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Method for reducing firing temperature of aluminum oxide ceramics

A technology of alumina ceramics and firing temperature, which is applied in the field of material science, can solve problems such as deterioration of ceramic performance, and achieve the effects of reducing dosage, promoting density, and promoting improvement

Active Publication Date: 2012-11-21
CHINA JILIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the introduction of a large amount of low-temperature sintering aids will have a negative impact on the properties of alumina ceramics; especially the addition of coarse-grained glass powder and micron-sized oxide aids to alumina powder will A large amount of second phase remains distributed on the grain boundaries of alumina, which deteriorates the performance of ceramics

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] Weigh 1mol silica sol and dissolve in 400ml deionized water, weigh 0.3mol calcium nitrate and dissolve in 400ml deionized water, weigh 0.2mol magnesium nitrate and dissolve in 300ml absolute ethanol; mix and stir the above three solutions evenly, then add 100ml of acetic acid was used to adjust the pH value of the mixed solution to 6.7. Add 50 mol of alumina powder (5098 grams) to the above mixed solution, put it into a ball mill jar for mixing and ball milling; place the above ball milled mixture in an oven at 90°C for drying, and then calcined at 1100°C to obtain a white ceramic Powder.

[0019] Add 400g of polyvinyl alcohol aqueous solution to the above ceramic powder, granulate after fully mixing, and then shape it under a pressure of 120Mpa. After debinding, keep the temperature at 1500°C for 2 hours to sinter the ceramic. The bulk density of alumina ceramics was tested by drainage method, and the results showed that its density reached 96.2% of the theoretical de...

Embodiment 2

[0021] Weigh 1mol of silica sol and dissolve in 400ml of absolute ethanol, weigh 0.2mol of calcium acetate and dissolve in 250ml of absolute ethanol, weigh 0.4mol of magnesium nitrate and dissolve in 450ml of deionized water; mix and stir the above three solutions evenly, and then Add 30 ml of 10% nitric acid to adjust the pH of the mixed solution to 4.8. Add 20 mol of alumina powder (2039 grams) to the above mixed solution, put it into a ball mill jar for mixing and ball milling; place the above ball milled mixture in an oven at 85°C for drying, and then calcined at 1150°C to obtain a white ceramic Powder.

[0022] Add 180g of polyvinyl alcohol aqueous solution to the above ceramic powder, mix well and then granulate, then mold under a pressure of 120Mpa, after debinding, keep the temperature at 1450°C for 2 hours to sinter the ceramic. The bulk density of alumina ceramics was tested by drainage method, and the results showed that its density reached 95.8% of the theoretical...

Embodiment 3

[0024] Weigh 1mol of silica sol and dissolve in 450ml of deionized water, weigh 0.5mol of calcium nitrate and dissolve in 500ml of absolute ethanol, weigh 0.3mol of magnesium acetate and dissolve in 300ml of absolute ethanol; mix and stir the above three solutions evenly, and then The pH value of the mixed solution was adjusted to 6.0 by adding 23 ml of ammonia water. Add 30 mol of alumina powder (3059 grams) to the above mixed solution, put it into a ball mill tank and mix ball mill; place the above ball milled mixture in an oven at 90°C for drying, and then calcined at 1200°C to obtain a white Ceramic powder.

[0025] Add 250g of polyvinyl alcohol aqueous solution to the above ceramic powder, mix well and then granulate, then mold under a pressure of 120Mpa, after debinding, keep the temperature at 1450°C for 2 hours to sinter the ceramic. The bulk density of alumina ceramics was tested by drainage method, and the results showed that its density reached 95.6% of the theoret...

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PUM

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Abstract

The invention discloses a method for reducing the firing temperature of aluminum oxide ceramics, which comprises the following steps of: dissolving silica sol, calcium compounds and magnesium compounds into a solvent to form mixed solution, and simultaneously adjusting the pH value of the mixed solution to be 4.5 to 8.0; adding aluminum oxide powder into the mixed solution and ball-milling, drying and performing calcination at 800 to 1,200 DEG C; and adding an adhesive into the calcinated powder, pelleting, tabletting and removing the adhesive, and then sintering at 1,350 to 1,550 DEG C. The method is simple; and as the gelation transformation of the silica sol is controlled by adjusting the pH value to uniformly coat the auxiliaries of silicon, calcium and magnesium onto the surface of the aluminum oxide powder and generate nanoscale particles in the calcination process, and the nanoscale particles with small particle sizes are utilized to fill gaps of the aluminum oxide powder and simultaneously are reacted with aluminum oxides due to high surface activity to produce a glass phase, the firing temperature of the aluminum oxide ceramics is maximally reduced on the basis of adding small amounts of auxiliaries.

Description

technical field [0001] The invention relates to a method for reducing the firing temperature of alumina ceramics, which belongs to the technical field of material science. Background technique [0002] Alumina ceramics have high mechanical strength, high hardness, small dielectric loss, high resistivity, high breakdown voltage, and excellent properties such as wear resistance, corrosion resistance, and high temperature resistance. Textile, metallurgy, aviation, thermal power, building materials, dyes, coatings and other industries have been widely used. However, alumina ceramics have strong ionic bonds, making their melting point as high as 2050 °C, and there is very little liquid phase at high temperatures, resulting in the firing temperature of alumina ceramics as high as 1750 °C or more. Such a high firing temperature will promote the rapid growth of ceramic grains and the accumulation of residual pores, resulting in a decrease in the mechanical properties of the materia...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C04B35/10C04B35/64
Inventor 徐时清王焕平陈金敏邓德刚赵士龙
Owner CHINA JILIANG UNIV