非氧化物陶瓷氧化动力学的研究现状与进展

Current research and development on the oxidation kinetics of nonoxide ceramics

  • 摘要: 非氧化物陶瓷作为一种性能优异的高温结构材料,广泛应用于冶金、化工等高温行业。在实际应用过程中氧化和应力耦合的服役环境加速了非氧化物陶瓷高温性能失效最终降低服役寿命,甚至引发安全事故。因此研究非氧化物陶瓷在复杂服役环境下尤其应力条件下的氧化进程尤为重要,建立此条件下的氧化动力学模型是掌握材料实际服役行为规律的有效手段。本文对比了非氧化物陶瓷分别在无应力和应力条件下的氧化机理和相应动力学模型,通过对不同模型的应用对比分析,从量化角度明确了应力对非氧化物陶瓷氧化过程的影响,在此基础上初步建立了考虑应力的非氧化物陶瓷氧化动力学模型,为进一步揭示非氧化物陶瓷在复杂条件下的服役行为提供科学模型,为提高材料服役寿命提供有效理论指导。

     

    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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