Platinum powder with high sphericity degree and preparation method thereof

Abstract

The invention provides high-sphericity platinum powder and a preparation method thereof.The high-sphericity platinum powder is concentrated in particle size distribution, high in sphericity and good in dispersity, the average particle size of the high-sphericity platinum powder is 1-2 microns, the apparent density of the high-sphericity platinum powder is 4.0-6.0 g / cm < 3 >, and the specific surface area of the high-sphericity platinum powder is 0.8-3.6 m < 2 > / g, and the preparation method is simple in technological process, free of platinum dissolving and reduction processes and high in powder preparation efficiency; the particles are smooth in morphology, free of obvious spinous protrusions and similar in shape.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparing precious metal powder for catalytic electrode slurry by high-temperature thermal decomposition method, and relates to a platinum powder with high sphericity and a preparation method thereof. Specifically, it relates to a platinum powder with concentrated particle size distribution, high sphericity and good dispersibility and a preparation method thereof. Background Art

[0002] In microelectronics technology, electronic paste is a very important conductor and catalytic material, and is widely used in integrated circuits, sensors, military industry, automobiles and other industries. Metal powder is the core component of electronic paste and the key to achieving the electrochemical performance of electronic paste. The quality of metal powder determines the performance of the paste. Therefore, the particle size, morphology, density, specific surface area, etc. of the powder will affect the preparation process of the electronic paste and the performance of the electrode produced.

[0003] Platinum has excellent optical, electrical, magnetic and mechanical properties and has been widely used in the fields of solar cells, fuel cells, automobile exhaust purification, electronics industry, military industry, aerospace, etc. Platinum has high catalytic activity and is an excellent material for making catalytic electrodes. During the electrocatalytic process, different powder morphology, particle size, and specific surface area will result in different electrode microstructures, which will give the electrodes different electrocatalytic activities. However, in the preparation process of the traditional chemical liquid phase reduction method, the particles are very easy to agglomerate to form larger agglomerates, the particle size distribution is not concentrated, the particle size is difficult to control, and the dispersion is poor. As a result, when it is prepared into electrode slurry and co-fired with the substrate, the matching is poor, which affects the electrode performance.

[0004] Therefore, the market is in urgent need of a platinum powder with concentrated particle size distribution, high sphericity and good dispersibility. Summary of the invention

[0005] In order to overcome the above technical problems, the present invention provides a platinum powder with high sphericity, characterized in that the average particle size of the platinum powder is 1-2 μm and the bulk density is 4.0-6.0 g / cm 3 Specific surface area: 0.8~3.6m 2 / g.

[0006] The present invention provides a method for preparing platinum powder with high sphericity, which comprises the following steps:

[0007] (1) mixing a certain mass and type of organic reagents to form an organic phase as a carrier for dispersing chloroplatinic acid powder;

[0008] (2) Alumina (99%) plate is used as substrate material, which is then cleaned and dried to be used as printed substrate;

[0009] (3) mixing the organic phase as a carrier mixed in the above step (1) with chloroplatinic acid powder in a certain mass ratio to obtain a paste;

[0010] (4) printing the paste obtained in step (3) on the alumina substrate treated in step (2) by screen printing;

[0011] (5) The alumina substrate printed in step (4) is placed in a muffle furnace that has reached a certain temperature for sintering, and platinum powder is obtained after the paste is completely decomposed.

[0012] Wherein, the organic reagent used in step (1) is a solvent, a binder, a leveling agent, a modifier, and a dispersant, wherein the solvent is one or more of 1,2-propylene glycol, 2-methyl-2-butanol, and butanone; the binder is one or more of glycerol monooleate, ethylene glycol dimethacrylate, and polytetrafluoroethylene; the leveling agent is one or two of diphenyl ether and castor oil polyoxyethylene ether; the modifier is one or two of alkane coupling agent KH-580 and silicone oil; the dispersant is one or two of N-methylpyrrolidone (NMP) and polyacrylic acid. The mixed phase is an organic phase prepared by mixing the above-mentioned solvent, binder, leveling agent, modifier, and dispersant in proportion.

[0013] In order to ensure that the viscosity and fineness of the paste meet the printing requirements, and to achieve the gradient volatilization of organic matter in the paste, and to avoid volatilization too fast, resulting in uneven dispersion of chloroplatinic acid particles, resulting in the appearance of large particles locally, etc., the above reagents are selected as the organic phase, and the ratio of each functional component in the organic phase is solvent: binder: leveling agent: modifier: dispersant is 1:1:1:1:1 to 2:3:1:2:2. The solvent is preferably 2-methyl-2-butanol, the binder is preferably glycerol monooleate, polytetrafluoroethylene, the leveling agent is preferably castor oil polyoxyethylene ether, the modifier is preferably alkane coupling agent KH-580, and the dispersant is preferably N-methylpyrrolidone (NMP). In addition, if the organic phase prepared according to this ratio is mixed with platinum powder to form a paste, the viscosity and fineness can meet the requirements of screen printing, so that it has good dispersibility, can achieve gradient sintering of the paste, and avoid the phenomenon of large particle agglomeration.

[0014] In step (3), the mass ratio of chloroplatinic acid powder to organic phase is 2:3-4:1, preferably 2:3-3:2; the paste fineness is less than 2um, and the mass fraction of platinum in the chloroplatinic acid powder is 35-45%, preferably 38%-42%.

[0015] In step (4), the printing thickness of the paste is controlled to be 5um to 20um, preferably 6um to 15um;

[0016] In step (5), the temperature of the muffle furnace is controlled at 500-700° C., preferably 500-650° C.; and the sintering time is 5-20 min, preferably 10 min-15 min.

[0017] Beneficial effects of the present invention:

[0018] The present invention uses a pyrolysis method to prepare platinum powder with concentrated particle size distribution, high sphericity and good dispersibility, prepares an organic phase with a certain mass and ratio, and screen-prints the organic phase and chloroplatinic acid powder after uniformly mixing them on an alumina substrate. The powder morphology is controlled by controlling the ratio of the organic phase as a carrier to chloroplatinic acid, the printing thickness, the sintering temperature, the sintering time and other factors. The method has the following advantages:

[0019] (1) The process is simple, without platinum dissolution and reduction process, and the powder making efficiency is high;

[0020] (2) Compared with the traditional aqua regia system that dissolves and then reduces, no nitrogen-containing compounds are produced, which is green and environmentally friendly;

[0021] (3) The particles are relatively smooth, without obvious thorn-like protrusions, and are spherical in shape;

[0022] (4) The powder has high dispersibility and no obvious agglomeration, which is conducive to the preparation of slurry in the subsequent process;

[0023] (5) The particle size distribution of the powder is relatively concentrated, so platinum powders of different particle sizes can be obtained by controlling the printing thickness, and the particle size is highly controllable;

[0024] (6) The slurry prepared by the platinum powder has a high electrode density and a large current density after sintering;

[0025] (7) After the prepared slurry is sintered, the shrinkage rate of the sintered structure is reduced and the porosity is reduced;

[0026] (8) The matching performance between the slurry and the substrate material is improved, and cracking and warping are reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a scanning electron microscope image of the platinum powder of Example 1.

[0028] Figure 2 This is a scanning electron microscope image of the platinum powder of Example 2. DETAILED DESCRIPTION

[0029] The highly spherical platinum powder prepared by the present invention is a platinum powder with concentrated particle size distribution, high sphericity and good dispersibility, and has an average particle size of 1 to 2 μm and a bulk density of 4.0 to 6.0 g / cm 3 Specific surface area: 0.8~3.6m 2 / g platinum powder, the specific preparation method is as follows:

[0030] (1) mixing a certain mass and type of organic reagents to form an organic phase as a carrier for dispersing chloroplatinic acid powder;

[0031] (2) Alumina (99%) plate is used as substrate material, which is then cleaned and dried to be used as printed substrate;

[0032] (3) mixing the organic phase as a carrier mixed in the above step (1) with chloroplatinic acid powder in a certain mass ratio to obtain a mixture paste;

[0033] (4) printing the paste obtained in step (3) on the alumina substrate treated in step (2) by screen printing;

[0034] (5) The alumina substrate printed in step (4) is placed in a muffle furnace that has reached a certain temperature for sintering, and platinum powder is obtained after the paste is completely decomposed.

[0035] Example

[0036] Example 1

[0037] The method for preparing platinum powder of this embodiment comprises the following steps:

[0038] (1) Weigh 10 g of 2-methyl-2-butanol, 15 g of glycerol monooleate, 5 g of castor oil polyoxyethylene ether, 10 g of silane coupling agent KH-580, and 10 g of N-methylpyrrolidone (NMP), and mix the above reagents evenly to obtain an organic phase as a carrier;

[0039] (2) preparing a 50×20×8 mm alumina (99%) plate as a substrate material, cleaning it, drying it, etc., and setting it aside;

[0040] (3) 50 g of chloroplatinic acid powder (the mass fraction of platinum is 38%) and the organic phase obtained in the above (1) were fully mixed at a mass ratio of 1:1, and then put into a three-roll mill for grinding at a speed of 80 r / min, a front roller spacing of 100 μm, and a rear roller spacing of 50 μm. The mixture was ground three times to obtain a paste;

[0041] (4) printing the mixture paste obtained in step (3) on an alumina substrate by screen printing with a thickness of 6 μm;

[0042] (5) The alumina substrate printed in step (4) is placed in a muffle furnace at a temperature of 530° C. and sintered for 13 minutes. After the paste is completely decomposed, black platinum powder is obtained.

[0043] Determination of platinum powder parameters and properties

[0044] Bulk density: Collect platinum powder, fill it in a bulk density measuring tool, and calculate the bulk density after weighing;

[0045] Average particle size and specific surface area: The average particle size and specific surface area of ​​platinum powder were measured using a laser particle size analyzer;

[0046] Properties: Take a certain amount of platinum powder and analyze it through a scanning electron microscope to observe the powder morphology and dispersion. Figure 1 As shown in the figure, it can be seen from the scanning electron microscopy results that the powder has a regular spherical shape, no thorn-like protrusions on the surface, and a high degree of dispersion. The particle size analysis results show that the particle size distribution is relatively concentrated, and the specific parameters are as follows:

[0047] Bulk density: 4.0g / cm 3

[0048] Average particle size: 1.0~1.2um

[0049] Specific surface area: 1.5m 2 / g

[0050] Example 2

[0051] The method for preparing platinum powder in this embodiment comprises the following steps:

[0052] (1) Weigh 10 g of 1,2-propylene glycol, 15 g of polytetrafluoroethylene, 5 g of castor oil polyoxyethylene ether, 5 g of silane coupling agent KH-580, and 5 g of polyacrylic acid, and mix the above organic reagents evenly to form the organic phase of the carrier;

[0053] (2) preparing a 50×50×8 mm alumina (99%) plate as a substrate material, cleaning and drying it, and using it as a printed substrate for later use;

[0054] (3) 60 g of chloroplatinic acid powder (the mass fraction of platinum is 38%) and the organic phase obtained as a carrier in (1) were mixed in a mass ratio of 3:2, and ground in a three-roll mill at a speed of 50 r / min, a gap of 50 μm before the rolls, and a gap of 25 μm after the rolls. The mixture was ground three times to obtain a mixture paste;

[0055] (4) printing the mixture paste obtained in (3) on an alumina substrate by screen printing with a thickness of 10 μm;

[0056] (5) The alumina substrate printed in (4) was transferred to a muffle furnace at a temperature of 550° C. and sintered for 10 min. After the paste was completely decomposed, black platinum powder was obtained.

[0057] Determination of platinum powder parameters and properties

[0058] Bulk density: Collect platinum powder, fill it in a bulk density measuring tool, and calculate the bulk density after weighing;

[0059] Average particle size and specific surface area: The average particle size and specific surface area of ​​platinum powder were measured using a laser particle size analyzer;

[0060] Properties: Take a certain amount of platinum powder and analyze it through a scanning electron microscope to observe the powder morphology and dispersion. Figure 2 As shown, the results of scanning electron microscopy show that the powder has a regular shape, no obvious protrusions on the surface, high sphericity, good dispersion, and no significant agglomeration; the results of particle size analysis show that the particle size distribution is relatively concentrated, and the specific parameters are as follows:

[0061] Bulk density: 4.8g / cm 3

[0062] Average particle size: 1.8~1.9um

[0063] Specific surface area: 1.0m 2 / g

[0064] In summary, the high-sphericity platinum powder prepared by high-temperature thermal decomposition method of the present invention is a platinum powder with concentrated particle size distribution, high sphericity and good dispersibility. It can be used as an electronic paste for conductors and catalytic materials, and is widely used in integrated circuits, sensors, military industry, automobiles and other industries.

Claims

1. A platinum powder with high sphericity, which has a concentrated particle size distribution, high sphericity and good dispersibility. The average particle size of the platinum powder is 1-2um and the bulk density is 4.0-6.0g / cm 3 Specific surface area: 0.8~2.5m 2 / g.

2. A method for preparing platinum powder with high sphericity, comprising the following steps: (1) mixing a certain mass and type of organic reagents to form an organic phase as a carrier for dispersing chloroplatinic acid powder; (2) Using an alumina plate as a substrate material, cleaning and drying it as a printed substrate; (3) mixing the organic phase as a carrier mixed in the above step (1) with chloroplatinic acid powder in a certain mass ratio to obtain a paste; (4) printing the paste obtained in step (3) on the alumina substrate treated in step (2) by screen printing; (5) The alumina substrate printed in step (4) is placed in a muffle furnace that has reached a certain temperature for sintering, and platinum powder is obtained after the paste is completely decomposed.

3. The preparation method according to claim 2, characterized in that: The organic reagents used in the step (1) are solvents, binders, leveling agents, modifiers, and dispersants. The solvent is one or two of 1,2-propylene glycol, 2-methyl-2-butanol, and butanone; the binder is one or more of glycerol monooleate, ethylene glycol dimethacrylate, and polytetrafluoroethylene; the leveling agent is one or two of diphenyl ether and castor oil polyoxyethylene ether; the modifier is one or two of alkane coupling agent KH-580 and silicone oil; and the dispersant is one or two of N-methylpyrrolidone and polyacrylic acid.

4. The preparation method according to claim 3, characterized in that: In the above organic phase, the ratio of solvent: binder: leveling agent: modifier: dispersant is 1:1:1:1:1 to 2:3:1:2:

2.

5. The preparation method according to claim 2, characterized in that: In the step (3), the mass ratio of chloroplatinic acid powder to organic phase is 2:3-4:1, the paste fineness is less than 2um, and the mass fraction of platinum in the chloroplatinic acid powder is 35-45%.

6. The preparation method according to claim 2, characterized in that: In the step (4), the printing thickness of the paste is controlled to be 5um to 20um.

7. The preparation method according to claim 2, characterized in that: In the step (5), the temperature of the muffle furnace is controlled at 500-700° C., and the sintering time is 10-15 minutes.

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