Method for preparing silicon nitride-based sealing coating

A technology based on silicon nitride and silicon nitride, which is applied in the field of silicon nitride-based sealing coatings to achieve the effects of clear interface, simple process, and low cost of raw materials and processes

Inactive Publication Date: 2010-05-05
WUHAN UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] According to the novelty search results of domestic and foreign patents and literatures, there is no report on the preparation of sealing coatings on the surface of silicon nitride-based porous ceramics by using silicon nitride and room temperature spraying method

Method used

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  • Method for preparing silicon nitride-based sealing coating
  • Method for preparing silicon nitride-based sealing coating
  • Method for preparing silicon nitride-based sealing coating

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preparation example Construction

[0017] The preparation method of the silicon nitride-based sealing coating provided by the present invention includes the steps of slurry preparation, room temperature spraying, drying, debinding and sintering, specifically as follows:

[0018] Slurry preparation: the silicon nitride, magnesium oxide, aluminum oxide, and silicon oxide powders with an average particle size of 0.3-0.5 μm are prepared in a weight ratio of (50-60): (6-12): (4-8) : (20-30) uniformly mixed, and then adding 0.3% polyvinyl alcohol, 0.3% sodium tripolyphosphate, and 0.8-1% water to the mixture in a mass percentage of the mixture for ball milling and mixing to obtain a silicon nitride-based slurry; During ball milling, a nylon ball mill pot is used, silicon nitride balls are used as a milling medium, and the ball milling time is 0.5 to 10 hours.

[0019] Normal temperature spraying: the silicon nitride based slurry is coated on the silicon nitride based porous ceramic surface (sample) by a normal temper...

Embodiment 1

[0025] Mix silicon nitride, magnesium oxide, aluminum oxide, and silicon oxide powder with an average particle size of less than 0.5 μm in a weight ratio of 50:12:8:30 to obtain a mixture, and then add 0.3% of the mass percentage of the mixture Polyvinyl alcohol, 0.3% sodium tripolyphosphate and 0.8% water ball mill were mixed for 2 hours to obtain a uniformly mixed slurry, which was coated on the surface of the silicon nitride-based porous ceramic substrate by normal temperature spraying, keeping The distance between the sample and the spray gun was 20 cm, and the spraying time was 10 minutes to obtain a green body. After drying at room temperature for 24 hours, the green body was degummed and kept at 400°C for 10 hours, and then the heat-treated product was heated in nitrogen Sintering under normal pressure at 1450°C under atmosphere protection, control the heating rate to 100°C / min, hold the temperature for 2 hours, and cool with the furnace to obtain the silicon nitride-bas...

Embodiment 2

[0029] Mix silicon nitride, magnesium oxide, aluminum oxide, and silicon oxide powder with an average particle size of less than 0.5 μm uniformly in a weight ratio of 60:12:8:20 to obtain a mixture, and then add 0.3% of the mass percentage of the mixture Polyvinyl alcohol, 0.3% sodium tripolyphosphate and 1% water ball mill were mixed for 1 hour to obtain a uniformly mixed slurry, which was coated on the surface of the silicon nitride-based porous ceramic substrate by normal temperature spraying, keeping The distance between the sample and the spray gun is 20 cm, and the spraying time is 10 minutes to obtain a green body. After drying at room temperature for 24 hours, the green body is degummed and kept at 500 ° C for 10 hours, and then the product after heat treatment is heated in nitrogen Sintering under normal pressure at 1700°C under atmosphere protection, control the heating rate at 100°C / min, hold for 5 hours, and cool with the furnace. That is to say, the main phase is ...

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Abstract

The invention provides a method for preparing a silicon nitride-based sealing coating, which comprises the steps: at first, sufficiently ball milling and mixing silicon nitride, magnesium oxide, alumina and silicon nitride powder with polyvinyl alcohol, sodium tripolyphosphate and water according to the proportion so as to prepare silicon nitride-based slurry, coating the slurry on the surface of a silicon nitride-based porous ceramic matrix according to a method for spray coating at normal temperature in order to result in a green body, after drying the green body at normal temperature for 12-24 hours, implementing binder removal on the green body at 200 DEG C to 400 DEG C and then carrying out heat presevation for 5-24 hours, and obtaining the compact silicon nitride-based sealing coating by sintering the binder-removed green body in the nitrogen-protective atmosphere at normal pressure at 1400 DEG C to 1700 DEG C and by carrying out heat preservation for 1-5 hours. The method has simple process, low cost of raw materials and process and good repeatability, and the prepared silicon nitride-based sealing coating has uniform and controllable thickness, compact structure, no micro-crack and good bonding with the silicon nitride-based porous ceramic matrix.

Description

technical field [0001] The invention relates to the field of ceramic sealing coating materials, in particular to a method for preparing a dense silicon nitride-based sealing coating on the surface of silicon nitride-based porous ceramics. Background technique [0002] In recent years, silicon nitride-based porous ceramics have attracted great attention from the global materials community because of their excellent properties of both silicon nitride ceramics and porous ceramics. Silicon nitride ceramics have the characteristics of high temperature resistance, corrosion resistance, thermal shock resistance, high hardness, good toughness, and low thermal expansion coefficient; while silicon nitride-based porous ceramics not only have the excellent performance of silicon nitride ceramics, but also have a small volume density. , large specific surface area, low thermal conductivity, low dielectric constant and dielectric loss, etc., so it has important application prospects in ga...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B41/87
Inventor 陈斐杨莹沈强王传彬张联盟
Owner WUHAN UNIV OF TECH
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