Preparation of silver tin oxide wire

[0026] ⑥ Extrusion: extruding the silver-tin oxide alloy ingot obtained by sintering to obtain a silver-tin oxide thick wire;

[0027] Further, in step ⑥, extrusion preferably uses a 1250-ton extruder.

[0028] Furthermore, in step ⑥, the specific operation of extrusion is: the extrusion barrel is heated to 380-420° C. (preferably 400° C.), the extrusion die is Φ6.0 mm, the extrusion speed is 1.5-2.5 mm / S, and the extrusion is water-cooled.

[0029] ⑦ Wire drawing: The silver tin oxide thick wire obtained in step ⑥ is drawn to obtain a silver tin oxide relay contact wire material.

[0030] Furthermore, in step ⑦ wire drawing, the wire drawing die is selected: Ф6.0 / annealing / Ф5.6 / annealing / Ф5.2 / annealing / Ф4.8 / annealing / Ф4.4 / annealing / Ф4.0 / annealing / Ф3.6 / annealing / Ф3.2 / annealing / Ф2.9 / annealing / Ф2.6 / annealing / Ф2.38–0.02mm.

[0031] Furthermore, in step ⑦, the annealing temperature is 550±10°C; the holding time is 0.8-1.2 hours (preferably 1 hour). Air atmosphere, directly out of the furnace. Annealing is performed once for each wire drawing.

[0032] Solution 2: Preparation of silver tin oxide sheets

[0033] ⑥ Extrusion: extruding the silver-tin oxide alloy ingot obtained by sintering to obtain a silver-tin oxide sheet;

[0034] Further, in step ⑥, extrusion preferably uses a 1250-ton extruder.

[0035] Furthermore, in step ⑥, the specific operation of extrusion is: the extrusion barrel is heated to 380-420° C. (preferably 400° C.), the extrusion die is 5*72 mm, and the extrusion speed is 1.5-2.5 mm / S.

[0036] ⑦ Composite peripheral argon arc welding: The silver tin oxide sheet extruded by the extruder is combined with a pure silver sheet of the same size, and composite peripheral argon arc welding is used to obtain a silver / silver tin oxide composite sheet after argon arc welding;

[0037] Furthermore, in step ⑦, the composite surface is cleaned with non-woven fabric soaked in ethanol before welding, and the two sides are welded after drying.

[0038] ⑧Hot rolling: hot rolling the silver / silver tin oxide composite plate after argon arc welding;

[0039] Further, in step ⑧, hot rolling is preferably carried out in a 15KW muffle furnace.

[0040] Furthermore, in step ⑧, the hot rolling temperature is 750-800° C. and the temperature is kept for 1.5-2 hours.

[0041] Furthermore, in step ⑧, the hot rolling reduction is greater than 50% to ensure the bonding strength of the silver / silver tin oxide composite plate.

[0042] ⑨Cold rolling: cold rolling the hot-rolled silver / silver tin oxide composite plate according to the size requirements;

[0043] ⑩ Annealing: Anneal the cold-rolled silver / silver tin oxide composite plate to obtain a silver tin oxide sheet.

[0044] Further, in step ⑩, annealing is preferably performed in a 15KW muffle furnace.

[0045] Furthermore, in step ⑩, the annealing operation is: heating to 550-600°C, keeping the temperature in a nitrogen atmosphere for 0.8-1.2 hours (preferably 1 hour), and air cooling to a temperature of ≤80°C before taking out of the furnace.

[0046] The present invention adopts a composite powder mixing method, which can effectively solve the oxidation process problem of silver tin oxide and the agglomeration problem of tin oxide in the silver matrix, so that the microstructure of the silver tin oxide is fully uniform. According to the metallographic diagram of the silver tin oxide contact material prepared by the present invention, it can be seen that the microstructure of the silver tin oxide is uniform and has almost no defective structure; and the physical properties and electrical life of the contact material are tested, and both can meet the design standards.

[0047] The present invention adopts a powder metallurgy method to prepare a silver tin oxide electrical contact material. The distribution and particle size of tin oxide in the mixed powder determine the performance of the silver tin oxide contact. Since the tin oxide particles are fine, traditional mechanical mixing will cause the tin oxide to agglomerate. The tin oxide agglomeration will cause a large number of defects to aggregate in the microstructure of the material, seriously affecting the performance of the silver tin oxide contact. Therefore, the present invention can solve the agglomeration problem of tin oxide in the silver matrix, making the microstructure of the silver tin oxide fully uniform.

[0048] The present invention adopts a powder metallurgy method and directly uses tin oxide powder as a raw material without oxidizing tin atoms, thereby effectively solving the oxidation process problem of silver tin oxide contact materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 This is a process flow chart of preparing silver tin oxide contact material by internal oxidation method in the prior art;

[0050] Figure 2 This is the metallographic structure diagram (50X) of the silver tin oxide relay contact material obtained in Example 1 of the present invention; 50X is a diagram magnified 50 times; the same below;

[0051] Figure 3 This is the metallographic structure diagram (200X) of the silver tin oxide relay contact material obtained in Example 1 of the present invention;

[0052] Figure 4 This is the metallographic structure diagram (50X) of the silver tin oxide relay contact material obtained in Comparative Example 1 of the present invention;

[0053] Figure 5 This is the metallographic structure diagram (200X) of the silver tin oxide relay contact material obtained in Comparative Example 1 of the present invention;

[0054] Figure 6 This is the metallographic structure diagram (50X) of the silver tin oxide relay contact material obtained in Comparative Example 2 of the present invention;

[0055] Figure 7 This is the metallographic structure diagram (200X) of the silver tin oxide relay contact material obtained in Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0056] The present invention is further described in detail below in conjunction with specific embodiments.

[0057] Example 1

[0058] The method for preparing silver tin oxide relay contact material by composite mixed powder of this embodiment comprises the following steps:

[0059] ① Powder drying: drying the silver powder and tin oxide powder;

[0060] In step ①, the mass percentage of silver powder is 88%, and the mass percentage of tin oxide powder is 12%. The drying temperature is 85° C., and the drying time is 2 hours.

[0061] ② Powder mixing step 1: Use a double motion powder mixer to mix the powder, add all the tin oxide into the powder mixing tank, and then add some silver powder, the amount of silver powder added is 1 / 2 of the total mass of the silver powder, the powder mixing time is 2 hours, and the speed of the powder mixer is 100 rpm;

[0062] ③ Powder mixing step 2: Use a shovel-type powder mixer to mix the powder, take out all the mixed materials in the double-motion powder mixer, and then add all of them into the shovel-type powder mixer, and add all of the remaining silver powder. The mixing time is 2.5 hours, and the speed of the powder mixer is 150 rpm to obtain a mixed powder;

[0063] ④ Isostatic pressing: isostatically pressing the mixed powder obtained in step ③ to obtain a silver tin oxide mixed powder ingot;

[0064] In step ④, the isostatic pressing pressure is 15 MPa and the holding time is 20 seconds.

[0065] ⑤ Sintering: The silver-tin oxide mixed powder ingot pressed in step ④ is sintered in air to obtain a silver-tin oxide alloy ingot, i.e., a silver-tin oxide embryo material.

[0066] In step ⑤, the silver-tin oxide mixed powder ingot is first heated to 500° C., then raised to 900° C., and kept at this temperature for 2 hours.

[0067] ⑥ Extrusion: extruding the silver-tin oxide alloy ingot obtained by sintering to obtain a silver-tin oxide thick wire;

[0068] In step ⑥, a 1250-ton extruder is used for extrusion.

[0069] In step ⑥, the specific operation of extrusion is: the extrusion barrel is heated to 400° C., the extrusion die is Φ6.0 mm, the extrusion speed is 1.5 mm / S, and the extrusion is water-cooled.

[0070] ⑦ Wire drawing: The silver tin oxide thick wire obtained in step ⑥ is drawn to obtain a silver tin oxide relay contact wire material.

[0071] Step ⑦ Wire drawing, use wire drawing die: Ф6.0 / annealing / Ф5.6 / annealing / Ф5.2 / annealing / Ф4.8 / annealing / Ф4.4 / annealing / Ф4.0 / annealing / Ф3.6 / annealing / Ф3.2 / annealing / Ф2.9 / annealing / Ф2.6 / annealing / Ф2.38–0.02mm.

[0072] Step ⑦ During wire drawing, annealing temperature: 550±10℃; holding time: 1 hour. Air atmosphere, directly out of the furnace. Anneal once for each wire drawing.

[0073] The physical properties and electrical life performance of the silver tin oxide contact wire material obtained in Example 1 were tested. The test results are shown in Tables 1 and 2.

[0074] The detection method standards are: JB / T 8444-2015, GB / T 20235-2006, GB / T 14048.4-2020.

[0075] It can be seen from Table 1 and Table 2 that the physical properties and electrical life of the silver zinc oxide contact material obtained in Example 1 of the present invention can meet the design standards.

[0076] Table 1

[0077] Physical Properties of Silver Tin Oxide

[0078]

[0079] Table 2

[0080] 32A relay temperature rise and electrical life test data

[0081]

[0082] From the above test results, it can be seen that the composite powder mixing method adopted in the present invention can effectively solve the agglomeration problem of tin oxide in the silver matrix, making the microstructure of silver tin oxide fully uniform, so that the physical properties and electrical life of the obtained silver zinc oxide contact material can meet the design standards.

[0083] Figure 2 This is the metallographic structure diagram (50X) of the silver tin oxide relay contact material obtained in Example 1 of the present invention; 50X is a diagram magnified 50 times; the same below;

[0084] Figure 3 This is the metallographic structure diagram (200X) of the silver tin oxide relay contact material obtained in Example 1 of the present invention.

[0085] The silver tin oxide contact material obtained in Example 1 was subjected to metallographic examination. The metallographic image of the silver tin oxide contact material prepared in this example shows that the microstructure of the silver tin oxide is uniform and has almost no defective structure. The physical properties and electrical life of the contact material were tested and both met the design standards.

[0086] Example 2

[0087] The method for preparing silver tin oxide relay contact material by composite mixed powder of this embodiment comprises the following steps:

[0088] ① Powder drying: drying the silver powder and tin oxide powder;

[0089] In step ①, the mass percentage of silver powder is 87%, and the mass percentage of tin oxide powder is 13%. The drying temperature is 90° C., and the drying time is 2 hours.

[0090] ② Powder mixing step 1: Use a double motion powder mixer to mix the powder, add all the tin oxide into the powder mixing tank, and then add some silver powder, the mass of silver powder added is equivalent to 1 / 3 of the total amount of silver powder, the mixing time is 2 hours, and the speed of the powder mixer is 100 rpm;

[0091] ③ Powder mixing step 2: Use a shovel-type powder mixer to mix the powder, take out all the mixed materials in the double-motion powder mixer, and then add all of them into the shovel-type powder mixer, and add all of the remaining silver powder. The mixing time is 2.5 hours, and the speed of the powder mixer is 180 rpm to obtain a mixed powder;

[0092] ④ Isostatic pressing: isostatically pressing the mixed powder obtained in step ③ to obtain a silver tin oxide mixed powder ingot;

[0093] In step ④, the isostatic pressing pressure is 15 MPa and the holding time is 15 seconds.

[0094] ⑤ Sintering: The silver-tin oxide mixed powder ingot pressed in step ④ is sintered in air to obtain a silver-tin oxide alloy ingot, i.e., a silver-tin oxide embryo material.

[0095] In step ⑤, the silver-tin oxide mixed powder ingot is first heated to 300° C., then raised to 900° C., and kept warm for 3 hours.

[0096] ⑥ Extrusion: extruding the silver-tin oxide alloy ingot obtained by sintering to obtain a silver-tin oxide sheet;

[0097] In step ⑥, extrusion preferably uses a 1250-ton extruder.

[0098] In step ⑥, the specific operation of extrusion is: the extrusion barrel is heated to 400° C., the extrusion die is 5*72 mm, and the extrusion speed is 1.5 mm / S.

[0099] ⑦ Composite peripheral argon arc welding: The silver tin oxide sheet extruded by the extruder is combined with a pure silver sheet of the same size, and composite peripheral argon arc welding is used to obtain a silver / silver tin oxide composite sheet after argon arc welding;

[0100] In step ⑦, the composite surface is cleaned with non-woven fabric soaked in ethanol before welding, and the two sides are welded after drying.

[0101] ⑧Hot rolling: hot rolling the silver / silver tin oxide composite plate after argon arc welding;

[0102] In step ⑧, hot rolling is carried out in a 15KW muffle furnace.

[0103] In step ⑧, the hot rolling temperature is 800° C. and the temperature is kept for 1.5 hours.

[0104] In step ⑧, the hot rolling reduction is 55% to ensure the bonding strength of the silver / silver tin oxide composite plate.

[0105] ⑨Cold rolling: cold rolling the hot-rolled silver / silver tin oxide composite plate according to the size requirements;

[0106] ⑩ Annealing: Anneal the cold-rolled silver / silver tin oxide composite plate to obtain a silver tin oxide sheet.

[0107] In step ⑩, annealing is performed in a 15KW muffle furnace.

[0108] In step ⑩, the annealing operation is: heating to 600° C., keeping the temperature in a nitrogen atmosphere for 1 hour, and air cooling to 80° C. before taking out of the furnace.

[0109] This embodiment adopts a composite powder mixing method, which can effectively solve the problem of tin oxide agglomeration in the silver matrix and make the microstructure of silver tin oxide uniform. The metallographic image of the silver tin oxide contact material prepared in this embodiment shows that the microstructure of silver tin oxide is uniform and has almost no defective structure; and the physical properties and electrical life of the contact material tested can meet the design standards.

[0110] Example 3

[0111] The method for preparing silver tin oxide relay contact material by composite mixed powder of this embodiment comprises the following steps:

[0112] ① Powder drying: drying the silver powder and tin oxide powder;

[0113] In step ①, the mass percentage of silver powder is 89%, and the mass percentage of tin oxide powder is 11%. The drying temperature is 90° C., and the drying time is 3 hours.

[0114] ② Powder mixing step 1: Use a double motion powder mixer to mix the powder, add all the tin oxide into the powder mixing tank, and then add some silver powder, the mass of silver powder added is equivalent to 1 / 4 of the total amount of silver powder, the powder mixing time is 2 hours, and the speed of the powder mixer is 120 rpm;

[0115] ③ Powder mixing step 2: Use a shovel-type powder mixer to mix the powder, take out all the mixed materials in the double-motion powder mixer, and then add all of them into the shovel-type powder mixer, and add all of the remaining silver powder. The mixing time is 3 hours, and the speed of the powder mixer is 150 rpm to obtain a mixed powder;

[0116] ④ Isostatic pressing: isostatically pressing the mixed powder obtained in step ③ to obtain a silver tin oxide mixed powder ingot;

[0117] In step ④, the isostatic pressing pressure is 20 MPa and the holding time is 15 seconds.

[0118] ⑤ Sintering: The silver-tin oxide mixed powder ingot pressed in step ④ is sintered in air to obtain a silver-tin oxide alloy ingot, i.e., a silver-tin oxide embryo material.

[0119] In step ⑤, the silver-tin oxide mixed powder ingot is first heated to 500° C., then raised to 850° C., and kept warm for 2 hours.

[0120] ⑥ Extrusion: extruding the silver-tin oxide alloy ingot obtained by sintering to obtain a silver-tin oxide thick wire;

[0121] In step ⑥, a 1250-ton extruder is used for extrusion.

[0122] In step ⑥, the specific operation of extrusion is: the extrusion barrel is heated to 420° C., the extrusion die is Φ6.0 mm, the extrusion speed is 2.5 mm / S, and the extrusion is water-cooled.

[0123] ⑦ Wire drawing: The silver tin oxide thick wire obtained in step ⑥ is drawn to obtain a silver tin oxide relay contact wire material.

[0124] Step ⑦ Wire drawing, use wire drawing die: Ф6.0 / annealing / Ф5.6 / annealing / Ф5.2 / annealing / Ф4.8 / annealing / Ф4.4 / annealing / Ф4.0 / annealing / Ф3.6 / annealing / Ф3.2 / annealing / Ф2.9 / annealing / Ф2.6 / annealing / Ф2.38–0.02mm.

[0125] Step ⑦ During wire drawing, annealing temperature: 550±10℃; holding time: 1.2 hours. Air atmosphere, directly out of the furnace. Anneal once for each wire drawing.

[0126] This embodiment adopts a composite powder mixing method, which can effectively solve the problem of tin oxide agglomeration in the silver matrix and make the microstructure of silver tin oxide uniform. The metallographic image of the silver tin oxide contact material prepared in this embodiment shows that the microstructure of silver tin oxide is uniform and has almost no defective structure; and the physical properties and electrical life of the contact material tested can meet the design standards.

[0127] Comparative Example 1

[0128] In this comparative example, except for steps ② and ③, the steps are modified as follows: using a double-motion powder mixer to mix the powder, adding all the tin oxide into a powder mixing tank, and then adding all the silver powder, the mixing time is 2 hours, and the speed of the powder mixer is 100 rpm to obtain a mixed powder;

[0129] The remaining operating steps and parameters are the same as those in Example 1.

[0130] The physical properties and electrical life performance of the silver tin oxide contact wire material obtained in Comparative Example 1 were tested, and the test results are shown in Tables 3 and 4.

[0131] The detection method standards are: JB / T 8444-2015, GB / T 20235-2006, GB / T 14048.4-2020.

[0132] It can be seen from Table 3 and Table 4 that the physical properties and electrical life of the silver zinc oxide contact material obtained in Comparative Example 1 of the present invention fail to meet the design standards.

[0133] From the above test results, it can be seen that the one-time powder mixing method used in this comparative example cannot solve the agglomeration problem of tin oxide in the silver matrix, making the microstructure of silver tin oxide uneven, so that the physical properties and electrical life of the obtained silver zinc oxide contact material fail to meet the design standards.

[0134] Figure 4 This is the metallographic structure diagram (50X) of the silver tin oxide relay contact material obtained in Comparative Example 1 of the present invention;

[0135] Figure 5 This is the metallographic structure diagram (200X) of the silver tin oxide relay contact material obtained in Comparative Example 1 of the present invention;

[0136] The silver tin oxide contact material obtained in Comparative Example 1 was subjected to metallographic examination. The metallographic image of the silver tin oxide contact material prepared in this comparative example shows that the microstructure of the silver tin oxide is uneven and has many defective structures. In addition, the physical properties and electrical life of the tested contact material failed to meet the design standards.

[0137] Table 3

[0138] Physical Properties of Silver Tin Oxide

[0139]

[0140] Table 4

[0141] 32A relay temperature rise and electrical life test data

[0142]

[0143] Comparative Example 2

[0144] This comparative example is modified as follows except that steps ② and ③ are as follows: using a shovel type powder mixer to mix the powder, adding all the tin oxide into a powder mixing tank, and then adding all the silver powder, the powder mixing time is 2.5 hours, and the speed of the powder mixer is 150 rpm to obtain a mixed powder;

[0145] The remaining operating steps and parameters are the same as those in Example 1.

[0146] The physical properties and electrical life performance of the silver tin oxide contact wire material obtained in Comparative Example 2 were tested, and the test results are shown in Tables 5 and 6.

[0147] The detection method standards are: JB / T 8444-2015, GB / T 20235-2006, GB / T 14048.4-2020.

[0148] It can be seen from Table 5 and Table 6 that the physical properties and electrical life of the silver zinc oxide contact material obtained in Comparative Example 2 of the present invention fail to meet the design standards.

[0149] From the above test results, it can be seen that the one-time powder mixing method used in this comparative example cannot solve the agglomeration problem of tin oxide in the silver matrix, and the microstructure of silver tin oxide is uneven, so that the physical properties and electrical life of the obtained silver zinc oxide contact material fail to meet the design standards.

[0150] Figure 6 This is the metallographic structure diagram (50X) of the silver tin oxide relay contact material obtained in Comparative Example 2 of the present invention;

[0151] Figure 7 This is the metallographic structure diagram (200X) of the silver tin oxide relay contact material obtained in Comparative Example 2 of the present invention.

[0152] The silver tin oxide contact material obtained in Comparative Example 2 was subjected to metallographic examination. The metallographic image of the silver tin oxide contact material prepared in this comparative example shows that the microstructure of the silver tin oxide is uneven and has many defective structures. In addition, the physical properties and electrical life of the contact material tested failed to meet the design standards.

[0153] Table 5

[0154] Physical Properties of Silver Tin Oxide

[0155]

[0156] Table 6

[0157] 32A relay temperature rise and electrical life test data

[0158]

[0159] Through the above physical property and electrical life performance tests on the silver tin oxide relay contact materials obtained in Examples 1-3 and Comparative Examples 1-2, it can be seen that the electrical life of the silver tin oxide relay contact materials obtained in Examples 1-3 of the present invention can meet the design standards, while Comparative Examples 1-2 use one-time powder mixing, and tin oxide will produce agglomeration problems in the silver matrix, making the microstructure of the silver tin oxide uneven, affecting the electrical life of the silver zinc oxide AC contactor contact material.

Claims

1. A method for preparing silver tin oxide relay contact material by composite mixed powder, characterized in that: The following steps are involved: Powder mixing step 1: add all the tin oxide into the powder mixer 1, then add part of the silver powder, 1 / 3 of the total amount of silver powder ≤ the mass of the silver powder added ≤ 1 / 2 of the total amount of silver powder, mix the powder, the mixing time is 1.5 to 2 hours, and the speed of the powder mixer 1 is 100 to 120 rpm; Powder mixing step 2: Take out all the mixed materials in the powder mixer 1, and then add all of them into the powder mixer 2, and add all of the remaining silver powder, mix the powder, the mixing time is 2.5 to 3 hours, and the speed of the powder mixer is 150 to 180 rpm.

2. The method for preparing silver tin oxide relay contact material from composite mixed powder according to claim 1, characterized in that: The powder mixer 1 is a double-motion powder mixer; and / or, the powder mixer 2 is a ploughshare type powder mixer.

3. The method for preparing silver tin oxide relay contact material from composite mixed powder according to claim 1 or 2, characterized in that: The specific steps include: ① Powder drying: drying the silver powder and tin oxide powder; ② Powder mixing step 1: Use a double motion powder mixer to mix the powder, add all the tin oxide into the powder mixing tank, and then add some silver powder, 1 / 3 of the total amount of silver powder ≤ the mass of silver powder added ≤ 1 / 2 of the total amount of silver powder, the mixing time is 1.5 to 2 hours, and the speed of the powder mixer is 100 to 120 rpm; ③ Powder mixing step 2: Use a shovel-type powder mixer to mix the powder, take out all the mixed materials in the double-motion powder mixer, and then add all of them into the shovel-type powder mixer, and add all of the remaining silver powder. The mixing time is 2.5 to 3 hours, and the speed of the powder mixer is 150 to 180 rpm to obtain a mixed powder; ④ Isostatic pressing: isostatically pressing the mixed powder obtained in step ③ to obtain a silver tin oxide mixed powder ingot; ⑤ Sintering: The silver-tin oxide mixed powder ingot pressed in step ④ is sintered in air to obtain a silver-tin oxide alloy ingot, i.e., a silver-tin oxide embryo material.

4. The method for preparing silver tin oxide relay contact material from composite mixed powder according to claim 3, characterized in that: In step ①, the mass percentage of silver powder is 87-89%, and the mass percentage of tin oxide powder is 11-13%; and / or, the drying temperature is 80-90° C., and the drying time is 2-3 hours.

5. The method for preparing silver tin oxide relay contact material from composite mixed powder according to claim 3 or 4, characterized in that: In step ④, the isostatic pressing pressure is 15 to 20 MPa, and the holding time is 15 to 20 seconds.

6. The method for preparing silver tin oxide relay contact material from composite mixed powder according to claim 3 or 4, characterized in that: In step ⑤, the silver-tin oxide mixed powder ingot is first heated to 300-500° C., then heated to 850-900° C., and kept warm for ≥2 hours.

7. The method for preparing silver tin oxide relay contact material from composite mixed powder according to claim 3 or 4, characterized in that: The obtained silver tin oxide embryo material is used to prepare wires and sheets, and the specific steps are as follows: Option 1: Preparation of silver tin oxide wire ⑥ Extrusion: extruding the silver-tin oxide alloy ingot obtained by sintering to obtain a silver-tin oxide thick wire; ⑦ Wire drawing: Drawing the silver tin oxide thick wire obtained in step ⑥ to obtain a silver tin oxide relay contact wire material; Step 7: Wire drawing, wire drawing die: Ф6.0 / annealing / Ф5.6 / annealing / Ф5.2 / annealing / Ф4.8 / annealing / Ф4.4 / annealing / Ф4.0 / annealing / Ф3.6 / annealing / Ф3.2 / annealing / Ф2.9 / annealing / Ф2.6 / annealing / Ф2.38–0.02mm; Solution 2: Preparation of silver tin oxide sheets ⑥ Extrusion: extruding the silver-tin oxide alloy ingot obtained by sintering to obtain a silver-tin oxide sheet; ⑦ Composite peripheral argon arc welding: The silver tin oxide sheet extruded by the extruder is combined with a pure silver sheet of the same size, and composite peripheral argon arc welding is used to obtain a silver / silver tin oxide composite sheet after argon arc welding; ⑧Hot rolling: hot rolling the silver / silver tin oxide composite plate after argon arc welding; ⑨Cold rolling: cold rolling the hot-rolled silver / silver tin oxide composite plate according to the size requirements; ⑩ Annealing: Anneal the cold-rolled silver / silver tin oxide composite plate to obtain a silver tin oxide sheet.

8. The method for preparing silver tin oxide relay contact material from composite mixed powder according to claim 7, characterized in that: Scheme 1: Preparation of silver tin oxide wire, in step ⑥, extrusion using a 1250-ton extruder; and / or, in step ⑥, the specific operation of extrusion is: extrusion barrel heating to 380-420°C, extrusion die Φ6.0mm, extrusion speed 1.5-2.5mm / S, water cooling; and / or, in step ⑦ wire drawing, annealing temperature: 550±10°C; holding time: 0.8-1.2 hours; air atmosphere, directly out of the furnace; annealing once for each wire drawing.

9. The method for preparing silver tin oxide relay contact material from composite mixed powder according to claim 7 or 8, characterized in that: Option 2: When preparing silver tin oxide sheets, in step ⑥, a 1250-ton extruder is used for extrusion; and / or, in step ⑥, the specific operation of extrusion is: the extrusion barrel is heated to 380-420° C., the extrusion die is 5*72mm, and the extrusion speed is 1.5-2.5mm / S; and / or, in step ⑧, hot rolling is carried out in a 15KW muffle furnace; and / or, in step ⑧, the hot rolling temperature is 750-800° C., and the temperature is kept for 1.5-2 hours; and / or, in step ⑧, the hot rolling reduction is greater than 50%.

10. The method for preparing silver tin oxide relay contact material from composite mixed powder according to claim 7 or 8, characterized in that: Option 2: In the preparation of silver tin oxide sheets, in step ⑩, annealing is performed in a 15KW muffle furnace; and / or, in step ⑩, the annealing operation is: heating to 550-600°C, keeping warm in a nitrogen atmosphere for 0.8-1.2 hours, and air cooling to a temperature of ≤80°C before taking out of the furnace.

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