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非氧化物陶瓷氧化動力學的研究現狀與進展

Current research and development on the oxidation kinetics of nonoxide ceramics

  • 摘要: 非氧化物陶瓷作為一種性能優異的高溫結構材料,廣泛應用于冶金、化工等高溫行業。在實際應用過程中氧化和應力耦合的服役環境加速了非氧化物陶瓷高溫性能失效最終降低服役壽命,甚至引發安全事故。因此研究非氧化物陶瓷在復雜服役環境下尤其應力條件下的氧化進程尤為重要,建立此條件下的氧化動力學模型是掌握材料實際服役行為規律的有效手段。本文對比了非氧化物陶瓷分別在無應力和應力條件下的氧化機理和相應動力學模型,通過對不同模型的應用對比分析,從量化角度明確了應力對非氧化物陶瓷氧化過程的影響,在此基礎上初步建立了考慮應力的非氧化物陶瓷氧化動力學模型,為進一步揭示非氧化物陶瓷在復雜條件下的服役行為提供科學模型,為提高材料服役壽命提供有效理論指導。

     

    Abstract: Nonoxide ceramics (NOCs) as representative high-temperature structural materials are widely applied in various key fields, such as metallurgy, electric power, and chemical industry, owing to combined excellent characteristics including high strength, lightweight, good thermal shock resistance, and erosion resistance. In practical applications, NOCs are often exposed to high temperatures containing oxygen; thus, they are inevitably confronted with the oxidation issue. In addition, NOCs are mostly used as lining materials for high-temperature containers and transmission components for high-temperature devices, in which they are also subjected to external loads. Simultaneously, internal stress will be generated inside the oxide film during oxidation, owing to the density difference and thermal expansion coefficient difference between the oxidation products and substrate. The coupled effect of oxidation and complex stresses accelerates the degradation of high-temperature performance and ultimately reduces the service life of NOCs, even causing severe industrial accidents. Therefore, studying the oxidation of NOCs under complex conditions is essential. However, limited by the high temperature and long serving time, an experimental approach to the oxidation of NOCs remains a challenge. By comparison, kinetic models based on specific reaction principles and different assumptions have become an effective tool for understanding and analyzing the oxidation of NOCs. This article compares the oxidation mechanism and corresponding kinetic models of NOCs under stressfree and stress conditions. Through comparing and analyzing the application effects of different models, the effect of stress on oxidation of NOCs is determined from a quantitative point, and the oxidation kinetic models of NOCs considering stress are preliminarily established, which can provide a scientific model for further recognition of service behavior of NOCs under complex conditions and provide effective theoretical guidance for improvement of the service life of materials.

     

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