Process for preparing graphite surface anti oxidation coating material silicon carbide for nuclear reactor

An anti-oxidation coating, nuclear reactor technology, applied in coating, metal material coating process, solid-state chemical plating and other directions, can solve the problems of difficult SiC composition, complex composition and structure process, reducing ceramic yield, etc. The effect of reducing the ceramic yield

Inactive Publication Date: 2004-12-15
TSINGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

It is more complicated to change the composition and structure of PCS, and it is difficult to accurately control the composition of SiC prepared; cracking in vacuum or hydrogen atmosphere can eliminate free carbon, but it will also reduce the yield of ceramics, and in order to obtain SiC with a certain composition, only Corresponds to a specific cracking temperature, which cannot be independently controlled

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0015] The first is to form a uniform film with a thickness of 2.0 μm on the surface by immersing the graphite substrate in a polycarbosilane / xylene solution with a polycarbosilane concentration of 10 wt%; after the xylene volatilizes, the surface of the substrate obtains a PCS coating . The carbon / silicon ratio of the SiC coating obtained by pyrolyzing the above-mentioned PCS coated sample at 1000°C in Ar gas is 3.7, and the SiC coating obtained at 2vol% SiH 4 SiH 4 The carbon / silicon ratio of the SiC coating obtained by pyrolysis at 1000 ° C in Ar gas is 1.5, and at 3vol% SiH 4 SiH 4 The carbon / silicon ratio of the SiC coating obtained by pyrolysis at 1000 °C in / Ar gas is 0.8.

Embodiment 2

[0017] The first is to form a uniform film with a thickness of 0.5 μm on the surface by immersing the graphite substrate in a polycarbosilane / xylene solution with a polycarbosilane concentration of 20 wt%; after the xylene volatilizes, the surface of the substrate obtains a PCS coating . The above-mentioned PCS-coated samples were prepared in H 2 The carbon / silicon ratio of the SiC coating obtained by pyrolysis at 1000 °C in gas is 3.6, and at 2vol% SiH 4 SiH 4 / H 2 The carbon / silicon ratio of the SiC coating obtained by pyrolysis at 1000 °C in gas is 1.2, and at 3vol% SiH 4 SiH 4 / H 2 The carbon / silicon ratio of the SiC coating obtained by pyrolysis at 1000 °C in gas is 0.6.

Embodiment 3

[0019] The first is to form a uniform film with a thickness of 1.5 μm on the surface by immersing the graphite substrate in a polycarbosilane / xylene solution with a polycarbosilane concentration of 30 wt%; after the xylene volatilizes, the surface of the substrate obtains a PCS coating . The carbon / silicon ratio of the SiC coating obtained by pyrolyzing the above-mentioned PCS coated sample at 1300°C in Ar gas is 4.2, and the SiC coating obtained at 2vol% SiH 4 SiH 4 The carbon / silicon ratio of the SiC coating obtained by pyrolysis at 1500 ° C in Ar gas is 1.7, and at 3vol% SiH 4 SiH 4 The carbon / silicon ratio of the SiC coating obtained by pyrolysis at 1000 °C in / Ar gas is 0.9.

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Abstract

The present invention discloses the preparation process of antioxidant silicon carbide coating on the surface of graphite for nuclear reactor. The preparation process includes first coating polycarbosilane (PCS) solution on the surface of substrate to form PCS coating after volatizing solvent; and high temperature cracking the PCS coating in protecting gas containing Si while regulate cracking temperature and cracking atmosphere independently to realize required C / Si ratio in silicon carbide. Adding gas containing Si component into the cracking atmosphere can make cracked PCS to react with gas containing Si component to avoid free carbon in prepared SiC while maintaining the ceramic yield.

Description

technical field [0001] The invention belongs to the technical field of nuclear reactor material manufacturing. In particular, it relates to a method for preparing silicon carbide, which is an anti-oxidation coating material for graphite surface used in nuclear reactors, by using controlled cracking polycarbosilane (PCS) to prepare the chemical composition of silicon carbide. technical background [0002] Silicon carbide coating is a high-tech material for anti-oxidation coating on graphite surface in nuclear reactor due to its high temperature strength, high thermal conductivity and good high temperature oxidation resistance. In the preparation method of silicon carbide, since Professor Yajima Seiji disclosed the successful synthesis of polycarbosilane and its conversion into SiC fibers in the document "S. Yajima et al., Chem. Lett., 931, 1975", due to the Due to the advantages of low preparation temperature, simple and easy control, high product purity, and excellent perfo...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23C20/08
Inventor 付志强唐春和梁彤祥
Owner TSINGHUA UNIV
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