CN109128213B - A kind of preparation method of silver tin oxide contact alloy - Google Patents

Abstract

A method for preparing a silver tin oxide contact alloy disclosed in the invention comprises the following steps: preparing a mixed solution A of Sn(NO ₃ ) ₄ and AgNO ₃ , adding a polyvinylpyrrolidone solution, a hydroboration solution to the mixed solution A in sequence A sodium solution, and stir evenly to obtain mixed solution B, add ammonia water dropwise to mixed solution B and adjust the pH value to obtain a precipitated product, use the precipitated product to prepare silver tin oxide composite powder, and combine silver tin oxide composite powder and graphite powder The powder is put into a ball mill in proportion to perform ball milling and powder mixing, and after annealing treatment, a uniformly mixed silver-carbon-tin oxide composite powder is obtained, and the silver-carbon-tin oxide composite powder is prepared into a silver-carbon-tin oxide electrical contact alloy. The amount of silver used can be saved, the product cost can be reduced, and the process is simple.

Description

A kind of preparation method of silver tin oxide contact alloy

technical field

The invention belongs to the technical field of alloy preparation methods, and relates to a preparation method of a silver carbon tin oxide contact alloy.

Background technique

AgC electrical contact material is a common contact material in low-voltage electrical equipment such as circuit breakers, relays, transfer switches and contactors.

At present, the known silver-carbon contact material patents are: 1) Patent "A kind of preparation method of silver/graphite/graphene sliding electrical contact material" (application number CN201710759776.5, publication number CN107695356A, publication date 2018.02.16) 2) Patent "a kind of preparation method of silver-plated graphene reinforced copper-based electrical contact material" (application number CN201610527507.1, publication number CN105950904A, publication date 2016.09.21); 3) patent "a silver-graphite electrical contact belt" Material Preparation Method" (application number CN200910153565.2, publication number CN101693955A, publication date 2010.04.14); 4) patent "a manufacturing method of silver-tungsten carbide-carbon electrical contact material" (application number 200510024287.2, publication number CN1658346 , published on 2005.8.24).

Although the silver-carbon electrical contact alloy has good welding resistance, good electrical conductivity and good temperature rise performance, the alloy has poor resistance to arc erosion under the condition of medium and above current.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a preparation method of silver tin oxide contact alloy, which can improve the arc erosion resistance of the alloy.

The technical scheme adopted in the present invention is, a preparation method of silver carbon tin oxide contact alloy, comprising the following steps:

Step 1. Prepare a mixed solution A of Sn(NO ₃ ) ₄ and AgNO ₃ ;

Step 2, adding polyvinylpyrrolidone solution and sodium borohydride solution to mixed solution A in sequence, and stirring evenly to obtain mixed solution B;

Step 3, adding ammonia water dropwise to the mixed solution B and adjusting the pH value to obtain a precipitated product;

Step 4, using the precipitation product to prepare silver tin oxide composite powder;

Step 5. Put the silver tin oxide composite powder and the graphite powder into a ball mill in proportion to carry out ball milling and powder mixing, and obtain uniformly mixed silver-carbon-tin oxide composite powder after annealing treatment;

Step 6, preparing the silver-carbon-tin oxide composite powder into a silver carbon tin oxide electrical contact alloy.

The present invention is also characterized in that,

The specific steps of step 1 are: firstly adding tin particles into the HNO ₃ solution with a mass fraction of 60% to 80% and fully dissolving it to obtain a 2mol/L Sn(NO ₃ ) ₄ solution; then the Sn(NO ₃ ) ₄ The solution was slowly added to the 2 mol/L AgNO ₃ aqueous solution to obtain mixed solution A.

In step 2: the concentration of the polyvinylpyrrolidone solution is 0.6-1 mol/L, and the concentration of sodium borohydride is 2-3 mol/L.

Step 3 is as follows: ultrasonically stir the mixed solution B at 60° C. for 2 to 3 hours, and in the process, adjust the pH value of the solution to 2 to 4 by dropwise addition of ammonia water, and then stir for 1 to 3 hours after the dropwise addition is completed. The precipitation was complete and the precipitated product was obtained.

Step 4 is specifically as follows: first put the precipitation product into a vacuum drying box, and dry it at 70-90° C. to obtain a dry powder; then put the dried powder in a muffle furnace, and calcine it at 500-650° C. for 2-4 hours ; Finally, the powder obtained after calcination is taken out, ground and refined to obtain a silver tin oxide composite powder.

In step 5: the mass fraction of the silver tin oxide composite powder is 60% to 80%, the mass fraction of the graphite powder is 20% to 40%, and the sum of the mass fractions of the two is 100%.

Step 5 In the ball milling process: the grinding balls are alumina grinding balls, the diameters of the grinding balls are 12mm, 10mm, and 5mm, respectively, and the ratio is 2:3:1. 400r/min, ball milling time is 8-12h.

In step 5: the annealing temperature is 500°C, and the annealing time is 2h.

Specifically in step 6, the silver-carbon-tin oxide composite powder is prepared by a traditional pressing-sintering-extrusion process to obtain a silver-carbon-tin oxide electrical contact alloy.

The beneficial effects of the present invention are:

The preparation method of the silver carbon tin oxide contact alloy of the present invention adopts the sol-gel process to use polyvinyl alcohol as a dispersant to control the size and dispersibility of the generated colloid, and at the same time uses sodium borohydride as a reducing agent to prepare silver oxide Tin powder; it can combine the advantages of silver carbon and silver metal oxide contact materials at the same time, which can not only ensure that the contact material has high resistance to welding and arc erosion, but also can make the contact alloy reach a higher level. High electrical conductivity and thermal conductivity; the preparation method of the silver carbon tin oxide contact alloy of the present invention can save the amount of silver used, reduce the product cost, and has a simple process.

Description of drawings

FIG. 1 is an electron microscope view of an embodiment of a method for preparing a silver tin oxide contact alloy according to the present invention.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

The preparation method of a kind of silver carbon tin oxide contact alloy of the present invention is specifically implemented according to the following steps:

Step 1. Prepare a mixed solution A of Sn(NO ₃ ) ₄ and AgNO ₃ ;

First add the tin particles into the HNO3 solution with a mass fraction of 60% to 80% to fully dissolve to obtain a 2mol/L Sn( _NO3 ) ₄ solution; then slowly add the Sn( _NO3 ) ₄ solution to 2mol/L In the AgNO ₃ aqueous solution, mixed solution A was obtained.

Step 2, adding polyvinyl pyrrolidone solution as a dispersing agent to the mixed solution A, after stirring uniformly, adding sodium borohydride solution as a reducing agent, and stirring continuously to obtain a mixed solution B;

The concentration of the polyvinylpyrrolidone solution is 0.6-1 mol/L, and the concentration of sodium borohydride is 2-3 mol/L.

Step 3, adding ammonia water dropwise to the mixed solution B and adjusting the pH value to obtain a precipitated product;

Specifically: ultrasonically stir the mixed solution B at 50-70°C for 2-3 hours, and adjust the pH of the solution to 2-4 by adding ammonia water dropwise during the process, and then stir for 1-3 hours after the dropwise addition is completed, until The precipitation was complete and the precipitated product was obtained.

Step 4, using the precipitation product to prepare silver tin oxide composite powder;

Specifically: first put the precipitated product into a vacuum drying box, and dry it at 70-90 °C until the water evaporates to obtain a dry powder; 4h; finally, the powder obtained after calcination is taken out, ground and refined to obtain a silver tin oxide composite powder.

Step 5, put the silver tin oxide composite powder with a mass fraction of 60% to 80% and a graphite powder with a mass fraction of 20% to 40%, and the sum of the mass fractions of the two is 100%; The powder is mixed by ball milling in a ball mill, and the uniformly mixed silver-carbon-tin oxide composite powder is obtained after annealing in a vacuum atmosphere. The annealing temperature is 500°C and the annealing time is 2h.

In the ball milling process: the grinding balls are alumina grinding balls, the diameters of the grinding balls are 12mm, 10mm, and 5mm, and the ratio is 2:3:1. min, the ball milling time is 8-12h.

Step 6, preparing the silver-carbon-tin oxide composite powder into a silver carbon tin oxide electrical contact alloy.

Specifically, the silver-carbon-tin oxide composite powder is prepared by a traditional pressing-sintering-extrusion process to obtain a silver-carbon-tin oxide electrical contact alloy.

Through the above methods, the preparation method of the silver tin oxide contact alloy of the present invention adopts the sol-gel process to use polyvinyl alcohol as the dispersant to control the size and dispersibility of the generated colloid, and simultaneously uses sodium borohydride as the reducing agent, The silver tin oxide powder is prepared; it can have the advantages of two contact materials, silver carbon and silver metal oxide at the same time. The tip alloy achieves higher electrical and thermal conductivity; the preparation method of the silver tin oxide contact alloy of the present invention can save the amount of silver used, reduce the product cost, and has a simple process.

As shown in Figure 1, tin dioxide with black dot-like morphology is uniformly distributed in the silver-carbon matrix, which can effectively improve the ablation resistance and fusion welding resistance of the alloy under the action of arc erosion.

Example 1

Step 1. First, add the tin particles into the HNO ₃ solution with a mass fraction of 80% to fully dissolve to obtain a 2mol/L Sn(NO ₃ ) ₄ solution; then slowly add the Sn(NO ₃ ) ₄ solution to a 2mol/L solution. _In the AgNO aqueous solution of L, mixed solution A was obtained;

Step 2, adding a polyvinylpyrrolidone solution with a concentration of 1 mol/L to the mixed solution A, stirring it uniformly, then adding a 3 mol/L sodium borohydride solution to it, and stirring it continuously to obtain a mixed solution B;

Step 3. The mixed solution B is subjected to ultrasonic stirring at 70°C for 3 hours, and during this process, the pH value of the solution is adjusted to 2 by dropwise addition of ammonia water, and then stirred for 3 hours after the dropwise addition is completed, until the precipitation is complete, and a precipitated product is obtained;

Step 4. First put the precipitated product into a vacuum drying box, and dry it at 70 °C until the water evaporates to obtain a dry powder; then put the dried powder in a muffle furnace and calcinate at 600 °C for 4 hours; The obtained powder is taken out and ground and refined to obtain a silver tin oxide composite powder;

Step 5. Put the silver tin oxide composite powder with a mass fraction of 80% and the graphite powder with a mass fraction of 20%; put them into a planetary ball mill in proportion to perform ball milling and powder mixing, and obtain a mixture after annealing in a vacuum atmosphere. Uniform silver-carbon-tin oxide composite powder, the annealing temperature is 500℃, and the annealing time is 2h;

In the ball milling process: the grinding balls are alumina balls, the diameters of the grinding balls are 12mm, 10mm, and 5mm, and the ratio is 2:3:1, the ball-to-material ratio is 15:1, and the ball milling speed is 400r/min. The ball milling time is 8h;

Step 6. The silver-carbon-tin oxide composite powder is prepared by a traditional pressing-sintering-extrusion process to obtain a silver carbon tin oxide electrical contact alloy with a composition of Ag70-C20-SnO ₂ 10.

Example 2

Step 1. First add the tin particles into the HNO ₃ solution with a mass fraction of 50% to fully dissolve to obtain a 2mol/L Sn(NO ₃ ) ₄ solution; then slowly add the Sn(NO ₃ ) ₄ solution to a 2mol/L solution. _In the AgNO aqueous solution of L, mixed solution A was obtained;

Step 2, adding a 0.8 mol/L polyvinylpyrrolidone solution to the mixed solution A, stirring it uniformly, then adding a 2.5 mol/L sodium borohydride solution to it, and stirring continuously to obtain a mixed solution B;

Step 3. The mixed solution B is subjected to ultrasonic stirring at 60° C. for 3 hours, and during the process, the pH value of the solution is adjusted to 3 by dropwise addition of ammonia water, and then stirred for 2 hours after the dropwise addition is completed, until the precipitation is complete, and a precipitated product is obtained;

Step 4. First put the precipitated product into a vacuum drying box, and dry it at 80°C until the water evaporates to obtain a dry powder; then put the dried powder into a muffle furnace and calcinate at 500°C for 4 hours; The obtained powder is taken out and ground and refined to obtain a silver tin oxide composite powder;

Step 5, put the silver tin oxide composite powder with a mass fraction of 70% and the graphite powder with a mass fraction of 30%; put them into a planetary ball mill in proportion to perform ball milling and powder mixing, and obtain a mixture after annealing in a vacuum atmosphere Uniform silver-carbon-tin oxide composite powder, the annealing temperature is 500℃, and the annealing time is 2h;

In the ball milling process: the grinding balls are alumina balls, the diameters of the grinding balls are 12mm, 10mm, and 5mm, and the ratio is 2:3:1, the ball-to-material ratio is 18:1, and the ball milling speed is 400r/min. The ball milling time is 10h;

Step 6, the silver-carbon-tin oxide composite powder is prepared by a traditional pressing-sintering-extrusion process to obtain a silver carbon tin oxide electrical contact alloy with a composition of Ag62-C30-SnO ₂ 8 .

Example 3

Step 1. First, add the tin particles into the HNO ₃ solution with a mass fraction of 60% to fully dissolve to obtain a 2mol/L Sn(NO ₃ ) ₄ solution; then slowly add the Sn(NO ₃ ) ₄ solution to a 2mol/L solution. _In the AgNO aqueous solution of L, mixed solution A was obtained;

Step 2. Add a 0.6 mol/L polyvinylpyrrolidone solution as a dispersant to the mixed solution A, and after stirring evenly, add a 2 mol/L sodium borohydride solution to the mixed solution A, and continuously stir it to obtain a mixed solution B;

Step 3, ultrasonically stir the mixed solution B at 50°C for 2 hours, and adjust the pH value of the solution to 4 by dropwise addition of ammonia water during the process, and then stir for 1 hour after the dropwise addition is completed, until the precipitation is complete, and a precipitated product is obtained;

Step 4. Put the precipitation product into a vacuum drying box and dry it at 90°C until the water evaporates to obtain a dry powder; then put the dried powder in a muffle furnace and calcinate at 500°C for 2 hours; The obtained powder is taken out and ground and refined to obtain a silver tin oxide composite powder;

Step 5, put the silver tin oxide composite powder with a mass fraction of 60% and the graphite powder with a mass fraction of 40%; put them into a planetary ball mill in proportion to perform ball milling and powder mixing, and obtain a mixture after annealing in a vacuum atmosphere Uniform silver-carbon-tin oxide composite powder, the annealing temperature is 500℃, and the annealing time is 2h;

In the ball milling process: the grinding balls are alumina balls, the diameters of the grinding balls are 12mm, 10mm, and 5mm, and the ratio is 2:3:1, the ball-to-material ratio is 20:1, and the ball milling speed is 400r/min. The ball milling time is 12h;

Step 6. The silver-carbon-tin oxide composite powder is prepared by a traditional pressing-sintering-extrusion process to obtain a silver-carbon-tin oxide electrical contact alloy with a composition of Ag55-C40-SnO ₂ 5 .

Claims (7)

1. A preparation method of a silver tin oxycarbide contact alloy is characterized by comprising the following steps:

step 1, preparation of Sn (NO)₃)₄And AgNO₃The mixed solution A of (1);

step 2, sequentially adding a polyvinylpyrrolidone solution and a sodium borohydride solution into the mixed solution A, and uniformly stirring to obtain a mixed solution B; the concentration of the polyvinylpyrrolidone solution is 0.6-1 mol/L, and the concentration of the sodium borohydride solution is 2-3 mol/L;

step 3, ultrasonically stirring the mixed solution B at 60 ℃ for 2-3 h, dropwise adding ammonia water in the process to adjust the pH value of the solution to 2-4, and stirring for 1-3 h after dropwise adding is finished until the precipitation is complete to obtain a precipitation product;

step 4, preparing silver tin oxide composite powder by using the precipitation product;

step 5, putting the silver tin oxide composite powder and the graphite powder into a ball mill according to a proportion for ball milling and mixing, and annealing to obtain uniformly mixed silver-carbon-tin oxide composite powder;

and 6, preparing the silver-carbon-tin oxide composite powder into the silver-carbon tin oxide electric contact alloy.

2. The method for preparing the silver tin oxycarbide contact alloy according to claim 1, wherein the specific steps in the step 1 are as follows: firstly, adding tin particles into 60-80 mass percent of HNO₃Fully dissolving in the solution to obtain 2mol/L Sn (NO)₃)₄A solution; then adding said Sn (NO)₃)₄The solution is slowly added to 2mol/L AgNO₃And (4) obtaining a mixed solution A in the aqueous solution.

3. The method for preparing the silver tin oxycarbide contact alloy according to claim 1, wherein the step 4 specifically comprises: putting the precipitate product into a vacuum drying oven, and drying at 70-90 ℃ to obtain dry powder; then, putting the dried powder into a muffle furnace, and calcining for 2-4 h at 500-650 ℃; and finally, taking out the powder obtained after calcination, grinding and refining to obtain the silver-tin oxide composite powder.

4. The method of claim 1, wherein in step 5: the mass fraction of the silver tin oxide composite powder is 60-80%, the mass fraction of the graphite powder is 20-40%, and the sum of the mass fractions of the silver tin oxide composite powder and the graphite powder is 100%.

5. The method for preparing the silver tin oxycarbide contact alloy according to claim 1, wherein in the ball milling process of the step 5: the grinding balls are alumina grinding balls, the diameters of the grinding balls are 12mm, 10mm and 5mm respectively, the grinding balls are mixed according to the quantity ratio of 2:3:1, the ball-material ratio is 15-20: 1, the ball-milling rotating speed is 400r/min, and the ball-milling time is 8-12 h.

6. The method of claim 1, wherein in step 5: the annealing temperature is 500 ℃, and the annealing time is 2 h.

7. The method for preparing the silver tin oxycarbide contact alloy according to claim 1, wherein the step 6 specifically comprises the following steps: and preparing the silver-carbon-tin oxide composite powder by adopting a traditional pressing-sintering-extruding process to obtain the silver-carbon-tin oxide electrical contact alloy.

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