A kind of silicon nitride ceramic and preparation method thereof

Abstract

The invention relates to the field of ceramic preparation, in particular to a silicon nitride ceramic and a preparation method thereof. The preparation method of a kind of silicon nitride ceramic provided by the present invention comprises the following steps: step 1: mix silica powder and melamine powder to obtain silica-melamine mixed powder; step 2: mix the The silicon-melamine mixed powder is prepared by a dry pressing method to obtain a silicon dioxide-melamine green body; step 3: the silicon dioxide-melamine green body is subjected to first sintering, heat preservation and second sintering to obtain silicon nitride ceramics. The invention provides a silicon nitride ceramic and a preparation method thereof, which solves the problem of long preparation period, complex process and low purity of the prepared silicon nitride ceramic powder in the prior art, which leads to low density of the silicon nitride ceramic and technical issues with poor performance.

Description

technical field

[0001] The invention relates to the field of ceramic synthesis, and specifically discloses a silicon nitride ceramic and a preparation method thereof. Background technique

[0002] In terms of machinery, silicon nitride ceramics are used for turbine blades, high-temperature bearings, high-speed cutting tools, etc.; Wear-resistant and corrosion-resistant parts, such as ball valves, pump bodies, burner vaporizers, etc. It can be seen that silicon nitride ceramics have shown their special value in the application of high temperature, high speed and strong corrosion conditions.

[0003] Existing preparation of silicon nitride (Si 3 N 4 ) The methods of ceramic powder mainly include silicon powder direct nitriding method, silicon imine pyrolysis method and SiO 2 Carbothermal reduction method. The silicon powder direct nitridation method requires high purity of the silicon powder, and there will be oxygen impurities in the powder after the reaction, which seri...

Examples

Embodiment 1

[0033] (1) Silica powder, melamine powder, aluminum oxide powder (Al 2 o 3 ) and Re 2 o 3 Powder as raw material, press C 3 h 6 N 6 : SiO 2 Mix the above two powders with a mole fraction ratio of 1:3. Among them, SiO 2 The purity of the powder is 98%~100%, the particle size is 5μm, C 3 h 6 N 6 The purity of the powder is 98%-100%, and the particle size is 5 μm. al 2 o 3 and Re 2 o 3 The purity of the powder is 98% to 100%, and the particle size is 0.1 μm

[0034] (2) With ethanol as solvent, with Si 3 N 4 The ball is a ball milling medium, mixed on a roller ball mill for 24 hours, the rotation speed is 100r / min, and after drying, the silica-melamine-Al 2 o 3 -Re 2 o 3 Mix powder.

[0035] (3) The above-mentioned mixed powder is formed by cold isostatic pressing to obtain a compact green body.

[0036] (4) Put the green body into a boron nitride crucible, first raise the temperature to 550°C at 10°C / min, and keep it for 1h; Dense silicon nitride ceramics...

Embodiment 2

[0038] 1) With silica powder, melamine powder, Al 2 o 3 and Re 2 o 3 Powder as raw material, press C 3 h 6 N 6 : SiO 2 Mix the above two powders with a mole fraction ratio of 1:3. Among them, SiO 2 The purity of the powder is 98%~100%, the particle size is 5μm, C 3 h 6 N 6 The purity of the powder is 98%-100%, and the particle size is 5 μm. al 2 o 3 and Re 2 o 3 The purity of the powder is 98% to 100%, and the particle size is 0.1 μm

[0039] (2) With ethanol as solvent, with Si 3 N 4The ball is a ball milling medium, mixed on a roller ball mill for 24 hours, the rotation speed is 100r / min, and after drying, the silica-melamine-alumina-Re 2 o 3 Mix powder.

[0040] (3) The above-mentioned mixed powder is formed by cold isostatic pressing to obtain a compact green body.

[0041] (4) Put the green body into a boron nitride crucible, first raise the temperature to 550°C at 10°C / min, and keep it for 1h; Dense silicon nitride ceramics are obtained after step v...

Embodiment 3

[0043] (1) Using silica powder, melamine powder, Al 2 o 3 Powder and Re 2 o 3 Powder as raw material, press C 3 h 6 N 6 : SiO 2 Mix the above two powders with a mole fraction ratio of 1:3. Among them, SiO 2 The purity of the powder is 98%~100%, the particle size is 5μm, C 3 h 6 N 6 The purity of the powder is 98%-100%, and the particle size is 5 μm. al 2 o 3 and Re 2 o 3 The purity of the powder is 98% to 100%, and the particle size is 0.1 μm

[0044] (2) With acetone as solvent, Si 3 N 4 The ball is a ball milling medium, mixed on a roller ball mill for 24 hours, the rotation speed is 100r / min, and after drying, the silica-melamine-alumina-Re 2 o 3 Mix powder.

[0045] (3) The above-mentioned mixed powder is formed by cold isostatic pressing to obtain a compact green body.

[0046] (4) Put the green body into a boron nitride crucible, first raise the temperature to 550°C at 10°C / min, and keep it for 1h; Dense silicon nitride ceramics are obtained after s...

technical field

[0001] The invention relates to the field of ceramic synthesis, and specifically discloses a silicon nitride ceramic and a preparation method thereof. Background technique

[0002] In terms of machinery, silicon nitride ceramics are used for turbine blades, high-temperature bearings, high-speed cutting tools, etc.; Wear-resistant and corrosion-resistant parts, such as ball valves, pump bodies, burner vaporizers, etc. It can be seen that silicon nitride ceramics have shown their special value in the application of high temperature, high speed and strong corrosion conditions.

[0003] Existing preparation of silicon nitride (Si 3 N 4 ) The methods of ceramic powder mainly include silicon powder direct nitriding method, silicon imine pyrolysis method and SiO 2 Carbothermal reduction method. The silicon powder direct nitridation method requires high purity of the silicon powder, and there will be oxygen impurities in the powder after the reaction, which seri...

Examples

Embodiment 1

[0033] (1) Silica powder, melamine powder, aluminum oxide powder (Al 2 o 3 ) and Re 2 o 3 Powder as raw material, press C 3 h 6 N 6 : SiO 2 Mix the above two powders with a mole fraction ratio of 1:3. Among them, SiO 2 The purity of the powder is 98%~100%, the particle size is 5μm, C 3 h 6 N 6 The purity of the powder is 98%-100%, and the particle size is 5 μm. al 2 o 3 and Re 2 o 3 The purity of the powder is 98% to 100%, and the particle size is 0.1 μm

[0034] (2) With ethanol as solvent, with Si 3 N 4 The ball is a ball milling medium, mixed on a roller ball mill for 24 hours, the rotation speed is 100r / min, and after drying, the silica-melamine-Al 2 o 3 -Re 2 o 3 Mix powder.

[0035] (3) The above-mentioned mixed powder is formed by cold isostatic pressing to obtain a compact green body.

[0036] (4) Put the green body into a boron nitride crucible, first raise the temperature to 550°C at 10°C / min, and keep it for 1h; Dense silicon nitride ceramics...

Embodiment 2

[0038] 1) With silica powder, melamine powder, Al 2 o 3 and Re 2 o 3 Powder as raw material, press C 3 h 6 N 6 : SiO 2 Mix the above two powders with a mole fraction ratio of 1:3. Among them, SiO 2 The purity of the powder is 98%~100%, the particle size is 5μm, C 3 h 6 N 6 The purity of the powder is 98%-100%, and the particle size is 5 μm. al 2 o 3 and Re 2 o 3 The purity of the powder is 98% to 100%, and the particle size is 0.1 μm

[0039] (2) With ethanol as solvent, with Si 3 N 4The ball is a ball milling medium, mixed on a roller ball mill for 24 hours, the rotation speed is 100r / min, and after drying, the silica-melamine-alumina-Re 2 o 3 Mix powder.

[0040] (3) The above-mentioned mixed powder is formed by cold isostatic pressing to obtain a compact green body.

[0041] (4) Put the green body into a boron nitride crucible, first raise the temperature to 550°C at 10°C / min, and keep it for 1h; Dense silicon nitride ceramics are obtained after step v...

Embodiment 3

[0043] (1) Using silica powder, melamine powder, Al 2 o 3 Powder and Re 2 o 3 Powder as raw material, press C 3 h 6 N 6 : SiO 2 Mix the above two powders with a mole fraction ratio of 1:3. Among them, SiO 2 The purity of the powder is 98%~100%, the particle size is 5μm, C 3 h 6 N 6 The purity of the powder is 98%-100%, and the particle size is 5 μm. al 2 o 3 and Re 2 o 3 The purity of the powder is 98% to 100%, and the particle size is 0.1 μm

[0044] (2) With acetone as solvent, Si 3 N 4 The ball is a ball milling medium, mixed on a roller ball mill for 24 hours, the rotation speed is 100r / min, and after drying, the silica-melamine-alumina-Re 2 o 3 Mix powder.

[0045] (3) The above-mentioned mixed powder is formed by cold isostatic pressing to obtain a compact green body.

[0046] (4) Put the green body into a boron nitride crucible, first raise the temperature to 550°C at 10°C / min, and keep it for 1h; Dense silicon nitride ceramics are obtained after s...

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