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Rapid nitridation preparation method of silicon nitride-boron nitride composite ceramic though reactive sintering

A technology of composite ceramics and silicon nitride, which is applied in the field of preparation of reaction sintered silicon nitride-boron nitride composite ceramics, can solve the problems of high heat release, offset cost advantages, and long nitriding time, and achieve good results Flexural strength and fracture toughness, effect of reducing difficulty and cost

Inactive Publication Date: 2013-05-08
XI AN JIAOTONG UNIV
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  • Abstract
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  • Claims
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Problems solved by technology

However, this process requires the pre-sintered body to be heated to a temperature close to the melting point of silicon for nitriding; at the same time, due to the high exothermic nature of the silicon-nitrogen reaction, the nitriding time of the process is particularly long, even reaching more than 60 hours, which seriously offsets the its cost advantage

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  • Rapid nitridation preparation method of silicon nitride-boron nitride composite ceramic though reactive sintering
  • Rapid nitridation preparation method of silicon nitride-boron nitride composite ceramic though reactive sintering
  • Rapid nitridation preparation method of silicon nitride-boron nitride composite ceramic though reactive sintering

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Embodiment 1

[0017] Such as figure 1 As shown, this embodiment is a rapid nitriding preparation method of reaction sintered silicon nitride-boron nitride composite ceramics. Hydrochloric acid was pickled for 12 hours, then washed with deionized water and dried, and the obtained pre-nitrided silicon powder was mixed with hexagonal boron nitride, zirconia and yttrium oxide powder, and the weight percentage of each component was: silicon 30% 60% of hexagonal boron nitride; 5% of zirconia; 5% of yttrium oxide; then use absolute ethanol whose weight is 1 times that of the basic raw material as the medium for ball milling for 12 hours to obtain a uniformly mixed slurry, and then place the slurry at 60°C Dry in a vacuum drying oven for 8 hours, and then disperse the powder through a 200-mesh sieve, then mold the powder into a green body with a thickness of 5mm in a mold, and process the green body by isostatic pressing at 200MPa; Put the pre-sintered body into the vacuum sintering furnace, quick...

Embodiment 2

[0020] Such as figure 1 As shown, the present embodiment is a rapid nitriding preparation method of reaction sintered silicon nitride-boron nitride composite ceramics, the process is as follows: first, the silicon powder with a median particle size of 15 microns is mixed with dilute hydrochloric acid with a concentration of 10%. Pickling treatment for 12 hours, then cleaning with deionized water and drying, the obtained pre-nitrided silicon powder will be mixed with hexagonal boron nitride, zirconia, yttrium oxide powder, the weight percentage of each component is: silicon 50% ; 40% hexagonal boron nitride; 5% zirconia; 5% yttrium oxide; then use absolute ethanol whose weight is 1 times that of the basic raw material as a medium for ball milling for 12 hours to obtain a uniformly mixed slurry, and then place the slurry at 60 ° C Dry in a vacuum drying oven for 10 hours, and then disperse the powder through a 200-mesh sieve, then mold the powder into a green body with a thickne...

Embodiment 3

[0023] Such as figure 1 As shown, the present embodiment is a rapid nitriding preparation method of reaction sintered silicon nitride-boron nitride composite ceramics. Hydrochloric acid was pickled for 24 hours, then washed with deionized water and dried. The obtained pre-nitrided silicon powder will be mixed with hexagonal boron nitride, zirconia, and yttrium oxide powder. The weight percentage of each component is: silicon 70 %; Hexagonal Boron Nitride 20%; Zirconia 5%; Yttrium Oxide 5%; Then take the dehydrated alcohol that is 2 times of the basic raw material as the medium ball milling for 24 hours to obtain a uniformly mixed slurry, and then the slurry is mixed at 60 Dry in a vacuum drying oven at ℃ for 12 hours, then disperse the powder through a 200-mesh sieve, and then mold the powder into a green body with a thickness of 7mm in a mold, and treat the green body by isostatic pressing at 200MPa; The obtained pre-sintered body was placed in a vacuum sintering furnace, an...

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Abstract

The invention discloses a rapid nitridation preparation method of silicon nitride-boron nitride composite ceramic though reactive sintering. According to the method, a reactive sintering process is adopted, silicon powder and hexagonal boron nitride powder are used as basic raw materials, zirconium oxide powder is used as a catalyst, and yttrium oxide is used as a sintering aid. By utilizing the preparation method disclosed by the invention, a completely nitrided silicon nitride-boron nitride composite material can be prepared in a nitriding and sintering mode within a shorter period of 2.3-5.5 hours; and compared with the conventional process, the method can prepare the silicon nitride-boron nitride composite ceramic which has the advantages of low cost, no size shrinkage and simple process, almost 100% of nitriding rate and excellent mechanical properties, and therefore, the method is suitable for preparing ceramic elements which are complexly shaped and are industrially popularized in large scale, and has remarkable application potentials in practical engineering fields.

Description

Technical field: [0001] The invention relates to a preparation method of reaction sintered silicon nitride-boron nitride composite ceramics, in particular to a rapid nitriding preparation method of reaction sintered silicon nitride-boron nitride composite ceramics. Background technique: [0002] Silicon nitride (Si 3 N 4 )-hexagonal boron nitride (h-BN) composite ceramics, as a typical composite material with strong and weak interfaces, has broad application prospects in the field of high-temperature structure and function, because of its good high-temperature mechanical properties and low thermal expansion coefficient, oxidation resistance, and excellent electrical properties. Especially due to the introduction of lamellar structure of hexagonal boron nitride (commonly known as white graphite) into the silicon nitride matrix, this composite material exhibits excellent corrosion resistance and wetting ability of molten non-ferrous metals, as well as good thermal shock resi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/583C04B35/584C04B35/622
Inventor 杨万利史忠旗乔冠军金海云金志浩李延军
Owner XI AN JIAOTONG UNIV
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