CN1948152A - High purity ultra fine zirconium biboride powder and its preparation method - Google Patents

Abstract

The present invention relates to a high-purity ultrafine zirconium diboride powder material and its preparation method. It is characterized by that the described powder material contains zirconium oxychloride, boron carbide powder and active carbon powder, their mole ratio is ZrOcl2:B4C:C=1:0.4-0.8:1.4-1.8. Its preparation method includes the following steps: firstly, mixing boron carbide powder, active carbon powder and water according to mixing ratio, regulating pH value to obtain mixed suspension; dissolving zirconium oxychloride in deionized water to obtain the zirconium oxychloride solution; mixing the above-mentioned suspension and zirconium oxychloride solution, adding ammonia water, making the zirconium oxychloride be fully hydrolyzed and precipitated; making suspension undergo the processes of solid-liquor separation, waster-washing, removing NH4+ and Cl-, drying and sieving; then placing the powder material into a vacuum furnace to make reaction synthesis, its synthesis temperature is 1500-1600 deg.C, heat-insulating for 0.5-4 h; grinding powder and sieving so as to obtain the invented powder material.

Description

A kind of high-purity ultrafine zirconium diboride powder and its preparation method

technical field

The invention relates to a low-cost preparation of high-purity ultrafine zirconium diboride (ZrB ₂ ) powder and a method thereof, belonging to the field of ceramic materials.

Background technique

Zirconium diboride (ZrB ₂ ) has the characteristics of high melting point, high hardness, good electrical and thermal conductivity, good flame retardancy, heat resistance, oxidation resistance, and corrosion resistance. Crucibles and refractory materials used in the industry, electrode materials for metal smelting and many other fields have very broad application prospects.

At present, there are four main methods for preparing this zirconium diboride powder: the first method is self-propagating high-temperature synthesis (SHS) (document 1: Chinese invention patent: 200510010014); the second method is zirconium dioxide boron reduction method (document 2: J.Am.Ceram.Soc., 78 [9] 2534-36 (1995)); the third method is the molten salt bath method of electrolysis containing metal oxide and B ₂ O ₃ (document 3: Ceramic-Metal Composite Materials: 53(2004)); The fourth method is the direct solid-state reaction synthesis method. Method 1 is simple in process, short in time, low in energy consumption, and high in activity of the synthetic powder, but because the reaction speed is too fast, the reaction may sometimes be incomplete, and there will be correspondingly more impurities, and its reaction process, product structure and performance Not easy to control. Method 2 is more suitable for industrial mass production, but its disadvantage is that it is easier to introduce impurities and the purity of the prepared product is not high. The third method is usually not easy to complete the reaction, the product particles are large, the activity is not high, and it is not conducive to post-processing. Method four is limited by expensive raw materials, and often the product activity is not high.

The carbothermal reduction borylation method of high-purity ultra-fine zirconium diboride (ZrB ₂ ) powder proposed by the present invention just fills the technical gap in the aspect of low-cost preparation of high-purity ultra-fine zirconium diboride powder.

Contents of the invention

The purpose of the present invention is to provide a low-cost method for preparing high-purity ultrafine zirconium diboride powder, which uses a carbothermal reduction boride method to prepare high-purity ultrafine zirconium diboride powder. The invention is simple and easy to implement, has high yield, high purity and high efficiency, and is suitable for industrial scale production.

A high-purity ultrafine zirconium diboride powder proposed by the present invention is characterized in that: the powder contains zirconium oxychloride, boron carbide powder, and activated carbon powder, and its molar ratio is: ZrOCl ₂ : B ₄ C :C=1:(0.4-0.8):(1.4-1.8).

The preparation method of a kind of high-purity ultrafine zirconium diboride powder proposed by the present invention is characterized in that: the method is carried out according to the following steps successively:

(1) The molar ratio is: ZrOCl ₂ : B ₄ C : C = 1: (0.4～0.8): (1.4～1.8) Weigh the ingredients, first put B ₄ C and C powder into the beaker, press Add deionized water at a ratio of solid: H ₂ O = 1:50-80, stir, and adjust the pH value to 2-5 to obtain a mixed suspension of B ₄ C and C powder;

(2) take zirconium oxychloride by formula, and zirconium oxychloride: deionized water is made zirconium oxychloride solution by the ratio of 1: 50～80;

(3) Mix the _B4C and C powder mixed suspension obtained in step 1 with the zirconium oxychloride solution obtained in step 2, stir magnetically, and add ammonia water drop by drop, so that the zirconium oxychloride is fully hydrolyzed and precipitated until the pH value greater than 9;

(4) Use centrifugation or suction filtration to separate the solid and liquid of the suspension obtained in step 3, and wash it with water to remove NH ₄ ⁺ and Cl ^- , then put it in an oven and dry it at 80-100°C, and pass it through a 100-mesh sieve ;

(5) Put the powder obtained in step 4 into a graphite or alumina crucible, carry out reaction synthesis in a vacuum furnace, flow argon protection, synthesis temperature 1500-1600 ° C, heat preservation 0.5-4 hours;

(6) Then further grind the powder obtained in step 5, and pass through a 300-500 mesh sieve to obtain a ZrB ₂ powder with a content greater than 99% and a particle size of micron or submicron order.

The present invention can utilize cheap raw material zirconium oxychloride and simple production equipment to synthesize high-purity (>99wt%), superfine (micron or submicron) zirconium diboride powder in large quantities. According to XRD detection, the main component in the powder is ZrB ₂ , and the particles are equiaxed.

The invention is simple and easy to implement, has high yield, high purity and high efficiency, and is suitable for industrial scale production.

Detailed ways

Below in conjunction with embodiment technical scheme of the present invention is described further:

(1). Raw materials:

Zirconium oxychloride (ZrOCl ₂ , ~300 mesh, purity >99%), boron carbide powder (B ₄ C, 3.5 μm, purity >99%), activated carbon powder (analytical pure), ammonia water (analytical pure).

(2). Proportion (molar ratio, the same below):

Raw material ratio: ZrOCl ₂ : B ₄ C: C = 1: (0.4～0.8): (1.4～1.8)

(3). Weigh the ingredients according to the formula in (2). First put B ₄ C and C powder into a beaker, add deionized water according to the ratio of solid:H ₂ O = 1:50~80, stir for 0.5~1h, adjust the pH value to 2~5, and obtain B ₄ C Mix suspension with C powder.

(4). Weigh zirconium oxychloride according to the formula in (2), and prepare zirconium oxychloride solution with zirconium oxychloride: deionized water in a ratio of 1:50-80.

(5). Mix the suspension of B ₄ C and C powder in (3) with the zirconium oxychloride solution in (4), stir magnetically, and add ammonia water drop by drop, so that the zirconium oxychloride is fully hydrolyzed and precipitated , until the pH value is greater than 9.

(6). The suspension in (5) was separated from solid and liquid by centrifugation or suction filtration, and washed 3 times with water to remove NH ₄ ⁺ and Cl ⁻ . Then put it into an oven and dry it thoroughly at 80-100°C, then pass through a 100-mesh sieve.

(7). Put the powder in the process (6) into a graphite or alumina crucible, and carry out reaction synthesis in a vacuum furnace, protected by flowing argon, at a synthesis temperature of 1500-1600°C, and keep warm for 0.5-4 hours.

(8) Then the powder obtained in (7) is further ground, and the method of ball milling or stirring milling can be adopted, and the powder with a content of more than 99% and a particle size of micron or submicron can be obtained by passing through a 300-500 mesh sieve. ZrB ₂ powder.

Embodiment one:

The selected formula is: ZrOCl ₂ :B ₄ C:C=1:0.5:1.5 (molar ratio). First, weigh B ₄ C and carbon powder according to the formula, put them into a beaker, add deionized water according to the ratio of solid:H ₂ O=1:50, adjust the pH value to 2-5, and then stir and disperse for 30 minutes. Take another beaker, weigh zirconium oxychloride according to the formula, add deionized water according to the ratio of zirconium oxychloride: H ₂ O = 1:80, fully dissolve the zirconium oxychloride, and obtain a transparent solution. Mix the dispersed _B4C and carbon powder suspension with the zirconium oxychloride solution, stir it with magnetic force, and add 25% ammonia water drop by drop to the mixed solution while stirring, so that the zirconium oxychloride is fully hydrolyzed and precipitated, until the pH value is greater than 9. Then the suspension was suction filtered and washed with water three times. Then put it into an oven and fully dry it at 100°C. Pass the dried powder through a 100-mesh sieve, put it into an alumina crucible, and carry out reaction synthesis in a vacuum furnace, protected by flowing argon, at a synthesis temperature of 1550°C, and keep warm for 1 hour. Take out the synthesized powder and put it into a ball mill jar for full ball milling, pass through a 300-mesh sieve to obtain ZrB ₂ powder. According to correlation analysis, the main component of the obtained powder is ZrB ₂ , the purity is 99.2wt%, and the average particle size is 1.2 μm.

Embodiment two:

The selected formula is: ZrOCl ₂ :B ₄ C:C=1:0.55:1.5 (molar ratio). First, weigh B ₄ C and carbon powder according to the formula, put them into a beaker, add deionized water according to the ratio of solid:H ₂ O=1:60, adjust the pH value to 2-5, and then stir and disperse for 1 hour. Take another beaker, weigh zirconium oxychloride according to the formula, add deionized water according to the ratio of zirconium oxychloride: H ₂ O = 1:60, fully dissolve the zirconium oxychloride, and obtain a transparent solution. Mix the dispersed _B4C and carbon powder suspension with the zirconium oxychloride solution, stir it with magnetic force, and add 25% ammonia water drop by drop to the mixed solution while stirring, so that the zirconium oxychloride is fully hydrolyzed and precipitated, until the pH value is greater than 9. Then the suspension was suction filtered and washed with water three times. Then put it into an oven and fully dry it at 100°C. Pass the dried powder through a 100-mesh sieve, put it into a graphite crucible, and carry out reaction synthesis in a vacuum furnace, protected by flowing argon, at a synthesis temperature of 1500°C, and keep warm for 4 hours. Take out the synthesized powder and put it into a stirring mill to fully grind it, and pass through a 300-mesh sieve to obtain ZrB ₂ powder. According to correlation analysis, the main component of the obtained powder is ZrB ₂ , the purity is 99.0wt%, and the average particle size is 0.8 μm.

Embodiment three:

The selected formula is: ZrOCl ₂ :B ₄ C:C=1:0.6:1.65 (molar ratio). First, weigh B ₄ C and carbon powder according to the formula, put them into a beaker, add deionized water according to the ratio of solid:H ₂ O=1:80, adjust the pH value to 2-5, and then stir and disperse for 1 hour. Take another beaker, weigh zirconium oxychloride according to the formula, add deionized water according to the ratio of zirconium oxychloride: H ₂ O = 1:50, fully dissolve the zirconium oxychloride, and obtain a transparent solution. Mix the dispersed _B4C and carbon powder suspension with the zirconium oxychloride solution, stir it with magnetic force, and add 25% ammonia water drop by drop to the mixed solution while stirring, so that the zirconium oxychloride is fully hydrolyzed and precipitated, until the pH value is greater than 9. Then the suspension was suction filtered and washed with water three times. Then put it into an oven and fully dry it at 80°C. Pass the dried powder through a 100-mesh sieve, put it into a graphite crucible, and carry out reaction synthesis in a vacuum furnace, protected by flowing argon, at a synthesis temperature of 1600°C, and keep warm for 1 hour. Take out the synthesized powder and put it into a stirring mill to fully grind it, and pass through a 300-mesh sieve to obtain ZrB ₂ powder. According to correlation analysis, the main component of the obtained powder is ZrB ₂ , the purity is 99.5wt%, and the average particle size is 1.5 μm.

Claims (2)

1. A high-purity ultrafine zirconium diboride powder, characterized in that: the powder contains zirconium oxychloride, boron carbide powder, and activated carbon powder, and its molar ratio is: ZrOCl ₂ : B ₄ C: C =1:(0.4~0.8):(1.4~1.8). 2. The method for preparing a high-purity ultrafine zirconium diboride powder as claimed in claim 1, characterized in that: the method is carried out in sequence as follows: (1) The molar ratio is: ZrOCl ₂ : B ₄ C : C = 1: (0.4～0.8): (1.4～1.8) Weigh the ingredients, first put B ₄ C and C powder into the beaker, press Add deionized water at a ratio of solid: H ₂ O = 1:50-80, stir, and adjust the pH value to 2-5 to obtain a mixed suspension of B ₄ C and C powder; (2) take zirconium oxychloride by formula, and zirconium oxychloride: deionized water is made zirconium oxychloride solution by the ratio of 1: 50～80; (3) Mix the _B4C and C powder mixed suspension obtained in step 1 with the zirconium oxychloride solution obtained in step 2, stir magnetically, and add ammonia water drop by drop, so that the zirconium oxychloride is fully hydrolyzed and precipitated until the pH value greater than 9; (4) Use centrifugation or suction filtration to separate the solid and liquid of the suspension obtained in step 3, and wash it with water to remove NH ₄ ⁺ and Cl ^- , then put it in an oven and dry it at 80-100°C, and pass it through a 100-mesh sieve ; (5) Put the powder obtained in step 4 into a graphite or alumina crucible, carry out reaction synthesis in a vacuum furnace, flow argon protection, synthesis temperature 1500-1600 ° C, heat preservation 0.5-4 hours; (6) Then further grind the powder obtained in step 5, and pass through a 300-500 mesh sieve to obtain a ZrB ₂ powder with a content greater than 99% and a particle size of micron or submicron order.