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Preparation method of silicon nitride ceramic granulation powder

A technology of silicon nitride ceramics and silicon nitride raw powder, applied in the field of silicon nitride ceramics, can solve the problems of long time consumption, wasteful operation process of remaining powder materials, difficulty in large-scale application, etc.

Active Publication Date: 2022-02-01
SINOMA ADVANCED NITRIDE CERAMICS CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The traditional vacuum ball milling method for preparing powders with high bulk density has the disadvantages of complex equipment, high cost, and long time consumption; although the method of rotary vibrating screen and double cone mixer can pack powders of various densities, the remaining powder The waste and the complexity of the operation process also make this method difficult to apply on a large scale in production
Although the spray granulation method is simple to operate, the bulk density of the prepared ceramic powder is low

Method used

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Examples

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preparation example Construction

[0024] The invention provides a kind of preparation method of silicon nitride ceramic granulated powder, comprises the following steps:

[0025] Grinding and mixing the sintering aid, water and silicon nitride raw powder to obtain the first slurry;

[0026] Polyvinyl alcohol and polyethylene glycol are dissolved in water to obtain a glue solution; the mass ratio of the polyvinyl alcohol and polyethylene glycol is (0.16-0.20): 1; the total mass of the polyvinyl alcohol and the alcohol polyethylene glycol It is 2-8% of the total mass of sintering aid and silicon nitride raw powder;

[0027] mixing the first slurry, glue solution and dispersant to obtain a second slurry;

[0028] The second slurry is subjected to spray granulation to obtain granulated powder; the inlet temperature of the spray granulation is 300-340°C.

[0029] In the present invention, unless otherwise specified, the raw materials used are commercially available products well known in the art.

[0030] In the...

Embodiment 1

[0049] Add 15kg of sintering aids (thorium oxide and magnesium oxide, the mass ratio of thorium oxide and magnesium oxide is 1:4, D50<1μm) and 15kg of water into the drum mill for grinding and mixing for 6 hours, then add 85kg of high-purity silicon nitride Raw powder and 85kg of water are ground to 0.8<D50<1.5 μm to prepare the first slurry with better uniformity and a solid phase content of 50%. Add 2.54kg of polyethylene glycol (PEG, molecular weight 20,000) into 20kg of water, heat and stir at 50°C for 0.5h to dissolve, then add 0.46kg of polyvinyl alcohol (PVB, molecular weight 200,000), heat and stir for 2h at 50°C to prepare a uniform glue solution. Add the prepared first slurry into the stirring mill and stir for 1 hour, then add the glue solution and continue stirring for 1 hour, add sodium hexametaphosphate to control the viscosity of the slurry at 3000mPa·s, and obtain the second slurry with good dispersibility and fluidity , the temperature of the second slurry is...

Embodiment 2

[0051] Add 15kg of sintering aids (thorium oxide and magnesium oxide, the mass ratio of thorium oxide and magnesium oxide is 1:4, D50<1μm) and 15kg of water into the drum mill for grinding and mixing for 6 hours, then add 85kg of high-purity silicon nitride Raw powder and 85kg of water are ground to 0.8<D50<1.5 μm to prepare the first slurry with better uniformity and a solid phase content of 50%. Add 2.50kg of polyethylene glycol (PEG, molecular weight 6000) into 20kg of water, heat and stir at 50°C for 0.5h to dissolve, then add 0.50kg of polyvinyl alcohol (PVA, molecular weight 200,000) at 50°C, stir and dissolve for 2h to prepare a uniform glue solution. Add the prepared first slurry into the stirring mill and stir for 1 hour, then add the glue solution and continue stirring for 1 hour, add sodium hexametaphosphate to control the viscosity of the slurry at 3000mPa·s, and obtain the second slurry with good dispersibility and fluidity , the second slurry temperature is 30°C...

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Abstract

The invention provides a preparation method of silicon nitride ceramic granulation powder, and belongs to the technical field of silicon nitride ceramics. The preparation method comprises the following steps: grinding and mixing a sintering aid, water and silicon nitride raw powder to obtain first slurry; dissolving polyvinyl alcohol and polyethylene glycol into water to obtain a glue solution, wherein the mass ratio of the polyvinyl alcohol to the polyethylene glycol is (0.16-0.20):1, and the total mass of the polyvinyl alcohol and the alcohol polyethylene glycol is 2-8% of the total mass of the sintering aid and the silicon nitride raw powder; mixing the first slurry, the glue solution and a dispersing agent to obtain second slurry; and carrying out spray granulation on the second slurry to obtain granulated powder, wherein the inlet temperature of the spray granulation is 300 to 340 DEG C. According to the method disclosed by the invention, the apparent density of the silicon nitride ceramic granulation powder can be improved to 0.92 g / cm<3> or above.

Description

technical field [0001] The invention relates to the technical field of silicon nitride ceramics, in particular to a method for preparing silicon nitride ceramic granulated powder. Background technique [0002] Silicon nitride ceramic material has the properties of high strength, low density, strong wear resistance, good corrosion resistance, high thermal shock resistance, self-lubrication and good electrical insulation. It is the preferred material for the production of various structural ceramic parts. At the same time, it still has huge development potential, and has a wide range of applications in aerospace, machinery, chemical and other fields. [0003] Increasing the green body density of silicon nitride can effectively increase the density after sintering and reduce the porosity, thereby improving the mechanical properties of the green body, and the improvement of the green body density is largely affected by the bulk density of the granulated powder. Usually Under th...

Claims

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Application Information

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IPC IPC(8): C04B35/626C04B35/584C04B35/634
CPCC04B35/62695C04B35/584C04B35/63416C04B2235/5436C04B2235/5445
Inventor 孙峰丁智杰张伟儒李洪浩丁浩刘阔地宋健徐金梦王晟杨厚萌
Owner SINOMA ADVANCED NITRIDE CERAMICS CO LTD
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