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Vacuum vibration casting and moulding method for Si3N4-SiC fireproof ceramic

A technology of refractory ceramics and vibration casting, which is applied in the field of refractory material production, can solve the problems of short service life, difficulty in material preparation, poor thermal shock resistance, etc., achieve small difference in physical properties, improve thermal shock resistance and service life, The effect of uniform density distribution

Inactive Publication Date: 2018-01-05
NAVAL UNIV OF ENG PLA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] However, there are many technical difficulties in the preparation of special-shaped silicon nitride and silicon carbide refractory ceramics for high-performance booster boilers using traditional machine-pressed forming technology. The particularity of the structure greatly increases the difficulty of material preparation, and the uniformity of the material is difficult to control.
Due to the difference in physical properties caused by poor material uniformity, the material has poor thermal shock resistance, short service life, and serious safety hazards.

Method used

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  • Vacuum vibration casting and moulding method for Si3N4-SiC fireproof ceramic
  • Vacuum vibration casting and moulding method for Si3N4-SiC fireproof ceramic
  • Vacuum vibration casting and moulding method for Si3N4-SiC fireproof ceramic

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Experimental program
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Effect test

Embodiment 1

[0029] Take by weighing 70% silicon carbide powder (by mixing industrial-grade black silicon carbide particles, silicon carbide fine powder, and silicon carbide micropowder in a mass ratio of 14:1:1), 25% silicon carbide, Alumina hydrate with a mass percentage of 3%, polyethyleneimine with a mass percentage of 2%, put the above raw materials into a stirring mixer, dry mix for 10 minutes, and then add water with a total mass of 8% of the raw materials at a uniform speed portion, stirred for 2 minutes and discharged to obtain a slurry. When molding, put the mixed slurry into the funnel of the vacuum vibration pouring device, evacuate to -0.09MPa, hold the pressure for 30 minutes, open the vibration table, and under the condition of vibration with a frequency of 50Hz, the slurry in the funnel flows downward Forming mold. After the slurry completely flows into the mold, vibrate for 1 minute, then stop the vibration, put in air, and dry for 24 hours to obtain a molded green body. ...

Embodiment 2

[0033] Take 70% silicon carbide powder (by mixing industrial-grade black silicon carbide particles, silicon carbide fine powder, and silicon carbide micropowder in a mass ratio of 10:1:1), silicon carbide powder with a mass percentage of 25%, and Alumina hydrate with a percentage of 3%, polyvinyl alcohol with a percentage of 2% by mass, put the above powder into a stirring mixer, dry mix for 5 minutes, and then add 6% of the total mass of raw materials at a uniform speed. , stirred for 3 minutes and discharged to obtain a slurry. When forming, put the mixed slurry into the funnel of the vacuum vibration pouring device, evacuate to -0.08MPa, hold the pressure for 40min, open the vibration table, and under the condition of vibration with a frequency of 50Hz, the slurry in the funnel flows downward Forming mold. After the slurry flows into the mold completely, vibrate for 1.5 minutes, then stop the vibration, put in air, and dry after curing for 12 hours to obtain a molded green...

Embodiment 3

[0037]Get the silicon carbide powder that mass percentage is 75% (by the silicon carbide powder of industrial grade black silicon carbide particle, silicon carbide fine powder, silicon carbide micropowder mixed according to mass ratio 12:1:1 and mass percentage is 20% silicon powder, mass percentage is The calcium aluminate cement of 3%, the ammonium polyacrylate of 2% by mass percentage.The above-mentioned raw materials are put into agitator mixer, dry mix 20 minutes, then add the moisture content of raw material gross mass 8% with uniform speed, stir Discharge in 4 minutes to obtain the slurry. When forming, put the mixed slurry into the funnel of the vacuum vibration pouring device, vacuumize to -0.07MPa, hold the pressure for 50min, open the vibration table, and under the vibration condition of 40Hz frequency Next, the slurry in the funnel flows down into the forming mold. After the slurry flows into the mold completely, vibrate for 2 minutes, then stop the vibration, put i...

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Abstract

The invention discloses a vacuum vibration casting and moulding method for Si3N4-SiC fireproof ceramic. The method comprises the following steps: preparation of slurry: silicon powder, silicon carbidepowder, a bonding agent, and a dispersant are placed in a container for dry blending and stirring, water is added and mixing and uniform mixing are carried out, in order to obtain slurry; (2) preparation of a blank body: the slurry obtained in the step (1) is placed in a tunnel of a vacuum vibration casting apparatus, under the condition of vacuum vibration, the slurry flows downwards into a diefrom the tunnel, after the slurry totally flows in to the die, vibration treatment is carried out, and finally the material is cured and dried in air, and a molded blank body is obtained; 3) a nitridation treatment: the blank body obtained the in the step 2) is placed in a nitridation furnace for carrying out the nitridation treatment, and finally the blank body is cooled in the furnace to a roomtemperature, and the product is obtained. The preparation method comprehensively utilizes advantages of vacuum vibration moulding as well as the casting and moulding process, overcomes disadvantages of traditional mechanical pressing technology, and the Si3N4-SiC fireproof ceramic has uniform density distribution and small differences of physical properties.

Description

technical field [0001] The invention relates to the technical field of refractory material production, in particular to a vacuum vibration casting molding method of silicon nitride combined with silicon carbide refractory ceramics. Background technique [0002] As a high-temperature structural material, the supercharged boiler lining refractory material for special ships is the key basic material for the normal operation of the ship. It is of great significance to research and develop high-efficiency, high thermal shock resistance and long-life lining materials. As the heart of the ship’s power, the booster boiler frequently starts, stops and changes loads during work, resulting in a rapid rise and fall of furnace temperature and pressure and constant changes. The furnace lining not only has to withstand high temperatures, but also resists Multiple damage effects such as thermal stress impact caused by temperature changes, erosion of high-temperature heavy oil residue, high-...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/66C04B35/565
Inventor 杨自春曹跃云陈国兵赵爽孙文彩陈俊张磊李昆锋
Owner NAVAL UNIV OF ENG PLA
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