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Porous ceramic surface compact silicon nitride coating and preparation method thereof

A technology of silicon nitride coating and porous ceramics is applied in the field of preparing dense silicon nitride coatings on the surface of porous ceramic substrates, which can solve the problems of inability to meet the requirements of material use, reducing the water absorption rate of the substrate, affecting the reliability of the substrate, etc., and reducing the impact , Guarantee high temperature performance, improve the effect of high temperature performance

Active Publication Date: 2017-08-18
HEBEI HUATONG WIRES & CABLES GRP CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Patent 201210396094.X (Wang Hongjie, Liu Yinchao, Wang Chao, Qiao Guanjun, Shi Zhongqi. A method for preparing a ceramic coating by slurry spraying on the surface of a porous ceramic substrate) discloses a method for preparing a ceramic coating on the surface of a porous ceramic substrate by using a slurry spraying method Coating method, the coating prepared by this method is dense and well combined with the substrate, which obviously reduces the water absorption of the substrate, but this coating mainly relies on Y 2 o 3 -Al 2 o 3 -SiO 2 Sintering in liquid phase, there are more glass phases inside, and the high temperature performance is poor, which cannot meet the use of materials in harsh environments
"Fabrication of denseβ-Si 3 N 4 -based ceramic coating on porous Si 3 N 4 Ceramic (Wang C, Wang H, Fan X, et al. Journal of the European Ceramic Society, 2015, 35(6): 1743-1750.)" adopts spraying a non-oxide coating and a layer of oxide coating The method prepares a layer of dense silicon nitride coating on the surface of porous silicon nitride, which significantly reduces the water absorption rate of the material and increases the Vickers hardness to 22.2GPa, but the coating needs to be heated at a temperature above 1700°C Sintering, re-sintering at a higher temperature will affect the reliability of the substrate

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  • Porous ceramic surface compact silicon nitride coating and preparation method thereof
  • Porous ceramic surface compact silicon nitride coating and preparation method thereof
  • Porous ceramic surface compact silicon nitride coating and preparation method thereof

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Experimental program
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Embodiment 1

[0037] (1) Glass powder preparation: the mass fraction percentage is BaCO 3 :Al 2 o 3 :SiO2 2 = The powder of 25:14:61 is mixed evenly, melted and quenched at 1400°C, crushed and ball milled, and dried for later use.

[0038] (2) Intermediate layer preparation: the BaO-Al 2 o 3 -SiO 2 Glass powder, BaAl 2 o 4 , Si powder and α-Si 3 N 4 Powder and other solid coating raw materials are mixed and ball-milled with absolute ethanol at a mass ratio of 25:26:18:31 to prepare the middle layer slurry with a solid content of 20vol%; put the prepared middle layer slurry into the spray gun , sprayed on the surface of the porous ceramic substrate to form a dense intermediate layer, and sintered in a nitrogen atmosphere at 1350 ° C for 0.5 h without pressure.

[0039] (3) Surface layer preparation: the BaO-Al 2 o 3 -SiO 2 Glass powder, BaAl 2 o 4 , Si powder and α-Si 3 N 4 Powder and other solid coating raw materials are mixed and ball-milled with absolute ethanol at a mass...

Embodiment 2

[0042] (1) Glass powder preparation: the mass fraction percentage is BaCO 3 :Al 2 o 3 :SiO2 2 = The powder of 29:15:56 is mixed evenly, then melted and quenched at 1500°C, crushed and ball milled, and dried for later use.

[0043] (2) Intermediate layer preparation: the BaO-Al 2 o 3 -SiO 2 Glass powder, BaAl 2 o 4 , Si powder and α-Si 3 N 4 Powder and other solid coating raw materials are mixed and ball-milled with absolute ethanol at a mass ratio of 29:27:16:28 to prepare the middle layer slurry with a solid content of 30vol%; put the prepared middle layer slurry into the spray gun , spray a dense intermediate layer, and sinter without pressure at 1200 ° C for 2 hours in a nitrogen atmosphere.

[0044] (3) Surface layer preparation: the BaO-Al 2 o 3 -SiO 2 Glass powder, BaAl 2 o 4 , Si powder and α-Si 3 N 4 Powder and other solid coating raw materials are mixed and ball-milled with absolute ethanol at a mass fraction ratio of 12:11:29:48 to prepare a surface ...

Embodiment 3

[0047] (1) Glass powder preparation: the mass fraction percentage is BaCO 3 :Al 2 o 3 :SiO2 2 = The powder of 32:17:51 is mixed evenly, melted and quenched at 1550°C, crushed and ball milled, and dried for later use.

[0048] (2) Intermediate layer preparation: the BaO-Al 2 o 3 -SiO 2 Glass powder, BaAl 2 o 4 , Si powder and α-Si 3 N 4 Powder and other solid coating raw materials are mixed and ball-milled with absolute ethanol at a mass ratio of 38:27:13:22 to prepare the middle layer slurry with a solid content of 20vol%; put the prepared middle layer slurry into the spray gun , spray a dense intermediate layer, and sinter without pressure at 1400 ° C for 1 h in a nitrogen atmosphere.

[0049] (3) Surface layer preparation: the BaO-Al 2 o 3 -SiO 2 Glass powder, BaAl 2 o 4 , Si powder and α-Si 3 N 4 Powder and other solid coating raw materials are mixed and ball-milled with absolute ethanol at a mass fraction ratio of 20:15:24:41 to prepare a surface layer slu...

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Abstract

The invention provides a porous ceramic surface compact silicon nitride coating and a preparation method thereof. The silicon nitride coating which is compact and high in substrate bonding strength can be prepared on the surface of a porous ceramic substrate at a low sintering temperature. The silicon nitride coating mainly comprises silicon nitride, and a grain boundary phase is barium feldspar. The preparation method includes: preparing sintering aid BaO-Al2O3-SiO2 glass powder according to a quenching method, spraying a silicon nitride coating with the glass powder as a sintering aid to the surface of the porous ceramic substrate, and performing presintering to form an intermediate layer; spraying the silicon nitride coating with different contents of glass powder as the sintering aid to the surface of the substrate, and sintering to obtain the compact silicon nitride coating. The porous ceramic surface compact silicon nitride coating and the preparation method thereof have advantages that low-temperature sintering of the silicon nitride coating is realized, and influences of the coating on the substrate are reduced; high bonding strength of the compact silicon nitride coating and the porous substrate is realized; the prepared silicon nitride coating is mainly composed of alpha-Si3N4, beta-Si3N4 and barium feldspar, and high-temperature performances of the coating are guaranteed.

Description

technical field [0001] The invention belongs to the technical field of ceramic coating preparation, and in particular relates to a dense silicon nitride coating and a method for preparing a dense silicon nitride coating on the surface of a porous ceramic substrate at a relatively low sintering temperature. Background technique [0002] Porous ceramics are light in weight, have good machinability, good thermal shock resistance, low thermal expansion coefficient, low thermal conductivity, and the existence of pores makes them have low dielectric constant and dielectric loss, which can be used as heat insulation materials and wave-transmitting materials, etc. . However, during use, the existence of pores will cause the porous ceramics to absorb water vapor and seriously affect their dielectric properties; in addition, the porous structure will also reduce the mechanical properties and thermal insulation properties. [0003] At present, the methods to solve the above problems m...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B41/87
CPCC04B41/009C04B41/5066C04B41/87C04B41/52C04B35/00
Inventor 李晓雷孙永强赵志浩孟庆宇季惠明
Owner HEBEI HUATONG WIRES & CABLES GRP CO LTD