Synthetic method of lead ruthenate powder

Abstract

The invention discloses a synthesis method of lead ruthenate powder, which comprises the following steps: S1, weighing ruthenium dioxide powder and lead oxide powder, mixing, and adding a solvent; s2, coarsely and uniformly mixing the mixture of the powder and the solvent, and scattering possible dry powder agglomerates; s3, adding the mixture into grinding equipment for grinding; s4, adding a surfactant into the mixture; s5, carrying out drying treatment on the mixture for 12 to 24 hours at the temperature of 130 to 180 DEG C; s6, putting the dried mixture into a crucible, and calcining at the temperature of 550-800 DEG C for 2-8 hours to form lead ruthenate powder; s7, the lead ruthenate powder is ground; s8, drying the ground lead ruthenate powder at the temperature of 130 to 180 DEG C for 12 to 24 hours; and S9, the dried lead ruthenate powder is packaged. According to the invention, the particle size of the initial powder can be reduced, the synthesis temperature is obviously reduced, the mixing uniformity of the initial powder is greatly improved, and the electrical properties of the resistance paste are finally improved.

Description

Technical Field

[0001] The invention relates to a method for synthesizing lead ruthenate powder. Background Art

[0002] The existing synthesis methods of lead ruthenate are divided into solid phase synthesis and liquid phase synthesis. The traditional solid phase process usually directly uses lead oxide and ruthenium dioxide, calcined at high temperature to obtain lead ruthenate. Although the solid phase method is simple, it is difficult to achieve full mixing of the two component units of lead oxide and ruthenium dioxide at the nanoscale before calcination, which affects the purity of the ruthenate. Therefore, in order to improve the purity, it is necessary to use a temperature of more than 850°C, and too high a temperature is likely to cause abnormal grain growth and increase the volatilization of lead oxide, resulting in a wide distribution of powder particles of the ruthenate, affecting the square resistance, static resistance and short-term overload performance of the resistor slurry. The traditional liquid phase process usually uses lead nitrate and ruthenium nitrate solution to react to obtain lead ruthenate. Although better component mixing, higher purity and narrower initial particle size distribution can be achieved, the process is complicated and the preparation process is difficult to control. After calcination, the agglomeration is serious and difficult to disperse, which ultimately affects the electrical properties of the resistor slurry. Summary of the invention

[0003] In view of the shortcomings of the prior art, the present invention provides a method for synthesizing lead ruthenate powder, which can reduce the particle size of the starting powder, significantly reduce the synthesis temperature, and greatly improve the uniformity of the starting powder mixing, thereby ultimately improving the electrical properties of the resistor slurry.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] A method for synthesizing lead ruthenate powder, characterized in that it comprises the following steps:

[0006] S1. Weigh and mix ruthenium dioxide powder and lead oxide powder according to a stoichiometric ratio in a well-ventilated environment, and add a solvent;

[0007] S2. Coarsely mix the mixture of powder and solvent to break up possible dry powder lumps;

[0008] S3, adding the roughly mixed mixture into a grinding device for grinding and mixing;

[0009] S4. Adding a surfactant to the ground mixture to prevent the powder from agglomerating again;

[0010] S5, drying the mixture at 130-180° C. for 12-24 hours;

[0011] S6, the dried mixture is placed in a crucible and calcined at 550-800° C. for 2-8 hours to form lead ruthenate powder;

[0012] S7, grinding the lead ruthenate powder;

[0013] S8, drying the ground lead ruthenate powder at a temperature of 130 to 180° C. for 12 to 24 hours;

[0014] S9. Packing the dried lead ruthenate powder.

[0015] Preferably, in step S1, the specific surface area of ​​ruthenium dioxide is 30 to 80 m 2 / g, the particle size of lead oxide is 0.5~5um.

[0016] Preferably, in step S1, the ratio of the total weight of the solvent to the total weight of the powder is 1 to 3:1.

[0017] Preferably, in step S1, the solvent is deionized water or ethanol or ethylene glycol.

[0018] Preferably, in step S3, the grinding equipment is a ball mill, a vibration mill or a sand mill.

[0019] Preferably, in step S4, the surfactant is Triton.

[0020] Preferably, in step S6, the calcination temperature is 600-750°C.

[0021] The advantages of the present invention are: based on solid phase reaction, using lead source powder lead oxide or lead dioxide and ruthenium dioxide powder as raw materials, wet mixing and grinding, and adding surfactant to achieve more uniform mixing at the microscopic scale, and having the following advantages:

[0022] 1. The wet mixing method is adopted to reduce dust during the mixing process and significantly reduce lead exposure during the processing;

[0023] 2. Ruthenium dioxide powder is used as a ruthenium source, and its specific surface area is 30 to 80 m 2 / g, due to its high specific surface area, ruthenium dioxide is very easy to agglomerate, and the grinding balls added in the mixing process of the present invention can play a role in deagglomeration, so that ruthenium dioxide can be more evenly dispersed, and at the same time, abnormally large particles can be ground to promote uniform mixing of substances;

[0024] 3. The mixing process is superimposed on the grinding process. While completing the mixing, the powder particle size is reduced, so the synthesis temperature can be significantly reduced. The traditional synthesis temperature is above 850°C. In the present invention, the synthesis temperature of lead ruthenate can be reduced to 600-700°C, avoiding abnormal grain growth and increased volatilization of lead oxide, which leads to the problem of wide distribution of ruthenate powder particles. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The SEM image of lead ruthenate obtained by calcining at 600° C. using the method provided in this embodiment;

[0026] Figure 2 The SEM image of the lead ruthenate obtained by calcining at 700° C. provided in this embodiment is provided in this embodiment;

[0027] Figure 3 This is the SEM image of lead ruthenate obtained by solid phase method at 850°C. DETAILED DESCRIPTION

[0028] Combination Figures 1 to 3 The synthesis method of the lead ruthenate powder of the present invention is further described.

[0029] A method for synthesizing lead ruthenate powder, characterized in that it comprises the following steps:

[0030] S1. Weigh and mix ruthenium dioxide powder and lead oxide powder according to the stoichiometric ratio in a well-ventilated environment, and add a solvent.

[0031] In this embodiment, deionized water is used as the solvent. In actual use, ethanol, ethylene glycol or other polar solvents may also be used as the solvent. The ratio of deionized water to the total amount of ruthenium dioxide powder and lead oxide powder is 1 to 3:1. The specific surface area of ​​ruthenium dioxide is 30 to 80 m 2 / g, preferably 45 to 60 m 2 / g, the particle size of lead oxide is 0.5-5um, preferably 1-3um.

[0032] S2. Roughly mix the powder and deionized water to break up any lumps of dry powder.

[0033] S3, adding the roughly uniform mixture into a grinding device for grinding and mixing.

[0034] The grinding equipment is a ball mill, a vibration mill or a sand mill. In this embodiment, the grinding equipment is a ball mill, and the diameter of the grinding balls in the ball mill is 0.3-2 mm, preferably 0.5-1.5 mm. During the grinding process, a laser particle size analyzer is used to monitor whether the grinding is completed, that is, grinding is performed until no abnormally large particles are detected.

[0035] S4. Add a surfactant to the ground mixture to prevent the powder from agglomerating again.

[0036] In this embodiment, the surfactant used is Triton. In actual application, other surfactants that can be used for inorganic oxides can also be used.

[0037] S5. Dry the mixture at 130-180°C for 12-24 hours, with the preferred drying temperature being 150°C.

[0038] S6. The dried mixture is placed in a crucible and calcined at 550-800° C. for 2-8 hours to form lead ruthenate powder.

[0039] The preferred calcination temperature is 600 to 750° C., and the preferred calcination time is 4 to 6 hours.

[0040] S7, grinding the lead ruthenate powder again, the grinding can be dry grinding or wet grinding. This embodiment uses wet grinding, the grinding of this step is the same as the mixing stage grinding in step S3, and a ball mill is used for grinding, and the specific surface area of ​​the lead ruthenate powder is ground to 6-20m 2 / g, preferably 8 to 15 m 2 / g.

[0041] S8, drying the ground lead ruthenate powder at 130-180°C for 12-24 hours, preferably at 150°C.

[0042] S9. Packing the dried lead ruthenate powder.

[0043] Example 1: Lead ruthenate is prepared by the method of steps 1 to 9 above, wherein the calcination temperature in step S6 is selected to be 600°C to obtain Figure 1 The SEM image of lead ruthenate shown in FIG. 1 was used to prepare a 10K resistor paste with the lead ruthenate powder to obtain the electrical properties shown in Table 1.

[0044] Example 2: Lead ruthenate is prepared by the method of steps 1 to 9 above, wherein the calcination temperature in step S6 is selected to be 700°C to obtain Figure 2 The SEM image of lead ruthenate shown in FIG. 1 was used to prepare a 1M resistor paste to obtain the electrical properties shown in Table 1.

[0045] Comparative Example 1: Solid phase method was used to calcine at 850°C to obtain Figure 3 The SEM image of lead ruthenate shown in FIG. 1 was used to prepare a 10K resistor paste from the lead ruthenate powder to obtain the electrical properties shown in Table 1.

[0046] Comparative Example 2: Solid phase method was used to calcine at 850°C to obtain Figure 3 The SEM image of lead ruthenate shown in FIG. 1 was used to prepare a 1M resistor paste to obtain the electrical properties shown in Table 1.

[0047] The electrical properties of the resistor paste prepared from lead ruthenate powder are shown in Table 1 below:

[0048]

[0049]

[0050] Table 1

[0051] HTCR is the temperature coefficient of resistance in a high temperature environment, and CTCR is the temperature coefficient of resistance in a low temperature environment.

[0052] By comparing the SEM images of the lead ruthenate obtained in Example 1, Example 2 and Comparative Example 1, it can be seen that the lead ruthenate powder prepared by the present method has a significantly smaller particle size, a more uniform size distribution, and a significantly improved mixing uniformity compared to the lead ruthenate powder prepared by the solid phase method.

[0053] By comparing Example 1 and Comparative Example 1 in Table 1, it can be seen that the ESD performance of Example 1 is significantly better than that of Comparative Example 1 for the medium resistance part, i.e., the 10K resistor paste; by comparing Example 2 and Comparative Example 2 in Table 1, it can be seen that the electrical performance of Example 2 is equivalent to that of the current Comparative Example 2 for the high resistance part, i.e., the 1M resistor paste, and meets the electrical performance requirements of the high resistance part. Therefore, it can be concluded that after the lead ruthenate powder prepared by the method is made into a resistor paste, the electrical performance of the medium resistance part and the resistor paste will be significantly improved, and the high resistance part can be equivalent to the current industry level.

[0054] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A method for synthesizing lead ruthenate powder, characterized in that: The following steps are involved: S1. Weigh and mix ruthenium dioxide powder and lead oxide powder according to a stoichiometric ratio in a well-ventilated environment, and add a solvent; S2. Coarsely mix the mixture of powder and solvent to break up possible dry powder lumps; S3, adding the roughly mixed mixture into a grinding device for grinding and mixing; S4. Adding a surfactant to the ground mixture to prevent the powder from agglomerating again; S5, drying the mixture at 130-180° C. for 12-24 hours; S6, the dried mixture is placed in a crucible and calcined at 550-800° C. for 2-8 hours to form lead ruthenate powder; S7, grinding the lead ruthenate powder; S8, drying the ground lead ruthenate powder at a temperature of 130 to 180° C. for 12 to 24 hours; S9. Packing the dried lead ruthenate powder.

2. The method for synthesizing lead ruthenate powder according to claim 1, characterized in that: In step S1, the specific surface area of ​​ruthenium dioxide is 30 to 80 m 2 / g, the particle size of lead oxide is 0.5~5um.

3. The method for synthesizing lead ruthenate powder according to claim 1, characterized in that: In step S1, the ratio of the solvent to the total weight of the powder is 1 to 3:

1.

4. The method for synthesizing lead ruthenate powder according to claim 1, characterized in that: In step S1, the solvent is deionized water or ethanol or ethylene glycol.

5. The method for synthesizing lead ruthenate powder according to claim 1, characterized in that: In step S3, the grinding equipment is a ball mill, a vibration mill or a sand mill.

6. The method for synthesizing lead ruthenate powder according to claim 1, characterized in that: In step S4, the surfactant is Triton.

7. The method for synthesizing lead ruthenate powder according to claim 1, characterized in that: In step S6, the calcination temperature is 600-750°C.

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