Ruthenium dioxide powder as well as preparation method and application thereof

Abstract

The invention provides ruthenium dioxide powder as well as a preparation method and application thereof, and belongs to the technical field of inorganic materials. The preparation method of the ruthenium dioxide powder provided by the invention comprises the following steps: carrying out ball milling on ruthenium hydroxide, and then carrying out freeze drying to obtain the ruthenium dioxide powder; the ball milling comprises first ball milling and second ball milling which are carried out in sequence; the diameter of a ball-milling bead of the second ball mill is smaller than that of a ball-milling bead of the first ball mill, and the rotating speed of the second ball mill is higher than that of the first ball mill. By controlling the rotating speed of two times of ball milling and the diameter of ball milling beads, the kinetic energy of the second ball milling is higher than that of the first ball milling, agglomeration of ruthenium hydroxide precipitates is broken, small and uniform particle size distribution is obtained, and the specific surface area is increased; ruthenium hydroxide is dehydrated through freeze drying to obtain ruthenium dioxide powder, dense tiny holes are formed in the ruthenium dioxide powder, thermal collapse caused by traditional high-temperature drying of the powder is avoided, and the specific surface area of the ruthenium dioxide powder is greatly increased.

Description

Technical Field

[0001] The invention relates to the technical field of inorganic materials, and in particular to a ruthenium dioxide powder and a preparation method and application thereof. Background Art

[0002] Thick film resistors are electronic components that achieve resistance by printing a layer of resistive paste on an insulating substrate. The manufacturing process of this resistor involves mixing ruthenium dioxide powder, glass powder and an organic carrier into a paste, which is then coated on a ceramic substrate by screen printing technology. After printing, the substrate is sintered at high temperature to solidify the resistor layer and have a stable resistance value. The conductive network composed of ruthenium dioxide particles in the resistor paste forms a path for the current, so the number of contact points between particles and the continuity of the conductive path directly affect the size of the resistance value. Ruthenium dioxide powder with a larger specific surface area generally has a smaller particle size or a higher porosity, more contact points between particles, and a higher surface energy, which promotes the sintering process, thereby improving the continuity and stability of the conductive network, and can effectively reduce the resistance of the resistor paste and its resistance volatility. Under the condition of a certain square resistance, the use of ruthenium dioxide with a high specific surface area can reduce the amount of ruthenium dioxide in the paste, thereby achieving the purpose of reducing costs.

[0003] In the current preparation process of ruthenium dioxide, the method for increasing the specific surface area is generally to add a dispersion medium or a dispersant in the front section of the preparation process (ruthenium trichloride hydrolysis and ruthenium hydroxide washing stage) to prevent the ruthenium hydroxide particles from agglomerating during the washing process. The principle of this method is to enable the ruthenium hydroxide precipitate to be stably suspended in the solution according to the action principle of different dispersion media or dispersants, the charge repulsion principle or the polymer steric effect, so that the ruthenium hydroxide exists independently in the form of particles, and the particles are avoided from agglomerating, thereby increasing the specific surface area of ​​ruthenium dioxide. However, there are two problems with this method: first, after the ruthenium hydroxide precipitate forms a stable suspension in the solution, the washing stage is more difficult and will cause greater losses, and the addition of a dispersion medium or a dispersant further increases the difficulty of washing; second, the amount of dispersion medium or dispersant added, as well as the coating of the powder particles, have a great influence on the specific surface area of ​​the final product, ruthenium dioxide powder, and the stable control of the specific surface area cannot be achieved.

[0004] Since it is difficult to break through the technical barriers in the preparation process, it is difficult to achieve a stable and controllable increase in the specific surface area of ​​ruthenium dioxide powder, resulting in large fluctuations in the resistance value and temperature coefficient of the resistor slurry after slurrying, which greatly affects the production and application of thick film resistors. Summary of the invention

[0005] The purpose of the present invention is to provide a ruthenium dioxide powder and a preparation method and application thereof. The preparation method provided by the present invention can increase the specific surface area of ​​the ruthenium dioxide powder, and is stable and controllable, simple to operate, and conducive to industrial promotion.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing ruthenium dioxide powder, comprising: ball-milling ruthenium hydroxide and then freeze-drying it to obtain ruthenium dioxide powder; the ball milling comprises a first ball milling and a second ball milling performed in sequence; the diameter of the ball milling beads of the second ball mill is smaller than the diameter of the ball milling beads of the first ball mill, and the rotation speed of the second ball mill is higher than the rotation speed of the first ball mill.

[0008] Preferably, the method for preparing ruthenium hydroxide comprises:

[0009] 1) mixing hydrated ruthenium trichloride with hot water for hydrolysis to obtain a ruthenium hydroxide solution; the mass concentration of ruthenium in the ruthenium hydroxide solution is 0.005-0.006 g / mL;

[0010] 2) adjusting the pH value of the ruthenium hydroxide solution obtained in step 1) to 6-8 to perform a precipitation reaction to obtain ruthenium hydroxide.

[0011] Preferably, the temperature of the hot water in step 1) is 70-100°C.

[0012] Preferably, the concentration of the pH adjuster used to adjust the pH value in step 2) is 0.02-0.03 g / mL.

[0013] Preferably, the diameter of the ball mill beads of the first ball mill is greater than 2 mm and less than or equal to 8 mm, the ball-to-material ratio is 1:(2-4), the rotation speed is greater than or equal to 70 r / min and less than 1000 r / min, and the time is 8-72 h.

[0014] Preferably, the diameter of the ball mill beads of the second ball mill is greater than or equal to 2 mm and less than 8 mm, the ball-to-material ratio is 1:(2-4), the rotation speed is greater than 70 r / min and less than or equal to 1000 r / min, and the time is 8-72 h.

[0015] Preferably, the freeze-drying comprises pre-freezing, sublimation and desorption performed sequentially.

[0016] Preferably, the pre-freezing temperature is -20 to -80°C, and the time is 4 to 12 hours; the sublimation temperature is -10 to -40°C, and the time is 4 to 12 hours; the decomposition temperature is 0 to 40°C, and the time is 4 to 12 hours.

[0017] The present invention also provides a ruthenium dioxide powder prepared by the preparation method described in the above technical solution, wherein the specific surface area of ​​the ruthenium dioxide powder is 85 to 97 m 2 / g.

[0018] The present invention also provides the use of the ruthenium dioxide powder described in the above technical solution in thick film resistors.

[0019] The present invention provides a method for preparing ruthenium dioxide powder, comprising: ball-milling ruthenium hydroxide and then freeze-drying to obtain ruthenium dioxide powder; the ball milling includes a first ball milling and a second ball milling performed in sequence; the diameter of the ball milling beads of the second ball milling is smaller than the diameter of the ball milling beads of the first ball milling, and the rotation speed of the second ball milling is higher than the rotation speed of the first ball milling. The present invention controls the rotation speed and the diameter of the ball milling beads during the two ball millings so that the kinetic energy of the second ball milling is higher than that of the first ball milling, thereby breaking the agglomeration of ruthenium hydroxide precipitation, obtaining a small and uniform particle size distribution, and increasing its specific surface area; dehydrating ruthenium hydroxide by freeze-drying to obtain ruthenium dioxide, so that dense micropores are formed inside the ruthenium dioxide, thereby avoiding thermal collapse of the powder caused by traditional high-temperature drying, and greatly increasing the specific surface area of ​​ruthenium dioxide. The results of the embodiment show that according to the preparation method provided by the present invention, the specific surface area of ​​the prepared ruthenium dioxide is between 81 and 97 m 2 / g. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is the reference method desorption curve of the ruthenium dioxide powder prepared in Example 1;

[0021] Figure 2 This is a SEM image of the ruthenium dioxide powder prepared in Example 1;

[0022] Figure 3 is the particle size distribution curve of the ruthenium dioxide powder prepared in Example 1;

[0023] Figure 4 is the reference method desorption curve of the ruthenium dioxide powder prepared in Example 2;

[0024] Figure 5 This is a SEM image of the ruthenium dioxide powder prepared in Example 2;

[0025] Figure 6 is the particle size distribution curve of the ruthenium dioxide powder prepared in Example 2;

[0026] Figure 7 is the reference method desorption curve of the ruthenium dioxide powder prepared in Example 3;

[0027] Figure 8 This is a SEM image of the ruthenium dioxide powder prepared in Example 3;

[0028] Fig. 9The particle size distribution curve of the ruthenium dioxide powder prepared in Example 3;

[0029] Fig.10 is the reference method desorption curve of the ruthenium dioxide powder prepared in Example 4;

[0030] Fig.11 This is a SEM image of the ruthenium dioxide powder prepared in Example 4;

[0031] Fig.12 is the particle size distribution curve of the ruthenium dioxide powder prepared in Example 4;

[0032] Fig.13 is the reference method desorption curve of the ruthenium dioxide powder prepared in Example 5;

[0033] Fig.14 This is a SEM image of the ruthenium dioxide powder prepared in Example 5;

[0034] Fig.15 is the particle size distribution curve of the ruthenium dioxide powder prepared in Example 5;

[0035] Fig.16 is the reference method desorption curve of the ruthenium dioxide powder prepared in Example 6;

[0036] Fig.17 This is a SEM image of the ruthenium dioxide powder prepared in Example 6;

[0037] Fig.18 This is the particle size distribution curve of the ruthenium dioxide powder prepared in Example 6. DETAILED DESCRIPTION

[0038] All raw materials of the present invention have no particular limitation on their sources and can be purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0039] There is no particular limitation on the purity of all raw materials in the present invention. The present invention preferably uses analytically pure materials or materials with conventional purity in the field of inorganic materials.

[0040] The first and second aspects of the present invention have no special meanings and are only used to distinguish the two ball millings.

[0041] The present invention provides a method for preparing ruthenium dioxide powder, comprising: ball-milling ruthenium hydroxide and then freeze-drying it to obtain ruthenium dioxide powder; the ball milling comprises a first ball milling and a second ball milling performed in sequence; the diameter of the ball milling beads of the second ball mill is smaller than the diameter of the ball milling beads of the first ball mill, and the rotation speed of the second ball mill is higher than the rotation speed of the first ball mill.

[0042] The present invention has no requirements on the source of the ruthenium hydroxide, and ruthenium hydroxide from different sources can obtain ruthenium dioxide powder with a high specific surface area.

[0043] In the present invention, the preparation method of ruthenium hydroxide preferably comprises: mixing hydrated ruthenium trichloride with hot water for hydrolysis to obtain a ruthenium hydroxide solution; adjusting the pH value of the ruthenium hydroxide solution to 6-8 for precipitation reaction to obtain ruthenium hydroxide.

[0044] The present invention preferably mixes hydrated ruthenium trichloride with hot water for hydrolysis to obtain a ruthenium hydroxide solution.

[0045] In the present invention, the ruthenium content of the hydrated ruthenium chloride is preferably 35-42%. There are two crystal forms of hydrated ruthenium chloride: α-type and β-type, wherein the α-type is insoluble and inactive, and the β-type is soluble and active; if the ruthenium content in the hydrated ruthenium chloride is too high, the α-type may appear; at the same time, the hydrated ruthenium chloride is easy to absorb moisture, resulting in a decrease in the ruthenium content, and if the ruthenium content is too low, the ruthenium chloride will hang on the wall, which is not conducive to use. The parameters of the hydrated ruthenium chloride are within the above range, and have good solubility and stability.

[0046] In the present invention, the temperature of the hot water is preferably 70-100° C., more preferably 80-90° C. The hydrolysis of ruthenium trichloride is an endothermic reaction, and heating is conducive to the hydrolysis. Too high a temperature may cause side reactions, affecting product purity and system stability. The temperature of the hot water is within the above range, which is conducive to the occurrence of the hydrolysis reaction and does not cause side reactions.

[0047] In the present invention, the mass concentration of ruthenium in the ruthenium hydroxide solution is preferably 0.005-0.006 g / mL. The mass concentration of ruthenium in the ruthenium hydroxide solution directly affects the specific surface area of ​​the final product. When other parameters are the same, the lower the mass concentration of ruthenium, the larger the specific surface area of ​​the final product, but the lower the mass concentration of ruthenium, the lower the production efficiency. The mass concentration of ruthenium within the above range is conducive to obtaining ruthenium dioxide with a high specific surface area while taking into account production efficiency.

[0048] In the present invention, the mixing of the hydrated ruthenium chloride and hot water is preferably as follows: firstly dissolving the hydrated ruthenium chloride in hot water 8 to 12 times its mass, hydrolyzing, and then continuing to add water until the mass concentration of ruthenium is 0.005 to 0.006 g / mL. The concentration of the ruthenium chloride solution affects the rate of hydrolysis, and the higher the concentration, the faster the hydrolysis rate, but too high a concentration will affect the stability of ruthenium hydroxide, and hydrolysis will produce hydrochloric acid, and too fast a reaction rate will easily cause acid corrosion; firstly dissolving the hydrated ruthenium chloride in hot water 8 to 12 times its mass can hydrolyze quickly and stably.

[0049] In the present invention, the hydrolysis is preferably carried out under stirring conditions; the stirring speed is preferably 1000-2000 r / min, more preferably 1200-1800 r / min. Stirring can avoid the occurrence of concentration gradients, fully mix the materials, and promote the hydrolysis reaction.

[0050] After obtaining the ruthenium hydroxide solution, the present invention preferably adjusts the pH value of the ruthenium hydroxide solution to 6-8 for precipitation reaction to obtain ruthenium hydroxide.

[0051] In the present invention, the pH regulator used to adjust the pH value is preferably an acidic regulator or an alkaline regulator; as an embodiment of the present invention, the alkaline regulator can be an aqueous solution of one or more of sodium borohydride, potassium borohydride, sodium hydroxide, hydrazine hydrate, methanol and triethanolamine; the acidic regulator can be an aqueous solution of one or more of ascorbic acid and hydrochloric acid. The pH value of the ruthenium hydroxide solution is affected by the concentration of the solution, and different acid and alkaline conditions may occur. If it is too acidic, an alkaline regulator is added, and if it is too alkaline, an acidic regulator is added. The acceptance capacity of methanol molecules for protons is weaker than that of water molecules for protons, which shows that the pH value of the methanol solution is slightly higher than that of the aqueous solution; in addition, the greater the concentration of the methanol solution, the smaller the dielectric constant value. According to Coulomb's law, the attraction of ions with opposite charges is inversely proportional to the dielectric constant of the solvent. Therefore, when the dielectric constant of the solvent decreases, the attraction of ions with opposite charges increases, which is conducive to the formation of ion pairs, thereby weakening the dissociation of protons, that is, weakening the strength of the solution acid; therefore, methanol can be used as an alkaline regulator.

[0052] As an embodiment of the present invention, the concentration of the pH regulator can be 0.02-0.03 g / mL; the addition rate of the pH regulator can be 40-60 mL / min; the volume ratio of the pH regulator to the ruthenium hydroxide solution can be 1:(4-6). The parameters of the pH regulator are within the above range, which is conducive to controlling the pH value to accurately reach 6-8.

[0053] In the present invention, the precipitation reaction is preferably carried out under stirring conditions; the stirring speed is preferably 1000-2000 r / min, more preferably 1200-1800 r / min. Stirring can avoid the concentration gradient, make the materials fully mixed, promote the reaction, and help improve the conversion rate.

[0054] In the present invention, the endpoint of the precipitation reaction is preferably based on the supernatant being clear, transparent and colorless.

[0055] After the precipitation reaction is completed, the product of the precipitation reaction is preferably filtered, washed and dried in sequence to obtain ruthenium hydroxide.

[0056] As an embodiment of the present invention, the washing can use water at 70-100°C; the end point of the washing is preferably that the conductivity K of the supernatant is ≤10μS / cm. The above operation is conducive to improving the utilization rate of raw materials and reducing the waste of raw materials.

[0057] As an embodiment of the present invention, the drying can be carried out in a forced air drying oven; the drying temperature can be 100-120° C.; the drying time can be greater than 48 hours, with no weight change within 30 minutes as the end point.

[0058] As an embodiment of the present invention, when the obtained ruthenium hydroxide is agglomerated, it can be lightly ground to obtain black, uniform and fine ruthenium hydroxide.

[0059] The present invention has no special requirements for the device for preparing ruthenium hydroxide, as long as ruthenium hydroxide can be obtained. In the embodiment of the present invention, it can be a reaction kettle.

[0060] The preparation method of ruthenium hydroxide provided by the present invention can obtain uniformly dispersed ruthenium hydroxide by controlling the mass concentration of ruthenium in the ruthenium hydroxide solution, which is beneficial to further increase the specific surface area of ​​ruthenium dioxide.

[0061] In the present invention, the ball milling includes a first ball milling and a second ball milling performed sequentially.

[0062] In the present invention, the diameter of the ball milling beads of the second ball mill is smaller than that of the ball milling beads of the first ball mill; the rotation speed of the second ball mill is higher than that of the first ball mill. In the present invention, the kinetic energy of the ball milling can be increased by reducing the diameter of the ball milling beads and increasing the rotation speed; by increasing the kinetic energy of the ball milling, the ruthenium hydroxide is fully dispersed to obtain a small and uniform particle size distribution, thereby increasing the specific surface area.

[0063] In the present invention, the diameter of the ball milling beads of the first ball mill is preferably greater than 2 mm and less than or equal to 8 mm. As an embodiment of the present invention, the diameter of the ball milling beads of the first ball mill can be 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, or 8 mm.

[0064] In the present invention, the rotation speed of the first ball mill is preferably greater than or equal to 70r / min and less than 1000r / min; as an embodiment of the present invention, the rotation speed of the first ball mill can be 100-900r / min, or 200-800r / min, or 200-600r / min; in an embodiment of the present invention, the rotation speed of the first ball mill is 200, 300 or 400r / min.

[0065] In the present invention, the ball-to-material ratio of the first ball mill is preferably 1:(2-4); in an embodiment of the present invention, the ball-to-material ratio is 1:2, 1:3 or 1:4.

[0066] In the present invention, the first ball milling time is preferably 8 to 72 hours. As an embodiment of the present invention, the first ball milling time can be 12 to 64 hours, or 24 to 48 hours. In an embodiment of the present invention, the first ball milling time is 72 hours.

[0067] In the present invention, the diameter of the ball milling beads of the second ball mill is smaller than that of the ball milling beads of the first ball mill, preferably greater than or equal to 2 mm and less than 8 mm; in the implementation of the present invention, the diameter of the ball milling beads of the second ball mill is 2 mm, 3 mm, 4 mm, 5 mm, 6 mm or 7 mm.

[0068] In the present invention, the rotation speed of the second ball mill is higher than that of the first ball mill, preferably greater than 70r / min and less than or equal to 1000r / min; as an embodiment of the present invention, the rotation speed of the second ball mill can be 500-1000r / min, or 400-800r / min, or 200-600r / min; in an embodiment of the present invention, the rotation speed of the second ball mill is 400, 600 or 800r / min.

[0069] In the present invention, the ball-to-material ratio of the second ball mill is preferably 1:(2-4); in an embodiment of the present invention, the ball-to-material ratio is 1:2, 1:3 or 1:4.

[0070] In the present invention, the second ball milling time is preferably 8 to 72 hours; as an embodiment of the present invention, the second ball milling time can be 12 to 64 hours, or 24 to 48 hours; in an embodiment of the present invention, the second ball milling time is 72 hours.

[0071] In the present invention, the parameters of the ball milling are adjusted according to the particle state of ruthenium hydroxide. When the ruthenium hydroxide particles are large and severely agglomerated, the time and intensity of the ball milling are increased; when the ruthenium hydroxide particles are small and well dispersed, the time and intensity of the ball milling are reduced. By adjusting the parameters of the ball milling, ruthenium hydroxide in different particle states can be fully dispersed, the particle size of ruthenium hydroxide can be reduced, and the specific surface area can be increased.

[0072] The present invention has no special requirements for the ball milling device, and any device familiar to those skilled in the art can be used as long as the ruthenium hydroxide can be fully dispersed. The present invention preferably uses a planetary ball mill.

[0073] In the present invention, the freeze-drying preferably includes pre-freezing, sublimation and analysis performed in sequence.

[0074] In the present invention, the pre-freezing temperature is preferably -20 to -80°C, and the time is preferably 4 to 12 hours. In the present invention, during the pre-freezing process, the morphology of the ruthenium hydroxide particles is fixed, which can prevent the collapse of the structure of the ruthenium hydroxide particles, and at the same time, the ruthenium hydroxide is decomposed into ruthenium dioxide and water molecules.

[0075] In the present invention, the sublimation temperature is preferably -10 to -40°C, and the time is preferably 4 to 12 hours. In the present invention, the water molecules obtained by decomposing ruthenium hydroxide during the sublimation process sublimate in the form of ice, thereby obtaining ruthenium dioxide.

[0076] In the present invention, the decomposition temperature is preferably 0-40°C and the time is preferably 4-12 hours. In the present invention, after the sublimation, there will be a certain amount of bound water and adsorbed water in the ruthenium dioxide. The temperature is raised by decomposition to further remove water molecules.

[0077] The present invention increases the rotation speed of the ball mill and decreases the diameter of the ball mill beads so that the kinetic energy of the second ball mill is higher than that of the first ball mill. The two ball mills with different kinetic energies are used to break the agglomeration of ruthenium hydroxide precipitation, obtain a small and uniform particle size distribution, and increase its specific surface area; the ruthenium hydroxide is dehydrated by freeze drying to obtain ruthenium dioxide, so that dense tiny pores are formed inside the ruthenium hydroxide, thereby greatly increasing the specific surface area of ​​the ruthenium dioxide powder.

[0078] The present invention also provides a ruthenium dioxide powder prepared by the preparation method described in the above technical solution, wherein the specific surface area of ​​the ruthenium dioxide powder is 85 to 97 m 2 / g.

[0079] The present invention also provides the use of the ruthenium dioxide powder described in the above technical solution in thick film resistors.

[0080] The present invention has no special requirements for the application method, and the application method commonly used in the art can be adopted.

[0081] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0082] Example 1

[0083] A method for preparing ruthenium dioxide powder with high specific surface area, the specific process steps are as follows:

[0084] Weigh 62.5 g of hydrated ruthenium trichloride with a ruthenium content of 40%, add it into a reaction kettle, then add 625 mL of 90° C. hot deionized water, continue stirring at 1500 r / min, and hydrolyze to generate a ruthenium hydroxide solution;

[0085] Add hot deionized water at a temperature of 90°C into the reactor, and adjust the concentration of the ruthenium hydroxide solution to a mass concentration of ruthenium of 0.005 g / mL. At this time, the volume of the ruthenium hydroxide solution is 5000 mL;

[0086] Prepare pH regulator, select sodium borohydride and sodium hydroxide as solutes in a mass ratio of 1:1, add deionized water to adjust the concentration to 0.02g / mL, and the amount of pH regulator is 833.3mL;

[0087] Under stirring conditions, a pH adjuster is added to the ruthenium hydroxide solution at a rate of 50 mL / min, and stirring is continued at 1500 r / min after the addition. When the pH of the system is measured to be 7, a ruthenium hydroxide precipitate is generated;

[0088] The obtained ruthenium hydroxide precipitate was filtered, repeatedly washed with deionized water, and placed in an oven for pre-drying at 110°C for 48 hours;

[0089] The dried ruthenium hydroxide precipitate was placed in a planetary ball mill for preliminary ball milling at 200 r / min for 72 hours. The ball milling beads were selected to be agate ball milling beads with uniform size and smooth surface, the size was selected to be 5 mm, and the ball-to-material ratio was 1 / 3;

[0090] The ruthenium hydroxide powder after preliminary ball milling was put into a planetary ball mill for secondary ball milling at 400 r / min for 72 hours. The ball milling beads were selected to be agate ball milling beads with uniform size and smooth surface, the size was selected to be 2 mm, and the ball-to-material ratio was 1 / 3;

[0091] The ball-milled ruthenium hydroxide powder was placed in a freeze dryer for further reaction, and the pre-freezing temperature was set to -40°C for 10 hours; the sublimation drying temperature was set to -30°C for 10 hours; the analytical drying temperature was set to 30°C for 10 hours;

[0092] After the reaction is completed, ruthenium dioxide powder with high specific surface area is obtained.

[0093] The specific surface area of ​​the ruthenium dioxide powder prepared in Example 1 was tested using the reference desorption method to obtain a reference desorption curve, such as Figure 1 As shown, Figure 1 The first peak in the curve is the standard sample (GBW13905, BET: 9.05m 2 / g), the third peak is the ruthenium dioxide powder prepared by the present invention (BET: 90.0501m 2 / g). The specific surface area tester has four sample tubes, so there will be four peaks at most. The first peak is the standard sample peak, the second, third and fourth peaks are the test sample peaks, among which the main peak is the peak of the ruthenium dioxide prepared by the present invention, and the other peaks are the peaks of other sample tubes.

[0094] The microscopic morphology of the ruthenium dioxide powder prepared in Example 1 was observed using a scanning electron microscope. The results are as follows Figure 2 As shown by Figure 2 It can be seen that the ruthenium dioxide powder has good dispersibility and no obvious large particle agglomeration phenomenon.

[0095] The particle size distribution of the ruthenium dioxide powder prepared in Example 1 was tested using a laser particle size analyzer. The results are as follows: Figure 3 As shown by Figure 3 It can be seen that the particle size distribution of ruthenium dioxide powder is 1 to 40 μm.

[0096] The ruthenium dioxide powder prepared in Example 1 has good dispersibility, small and uniform particle size and particle size distribution, and high specific surface area, and can be used to prepare film thickness resistor slurry.

[0097] Example 2

[0098] A method for preparing ruthenium dioxide powder with high specific surface area, the specific process steps are as follows:

[0099] The ruthenium hydroxide precipitate prepared in Example 1 was placed in a planetary ball mill for preliminary ball milling at 300 r / min for 72 hours. The ball milling beads were selected to be agate ball milling beads with uniform size and smooth surface, the size was selected to be 6 mm, and the ball-to-material ratio was 1 / 3;

[0100] The ruthenium hydroxide powder after preliminary ball milling was put into a planetary ball mill for secondary ball milling at 600 r / min for 72 hours. The ball milling beads were selected to be agate ball milling beads with uniform size and smooth surface, the size was selected to be 3 mm, and the ball-to-material ratio was 1 / 3;

[0101] The ball-milled ruthenium hydroxide powder was placed in a freeze dryer for further reaction, and the pre-freezing temperature was set to -40°C for 10 hours; the sublimation drying temperature was set to -30°C for 10 hours; the analytical drying temperature was set to 30°C for 10 hours;

[0102] After the reaction is completed, ruthenium dioxide powder with high specific surface area is obtained.

[0103] The specific surface area of ​​the ruthenium dioxide powder prepared in Example 2 was tested using the reference desorption method to obtain a reference desorption curve, such as Figure 4 As shown, Figure 4 The first peak in the curve is the standard sample (GBW13905, BET: 9.05m 2 / g), the fourth peak is the ruthenium dioxide powder prepared by the present invention (BET: 91.2996m 2 / g).

[0104] The microscopic morphology of the ruthenium dioxide powder prepared in Example 2 was observed using a scanning electron microscope. The results are as follows Figure 5 As shown by Figure 5 It can be seen that the ruthenium dioxide powder has good dispersibility and no obvious large particle agglomeration phenomenon.

[0105] The particle size distribution of the ruthenium dioxide powder prepared in Example 2 was tested using a laser particle size analyzer. The results are as follows: Figure 6 As shown by Figure 6 It can be seen that the particle size distribution of ruthenium dioxide powder is 1 to 10 μm.

[0106] The ruthenium dioxide powder prepared in Example 2 has good dispersibility, small and uniform particle size and particle size distribution, and high specific surface area, and can be used to prepare film thickness resistor slurry.

[0107] Example 3

[0108] A method for preparing ruthenium dioxide powder with high specific surface area, the specific process steps are as follows:

[0109] The ruthenium hydroxide precipitate prepared in Example 1 was placed in a planetary ball mill for preliminary ball milling at 400 r / min for 72 hours. The ball milling beads were agate ball milling beads with uniform size and smooth surface, the size was 7 mm, and the ball-to-material ratio was 1 / 3;

[0110] The ruthenium hydroxide powder after preliminary ball milling was put into a planetary ball mill for secondary ball milling at 800 r / min for 72 hours. The ball milling beads were selected to be agate ball milling beads with uniform size and smooth surface, the size was selected to be 4 mm, and the ball-to-material ratio was 1 / 3;

[0111] The ball-milled ruthenium hydroxide powder was placed in a freeze dryer for further reaction, and the pre-freezing temperature was set to -40°C for 10 hours; the sublimation drying temperature was set to -30°C for 10 hours; the analytical drying temperature was set to 30°C for 10 hours;

[0112] After the reaction is completed, ruthenium dioxide powder with high specific surface area is obtained.

[0113] The specific surface area of ​​the ruthenium dioxide powder prepared in Example 3 was tested using the reference desorption method to obtain a reference desorption curve, such as Figure 7 As shown, Figure 7 The first peak in the curve is the standard sample (GBW13905, BET: 9.05m 2 / g), the third peak is the ruthenium dioxide powder prepared by the present invention (BET: 95.9423m 2 / g).

[0114] The microscopic morphology of the ruthenium dioxide powder prepared in Example 3 was observed using a scanning electron microscope. The results are as follows Figure 8 As shown by Figure 8 It can be seen that the ruthenium dioxide powder has good dispersibility and no obvious large particle agglomeration phenomenon.

[0115] The particle size distribution of the ruthenium dioxide powder prepared in Example 3 was tested using a laser particle size analyzer. The results are as follows: Fig. 9 As shown by Fig. 9 It can be seen that the particle size distribution of ruthenium dioxide powder is 1 to 20 μm.

[0116] The ruthenium dioxide powder prepared in Example 3 has good dispersibility, small and uniform particle size and particle size distribution, and high specific surface area, and can be used to prepare film thickness resistor slurry.

[0117] Example 4

[0118] A method for preparing ruthenium dioxide powder with high specific surface area, the specific process steps are as follows:

[0119] Weigh 75 g of hydrated ruthenium trichloride with a ruthenium content of 40%, add it into a reaction kettle, then add 750 mL of 90° C. hot deionized water, continue stirring at 1500 r / min, and hydrolyze to generate a ruthenium hydroxide solution;

[0120] Add hot deionized water at a temperature of 90°C into the reactor, and adjust the concentration of the ruthenium hydroxide solution to a mass concentration of ruthenium of 0.006 g / mL. At this time, the volume of the ruthenium hydroxide solution is 5000 mL;

[0121] Prepare pH adjuster, select sodium borohydride and sodium hydroxide as solute in a mass ratio of 1:1, add deionized water to adjust the concentration to 0.03g / mL; the amount of pH adjuster is 1250mL;

[0122] Under stirring conditions, a pH adjuster was added to the ruthenium hydroxide solution at a rate of 50 mL / min, and stirring was continued at 1500 r / min. When the pH of the system was measured to be 6.5, a ruthenium hydroxide precipitate was generated;

[0123] The obtained ruthenium hydroxide precipitate was filtered, repeatedly washed with deionized water, and placed in an oven for pre-drying at 110°C for 48 hours;

[0124] The dried ruthenium hydroxide precipitate was placed in a planetary ball mill for preliminary ball milling at 200 r / min for 72 hours. The ball milling beads were selected to be agate ball milling beads with uniform size and smooth surface, the size was selected to be 5 mm, and the ball-to-material ratio was 1 / 3;

[0125] The ruthenium hydroxide powder after preliminary ball milling was put into a planetary ball mill for secondary ball milling at 400 r / min for 72 hours. The ball milling beads were selected to be agate ball milling beads with uniform size and smooth surface, the size was selected to be 2 mm, and the ball-to-material ratio was 1 / 3;

[0126] The ball-milled ruthenium hydroxide powder was placed in a freeze dryer for further reaction, and the pre-freezing temperature was set to -80°C for 10 hours; the sublimation drying temperature was set to -40°C for 10 hours; the analytical drying temperature was set to 40°C for 10 hours;

[0127] After the reaction is completed, ruthenium dioxide powder with high specific surface area is obtained.

[0128] The specific surface area of ​​the ruthenium dioxide powder prepared in Example 4 was tested using the reference desorption method to obtain a reference desorption curve, such as Fig.10 As shown, Fig.10 The first peak in the curve is the standard sample (GBW13905, BET: 9.05m 2 / g), the third peak is the ruthenium dioxide powder prepared by the present invention (BET: 97.0744m 2 / g).

[0129] The microscopic morphology of the ruthenium dioxide powder prepared in Example 4 was observed using a scanning electron microscope. The results are as follows Fig.11 As shown by Fig.11 It can be seen that the ruthenium dioxide powder has good dispersibility and no obvious large particle agglomeration phenomenon.

[0130] The particle size distribution of the ruthenium dioxide powder prepared in Example 4 was tested using a laser particle size analyzer. The results are as follows: Fig.12 As shown by Fig.12 It can be seen that the particle size distribution of ruthenium dioxide powder is 1 to 10 μm.

[0131] The ruthenium dioxide powder prepared in Example 4 has good dispersibility, small and uniform particle size and particle size distribution, and high specific surface area, and can be used to prepare film thickness resistor slurry.

[0132] Example 5

[0133] A method for preparing ruthenium dioxide powder with high specific surface area, the specific process steps are as follows:

[0134] The ruthenium hydroxide precipitate prepared in Example 4 was placed in a planetary ball mill for preliminary ball milling at 200 r / min for 72 hours. The ball milling beads were selected to be agate ball milling beads with uniform size and smooth surface, the size was selected to be 5 mm, and the ball-to-material ratio was 1 / 3;

[0135] The ruthenium hydroxide powder after preliminary ball milling was put into a planetary ball mill for secondary ball milling at 400 r / min for 72 hours. The ball milling beads were selected to be agate ball milling beads with uniform size and smooth surface, the size was selected to be 2 mm, and the ball-to-material ratio was 1 / 3;

[0136] The ball-milled ruthenium hydroxide powder was placed in a freeze dryer for further reaction, and the pre-freezing temperature was set to -60°C for 10 hours; the sublimation drying temperature was set to -20°C for 10 hours; the analytical drying temperature was set to 35°C for 10 hours;

[0137] After the reaction is completed, ruthenium dioxide powder with high specific surface area is obtained.

[0138] The specific surface area of ​​the ruthenium dioxide powder prepared in Example 5 was tested using the reference desorption method to obtain a reference desorption curve, such as Fig.13 As shown, Fig.13 The first peak in the curve is the standard sample (GBW13905, BET: 9.05m 2 / g), the third peak is the ruthenium dioxide powder prepared by the present invention (BET: 94.0305m 2 / g).

[0139] The microscopic morphology of the ruthenium dioxide powder prepared in Example 5 was observed using a scanning electron microscope. The results are as follows Fig.14 As shown by Fig.14 It can be seen that the ruthenium dioxide powder has good dispersibility and no obvious large particle agglomeration phenomenon.

[0140] The particle size distribution of the ruthenium dioxide powder prepared in Example 5 was tested using a laser particle size analyzer. The results are as follows: Fig.15 As shown by Fig.15 It can be seen that the particle size distribution of ruthenium dioxide powder is 1 to 20 μm.

[0141] The ruthenium dioxide powder prepared in Example 5 has good dispersibility, small and uniform particle size and particle size distribution, and high specific surface area, and can be used to prepare film thickness resistor slurry.

[0142] Example 6

[0143] A method for preparing ruthenium dioxide powder with high specific surface area, the specific process steps are as follows:

[0144] The ruthenium hydroxide precipitate prepared in Example 4 was placed in a planetary ball mill for preliminary ball milling at 200 r / min for 72 hours. The ball milling beads were selected to be agate ball milling beads with uniform size and smooth surface, the size was selected to be 5 mm, and the ball-to-material ratio was 1 / 3;

[0145] The ruthenium hydroxide powder after preliminary ball milling was put into a planetary ball mill for secondary ball milling at 400 r / min for 72 hours. The ball milling beads were selected to be agate ball milling beads with uniform size and smooth surface, the size was selected to be 2 mm, and the ball-to-material ratio was 1 / 3;

[0146] The ball-milled ruthenium hydroxide powder was placed in a freeze dryer for further reaction, and the pre-freezing temperature was set to -40°C for 10 hours; the sublimation drying temperature was set to -30°C for 10 hours; the analytical drying temperature was set to 30°C for 10 hours;

[0147] After the reaction is completed, ruthenium dioxide powder with high specific surface area is obtained.

[0148] The specific surface area of ​​the ruthenium dioxide powder prepared in Example 6 was tested using the reference desorption method to obtain a reference desorption curve, such as Fig.16 As shown, Fig.16 The first peak in the curve is the standard sample (GBW13905, BET: 9.05m 2 / g), the second peak is the ruthenium dioxide powder prepared by the present invention (BET: 85.0369m 2 / g).

[0149] The microscopic morphology of the ruthenium dioxide powder prepared in Example 6 was observed using a scanning electron microscope. The results are as follows Fig.17 As shown by Fig.17 It can be seen that the ruthenium dioxide powder has good dispersibility and no obvious large particle agglomeration phenomenon.

[0150] The particle size distribution of the ruthenium dioxide powder prepared in Example 6 was tested using a laser particle size analyzer. The results are as follows: Fig.18 As shown by Fig.18 It can be seen that the particle size distribution of ruthenium dioxide powder is 2 to 10 μm.

[0151] The ruthenium dioxide powder prepared in Example 6 has good dispersibility, small and uniform particle size and particle size distribution, and high specific surface area, and can be used to prepare film thickness resistor slurry.

[0152] The specific surface areas of the ruthenium dioxide powders prepared in Examples 1 to 6 are shown in Table 1:

[0153] Table 1 Specific surface area of ​​ruthenium dioxide powder prepared in Examples 1 to 6

[0154]

[0155] By comparing Example 1 and Example 6, it can be seen that different ruthenium hydroxides use the same ball milling parameters and freeze-drying parameters to obtain ruthenium dioxide with different specific surface areas. By comparing Examples 1 to 3, it can be seen that the same ruthenium hydroxide uses different ball milling parameters and the same freeze-drying parameters to obtain ruthenium dioxide with different specific surface areas. By comparing Examples 4 to 6, it can be seen that the same ruthenium hydroxide uses the same ball milling parameters and different freeze-drying parameters to obtain ruthenium dioxide with different specific surface areas.

[0156] It can be seen from the above embodiments that the present invention can adjust the specific surface area of ​​ruthenium dioxide by using two ball millings with different rotation speeds and different diameters of ball milling beads, and freeze-drying with different parameters, and the obtained ruthenium dioxide has a higher specific surface area.

[0157] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing ruthenium dioxide powder, characterized in that: include: Ruthenium hydroxide is ball-milled and then freeze-dried to obtain ruthenium dioxide powder; the ball milling includes a first ball milling and a second ball milling performed in sequence; the diameter of the ball milling beads of the second ball mill is smaller than the diameter of the ball milling beads of the first ball mill, and the rotation speed of the second ball mill is higher than the rotation speed of the first ball mill.

2. The preparation method according to claim 1, characterized in that: The preparation method of ruthenium hydroxide comprises: 1) mixing hydrated ruthenium trichloride with hot water for hydrolysis to obtain a ruthenium hydroxide solution; the mass concentration of ruthenium in the ruthenium hydroxide solution is 0.005-0.006 g / mL; 2) adjusting the pH value of the ruthenium hydroxide solution obtained in step 1) to 6-8 to perform a precipitation reaction to obtain ruthenium hydroxide.

3. The preparation method according to claim 2, characterized in that: The temperature of the hot water in step 1) is 70-100°C.

4. The preparation method according to claim 2, characterized in that: The concentration of the pH adjuster used to adjust the pH value in step 2) is 0.02-0.03 g / mL.

5. The preparation method according to claim 1, characterized in that: The diameter of the ball mill beads of the first ball mill is greater than 2 mm and less than or equal to 8 mm, the ball-to-material ratio is 1:(2-4), the rotation speed is greater than or equal to 70 r / min and less than 1000 r / min, and the time is 8-72 h.

6. The preparation method according to claim 1, characterized in that: The diameter of the ball mill beads of the second ball mill is greater than or equal to 2 mm and less than 8 mm, the ball-to-material ratio is 1:(2-4), the rotation speed is greater than 70 r / min and less than or equal to 1000 r / min, and the time is 8-72 h.

7. The preparation method according to claim 1, characterized in that: The freeze-drying comprises pre-freezing, sublimation and analysis performed in sequence.

8. The preparation method according to claim 7, characterized in that: The pre-freezing temperature is -20 to -80°C, and the time is 4 to 12 hours; the sublimation temperature is -10 to -40°C, and the time is 4 to 12 hours; the decomposition temperature is 0 to 40°C, and the time is 4 to 12 hours.

9. The ruthenium dioxide powder prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The specific surface area of ​​the ruthenium dioxide powder is 81 to 97 m 2 / g.

10. Use of the ruthenium dioxide powder according to claim 9 in thick film resistors.

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