A method for preparing a water-based slurry of metallic silicon powder for reactive re-sintered silicon nitride ceramics
The metal silicon powder is wrapped by a modifier and dispersant, which solves the hydration problem of metal silicon powder during ball milling, and realizes the treatment under an aqueous medium, reducing the preparation cost.
Patent Information
- Application Number
- CN202411895595.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-22
- Publication Date
- 2025-04-04
AI Technical Summary
During the preparation process of resintered silicon nitride ceramics, metal silicon powder is prone to react with water, resulting in hydration problems during ball milling and increasing the preparation cost.
The surface of the metal silicon powder is wrapped by a modifier and secondary wrapping with a dispersant is solved, which makes the wetting problem of the metal silicon powder more tight and evenly combined with the binder.
The problem of hydration of metal silicon powder during ball milling is overcome, so that metal silicon powder can be treated with water as a medium, and is suitable for the preparation of water-based spray granulated slurry and grouting slurry.
Abstract
Description
Technical Field
[0001] The invention relates to a method for preparing a water-based slurry, and in particular to a method for preparing a metal silicon powder water-based slurry for reaction-re-sintered silicon nitride ceramics. Background Art
[0002] The preparation of silicon nitride ceramics by reactive resintering can effectively reduce the current production and preparation costs of silicon nitride ceramics, because reactive resintering uses silicon powder as raw material, and silicon and nitrogen react at high temperature to achieve the preparation of silicon nitride ceramics. Although the reactive resintering method can reduce the raw material cost of silicon nitride, it also brings certain difficulties in the production and processing of silicon powder. Because silicon powder has metallic activity and easily reacts with water, in the preparation process of reactive resintered silicon nitride ceramics, reactive sintered silicon nitride ceramics, silicon nitride powder, etc., silicon powder is generally treated by dry method or organic solvent, which will undoubtedly increase the preparation cost. Summary of the invention
[0003] In order to solve the above problems, the present invention provides a method for preparing a water-based slurry of metallic silicon powder for reactive re-sintered silicon nitride ceramics. The specific technical scheme is as follows:
[0004] A method for preparing a metallic silicon powder aqueous slurry for reactive re-sintered silicon nitride ceramics comprises the following steps:
[0005] The metal silicon powder is mixed with a modifier, a dispersant and a solvent to obtain pretreated metal silicon powder; a sintering aid, a nitriding catalyst and a diluent are added to deionized water and the pH value is adjusted before ball milling to obtain a premixed slurry; the obtained pretreated metal silicon powder is added to the premixed slurry for mixing to obtain a metal silicon powder aqueous slurry.
[0006] Preferably, the modifier is one of organic silicon, silane coupling agent, aluminate coupling agent, zirconium aluminate coupling agent, and the dispersant is polyethylene glycol. The pretreatment method is: 1. Mix the modifier with anhydrous ethanol, stir at room temperature for 10-50 minutes to obtain a modified solution; 2. Add metal silicon powder to the modified solution, stir under ultrasonic vibration for 1-2 hours to disperse the powder evenly, and then let it stand for 1-3 hours; 3. Add 1%-5% of the dispersant, stir at 50-70°C for 0.5-1.5 hours, and then dry to obtain pretreated metal silicon powder.
[0007] The sintering aid is one or more of yttrium oxide, magnesium oxide, aluminum oxide, cerium oxide, and lanthanum oxide; the nitriding catalyst is one or more of iron oxide, zirconium oxide, and calcium fluoride; the diluent is silicon nitride; the mass ratio of the sintering aid to the silicon nitride generated by nitriding the metal silicon powder is (10-15): (85-90), the mass ratio of the nitriding catalyst to the metal silicon powder is (1-5): 100, the mass ratio of the diluent to the metal silicon powder is (1-10): 100, the pH value of the solution is 5-7, and the ball milling time is 6-10 hours.
[0008] Furthermore, the pretreated metallic silicon powder is added to the premixed slurry for ball milling, and the ball milling time is 1-3 hours.
[0009] Furthermore, a binder is added to the slurry, the binder is a polyvinyl alcohol aqueous solution, and the added content of the binder is 1-5% of the total mass of the metallic silicon powder and the sintering aid;
[0010] Compared with the prior art, the present invention has the following beneficial effects:
[0011] The present invention provides a method for preparing a water-based slurry of metal silicon powder for reactive re-sintered silicon nitride ceramics. The method involves coating the surface of the metal silicon powder with a modifier, thereby solving the problem of the metal silicon powder reacting with water during ball milling. The method also involves coating the metal silicon powder with a dispersant for a second time, thereby solving the wettability of the surface of the metal silicon powder, and making the metal silicon powder and the binder more tightly and evenly combined. The present invention overcomes the hydration problem of the metal silicon powder during ball milling, and allows the metal silicon powder to be processed with water as the medium. The method is not only suitable for the preparation of water-based spray granulation slurry and grouting slurry, but also suitable for the processing of all other metal silicon powders with water as the medium. DETAILED DESCRIPTION
[0012] The present invention will be further described with reference to the embodiments.
[0013] Specifically, a method for preparing a metal silicon powder aqueous slurry for reactive re-sintered silicon nitride ceramics comprises the following steps:
[0014] Step 1: Mixing metallic silicon powder with a modifier, a dispersant and a solvent to obtain pretreated metallic silicon powder;
[0015] Step 2: adding a sintering aid, a nitriding catalyst, and a diluent to deionized water and adjusting the pH value before ball milling to obtain a premixed slurry;
[0016] Step 3: Add the pretreated metallic silicon powder and the binder into the premixed slurry and perform ball milling to obtain a metallic silicon powder aqueous slurry.
[0017] In step one, the metal silicon powder is 1-10 μm, the modifier is one of silicone, silane coupling agent, aluminate coupling agent, zirconium aluminate coupling agent, the dispersant is polyethylene glycol, the mass ratio of the metal silicon powder to the modifier is 100:(1-5), and the mass ratio of the metal silicon powder to the dispersant is 100:(1-5). The metal silicon powder is pretreated by the modifier and the dispersant.
[0018] The pretreatment method is as follows: 1. Mix the modifier with anhydrous ethanol, and stir at room temperature for 10-50 minutes to obtain a modified solution; 2. Add metal silicon powder to the modified solution, stir for 1-2 hours under ultrasonic vibration conditions to evenly disperse the powder, and then let it stand for 1-3 hours; 3. Add 1%-5% of the dispersant, stir at 50-70°C for 0.5-1.5 hours, and then dry to obtain pretreated metal silicon powder.
[0019] In step 2, the sintering aid is one or more of yttrium oxide, magnesium oxide, aluminum oxide, cerium oxide, and lanthanum oxide; the nitridation catalyst is one or more of iron oxide, zirconium oxide, and calcium fluoride; the diluent is silicon nitride, and the mass ratio of the sintering aid to the silicon nitride generated by nitriding the metal silicon powder is (10-15): (85-90), the mass ratio of the nitridation catalyst to the silicon powder is (1-5): 100, the mass ratio of the diluent to the silicon powder is (1-10): 100, the pH value of the solution is 5-7, and the ball milling time is 6-10h.
[0020] In step three, the binder is polyvinyl alcohol, the addition amount is 1-5%, and the ball milling mixing time of the pretreated metallic silicon powder and the premixed slurry is 1-3 hours.
[0021] Embodiment 1
[0022] Weigh 2 g of silane coupling agent, add 80 g of anhydrous ethanol and stir for 30 min, then add 100 g of metal silicon powder and continue ultrasonic stirring for 2 h, let it stand for 2 h, then add 5 g of polyethylene glycol, stir at 60 ° C for 1 h, and dry to obtain pretreated metal silicon powder.
[0023] Weigh 9.8 g of lanthanum oxide, 9.8 g of aluminum oxide, 9.8 g of magnesium oxide, 2 g of calcium fluoride and 8 g of silicon nitride powder, mix them, add 95 g of deionized water, adjust the pH value to 6, add them into a ball mill and mill them for 8 hours to obtain a premixed slurry.
[0024] The pretreated metallic silicon powder was added to the premixed slurry and ball-milled again for 2 h, and 27 g of polyvinyl alcohol aqueous solution was added to obtain an aqueous metallic silicon powder slurry.
[0025] Embodiment 2
[0026] Weigh 4 g of organosilicon, add 100 g of anhydrous ethanol and stir for 30 min, then add 100 g of metal silicon powder and continue ultrasonic stirring for 1 h, let it stand for 2 h, then add 4 g of polyethylene glycol, stir at 50°C for 1 h, and dry to obtain pretreated metal silicon powder.
[0027] Weigh 9.8 g of yttrium oxide, 9.8 g of aluminum oxide, 9.8 g of magnesium oxide, 1 g of iron oxide and 5 g of silicon nitride powder, mix them, add 95 g of deionized water, adjust the pH value to 5.5, add them into a ball mill and mill them for 6 hours to obtain a premixed slurry.
[0028] The pretreated metallic silicon powder was added to the premixed slurry and ball-milled again for 1 hour, and 27 g of polyvinyl alcohol aqueous solution was added to obtain an aqueous metallic silicon powder slurry.
[0029] Embodiment 3
[0030] Weigh 5 g of silane coupling agent, add 120 g of anhydrous ethanol and stir for 30 min, then add 100 g of metal silicon powder and continue ultrasonic stirring for 2 h, let it stand for 2 h, then add 5 g of polyethylene glycol, stir at 70 ° C for 1 h, and dry to obtain pretreated metal silicon powder.
[0031] Weigh 9.8 g of cerium oxide, 9.8 g of aluminum oxide, 9.8 g of magnesium oxide, 5 g of zirconium oxide and 5 g of silicon nitride powder, mix them, add 95 g of deionized water, adjust the pH value to 6, add them into a ball mill and mill them for 6 hours to obtain a premixed slurry.
[0032] The pretreated metallic silicon powder was added to the premixed slurry and ball-milled again for 2 h, and 27 g of polyvinyl alcohol aqueous solution was added to obtain an aqueous metallic silicon powder slurry.
[0033] The technical principle of the present invention is described above in conjunction with specific embodiments. These descriptions are only for explaining the principle of the present invention and cannot be interpreted as limiting the protection scope of the present invention in any way. Based on the explanations herein, those skilled in the art can associate other specific implementations of the present invention without paying creative labor, and these methods will fall within the protection scope of the claims of the present invention.
Claims
1. A method for preparing a water-based slurry of metallic silicon powder for reactive re-sintered silicon nitride ceramics, characterized in that: The following steps are involved: Mixing metallic silicon powder, a modifier, a dispersant, and a solvent to obtain pretreated metallic silicon powder; Adding a sintering aid, a nitriding catalyst, and a diluent to deionized water and adjusting the pH value before ball milling to obtain a premixed slurry; The pretreated metal silicon powder and the binder are added to the premixed slurry and ball milled to obtain a metal silicon powder water-based slurry.
2. The method for preparing a water-based slurry of metallic silicon powder for reactive re-sintered silicon nitride ceramics according to claim 1, characterized in that: The average particle size of the metal silicon powder is 1-10 μm; The modifier is one of organic silicon, silane coupling agent, aluminate coupling agent and zirconium aluminate coupling agent; The solvent is anhydrous ethanol; The dispersant is polyethylene glycol; Wherein, the mass ratio of the metal silicon powder to the modifier is 100:(1-5); The mass ratio of the metal silicon powder to the dispersant is 100:(1-5); The mass ratio of the metal silicon powder to the solvent is 1:(0.8-1.2).
3. The method for preparing a water-based slurry of metallic silicon powder for reactive re-sintered silicon nitride ceramics according to claim 2, characterized in that: The preparation of pretreated metallic silicon powder comprises the following steps: The modifier and the solvent are mixed, and stirred at room temperature for 10-50 minutes to obtain a modified solution; Add metallic silicon powder to the modified solution, stir under ultrasonic vibration for 1-2 hours to make the powder disperse evenly, and then let it stand for 1-3 hours; Add 1%-5% of the mass of the metal silicon powder as a dispersant, stir at 50-70° C. for 0.5-1.5 h, and then dry to obtain pretreated metal silicon powder.
4. The method for preparing a metal silicon powder aqueous slurry for reactive re-sintered silicon nitride ceramics according to claim 1, characterized in that: The sintering aid is one or more of yttrium oxide, magnesium oxide, aluminum oxide, cerium oxide, and lanthanum oxide; The nitriding catalyst is one or more of iron oxide, zirconium oxide, and calcium fluoride; The diluent is silicon nitride; The mass ratio of the sintering aid to the silicon nitride generated by nitriding the metal silicon powder is (10-15): (85-90); The mass ratio of the nitriding catalyst to the metallic silicon powder is (1-5): 100; The mass ratio of the diluent to the metallic silicon powder is (1-10): 100; The pH value of the solution is 5-7, and the ball milling time is 6-10h.
5. The method for preparing a water-based slurry of metallic silicon powder for reactive re-sintered silicon nitride ceramics according to claim 1, characterized in that: The binder is polyvinyl alcohol, and the added amount is 1-5% of the total mass of the powder. The ball milling mixing time of the pretreated metallic silicon powder and the premixed slurry is 1-3 hours.